56 Rochester 4GC Float Level

[Beemon]

I was going to post this in my other thread over in modified, but I figured this would get more hits. I also want to point out that this isn't my original carb, it works ok but has it's issues - this is the carb I received from Mr. Earl.

 

I purchased a carb rebuild kit from Jon last week and had the carb cleaned, dipped and re-assembled by yours truly. I want to point out that this was my first carb I've ever worked on period. I grew up playing with LEGOs, so this was extremely fun for me. I kept all the different parts in separate plastic bowls per area, especially the different check balls, so not to get them confused. (Put the last of the linkage back together and checked to see it was 8:00 AM! ) The only piece of information I used the shop manual for was setting the floats. I think this is where my issue is. The car started perfectly, I set fast idle with no problem at all. Choke was set too rich, so I backed it off after it fully warmed up and set it so the choke was fully open. Got the idle down to ~600 after some linkage adjustments and started playing with the idle screws. I set each idle screw in all the way while the other was at factory level and the car did not die, so idle circuits are good (checked them with water before assembly anyways but wanted to test anyways). It was idling great, but the accelerator was bogging pretty bad and when both barrels went open the car died. When I was setting fast idle, the accelerator pump worked flawless, even better than it had before, so I know it has nothing to do with the accelerator pump and power piston. There's no vacuum leaks around the base or gaskets, checked with some spray and idle remained neutral. Even the starter switch, which was pulling vacuum on my other carb, wasn't pulling vacuum because the right check ball was in there and sealing up against the flange.

 

I think it's the floats because when I was setting them, they were way out of factory spec. I had to bend them up to achieve max float level and then I had to bend the tang to achieve min float level. I had a feeling in the back of my head that this was wrong, but I kept moving forward (It was early in the AM, I was ecstatic I was on the last leg). I'd also like to point out that I love fuel filters where I can see what the fuel is doing. On startup and idle, the fuel filter filled with fuel like it always did and I don't recall when exactly it turned into a trickle of fuel going through the filter, but that was my first clue. When the engine went off the choke and was at warm temp, the fuel filter was almost empty and the accelerator bogged. My second clue was when I opened all four barrels during a bog, the engine died and I couldn't get it to start again. I immediately checked the float level screws and not even a slight trickle from the secondaries (both primary and secondary floats are supposed to be the same per the shop manual), that was my third clue.

 

So my question is, what is the correct float level for a Rochester 4GC off a 1956 Buick? I'm figuring that because of the Ethanol gas, the floats don't float like they used to and the fuel is either more or less dense, causing the factory spec to be out of alignment with the carb. I haven't pulled the float cover yet to see what's wet and what isn't, but I'm going to assume either the floats aren't lifting high enough to allow fuel into the accelerator pump or  the floats aren't rising high enough to shut off the fuel flow and it's flooding the engine. I'm pretty sure it's that second one because it didn't want to start after it died.

 

Also I painted the carb bronze because the original plating was pitted and worn on a lot of the carb after it cleaned up... I figure when I'm rich and famous, I'll have it replated but for now at least it looks good and consistent. I also found the original choke stove pipe that was cut off the car way back whenever my Uncle dismantled the engine and left it for me to pick up - I crimped the end so it wouldn't cause a vacuum leak and just stuck it into the original hole haphazardly. Worked out pretty well, better than the electric choke ever did, but that's to be expected. I also attached a pic of the original carb (#1 (the one that has been rebuilt by two different people), not #2 I just rebuilt) because it has the original idle screws. Jon's kit is the only kit I know that uses a leather accelerator pump and includes brand new idle screws. Here are the pics:

Edited May 1, 2016 by Beemon (see edit history)

[JohnD1956]

7 hours ago, Beemon said:

I think it's the floats because when I was setting them, they were way out of factory spec. I had to bend them up to achieve max float level and then I had to bend the tang to achieve min float level.

 

I wish I could say my 56 does not have that hesitation, but I can say it does not happen all the time, and never happens before the engine is fully warmed up.  Which leads me to believe my choke is still not set correctly and there is too much air being drawn in as opposed to fuel.  I would tamper with a different jet to see if that worked but,  recently I discovered that the hesitation was less prevalent if I applied my brakes with the right foot.  Over the years I tended to drive this car using my left foot on the brake, just in case it was going to run rough.  Now, after my last carb rebuild I find I do not need that reassurance.   Anyway, since I only have the hesitation on occasion, I'm not pulling this carb apart again.

 

To get to your choke setting I would recommend looking at the literature which should have been in your carb kit. Usually there is the setting chart in there.  It may be different depending on the style needle valve and seat.  I know it was different for the Daytona Valve I used,  Further I wanted to ask about your statement quoted above.  I cannot determine if the "max float level" means the upper limit, where the needle valve is closed, or the lowest level where the needle valve is wide open? 

Edited May 1, 2016 by JohnD1956
typo's (see edit history)

[Beemon]

By max I mean how high they float when the bowl is full. The choke is not the issue because its fully open and Jon 'Carb King' 's kit came with brand new primary jets, etc.The carb was operating as it should when it was on the fast idle cam.

Edited May 1, 2016 by Beemon (see edit history)

[JohnD1956]

Yes, mine runs right while it's on fast idle too.  Again, that may mean the choke butterfly is partially closed keeping the fast idle in play and forcing a richer mixture, resulting in less to no hesitation.

 

You may be on to something with the floats.  The bending process can be tricky.  If you bent the arms of the float to get the floats to the needle valve shut off position and then the tang to get to the max open position, that sounds like the right beginning.  After adjusting the tang for the max open, did you go back and readjust the arms for the closed position?  Also, are you sure each float is adjusted the same?  I watched my friend do my floats.  He laid the float assembly on a flat steel surface and then methodically bent each float arm till they were evenly touching the steel surface.  Then he went for the side to side adjustments to ensure they would not hit the sides of the float bowls, then he went for the float drop and then he want back to step one to make sure everything was still the same.

[Beemon]

Yes I must have played with each one for a good while. I adjusted the "full" position first, squared them, checked their full position again, and then their "empty" hanging position, and then back to their full position. I had to really bend them out, though. It was a radical change compared to how they came, which leads me to believe either it was taken apart before, or at some point at the factory, the specs were changed. Or maybe I just dropped them really hard, but I don't remember doing that at any point. I even opened up the peep screw and rocked the carb back and forth to ensure they were moving up and down in the bowl. I wish I took the top of the carb off last night to see what was and wasn't wet but it was near 1 AM when I got off work last night.

[Beemon]

I took apart carb #2 (the one I had rebuilt by someone else) this morning and checked the float levels. The primary and secondary floats were two different sizes, to my surprise. The float on the front was about 1 1/8 to 1 1/16 for the full position and the drop was 1 3/4. The rear float had a 1 5/16 full position and a 2 inch drop. I also attached a picture of the shop manual that depicts the 1 35/64 inch max full position with the 2 1/4 inch drop. There must be some type of witchcraft going on here.

 

Also the carb had a leather accelerator pump.

 

Edited May 1, 2016 by Beemon (see edit history)

[JohnD1956]

Considering how much force is needed to bend any of the float assembly I am always left to wonder how they could get out of adjustment to begin with? Needless to say however, short of opening the carb you did last night, you're never going to know if somehow you adjusted those wrong. 

 

I'd be inclined to adjust the ones on the carb you have open now, and then swap tops to see if things are any better.

[Beemon]

Thats a good point. When I get off work tonight, I'll pull the air horn off the new carb and put the floats from the old carb in there and see if I can get it to run. You know if it ain't broke, don't fix it. Or so they keep telling me.

[JohnD1956]

Don't switch floats yet.  Adjust the ones you have open and then switch the entire top. 

[Beemon]

I'm a bit weary about adjusting the floats in the other carburetor because then I would have two floats that are the same. I'll put the ones I adjusted in the working carb and the others in the one in the car and see what I can learn.

 

I'm thinking of maybe bench testing the floats by filling the bowl with gas and then adjusting the floats until the gas comes up to the threads on the inspection hole.  Guess I should have done that in the first place...

Edited May 2, 2016 by Beemon (see edit history)

[Ttotired]

I am wondering about your fuel pressure/volume. You said your fuel filter went dry, doesnt that mean its ran out of fuel? Assuming plenty of fuel in the tank, you may have a problem with the fuel pump more so than the carby?

 

Mick

[Beemon]

The fuel pump is working, it still pumps fuel into the filter. The filter just isn't holding fuel like it used to and the floats are different between the two carbs so I think there's a fuel metering error going on. 

[JohnD1956]

In my view, you are in a good position to determine where that hesitation lies.  Presuming the carb that is off the car had no hesitation issue, then if you swap the complete top and the hesitation goes away you know there is a problem in the top unit.  If the hesitation stays then you know it is in the middle or the base.  If you plan to simply pull the floats and install them as they are, then you might just as well swap the tops with the floats attached.

[Beemon]

Also another good point. I'll pull the top tonight and swap tops and report back in the morning. 

[NTX5467]

From my experience with float levels, going by the "pattern" on the brass float left by the fuel level, over time, should be parallel with the carb air horn gasket surface.  In that orientation, the float on the right (in the picture above) is a little "high" and the one on the left is "low".  Adjusting the "float drop" is not critical as long as it lets the floats drop from their "off" level, to me.

 

I believe your 600 rpm idle speed could be a little high.  Look to see that the length of the transition port in the primary side carb barrels is not more than about .020"  (might be .040"?) BELOW where the throttle blade is at hot curb idle.  If too much of the transition port is uncovered, a hesitation can occur. 

 

The other issue with the accel pump could be "normal wear" in the accel pump's bore.  With the leather pump "cup", you need to fluff it up before installation and it should be a firm fit in the bore.  Ethanol fuel can make it shrink, BUT I remember one of our members (who had a '55 Roadmaster Riviera at the time) who was having issues with an off-idle flat spot on his carb . . . which had been rebuilt by "good people" recommended by others.  One of our AZ members mentioned that he went back to a fresh leather accel pump "cup" and the hesitation (from the accel pump) went away.  This was in the later 1980s before we had E10 fuels.

 

The reason the engine dies when you open the rear barrels (IF I understood correctly, at idle), is that there is no real idle circuit for the rear (secondary) barrels, so too much additional air kills the motor with no additional fuel being added.  Too soon for fuel to be fed by the main system(s), too..

 

Most automatic choke coils will tighten with age.  This is why yours, "set to specs", didn't let the choke off soon enough.  The choke is supposed to just close the choke blade with the engine at ambient 70 degrees.  Not a HARD close, an easy close.  Everything at AMBIENT BEFORE the engine is started.  Might end up with it being 1-2 notches lean from the factory spec.  This is one of "the specs" where some finessing and tweaking can be necessary for best operation and performance.  Personally, I like to get the choke off as soon as the car will run reliably during the first mile from a cold start in cold weather. 

 

Idle mixture?  Sets as normal.  Using the base setting on both screws at hot idle, then finding the highest rpm where a 1/4 turn will result in an rpm drop of about 20 rpm or so, each.  That is called "lean best idle" and might not be the same as going for maximum manifold vacuum at idle, but probably close.  Might not be the exact same setting which could be had with "old-spec gas", though . . . unless you might find some 100 Research Octane leaded (or unleaded) non-ethanol racing fuel somewhere.

 

When you find the right combination of base ignition timing, idle speed, idle mixture, you'll know it as the engine will act like it should.  Do ensure the floats are set correctly, though.

 

One final "experience" thought.  Just because you can "get flow" (from water or pressurized carb cleaner) though a passageway in a carb is NOT an indication that the particular flow circuit is "open".  It can be "open" and still not flow ENOUGH fuel to satisfy demands.  I chased a "no idle circuit fuel" issue on a Carter 2bbl on my '80 Chrysler.  I did my normal "clean: with Berryman's B-12 spray and the idle tube did "flow" cleaner, but there was an internal obstruction (which a carb soak would not have removed) that was not letting enough flow.  When I finally found a drilled orifice inside of the bottom of the idle tube, probed that tube with a bent-wire spark plug gap gauge, and found the hole enlared (feeling something crusty in there, too), I got a selection of small twist drills.  I went until I "got brass" and that fixed that "no idle" (even when decelerating from highway speeds!) issue that other people couldn't fix.

 

The inline fuel filter in your picture can be problematic if you use that to judge fuel flow into the engine.  Chrysler had used something similar for many years, but mounted somewhat vertically on the front of the engine.  The "factory" filters were metal, but many replacement filters were translucent plastic (as yours is).  Over the years, it was somewhat normal to see fuel in the filter, but there were also other times when the filter would appear empty and the engine ran as it should.  It might well be that the only time you'll reliably see fuel in the filter is with the OEM clear-bowl filter mounted in its original location.  I felt the same way you do as to seeing fuel in the filter on our Chryslers, but it doesn't seem to work as we suspected, in all cases. 

 

You've got a good deal done, so far, but the "last 10%" can be a little onerous to diminish.  But when you do diminish it, even a little, the additional feeling of accomplishment is worth the trip!

 

Keep us posted,

NTX5467

 

[Beemon]

Thanks for the write-up NTX, always appreciated!

 

600 RPM is high, the Neutral idle is supposed to be 450 RPM, but I was never able to get it that low and steady with the old carb.

 

The only reason I noticed the fuel filter was because on the other carb, it would stay at least half full whenever I was looking at it. This one flows fuel but didn't fill after coming off fast idle.

 

So this is another theory that I've come up with while I was at work. If the float is set too low and cuts off flow before it can fill fuel to the accelerator pump level, then the accelerator pump can't squirt fuel into the venturi and cause it to bog. Is this a correct assumption? I only now put it together based on what you said about the secondaries allowing too much air and killing the engine. If it was flooding, I feel like the secondaries opening would actually help it run better and not kill it. I also recall not smelling any fuel vapors. If it was flooding, I feel like gas would have poured out of the inspection holes as well, which was not the case.

 

I'm going to run over now and pop the old top on the new carb and see what comes out of it.

[carbking]

Maybe this will help:

 

http://www.thecarburetorshop.com/WCFB_and_4GC_floats.htm

 

Jon.

[JohnD1956]

I would like that post Jon, except it means going back into my own carb.  19 different float assemblies is a nightmare, especially when one float develops a leak, like one of mine did.  Sure glad I kept all my old parts!

[Beemon]

If that's the case, why would the shop manual specify setting the floats the same level? I'm assuming the floats are higher in the primary to accompany the added volume from the accelerator pump and power valve assembly? So if this is the case with the arms, then the float with the arm soldered higher would be for the secondaries since they would drop more?

 

I'll be giving you a call later today when I purchase my second carb kit and a new bowl gasket.

[old-tank]

I can't be there to see what is actually happening, but I doubt it is the floats.  The same basic carb was used on many models and years all with different float settings, some varying by 1/64 inch or 0.0156 (the point gap on your car).  Also note that these cars drive up and down hills and on crowned roads.

Back when I had a 4gc on one of mine the biggest problem was off idle stumble with no problem with vigorous acceleration.  The problem was in the idle/low speed system which should be detailed and diagrammed in your service manual.  There are small passages for fuel and air that need to be probed and cleaned.  I could get it to run well after cleaning, but even the residue from dried gas in the carb would cause problems again.

Willie

[carbking]

Willie - I agree, I don't think the floats are the issue here either; I posted the link, as the OP had discovered different floats. Many do not notice this. Excessive bending on a 65 year-old brass float can be expensive (kind of like excessive bending on my body that is somewhat older  ). A partially clogged idle circuit can require too much thottle opening which can upset the geometry of the fast idle/transition circuits and cause a bog or hesitation.

 

Without looking, I believe this early a 4-GC would have the 2 check ball pump system, so a low float would not effect the operation of the pump.

 

Beeman - when you call have the carb number, and I will pull the print to check if both floats in your specific carb are identical or different.

 

And while we are on the subject of adjusting floats.........often one can effect the adjustment of the float WITHOUT bending. Changing the thickness of the gasket under the seat can easily change the height of the float +/- more than a 1/16 of an inch. The less bending, the better!

 

Jon.

[Beemon]

Apologies for not doing what I said I would do today. Between work and a perilous differential equations exam today, I didn't have time to exchange air horns. What I did do, however, was contact CarbKing and put together a plan of attack. Between studying, I was also doing some research on the side. Having a lower float level than the peep hole causes an atmospheric imbalance that inhibits the operation of the venturi and likewise having a higher float level causes the engine to dump too much gasoline. This pressure differential is balanced by the floats at that specific level for the purpose of proper venturi operation. So a lower float level creates an overly lean condition. As we were discussing via phone, compensating for this lean condition by adjusting the idle mixtures to be more rich causes puddling in the intake that bogs acceleration to the point of shut down. So, I can assume all floats are different despite their solder joint and will be bench testing the floats for proper fluid levels with the carb that is off and then swap floats between the two and continue bench testing. The key fluid level is the peep hole bottom threads, outlined in the shop manual as the correct float level, which is funny that their specification of 1 35/64" was too low in the bowl... also makes sense to have the primary floats sit higher due to the added volume in the bowl from the accelerator pump shaft...

 

I must also admit right now that I have a pertronix ignition module. This question wasn't asked of me, but through my research I've obviously messed this up big time. No need to scold me, the speed shop that rebuilt my distributor almost one year ago talked me into the 'benefits' that I was naive about and didn't know any better. I'm picking up the points, condenser and coil tomorrow from NAPA. You guys must shake your head a lot at my threads. "Dumb kid, he'll learn eventually." In my defense, only two people in my family owned and maintained classics - my grandfather, whom cared for his Buick from 1956 to 1978 (when his son junked the Dynaflow) and is too old to help me or remember how to help me, and my father, whose eager to help and his earliest car was a high performance 1968 Dodge Charger with an alternator... if you get what I mean. Maybe my first carb was perfectly okay and it was the pertronix playing tricks on me? Who knows, we'll find out by the end of the week!

Edited May 3, 2016 by Beemon (see edit history)

[MrEarl]

 

3 hours ago, Beemon said:

Maybe my first carb was perfectly okay and it was the pertronix playing tricks on me? Who knows, we'll find out by the end of the week!

 

You may want to start watching the southeastern sky, I think Willie just threw a tire iron at you and it should be arriving soon! 

Just curious, could you tell if the carb you got from me had ever been into? I've failed to follow close enough to know, is it the one you are having problems with or your original, or both. 

[Beemon]

I don't think the carb you sent me had ever been in to. I found a cocoon inside the fuel inlet ports and the jet and accelerator pump were original as far as I could tell. The accelerator pump actually was broken and doesn't compress all the way and the carb must have had a fire because the primaries were deeply scored with soot.

 

It works great now,  it's just I didn't set the floats right so when I can adjust them and eliminate them as the problem, then I'll move on to the next problem. 

 

The carb was in really good shape otherwise, cleaned up extremely well but the surface was just tarnished on most of it so I painted it. 

[NTX5467]

You might be a little aggressive in the use of the term "overly" in relationship to the fuel mixture with the MINUTE change of  float levels.  Just my own orientation.

 

To me, an "overly rich" mixture puts black smoke out the tail pipe with a "blubbering" engine response to throttle.  Similar, in reverse, with "overly lean".  When "bowl vents" were deleted on the air horns, I did not notice any change in main jet sizes, although as this was an emissions change, the sizes were generally getting a little smaller, but not much.  The vapors from the float bowl were collected by the carbon canister, for recycling later, but I did not know of (OR read of) any fuel curve calibration changes regatding this.  I also know that a little more fuel in the bowl can better ensure fuel for "heavy load" situations AND going up steep hills/mountains under heavy throttle.  Key thing is that the main jets and accel pump "fill slot" stays wet with fuel.

 

In the case of the beloved Holley 1850, which was originally OEM on Ford V-8s, starting in about 1957 or 1958, that one carb went "everywhere" for them back then.  Cars, trucks, and whatever else they used it on.  Although the float level was pretty normal, I understand that it had to be re-checked/set from one vehicle use to another, due to the final angle it was mounted at on the intake manifold (probably due to hood contours?).  When the floats were externally adjustable, OEM.  If the carb was mounted "downhill", one float setting.  If it was mounted "level", another float setting.  If the same engine/manifold combination was tilted rearward, another float setting.  In other words, I suspect there is far more leeway in float settings than you might suspect, producing the same fuel/air ratio in all cases.

 

Key thing, to me, right now, is to make sure you have the correct "guts" in the carb and everything is adjusted "to their respective specs".  The correct seal washers under the needle/seat assemblies, and all linkages operating "as designed".

 

With the distributor out of the engine, chucked firmly into a vice, put a dial indicator on the lobes of the distributor.  Then check EACH lobe for height variation and shape of "each peak".  I highly suspect you'll see MORE variations than you might suspect . . . at least that's what I did when I did that on one of my cars.  The variation of those peaks WILL impact the point gap setting with ignition points.  And, the OTHER thing impacted is "point dwell" readings, which will ALSO affect ignition timing.  Which lobe do you use to set the point gap on?  A "low" one or a "high" one?  Or as we did for years, take "pot luck" and presume they were "all the same"?  This is the beauty of the Delco distributors with "The Window" that could be set with the engine running AND possibly a dwell tach hooked up to read the dwell reading!  Or use the "by ear" method of using an "engine miss" to determine when the adjustment was not right, then go back the other way until it does it again, then seek the "middle ground" between those two extremes.

 

There IS an advantage of points, though.  It is that it'll produce a spark and fire the plugs when the battery supply voltage is LOW.  An electronic system meeds a minimum amount of voltage to fire the plugs, which is generally higher than needed for a point system to fire the plugs.  A plus for cars with normally weak batteries.  So don't feel like you were a "wet behind the ears kid" who got taken advantage of by a "fast buck artist" at the speed shop!  Advantages both ways for ignition systems.  Just like being single or married, just depends upon which set of advantages you might determine are best at the time.

 

Keep us posted,

NTX5467

[MrEarl]

10 hours ago, Beemon said:

I don't think the carb you sent me had ever been in to. I found a cocoon inside the fuel inlet ports and the jet and accelerator pump were original as far as I could tell. The accelerator pump actually was broken and doesn't compress all the way and the carb must have had a fire because the primaries were deeply scored with soot.

 

It works great now,  it's just I didn't set the floats right so when I can adjust them and eliminate them as the problem, then I'll move on to the next problem. 

 

The carb was in really good shape otherwise, cleaned up extremely well but the surface was just tarnished on most of it so I painted it. 

 

Sorry about the cocoon (probably a dirt dauber nest, they will build in your ears if you stand still too long, I hate them!!) and honestly wasn't aware the accelerator pump was broken, was that evident from just looking at it, if so I missed it sorry.  I bet half my parts cars show signs of under hood fires, fairly common in those days. 

[Beemon]

I didn't notice the accelerator pump was broken until I had it out. It only depressed halfway, but was no big deal because the kit came with a brand new one. Still very grateful for the carb!

 

A little update this afternoon, I re-adjusted the floats so now the fuel level sits comfortably at the peep hole. When I pulled the floats, the fuel barely seeped into the accelerator pump reservoir and was extremely low in the bowl. The fuel filter, at least when cranking, was holding fuel again like it did with the other carb so that's also a plus. Per the shop manual, I reset the idle screws to 1 1/4 turns out and the throttle plates 1 turn out from fully closed, so hopefully she's ready to fire.

 

I also tossed the Pertronix. I picked up a set of points, a condenser, an OEM coil and 8 new spark plugs. Except wouldn't you know, the terminals on the coil were stripped and the parts store was closed when I got to it so more waiting. As for setting lobe adjustment, I didn't have the luxury of pulling the distributor at this time, so I was belly over inside the engine compartment trying to set the point gap with a .016 feeler gauge. The shop manual said no more than .0175 and no less than .0125, so I feel on the specific lobe, .016 will be a decent middle ground for initial point timing. The shop manual was also specific in saying to achieve the highest point gap possible, my feeler gauges went from .016 to .018 so that's the best I could do with what I have. I won't know if everything is working until I get a replacement coil tomorrow.

[Beemon]

I don't know if I should start another thread, but I'm not sure what's going on here.

 

 

Does this look right? I've cranked the engine to the point where I need to go have it charged. At first I thought it wasn't cranking because the ground and lead wire were touching, but they're separated now and still nothing. Could it still be the coil? I tested it with a meter and it checked out to the factory specs. I'm also running it across the ballast resistor. Maybe one of the connectors at the points is grounding out? They didn't seem to be touching the breaker plate when I tightened them down. Should the lead and capacitor connector not be touching on the terminal? Am I safe to think this is a ground issue?

 

To be fair, I never saw the inside of the distributor when I sent it to be rebuilt other than a brief glimpse one year ago. What I've done is based off the shop manual.

Edited May 4, 2016 by Beemon (see edit history)

[Ttotired]

All looks right, although the nut on the insulator block inside the dissy looks really close to the breaker plate

You need a test light to see whats going on before you go ripping things apart

With the key on, you should have power (voltage is not an issue yet unless its really low, test light really dull) at the + on the coil and if the points are open, you will also have power on the - of the coil. If the points close, there should be no voltage shown on your light on the - post

 

If points are closed and you have voltage, the wire to the dissy is broken, the points are incorrectly (or not) connected or the common one, the points have an oxidized coating on them that you need to file off and it hasnt been done, so they dont make a circuit

 

If the points are open and your test light shows no voltage on the - post, coil could be open circuit (disconnect the wire off the - post and test for voltage on the post again, voltage yes, coil ok, no voltage, coil is open and faulty), so coil ok, continue, check for the wiring between the coil and the dissy being shorted out, check for the wire inside the dissy shorting out (including the nut I mentioned earlier) and that its all wired right (looks right from the pictures) You can also disconnect the condensor inside the dissy incase that is shorted out

Last advice, I would not have messed with the ignition system yet (test first, replace later), once you start throwing stuff at it higldy pigldy it becomes really hard to diagnose as you now have 2 potential problem areas instead of one (it used to start and run, then die, now it wont start, so its worse)

 

Check the ignition as above, make sure you have spark and that the timing ect is all correct before doing anything else with the carby

 

Mick

Edited May 4, 2016 by Ttotired
More info (see edit history)

[Beemon]

7 minutes ago, Ttotired said:

the points have an oxidized coating on them that you need to file off and it hasnt been done, so they dont make a circuit

Thats probably it because I didn't file anything. How would I go about doing that?

[old-tank]

Clean the contacts with brake cleaner dress with some really fine sandpaper then clean the brake cleaner again.  Crank with the cap off and you should see sparking at the points.

[JohnD1956]

If your points are new you should not have to file them. 

 

Re this picture:

 

The red wire from the condenser looks like it has no connector on the points terminal? Maybe it's just the angle?  At any rate, if that is not making good contact, you will not have fire at the points.  In addition, the other wire to this terminal looks like it is touching the inside of the distributor shell.  If you loosen the connector nut, and rotate that wire till the terminal end is directly vertical, that ought to pull the wire away from the outer shell of the distributor.

 

Did you buy a new Rotor for the distributor?  Doesn't the Pertronics use a different rotor?  Maybe that's not a problem.  I am not sure about that. 

 

Further, it's not shown but there is a gap at the points when the red block on the points rests on any one of the 8  the crowns on that center shaft ( The points cam), right?

 

Lastly, the arm of the points set looks to have some grease on it?  Not sure why if it does but perhaps some grease got between the points themselves?.

 

 

[JohnD1956]

Also, I forgot to mention, the plate that the points are on contains one hole with the label "oil" .  A few drops of a light or medium weight oil in that hole would be helpful in lubricating the rotating parts of the points plate. I believe that is in the manual.

[Ttotired]

Points file will be best, but sand paper will do, but make sure you clean them well, otherwise the "sand" can melt with the spark and and sort of glass coat the contacts

Sometimes, filing is not necessary, but I have been caught (cheating) enough times not doing it that I now do it as a matter of coarse.

Grease behind the rubbing block is required to lubricate it as it wears down (common mistake not to do this and have the rubbing block wear out quite fast)

The wire from the insulator block to the points must have a bit of "slack" to it or the breaker plate can not move with the vacuum advance, although, I would set that wire up with the terminal around the other way so the wire comes up and away instead of down as it is now

 

Mick

[Beemon]

Just to be clear the carb would idle and start fine so I'm not concerned with that aspect right now. 

 

I was looking at the shop manual and it had shown a plastic horse shoe for the lead wire. I'm guessing it touching the housing is probably grounding it out? I don't have this part so I'll do as suggested and move it away by rotating the terminal connector on the points. 

 

The condenser is wired to the points as well but it's kinda pushed down, so I'll make sure that's not contacting the breaker plate as well. 

 

The grease is from me greasing the lobes and the breaker contact, I'll be sure to wipe that all down. I'll try sanding with 600 grit sand paper and see how it goes. Also the vacuum advance pulls the plate CCW so slack shouldn't be an issue. 

 

Thanks for all the feedback! The battery is almost dead from cranking so much so I'm going to have to get it charged tomorrow while I'm at the college if I can't get her to fire off. 

[JohnD1956]

The vacuum advance will rotate the breaker plate counter clockwise, and push that wire firmly against the shell of the distributor if left the way it is. Changing the condenser and coil lead wires from a top down orientation at the points to a bottom up could work but will mean twisting the coil lead wire which does not look like what the engineers anticipated.

[Beemon]

Okay I followed everyone's advice and....

 

 

We have contact! (Or really, no contact since the contact points are opened...) The battery is dead from over cranking it and not driving the car (supposed to get my power steering pump back this weekend), so I had to use my trusty test light. I just stuck it on the negative terminal and boy was I happy when I started rotating the distributor and having the light go on and off. I moved the connectors vertical like suggested and it pulled both lines away from the edges. I pulled the points back out and ran them over with 600 grit sandpaper and then sprayed with electronic parts cleaner and let dry before re-installing.

 

Thanks for the tremendous help guys! I'll get to timing tomorrow when I get the battery back from Autozone and then back on topic!

[Beemon]

Another update:

 

 

double checked points gap at .016". I had to move all my spark plug wires back one terminal on the distributor cap because the Pertronix was that far out of sync. Is that common? I couldn't figure out why the car wouldn't start so I had to bump the crank with the starter until the timing mark was in range, then turn the engine over by hand to set timing at 5* on the balancer. I then put the distributor cap on the distributor with the wires, marked with a silver sharpie where #1 was, took the cap off and then rotated the distributor so the dot and rotor were next to each other for initial timing. Car started up, checked the dwell and it was steady 28.5. I checked another source because my book was missing the page and Dwell is supposed to be between 26-33. Is the lower the better or the other way around?

 

I any case, I waited for the car to warm up, just to be sure, gave it a good ten minutes. I couldn't figure out why I couldn't get it to idle below 800RPM. Well, when I set the initial throttle blade adjustment to 1 turn in, it was connected to the throttle shaft. I disconnected the throttle shaft and it allowed the throttle arm to fall forward (not by a lot). I readjusted the throttle shaft and the car was idling between 450-650. So then I set my idle screws, initially 1 turn out, to about 1 1/2 turns as a final adjustment at 450-500 RPM and it was running pretty smooth. Checked off idle, the stumble wasn't there and it let me go to the floor. The car also idles and runs a lot better without the Pertronix. Before it would idle hunt and do all sorts of weird things, now the idle is smooth and there isn't any surging or jumping.

 

I haven't been able to drive it yet, my power steering pump should be arriving tomorrow (Monday at the latest), so I'll report back after a road test, idle post idle adjustment and another road test. From what happened today, though, I am extremely pleased with myself and how well everything has turned out. I'm sure there's still some stuff in the idle circuits that didn't get cleaned 100%, but every other fill up I dump seafoam into the tank so we'll see if it cleans up. On my other carb, I had a clogged idle circuit and the car ran like crap. I was advised to use seafoam in the tank, and under load going up a steep hill, the idle circuit was unclogged when I stopped at the light. I'm sure people have difference of opinions when it comes to additives, but it's helped me out before.

[Beemon]

Just wanted to give an update because I said I would.

 

I got my power steering unit back today, so I had the system bled and took the car for a spin. Turning the wheel with my pinky felt great again and for the most part, the ride was smooth. It's about a 15 minute drive to the college from my grandfather's residence, and about 5 minutes in the car started running rich and lopey. At one point the car started shaking while waiting at a stop light. I cracked the throttle open at every green light where I could and the carburetor started to flush itself out for a lack of a better term. When I got to the school, I didn't have time to play with the carb or check timing (I keep the timing light, tach, a distributor ratchet and a screw driver in the trunk). When I got out of class, the car fired up and I drove it out of the parking lot. It seemed to start smoothing out and by the time I got home, the car was idling fine. I rechecked the idle screws by playing with them, they felt right around 1 1/2 turns out like before. When I stuck my hand over the snorkel air cleaner, it almost killed the engine, so that was a good sign. Dropped idle to around 350 RPM and checked timing, just a little bit advanced of 5* but not quite 7*.

 

One thing I did notice, however, was that the car liked to choke itself when dropping the pedal to the floor. If I give it some gas and then drop the hammer, it's fine. My idle vacuum also won't rise above 17 inches, and in comparison to other vacuum readings on the net, it could be anything from a bad muffler, bad oil (need to do an oil change next) or late ignition timing. From idle to go, the transition is fine, it just doesn't like opening up the butterflies. Could it maybe also be that the throttle isn't pushing the accelerator pump all the way down on throttle up, and that I need to adjust the throttle arm a little bit?

 

Out of curiosity, but since I had the block bored .030 over when it was rebuilt and my uncle rumored to have shaved the heads by a thousandth, what would be an adequate spark gap? About the only thing I haven't checked is spark plugs, but the shop manual says .035 gap, which is what I set it to before, and the car runs great in every range. It's just that sharp bark of the gas pedal that gives it a little choke.

 

In any case, another Buick back on the road! I'll be driving it daily for the next couple of days to see if it clears up the stuffy nose issue or not.

[old-tank]

Good to see some progress!  It has been awhile since I played with a 4GC, but seems I remember that the accelerator pump stroke is adjustable.  Plug gap is OK...what brand and number are you using?  If the tank still has winter blend fuel, run that out before changing anything.  All of mine had drive-ability problems on winter blend gas until my most recent fill ups.

Willie