Sign in to follow this  
Beemon

1956 Buick WCFB Rebuild

Recommended Posts

2carb40    426
On 4/21/2017 at 5:25 PM, Beemon said:

Carb soaked overnight, with no progress. Went to the local carb shop today and they said good luck. Thanks.  Walked into the local NAPA today and it was a pretty good business day. A gentleman with a 56 Ford and the local high end back yard hot rod shop owner were in there talking with the in-the-know counter guy. The shop owner specifies in carbs, and told me to use a torch lightly on the throttle shaft and spray with wd-40. If I can't get it loose, he told me to bring it by and he'd get it loose for free. He said it's rare for just the secondaries to seize and that the car was probably driven by some guy who never used them. 

If you buy a cheap toaster oven the carb base can fit inside. Keep temp below carb melting. Heat expands whole base to release lock on shafts. Carefull so Mom doesnt find out. Reason I bought a new cheap one under 20 bucks.

Edited by 2carb40 (see edit history)
  • Like 1

Share this post


Link to post
Share on other sites
Beemon    1,103
3 hours ago, old-tank said:

My guess on the detonation would be possible differences in the vacuum advance.  Maybe the Rochester is not supplying vacuum?  If there is no detonation  on full throttle , but present  on part throttle, consider maybe even the wrong vacuum advance with too light spring?

On the phone, Jon went over what may cause a lean transition to cruise throttle that may cause detonation. One was an incorrect accelerator pump that has a hard time clearing the percolation in the pump well. He told me to start off the line strong so I get detonation, then stop and go again and see if the detonation goes away. While the accelerator pump was a bit longer than the original, I had detonation both times, which ruled out the pump by his explanation. The other issue was whether or not floats were set properly and if the float in the front was different from the float in the rear. By observation, both floats were soldered the same but the needle and seats had different heights. I took note of this and made sure everything went back together the way it came out. With the sight plugs out, the fuel level is right at the threads. The last thing he noted was if the jets were mismatched, but I assured him that the jets were installed correctly by the instructions in the shop manual, with the primary and secondary jets properly set. The last thing he told me to check was to adjust the floats so the fuel level is higher in the primary bowls to see if I could richen the primary jets. And of course, open the low speed idle jets by .002". If the change in float level makes the car run without detonation, then he suggested opening up the primary jets or find a set of larger jets or a set of smaller metering rods.

 

Both carbs supply vacuum, I tested the vacuum advance port for both carbs with a vacuum gauge and it seems to be working fine at part throttle. That was one of the first things I considered, too. Without access to a mil and jig, or lathe to properly machine down parts and make the required adjustments to really make a 60 year old carb run properly on today's oxygenated gasoline, I guess I'm going with plan C. It was a fun experience, for sure, but without access to a swath of vintage jets, rods and/or the tools to modify them properly, I don't want to mess anything up. Back on the shelf for now...

Share this post


Link to post
Share on other sites
1956322    60

My experience is the majority of these old carbs don't age well...I  always  try to find a nice adapter and go with a modern carb I can get new.. It has always worked out well for me vs spending more money and time trying to get something to work that's worn out and not designed for today's gas 

  • Like 2

Share this post


Link to post
Share on other sites
NTX5467    576

The "low speed jet", at least on the BBD and some other Carters is an elusive character!  I finally found it in a Chrysler service manual.  It's a drilled restriction near the bottom of the SOLID brass idle tube(s), the skinny one with NO side holes in it.  The emulsion tubes (the larger ones with the holes in the sides) is for the main jets only.

 

If the low speed jet is restricted, the car will NOT idle.  I took a bent-wire spark plug gap gauge and probed the "hole" and it kept getting bigger.  Using that size, I go a set of twist drills in that size range and went large enough to "get metal".  Then cleaned it up, flushed it with B-12 spray and reinstalled.  Whereas I had a "no base idle" situation, it now idled with good sensitivity on the idle mixture screws.  My original issue was that as soon as the engine warmed enough to get off of the fast idle cam, it would die . . . even when coasting at 60+mph.  Since 1966 emission carbs, the low speed jet dimension became more important.

 

According to a Holley engineer that gave a seminar once, which I attended, he noted that the air from around the throttle shafts was a "calibrated vacuum leak", which was compensated for in the metering calibration of the carb.  In other words, it's figured into the mix.  The wear you describe would need to be addressed, but is probably not unusual for an older used carb.  What would be affected would be how the throttle plates close in the throttle bore and the off-idle transition slots.  I think the spec is for the transition slot to have about .020" open below the blade at hot base idle? 

 

If the vacuum advance is "ported" (no or little vacuum at idle, but after the throttle opens, it gets vacuum), look to see that the supply hole in the throttle bore is a little above the throttle plates at idle.  If the vacuum advance is "manifold vacuum", then it'll use a vacuum port below the throttle plates, I suspect.  If the system is designed for "ported", it sounds like you're getting too much vacuum to the vacuum advance.  The OTHER consideration (which many Chrysler sales training videos mention, for wedge-shaped combustion chamber GM engines) is carbon build-up in the combustion chamber . . . especially since an earlier comment about "black smoke" from the car's exhaust pipe.

 

IF you like the way the Carter operates on the engine, then put it back on and run it with the vacuum advance port plugged.  This puts the engine in "full mechanical advance" mode.  It'll run pretty good, but mpg at part throttle will suffer until you can figure out what's going on. 

 

Next time you pull the air horn off the carb, use a straight straight-edge to check the flatness of the carb gasket surfaces of the main body and the air horn . . . for general principles and to verify they ARE flat, both of them.

 

Please advise of progress . . .

NTX5467

Share this post


Link to post
Share on other sites
NTX5467    576

  How much different are the WCFB jets and rods from an AFB?  Reason is that the AFB jet and rods ARE available in a "strip kit" from Edelbrock, as they used to be available from Carter.  Have yo checked the jets against the service manual specs?  Just curious.

 

Rather than worrying about jets and such, you can restrict the air bleeds on the air horn/venture cluster.  Holley talks about soldering them closed (once you know how big they are) and then re-drilling them to a smaller size.  But if the AFB jets will work, no need.  Individual jets are available from Summit, I believe, as is the Strip Kit/Calibration Kit.  Until you get the throttle shaft wear issue addressed, the metering characteristics at idle/low speed can be "different", I suspect.

 

Just curious . . .

NTX5467

Edited by NTX5467 (see edit history)

Share this post


Link to post
Share on other sites
Beemon    1,103

Willis, thanks for the write up. I think I'm going to let the carb sit for now. The WCFB has four low speed idle jets located at the top of the float bowl casting. There are two economizer restrictors in the primary circuit that is not accessible, right before the venturi. I don't trust myself enough to get four idle jets hand drilled the same. When I had the carb apart, just like the two 4GC s before it, I was pretty through with cleaning. That includes soldering and modifying, too.

 

I'm not 100% sure but I think the WCFB jets and rods are different from the AFB. The Jets and rods in the carb are correct for this year carb, as well. 

 

Based on my experiences with the 4GCs, I figured this would be a pretty straight forward run, but the WCFB is much more complicated in terms of design and function. Where the 4GC ran decent but not great on ethanol due to its simplicity, the WCFB seems to need much more to go right with all the different restrictors in the passageways (idle jet, primary jet and rod, economizer, acc. pump, pump needle). Which is a shame because the WCFB out performed the 4GC at every step except the spark knock. Maybe when I can afford a lathe and mill, I can really dial this thing in... one can only hope anyways. This thread is a wrap.

 

P.s. I pulled the trigger and got the Edelbrock 1406. A bit more than what I really wanted to spend, but no horseplay involved other than wiring a starter switch. I want to drive the car, and it's not going to be winning any awards anytime soon. 

  • Like 2

Share this post


Link to post
Share on other sites
NTX5467    576

Thanks for the information on the WCFB carb!

 

It seemed to me that when GM was engineering a competing product (in this case, the 4GC), they'd look at what others were doing and spend $$$$ to learn how to do the same thing with less complexity and related production cost, then save $$$$ by building massive amounts of them for years.  It also seems that in the process of designing-out complexity in design and related production issues, they tended to come up with some "bullet-proof" designs with pretty decent design longevity, by observation.

 

In that middle-1950s time, Holley hadn't become the powerhouse in hot-rod carburetors it started to become by 1958 with their first generation of "1850" Ford carbs.  Plus the innovative "metering block" concept they used.

 

Search out a thread by Vicky Blue on adapting an Edelbrock to his middle-1950s Buick V-8.  He seemed to have great success with what he did and it's all detailed in his posted thread.  Some of the "only use the correct carb" posters seemed to be impressed!

 

To me, the issue with "oxygenated fuels" is not the oxygenation per se, but that it takes more fuel for a slightly lower air/fuel ratio number for "stoich" . . . 14.2 vs 14.8, I believe.  This is NOT a big change, but what E15 and higher ethanol blends need for their related "stoich" will take more to make happen, I suspect.

 

In the "Rochester Carb" book by S-A Designs, it details how to do metering changes by not jet size per se, but "metering area of the jet/rod combination".  A finer way of doing it, it appears.  For "fixed jet" applications, you would use the area of the jet orifice hole for your calculations.  If a "metering rod" application, you'd take the area of the jet orifice and subtract the area of the intruding metering rod for the final result.  As another carb book mentions, the shape of the approach to the jet orifice influences the flow through the orifice itself.  The jet "size" relates both to the physical size of the orifice, but also the flow through it, but Is generally related to the orifice size.

 

In doing metering calculations related to metering area, you can end up with a 15-digit string of numbers, but when they are all assembled, it makes sense when you compare for the best sizing.  It might also result in a slightly leaner calibration than suspected, which can result in higher engine efficiency.  Best top end power is not achieved by going slightly rich at the top end, although that is perceived to have "protective affects", but with a slight lean-out at top end for a little more heat of combustion and power.  Not a huge "lean out", though, but just very slightly.  As in a 1/4 mile race, just as you pass the finish line (hopefully in front!).

 

Check out the Vicky Blue thread on the Edelbrock AFB installation!

 

NTX5467

Share this post


Link to post
Share on other sites
carbking    278
13 hours ago, Beemon said:

 

 

I'm not 100% sure but I think the WCFB jets and rods are different from the AFB. The Jets and rods in the carb are correct for this year carb, as well. 

 

Where the 4GC ran decent but not great on ethanol due to its simplicity, the WCFB seems to need much more to go right with all the different restrictors in the passageways (idle jet, primary jet and rod, economizer, acc. pump, pump needle).

 

P.s. I pulled the trigger and got the Edelbrock 1406. A bit more than what I really wanted to spend, but no horseplay involved other than wiring a starter switch. I want to drive the car, and it's not going to be winning any awards anytime soon. 

 

Since the 4GC DOES run, and you plan to drive the car, you might consider dumping any fuel left in the 4GC, drying it so there are no fumes, AND BOX IT AND CARRY IT IN THE TRUNK WITH ENOUGH TOOLS TO CHANGE CARBS, JUST FOR INSURANCE WHEN THE CLONE FAILS ;)

 

The WCFB jets and the genuine Carter AFB jets are the same; I would NOT suggest using clone jets. Metering rods are totally different.

 

Good luck with the clone; you will probably need it.

 

EDIT: Should have said the WCFB and MOST genuine Carter AFB jets are the same; there are three different physical configurations of genuine Carter AFB jets. 

 

Jon.

Edited by carbking (see edit history)
  • Like 1

Share this post


Link to post
Share on other sites
Beemon    1,103

This goes back to another thread I had about leaking solder plugs on a 4GC. I just can't win. I may or may not have to spend time playing with the Edelbrock, but at least it's manufactured to run on today's fuels and doesn't have any where for fuel to leak besides the top bowl gasket. 

  • Like 1

Share this post


Link to post
Share on other sites
1956322    60

The only thing I would suggest doing to that edelbrock is right away open her up and check the float levels they're known to be wrong from the factory

Share this post


Link to post
Share on other sites
carbking    278
1 hour ago, Beemon said:

This goes back to another thread I had about leaking solder plugs on a 4GC. I just can't win. I may or may not have to spend time playing with the Edelbrock, but at least it's manufactured to run on today's fuels and doesn't have any where for fuel to leak besides the top bowl gasket. 

Actually, it isn't; as it is made from aluminum. The ethanol absorbs moisture, and the absorbed moisture will attack the aluminum bowl. Also, and I do NOT know this (these carbs are permanently banned from our shop, so I don't have one to observe), but have been told by several that neopreme accelerator pumps are used, which do not hold up well in the ethanol.

 

Both the WCFB and the 4GC have zinc alloy bowls which were treated with a chromate solution to prevent damage from the moisture (until someone cleaned them in the 2-layer carb cleaner, removed the coating, and did not have the coating reapplied.

 

On another front, does anyone offer aftermarket saddle tanks for Buick? ;)  :P

 

Jon.

 

 

Share this post


Link to post
Share on other sites

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now
Sign in to follow this