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AAV-1 Choke/Plug Fouler advice please?


Shaggy
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Hello again.

After cleaning up the points, cap and rotor, my '38 Model 41 runs much better, <img src="http://forums.aaca.org/images/graemlins/grin.gif" alt="" /> but still has a persistent intermittent miss. New parts will be in tomorrow for an ignition tune up.

In the meantime, my choke seems to take forever to fully open. This fouls the plugs to black fairly quickly. I noticed a small allen set screw at the bottom of the helical element in the choke assembly when I had it apart for cleaning. (Part that goes into the heat riser)

Please see the attached photo of my spare.

If I make small adjustments to this, turning it a degree or 2 at a time on the shaft to take up the "slop", will it make the choke come off a bit faster? The octane selector seems to have little to no effect.

Your sage advice is appreciated in advance. <img src="http://forums.aaca.org/images/graemlins/smile.gif" alt="" />

Shag

Kittitas, WA

post-48075-1431379073_thumb.jpg

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I don't have much advice, but I can tell you how I solved a similar problem on my 37 with the same carb. First be sure that your float hasn't leaked. Mine leaked badly and caused alot of trouble until I discovered that problem. I then acquired a NOS carb from a later Buick but didn't have the knowledge and confidence to try the exchange. The car ran roughly and had really poor mileage. Finally I sought and got advice from "carbking". I also read an explanation of the newer carb choke system by Lamar. Fueled with this new gotten cognition I made the switch and was amazed at the difference. From my experience and what I learned from the experts you will likely never get that excuse for a carburetor to work well.

Rollie

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Footnote:

Put the vacuum gauge on it last night to see a consistent wiggle 3" above and below 15" at idle and above. This indicated to me either an ignition problem or head gasket. Compression test ruled out a head gasket. Advance dash pot on the distributor is the only thing not inspected for a vacuum leak yet. It appears to be functioning.

This car sat on an island in South Puget Sound and was exposed to moist sea air for several years. I'll be going thru the entire electrical system. A new harness is a definite possibility.

Inside of the cap, rotor and points were badly corroded, car ran better after I cleaned em up with a pencil eraser, but I still ordered new parts.

When bumping the starter to get the points on the top of the point cam, I saw the points break while energized. Orange sparks in a pea sized cloud. In my book, that's used up.

Fresh ignition parts did the trick! I'll be putting a kit in the carb soon. Purrs like a happy cat now with an occasional stumble. The consistent missing and resultant vacuum pulses were no doubt fattening up the mixture, since the plugs look good now.

I figure that in 1938 this car ran perfectly well with the AAV-1, so there's no reason I can't make it do so again with a little effort.

I'm not the type to give up on something and take the easy route. Otherwise I would have bought a Buick that was already restored! <img src="http://forums.aaca.org/images/graemlins/grin.gif" alt="" />

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You're on the right track with that adjustment - do you have the shop manual to consult? I can check mine this evening, but it stands to reason that the set screw is the adjustment point. It would be similar to the method of adjusting the newer type of bi-metal spring. You loosen the little cover and rotate it, tightening or loosening the bi-metal spring to get the desired result.

The AAV1 should be very serviceable - this comment coming from an old friend who worked in a Buick dealership at the time. Seems there were two carbs used that year, Stromberg and some other (name escapes me). This gentleman told me many times that the Stromberg was the carb of choice, the other brand being impossible to work with.

Stick with it.

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<div class="ubbcode-block"><div class="ubbcode-header">Quote:</div><div class="ubbcode-body"> Seems there were two carbs used that year, Stromberg and some other (name escapes me). This gentleman told me many times that the Stromberg was the carb of choice, the other brand being impossible to work with.</div></div>

Marvel-Schebler... and Marvel is not short for marvelous. <img src="http://forums.aaca.org/images/graemlins/grin.gif" alt="" />

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Heh. I heard the same thing about the Marvel. Run away!

Got all new ignition parts in her today and she started up and ran smooth as a baby's behind, but started stumbling as she warmed up a little. Vacuum gauge still flickers regularly, so I'll be looking at valve adjustments next. I'm thinking I've got a tight intake valve or 2. If the level of expertise I've seen so far also applies to the valve lash settings, I no doubt have to reset everything.

Fortunately, I don't believe the car has any serious road time on it since the head was done, so it's likely I won't have to re-grind the valves... (That's my hopeful side talking) <img src="http://forums.aaca.org/images/graemlins/tongue.gif" alt="" />

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<div class="ubbcode-block"><div class="ubbcode-header">Quote:</div><div class="ubbcode-body">Footnote:

I figure that in 1938 this car ran perfectly well with the AAV-1, so there's no reason I can't make it do so again with a little effort.

<img src="http://forums.aaca.org/images/graemlins/grin.gif" alt="" /> </div></div>

Actually, it did AFTER the engine warmed up, but the auto choke never did work properly. Stromberg tried for two years to get Buick to use the integral choke, but since Delco was a GM company, Buick held on the the Delco choke in 1937 and 1938. In 1939 Buick surrendered (to the better choke assembly), and added a different second supplier (Carter) dropping Marvel. Both Carter and Stromberg were asked by Buick to offer service carburetors (with real chokes) for the 1937 and 1938. MANY of the original 1937 and 1938 Buick carbs were replaced in 1939 by owners who wanted to drive the car if the temperature was below 50 degrees. These were sold in the Buick dealerships.

Jon.

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Thanks for the history lesson Jon. I love this stuff. <img src="http://forums.aaca.org/images/graemlins/grin.gif" alt="" />

Choke seems to work fairly well at this point. I'm gonna tweak with it a little and try and get it to come off sooner. I'm stubborn that way. So far it seems to work fairly well. Just slow to come off.

Below 50 isn't too much of a problem here. When it starts dipping down to that point during the day I'll be driving the 4X4, as it'll likely be snowing at night. <img src="http://forums.aaca.org/images/graemlins/crazy.gif" alt="" />

I'll be warming it up and adjusting the valves later.

Is there such a thing as a *cold* valve adjustment for these? Much more fun to deal with a cold motor than a hot one. Was the linear expansion coefficient on the valvetrain components so unpredictable? <img src="http://forums.aaca.org/images/graemlins/confused.gif" alt="" />

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I have tried cold setting the tappets without success. Tis best to get her good and warm, 20 minutes fast idle , then return to 350 rpm, you'll have 20 minutes before the temperature will not yield an accurate setting. I also tried a dial indicator, a PG valve gapper, see photos, which was accurate, but at operating temperature, not cold.

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Don't know about one of these. Every motorcycle I've ever owned have the mechanical tappets set on timing marks. Cold. Had a hotrodded Chev 6 with solids that was set up the same way.

I've got to get a tappet wrench. You need 3 hands to do this with a wrench, screwdriver and feeler gauge with it running. Can you get the engine hot and adjust the valves like the hydraulic lifter motors?

As seen at the bottom of this page:

VALVE LASH ADJUSTMENT (Buicks.net)

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I've tried a lot of combinations, but here is the way that works best.

A box end wrench, and screwdriver, and feeler gauges.

With engine running I go thru with just the feeler gauge and write down the number of the rocker arm counting from the front. 16 total. Will write tighten #1 loosen #3 etc.

When done I shut engine off, make adjustments from my notes, start her up check clearances, and repeat where necessary.

I tried the PG gapper, it is kinda neat, but the dial is fluxuating with the operation of the rocker arm and valve.

If once you get um all done, and there is a poof poof, one is set too tight. Just recheck with engine running til you find the one with the greatest drag on the feeler gauge. You should have a new set of gauges to start out. Also note the picture on the attachment above. With wear, it is difficult to get an accurate reading.

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I saw a reference to using a vacuum gage to diagnose an engine in one of your previous postings. I decided to pick one up last night, and also found some reference materials. Any other advice?

I'm trying to figure if I should be getting more power and better efficiency from my '38 Special. Mine lays down and dies around 55, and delivers 12 mpg when I run 45 -50 mph. The top speed I can believe (4.40:1 gearing), but 12 mpg??? All the obvious stuff checks out, and the engine runs beautifully at 35 - 40 mph. I saw the "poof-poof" comment above, and thought I would re-check the valves.

How's the Stromberg coming?

Jeff

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Shag,

Wasn't your original posting about looking for a source for body panels? There is a guy on the AACA site (you can get there from here) under Forums - General Discussion - Buy/Sell who is looking to begin fabrication of '37 - '38 Buick stuff. Check it out.

Jeff

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I tried doing it by the book and got nowhere. Finally gave up and did it the way I understand.

Got the engine hot.

Shut down

Pull coil wire

Bump starter until #1 intake valve opens and closes, then a hair more.

Feeler gauge and adjust both valves using a .016 go .018 no-go.

Continued thru the firing order. Took about 10 minutes. Runs a lot better, but...

Found 4 *way* tight valves with zero lash. <img src="http://forums.aaca.org/images/graemlins/shocked.gif" alt="" /> Vacuum now only fluxuates around 2" instead of the previous 5-6", but that's still not acceptable. Lord knows how long it's been run with tight valves. Likely I'll be grinding valves and resetting guides sometime this winter. That head looks like one heavy SOB.

I feel like I'm cleaning up after somebody. <img src="http://forums.aaca.org/images/graemlins/mad.gif" alt="" />

Replaced all ignition but the coil and wires and still have an intermittent miss. New wires on order. At that point the coil will be the only thing not replaced. Even found a new vacuum advance canister. Still haven't received the carb rebuild kit. That may help a lot too.

I'd like to get thru this part and atack the brakes, but I'm sort of obsessive compulsive about finishing a step. Not gonna quit till I find this gremlin.

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My engine seems to have a slight miss also. Biggest issue is it only gets about 12 mpg at 50 mph, and really run out of steam after about 55 mph. Vacuum gage fluctuates about 1 inHg (how steady should it be?) when running at a fast idle. I'll be checking valve adjustment this weekend, may also swap coils. All the other ignition stuff has been looked over pretty closely over the recent past.

I'll let you know what I end up with.

Jeff

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More than one tight one. Four.

No mileage to put on at this point. Local law enforcement frowns on driving cars that lack interiors, seats and glass. <img src="http://forums.aaca.org/images/graemlins/grin.gif" alt="" />

I'm going to be receiving the carb kit and ign. wires soon. I think I'm going to wait until then. Anything else is wasted gas.

Please see my thread about the thermostatic idle speed gizmo. I'm tearing my hair over it.

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<div class="ubbcode-block"><div class="ubbcode-header">Quote:</div><div class="ubbcode-body">My engine seems to have a slight miss also. Biggest issue is it only gets about 12 mpg at 50 mph, and really run out of steam after about 55 mph. Vacuum gage fluctuates about 1 inHg (how steady should it be?) when running at a fast idle. I'll be checking valve adjustment this weekend, may also swap coils. All the other ignition stuff has been looked over pretty closely over the recent past.

I'll let you know what I end up with.

Jeff </div></div>

Jeff.

Can't advise regarding road mileage, but...

My rig ran a *lot* better when I discovered the vacuum advance was holed and the centrifugal advance was froze up. Replacing the advance pot and freeing up the centrifugal advance made a ~huge~ difference. Acceleration from idle became downright snappy.

I know that running without enough "lead" will result in poor economy. Might want to verify they're both working properly.

(Free advice always being worth what you pay for it <img src="http://forums.aaca.org/images/graemlins/grin.gif" alt="" />)

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