1934 throttle sticking

[JeffHealey7]

Hi guys, first post here. I just bought a '34 V8 sedan and it runs and drives pretty well, but the throttle sticks, which can be scary (of course). I've lubricated all the joints, made sure everything is freed up, both the spring on the firewall pedal rod and the one on the carburetor (up top on the accelerator pump rod) are in good shape.

Here's the funny thing. When it isn't running, nothing sticks and it works fine with no binding or sticking. But when I fire it up, it sticks. It won't stick all the time, but if I've been driving at constant speed and let off the gas, it stays there and if I clutch in, the engine races. I can put my foot under the pedal and return it to idle or if it quickly snap the throttle it usually returns to idle, but it will hang the next time. Quick movements don't make it stick, but it doesn't return to idle if I use gentle movements.

I don't want to put more/heavier springs on it, mostly because it seems fine with the engine off so something else is wrong. Could engine vacuum be causing it to hang somehow?

This is a stock 21-stud flathead with a standard Stromberg 97 carb, by the way.

Any thoughts? My wife is afraid to ride in the car and definitely won't let the kids in it! Thank you!

Jeff

[FL&WVMIKE]

JeffHealey7 ........................
Sometimes your pedal can rub on the floorboard, itself, or even the floormat and cause it to stick.
Check for your clearance,
MIKE (mikeburch)

[JeffHealey7]

It's definitely not the pedal. I've disconnected each link in the chain and it sure seems to be the lever on top of the carburetor that's hanging up. Everything else moves smoothly and as I said, it's ONLY when the car's running, which is really weird.

Thanks for the feedback!

[Bruce Lancaster]

Well, you're talking about the rocker for the accelerator pump as the suspect??
If I have that right, diconnect the vertical link and go for a ride...just accelerate slowly to get by without pump. If that eliminates binding, then at least we have the general area of the problem identified...

[Terry,OH]

I would suggest you disconnect the throttle linkage at the Carb base and try the Carb throttle by itself. You can get any part of the Stromberg by contacting Max Musgrove the Stromberg repair technician on their web site. The original Carb for the 34 is the model 48 (not marked 48 or 97) not the 97 but this is not the problem. Disconnect the accelerator pump from the accelerator lever (remove the cotter pin). try it again. Look for a Carb diagram showing all the parts and make sure they are all in proper position. The accelerator lever should have a spring, it may not be in place properly or it may have broken. I do not believe this has anything to do with engine vacuum. You can add a drop of oil here and there to lube linkage on the Carb.

[Bruce Lancaster]

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Another thing on that rocker: The shoulder screw that holds it and serves as its pivot looks a great deal like the screw that the coke lever pivots on. If that screw, which has a shorter shoulder than the pump one, has been used up there it might well be a binding point.
Carb would have been a model 40, actually, a nearly extinct beast. 48's look about the same.

[Terry,OH]

Bruce is correct the original 34 Carb was a model 40 Stromberg not the model 48. This is the Stromberg web site.
http://www.stromberg-97.com/service_...service.asp#sp

[JeffHealey7]

Well, I did some playing around, and the sticking is still only happening when it's running. Sitting still with the engine off, the throttle action is smooth and it doesn't hang. Once it's running, though, there's a definite hitch in the return action. I ran it with the throttle linkage that connects to the accelerator pump disconnected and while the throttle was pretty soggy (the spring on the pedal return might be weak) it eliminated the hitch. So it's obviously in the accelerator pump.

As a temporary fix, I installed a helper spring on the linkage and it totally solved the problem and actually firmed up the pedal nicely, but I know it's not correct. I don't know much about carburetors so I don't want to go digging in there without really knowing what I'm looking for.

Thanks for the advice!

[Terry,OH]

Max and Stromberg offer the accelerator pump as an assembly with both of it's springs attached or you can buy just the pump without springs and replace your old springs. They also offer the spring on the accelerator lever as a HD version (ask). You may want to have them do the work and rebuild the entire Carb. Contact Max . I will PM you his contact info.

[FlatheadTed]

Re popped stuff is Phhhhh, I would rather stay original ,Some replacement kits have the spring on the pump to weak ,so the leather hangs up .Also the pump barrel needs a polish in some cases so the leather slides smooth .The last one I did I had to remove the little coil spring under the leather so it didn't hang up .Also the kit needle valves seat are to short and the float stop bottoms out.Ted

[scooder]

Ted,
This "repopped stuff" ain't a fair comment on the new genuine Stromberg parts (made in the UK) that Terry mentioned. These parts are not to be confused with that 9super7 thing (guess where it's made) that speedway hock.
Jeff,
it does sound like the accelerator pump lever part may be worn a bit, but the real issue, from your test, appears to be a weak throttle return spring. As with the accelerator pump link removed, the pedal shouldn't feel spongy. It should snap back quite smartly.
Martin.

[FlatheadTed]

Generally parts produced by the original manufacture couldn't be described as re popped or pirate parts ,Ted

[uncle max]

PM me and I'll send you one of my heavy accelerator fulcrum springs.
They are heat treated polished .048" diameter 302 stainless, as opposed to the old .040" mild steel. Your neighbor will thank you for not stealing the return spring off his screen door. Free.

[JeffHealey7]

Uncle Max very generously sent me a spring, which I'll have installed this weekend. Hopefully this cures it, because it runs so well--I just don't like the big return spring I had to use.

Thank you, Max and Ford Barn!

[V8COOPMAN]

There ain't NOTHIN' bad that can be said about Uncle Max, plus.........he knows what he's talkin' about. DD

[FrankWest]

Originally Posted by Terry,OH

Bruce is correct the original 34 Carb was a model 40 Stromberg not the model 48. This is the Stromberg web site.
http://www.stromberg-97.com/service_...service.asp#sp

Terry, the ford restoration 1933/1934 handbook says 48 not 40? Am I missing something?

[COE Dan]

Originally Posted by FrankWest

Terry, the ford restoration 1933/1934 handbook says 48 not 40? Am I missing something?

The Stromberg 48 is the correct 1934 carb for the Model 40 (1934 V-8 vehicles). The Ford part number may be preceded by a 40...someone else may be more knowledgeable precise.

A note on the Stromberg 48 and 97s - many of the parts are interchangeable/identical. These include emulsion tubes, accelerator pumps, needle valves, etc. While they also fit, the power valve numbers and jets are different for a stock 48 vice a 97. The only real difference in the carbs is the venturi size.

Lastly, I'm following this thread since I'm currently rebuilding my Stromberg 48 on a '34 for a sticking accelerator pump. Uncle Max helped with his suggestion to clean up the pump bore.

My sticking pump experience leads me to conclude that a sticking accelerator pump isn't going to cause the throttle to stick open. When actuated, the accelerator pump shoots one charge of fuel into the carb to overcome the lag in the main fuel circuit before it catches up with the increased air available from the opening throttle plates (i.e. neutralizes the development of a lean mixture condition at the moment of acceleration). If stuck in the actuated position, the accelerator pump doesn't continue to push fuel into the carb throat.

While a sticking accelerator pump might cause the power valve to stick open, that would likely create a slightly rich condition vice a higher throttle/power setting. That's controlled by throttle plate position.

That's how I'm visualizing the problem. I'd go with replacing the throttle return spring and checking to ensure that cross shaft on the firewall isn't binding when you actuate the throttle.

Just my thoughts,

Dan

[COE Dan]

Clarification of first sentence - I think I've got it backwards - 48-xxxx was the Ford part number for the Stromberg. Have I succeeded in further confusing anyone?

[Bruce Lancaster]

OK...the Model 40 with a letter after it, don't remember quite what, is the '34 V8 Carb. There is also a 40-A carb that is irrelevant here, as it is the one-barrel DL from 1933.
The Stromberg 40 has differences in the idle bleed area that make the upper castings not compatible with the later Strombergs...this may have been the root area of the gas-hog reputation that moved Ford on to new versions. The 40 part number seems a reasonable label. I think I have read that early 1935 Fords got this carb because the 48 didn't arrive on time. The 48 has a 48 as its PN prefix because it was introduced for 1935 and that was the parts label for that year...many also have a small "48" cast into left top of main body and left lower of airhorn, probably to help the parts man from swapping with 40 carb parts.

(edit...not all 48's have the little "48" castings on main and upper casting. These marks are small, not like the conspicuous "97" marks on those. And most 40's and 48's will have 48 stamped (NOT cast) on back edge...these stampings just mean that they left the factory with the standard 048 jets and have nothing to do with carb model.)

[FrankWest]

Originally Posted by Bruce Lancaster

OK...the Model 40 with a letter after it, don't remember quite what, is the '34 V8 Carb. There is also a 40-A carb that is irrelevant here, as it is the one-barrel DL from 1933.
The Stromberg 40 has differences in the idle bleed area that make the upper castings not compatible with the later Strombergs...this may have been the root area of the gas-hog reputation that moved Ford on to new versions. The 40 part number seems a reasonable label. I think I have read that early 1935 Fords got this carb because the 48 didn't arrive on time. The 48 has a 48 as its PN prefix because it was introduced for 1935 and that was the parts label for that year...many also have a small "48" cast into left top of main body and left lower of airhorn, probably to help the parts man from swapping with 40 carb parts.

1933 ford v8 had the DL carb "single Barrel"
1934 ford V8 had Stromberg 48 "double Barrel"