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Old 02-26-2024, 07:43 PM   #1
Vanspeed
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Default Carb issue?

Hey fellas,
Working on a barn find 49 F-1 that sat since the 60s. Carb was completely taken apart, all passages cleaned and blown out with compressed air. Truck starts immediately and idles all day long. When giving it throttle it hesitates a little, sometimes a small pop out of the top. Close the choke just a little and it has great throttle response. Thoughts?
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Old 02-26-2024, 07:53 PM   #2
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Default Re: Carb issue?

Three carb possibles and one distributor possible. In any case, the backfiring through the carb will necessitate replacement of the power valve.
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Old 02-26-2024, 11:39 PM   #3
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Default Re: Carb issue?

I'd carefully check the accelerator pump action,adjustment, and delivery if it were mine. It should shoot a stream into each side as soon as the throttle is opened.If it doesn't it will give the symptoms you describe.
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Old 02-29-2024, 05:55 PM   #4
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Default Re: Carb issue?

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Originally Posted by cadillac512 View Post
I'd carefully check the accelerator pump action,adjustment, and delivery if it were mine. It should shoot a stream into each side as soon as the throttle is opened.If it doesn't it will give the symptoms you describe.
The linkage to the accelerator pump has lots of slop. Could be a culprit.
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Old 02-27-2024, 12:31 PM   #5
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Default Re: Carb issue?

What cadillac512 said, plus check for slop in the accereator pump link. When you open the throttle the pump link and pump rod shoud move down with the slightest movement of the throttle.

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Old 02-27-2024, 12:52 PM   #6
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Default Re: Carb issue?

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Would the backfire through the carb indicate a lean issue? What about vacuum leaks? Also you say the engine has not ran since the 1960;s...... do you have sticky valves?
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Old 02-27-2024, 02:02 PM   #7
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Default Re: Carb issue?

Which engine?
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Old 02-27-2024, 02:12 PM   #8
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Default Re: Carb issue?

New accelerator pump? is the check valve under the acc. pump working, blocked nozzle bar, is the check valve under the nozzle bars free to move? Yes many times backfire will rip the power valve diaphragm. Remove the top and get a level of fuel in the bowl come back after 1/2 hr is the level the same? If not there is a leak maybe in the PV or it's gasket.
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Old 02-29-2024, 05:53 PM   #9
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Default Re: Carb issue?

Engine was completely cleaned inside. All valve train is free. Engine starts immediately and runs terrific for sleeping so long. When warm with choke completely open it stutters when you give it gas unless you close the choke a bit. Indicates a lean situation I agree. Carb was completely taken apart, ball under accelerator pump removed and all passages cleaned and blown out with compressed air. Engine is the factory engine. Carb was rebuilt with a typical kit but it did not include a new power valve.
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Old 02-29-2024, 06:50 PM   #10
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Default Re: Carb issue?

To lean is it if the choke cures the problem. The power valve would be my first thought, then the Accelerator pump. One other thing would be a vacuum leak like a bad wiper hose. If you go down the power valve path make SURE you are getting the correct one. Only a very few people sell them and most rebuild kits you buy DON'T have the correct one that will seal in your carburetor. Tim
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Old 02-29-2024, 09:44 PM   #11
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Default Re: Carb issue?

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To lean is it if the choke cures the problem. The power valve would be my first thought, then the Accelerator pump. One other thing would be a vacuum leak like a bad wiper hose. If you go down the power valve path make SURE you are getting the correct one. Only a very few people sell them and most rebuild kits you buy DON'T have the correct one that will seal in your carburetor. Tim
This is especially true for the 226 I6 carb.
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Old 02-29-2024, 07:26 PM   #12
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Default Re: Carb issue?

Vintage Speed has all the component for your carb.
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Old 02-29-2024, 07:35 PM   #13
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Default Re: Carb issue?

I would check out Vintage Speed's reputation on the H.A.M.B. if I were you.
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Old 03-08-2024, 05:11 PM   #14
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Default Re: Carb issue?

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I would check out Vintage Speed's reputation on the H.A.M.B. if I were you.
I looked up the vintage speed on the HAMB and what I see is a guy selling vintage speed parts on FB, Charlie Price in Florida is the business called Vintage Speed and he has lots of videos and I have been buying parts from him and I have had no problems at all. So I believe the other vintage speed on FB is the scam.
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Old 03-05-2024, 04:32 PM   #15
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Default Re: Carb issue?

Update. Had the customer bring over another carb he had. I swapped the bases as the throttle plates and shaft had lots of play in them and the donor carb was nice and tight. Swapped the power valve and accelerator pump as well. Starts and idles perfect. Open choke no hiccups, runs as it should.
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Old 03-05-2024, 05:11 PM   #16
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Default Re: Carb issue?

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Originally Posted by Vanspeed View Post
Update. Had the customer bring over another carb he had. I swapped the bases as the throttle plates and shaft had lots of play in them and the donor carb was nice and tight. Swapped the power valve and accelerator pump as well. Starts and idles perfect. Open choke no hiccups, runs as it should.
Thanks for the update. Sounds like it was a vacuum leak causing a lean condition.
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Old 03-05-2024, 05:18 PM   #17
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Default Re: Carb issue?

Power valve all day long
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Old 03-05-2024, 05:22 PM   #18
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Default Re: Carb issue?

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Power valve all day long
Power valve leak would also cause a hard start and flooding type of problem after the engine was shut down and restarted. I've never had a leaking power valve cause popping.

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Old 03-08-2024, 07:58 PM   #19
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Default Re: Carb issue?

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Power valve leak would also cause a hard start and flooding type of problem after the engine was shut down and restarted. I've never had a leaking power valve cause popping.



Exactly.
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Old 03-08-2024, 04:43 PM   #20
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Default Re: Carb issue?

Power valve that was taken out was tested and appears to be ok still. I beleive it was pulling air around the throttle shaft and causing a vacuum leak.
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