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Pontiac carb Carter DRO or DRJHO


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Not sure which I have, but this is on a restored 1928 Pontiac 6.  I've read the manual about setting idle mix, then hi speed mix.

 

Am I correct that this carb has no accelerator pump?. I was restored with the car, and still looks fine. It has a dead spot from off idle, You cant just take off as normal but have to bump the rpms so it wont die when starting off. If you don't it dies as soon as you try to accelerate. Other than that it runs fine above an idle, Does this carb have an accelerator pump, or is this just the way this carb is?

 

If there is a good way to tune it, please let me know. THe car was fully restored in 2011, and everything including the engine was rebuilt,.

 

Thank you

 

Mike

 

Edited by Delco32V (see edit history)
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At least until Series 30B and Series 401 Pontiac carbs did not have accelerator pumps.  The device on the Marvel carbs that looked like a pump was actually an economizer control.

Hope the attached data helps you.

Carburator and Engine Tune Up Data - Pontiac and Oakland 00 Cover.jpg

Carburator and Engine Tune Up Data - Pontiac and Oakland 01.jpg

Carburator and Engine Tune Up Data - Pontiac and Oakland 02.jpg

Carburator and Engine Tune Up Data - Pontiac and Oakland 03.jpg

Carburator and Engine Tune Up Data - Pontiac and Oakland 06.jpg

Carburator and Engine Tune Up Data - Pontiac and Oakland 11.jpg

Carburator and Engine Tune Up Data - Pontiac and Oakland 12.jpg

Edited by Guest (see edit history)
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  • 2 weeks later...

So I've been thinking about this. I took the car out yesterday for the first time in several weeks.It is a trailer queen and is only taken out to run it a little bit. Through the winter it only was started and run for a short time, couldn't drive it.  It ran OK, but was exhibiting the same issue as described. Then I heard a noticeable knocking as I started to drive it. This went on for several minutes ,then all of the sudden the knocking stopped and the engine ran better and smoother and stayed that way. The engine was fully rebuilt, new bearings, rods etc. Oil pressure was good. I realized this was not a rod, but a hung valve that finally though heat and enough oil splash finally got completely free. I'll bet that it was slightly sticky throughout the winter and that is why it ran the way it had. It may have had more than one doing it for all I know. I run the car on 100 low lead av gas, so no ethanol issues here.

 

I've had sticking overhead valves before in other engines. I would guess this happened as it just wasn't run enough or long enough to free it completely. I do not believe the lash is too tight. 

I've read that some folks will put a little 2 stroke oil in the fuel to help keep the valve stems happy. What say you?

 

 

 

Thank you

 

Mike

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The simplest solution would be to drive the car.  They were built to be driven not to be started and driven for five minutes a few time a year.  A ten mile drive every time it was out would probably eliminate your problem.  Even if you had a temperature gauge and ran the engine up to operating temperature the block, valve guides etc are not fully warmed up for a lot longer.

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