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Pontiac Carter carb, 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

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The early production 1928 Pontiac came with Carter DRJH-0 identification number 101s. Pontiac unfortunately switched to Marvel in mid-1928.

 

The Carter DRJH-0 was equipped with an external accelerator pump with a zinc alloy (pot metal housing). In 61 years of working on carburetors, I have yet to see one of these that was unbroken and usable. Generally, on that model, they are missing, and the cast iron housing plugged.

 

The amount of fuel originally delivered by that accelerator pump was maybe 5 percent of the fuel delivered by a more modern carburetor.

 

The value of the accelerator pump in 1928 was largely in the mind of the driver; it had little to do with car performance. Low speed issues are likely to be ignition related (timing/advance), or, if carburetor related, an idle tube that is not sealing.

 

The 1926/27 Pontiac used a Carter DR-0 which had no accelerator pump.

 

The type, DR-0 or DRJH-0 is cast on the side of the carburetor throat.

 

Jon.

 

 

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Thank you Jon. We are the latest caretakers of the car.  I'll check to see which one it is. Do you have a diagram of these that I can see?. I don't know who rebuilt that carb before, and like I said, it seems to operate fine once you are moving along in higher rpm. As for adjusting it, any magic I should know, or is it straight forward, ie do the low speed screw first, then the high speed?. It seems off on idle, doesn't sound right to me.....

 

Thank you

 

Mike

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  • 1 month later...

Read a quote once that said (paraphrase) "  90% of my gas problems were electrical."     

I once worked on my 1921 Paige carburetor for months because of poor running.   Turned out to be a bad spark plug wire.

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Or better yet, a sticky exhaust valve. I didn't touch anything except (as advised) drove the car for a good 30-45 min in 85 degree weather.  When I took it out of the trailer, It had a knock like a rod. As the whole engine had been restored (new bearings rings etc) that wouldn't make sense with normal oil pressure. Turns out it fixed itself. It stopped knocking spontaneously and ran noticeably better. Still does.

 

It has been a trailer queen for nearly 10 years, and only had been driven short distances and short times. In the winter run about 10-15 min trailer door open and shut off, no outside exposure. TinIndian was correct, you just have to drive them. Sitting and short outings does not help, except keep the manifold pristine. I will just step up my cleaning maintenance and touch ups to keep it the way it is.

 

That 6 cylinder has a nice sound to it :)

 

Mike

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