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Updraft Carb question


Guest Merchant Xpress

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Guest Merchant Xpress

I need to put another carb on my 29 DB pickup. I can buy a new Zenith carb for the same price as a rebuilt Carter but the Zenith is an industrial carb and doesn't have an accelerator pump. Has anyone used a carb that doesn't have an accelerator pump on their car? Will it work in an automotive application? If not why not? I know the Carter BB-1 is a good carb but it is a 70 year old carb or older while the Zenith is brand new. I can't seem to find anyone who can give me an answer to this question one way or the other.

Harry

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I am not a carburetor guy, but it would seem to me that with an in-line fuel pump and fuel regulator, you could push about 1 1/2 lbs to 3 lbs of pressure through without having to use a carb WITH an accelerator pump. Just guessing...

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Guest Merchant Xpress

Keiser, thank you for answering my question. I have a vacuum tank fuel supply that uses gravity feed. At least with this Tillotson carb on the truck now I can't have any feed pressure without flooding out the carb, heck it even leaks with gravity feed.I think the Carter and the Zenith will hold better. I think without an accelerator pump there may be lag when I step on the throttle but I'm not sure. I do know with an accelerator pump you can flood the carb and start without a choke if you have to.I can use the choke so that isn't an issue. Both carbs come highly recommended but the lack of I'm not sure what issues I'll face without the accelerator pump. Maybe none?

Harry

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The purpose of an accelerator pump is to give the engine an extra shot of fuel when you step on the throttle. If you don't have one you will have a flat spot or an hesitation every time you step seriously on the gas. If you are driving seriously sedately (and I mean 99 year old woman on a Sunday afternoon drive sedately) you would not miss it. However Having driven my car for a few days when the pump wasn't working I would not wish to voluntarily drive that way.

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Guest Merchant Xpress

I thought so too, shopped around until I found one that would go down to 1 psi and the carb still flooded. That is a problem of the Tillotson though, from carb guys I've talked with the carb was notorious for overflowing or flooding. Once the vacuum tank is working properly there will be plenty of fuel, mostly I'm trying to figure out if a carb with no accelerator pump will work properly. They work fine on industrial engines so I'm not sure why it wouldn't work for my truck. I often wish I were smarter about these things.

Harry

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You can't really compare a carb with a broken accelerator pump to a carb that was designed without a pump.

There are many early cars without accel pumps, as well as countless farm tractors, equipment, etc. Even a governor controlled carb on a tractor takes the gas OK without hesitation as you start to move and the governor slams the carb wide open.

I would not expect it to hesitate, but at 250 plus shipping, I'll refrain from making a guarantee smile.gif

I did run a tiny industrial carb on a 29 U, but that was just around the driveway...maybe 1971..

If your carb flange is opposite than most early carbs that would be cheaper, I have seen an adapter that rotates the pattern 90 degrees. Don't recall where it was, but they would be easy to make. Then put on a new Model A carb? if cheaper? or is that the carb you listed?

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Guest Merchant Xpress

F&J, my truck has the 29 U engine in it. The Carter carb has to have an adapter as the bolt spread is 2" The Zenith has the correct spacing of 2 3/8" and is rated for engines up to 250 CI. The U engine is 170 CI so the carb will if anything be over rated. I would really like to hear from someone though who is running a carb without an accelerator pump for their input on how it operates.

Harry

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