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I know most of us are running fuel injection, but I have a buddy that is building a street/auto-x car and he is going to run a carburetor. when I used to run carbs, I think you could get a carb that had a center pivot float. Is that right and is that what he needs?

Barry
 

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Barry,
Look into the Holley street avenger Carbs. They have the Center Pivot's.
I run a 570 CFM on my 84, and it's Tune right out of the Box is pretty Good.
My Car is basically Stock with an 86-93 Factory Exhaust and Under Drives, so depending on How wild and Engine your friend is going to Build, you my have to Jet it up a bit.

Scott
 

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Discussion Starter #4
That's good info. I looked on Holley's website and they also show a "lowrider" car that says is designed for extreme angles. That might be a good application as well.

Barry
 

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I run a 750dp on my 408W and it's a center hung design. Floats are beveled on both sides to account for fuel slosh in the corners. I initially had the Carb Shop build it to my engine specs and usage.
 

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I run a 750dp on my 408W and it's a center hung design. Floats are beveled on both sides to account for fuel slosh in the corners. I initially had the Carb Shop build it to my engine specs and usage.
May I ask what the Carb Shop charged you for a custom tune? Did you have to do any additional dial in to get it "perfect"? Does changing weather require you to change jets? (Think cool dry spring day vs hot humid summer day).

I run a 750 dp on my 383W and can't say that I am totally satisfied with it. I have a stalling problem under heavy braking that I am masking by using a 1500 rpm idle sped.


Thanks
 

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Eric, I didn't give them a carb to tune, I bought a carb from them set up for my application as I had nothing to work from. It was about 8yrs ago and I think it was in the $500-600 range. We had to make a minor jet change on the dyno but other than that it was spot on.

I'm sure you checked the obvious but I'd put the power valve on suspicion.
 

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Steps to make carb work in AutoX:

Center pivot circle track float front and back.

Cut other side of float at angle to match OTS circle track cut.

Set float level EXACTLY. If it takes less than 15 minutes of bumping the car around, you did it wrong...:)

Some cars with a lot of pitching and body roll (a lot being more than 2 degrees of a super stiff CP car) may need to run a hose from the front vent to the back vent that has holes in the very top of it to vent. This keeps fuel from sloshing out the vent under hard braking, into the venturi, killing the motor.

Also, if you do this, don't seal the hose shut with the air cleaner lid....don't ask me how I know about this. :)

Once budget and time allows, I may switch to EFI, but in reality for a purely autocross application, the carb works fine. Also, typical EFI tuned port manifolds really kill power compared to a good carb intake (I use a super victor).

DaveW
 

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Or, i could read "Toys" post before typing the same darn thing....:)

I run a 750dp on my 408W and it's a center hung design. Floats are beveled on both sides to account for fuel slosh in the corners. I initially had the Carb Shop build it to my engine specs and usage.
DaveW
 

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Or, i could read "Toys" post before typing the same darn thing....:)
Yeah but I applaud your effort. Plus the vent tip is a good one.
 

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I am definitely going to try the hose on the vent trick first. The engine runs well in all situations with the exception of hard braking.

Toys said:
Eric, I didn't give them a carb to tune, I bought a carb from them set up for my application as I had nothing to work from. It was about 8yrs ago and I think it was in the $500-600 range. We had to make a minor jet change on the dyno but other than that it was spot on.

I'm sure you checked the obvious but I'd put the power valve on suspicion.
I guess I stated my question wrong, but you answered the question I was trying to ask about the cost of a carb tuned to my engine specs. Power valve now on order too!

Thanks guys.

Here is a link to a page by Bo Laws Performance discussing the design of floats and valves.

http://www.blp.com/pdf/install/BLPFloats.pdf
 

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I would definitely suspect fuel coming out of the vent tube in hard braking. I had a float problem once and it was shooting fuel out the rear vent tube and it would stall the engine. I re-adjusted the float and haven't had the problem since.

I also have the double beveled floats. I'm running an 850 Quick Fuel Technologies carb on my car.
 
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