I have a new 500cfm carb that id like to put on a large engine (lets say 468) for a short period of time.

I want to do this so i can set the engine up with a carb that i know is working.

Will this damage anything, or will this cause the engine to idle badly? As long as i dont get on the gas too much, do you guys think i can use this engine for the 500 mile break in period?

Im sorry for all the weird questions, but i have to cut corners because im on a budget.

Thanks
-Ryan

Maybe I'm simple minded, but as long as you jet the carb properly, what's the difference between a 500CFM carb at full throttle, and a 750CFM running at 2/3 throttle? I don't think it would hurt anything. The only thing that comes to mind is that the power valve (and jets, like I suggested) may need to be modified for such a small carb on a big engine. As long as you don't go too lean, you should be OK.

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Mike Newby

69 Chevelle 355/TH200-4R
97 Grand Prix GTP
64 Chevy C10 Pickup
79 Suzuki GS550

Just make sure it's not too lean as stated, and it will be fine.

Look at like this, the Winston cup cars run a restrictor plate that reduces the 750 down to less than 400cfm, and they make what, 700 plus hp and spin those things over 9000, wow!

Jetting is everything. You set that up right and it will bust so hard it will scare you, you might not take it off http://www.chevelles.com/forum/smile.gif

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www.muncie4speed.com (http://www.muncie4speed.com)
Gold 67
A.C.E.S. 5602
M.C.C. 559
1967 Malibu, 2nd owner.
1971 Malibu, new rat is in. It's the details that take the time!
There is nothing like rowing through the gears at 7500. Stick cars are so much fun they should be a controlled substance!

I ran a 600 cfm on my 462 for awhile,ran fine.

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My 70 SS396 (http://www.chevelles.com/showroom/mr4speed70SS1)
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101.84 Best MPH
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1968 Oldsmobile Cutlass convertible
1973 GMC Sierra 454 p/u
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Chris Corwel,TC Member # 785
Member # 141 AMCA

Thanks guys - good point Wally

Ok - another question - should i go with a Performer (dual) or Torquer (single) intake manifold.

If you didnt notice yet, im not too concerned with power - more with drivability and low end torque.

I remember an ex Trans Am racer (Boss 302 Mustang) told me that motors with large bores and short strokes need a larger cfm carb whereas a motor that has a bore and stroke that are nearly identical (square) will often work better with a smaller cfm carb.

Least thats what he told me.

Burke

Put the Performer on, it will work better with that carb.

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www.muncie4speed.com (http://www.muncie4speed.com)
Gold 67
A.C.E.S. 5602
M.C.C. 559
1967 Malibu, 2nd owner.
1971 Malibu, new rat is in. It's the details that take the time!
There is nothing like rowing through the gears at 7500. Stick cars are so much fun they should be a controlled substance!

Ya dual plane for sure. Hey, I ran my 433ci with ONE 500cfm 2 bbl. ( the other two were unhooked). No probs. Ran strong to 4000 rpm.

The only real potential problem I can see is if the idle circut is lean to begin with IE:
An emmissions type carb you may have some driveability problems.If not then it will likely run fine.If you have alot of gear and driving on the freeway you are spinning the engine 3000 RPM you just might find that you will actually be into the secondaries at that rpm.Thats the reason I'm not a fan of Qjets if you have gears.Fuel consumption can be rough when spinning a large engine at those RPM's.Gas mileage goes down when cruzing alonng and your in the secondaries just to maintain that MPH.If you have gearing that puts you in the 2500 and under range it should work deciently.

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1969 El Camino
69 LS1 335 HP 427
( not the origional engine)
M21 12 Bolt 3:07's.
Daily Driver work truck.

For a street driven car you are much better off with too small a carb than too big a one. Don't worry about the jetting as long as you don't put some type of race manifold on it. The bigger the engine the stronger the signal to the carb so it automatically compensates for the larger amount of fuel needed. That small a carb on that big an engine will have super throttle response, you might even like it.