Holley 4780 - Team Camaro Tech
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post #1 of 5 (permalink) Old Oct 1st, 09, 11:05 AM Thread Starter
Dave
 
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Holley 4780

So I was given a Holley 4780 (I believe its a 780-800CFM). I have a 350 bored to a 362 with an aluminum hi-rise holley manifold. The cam from what I've been told is pretty big, its a TRW hydraulic cam, .456 LIFT, .292 DURATION, and it also has #041X 160cc int. 60cc chamber (2.02) heads. My question is should I rebuild this beast of a carb or would you reccomend something smaller? Appreciate your feedback!
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post #2 of 5 (permalink) Old Oct 1st, 09, 01:31 PM
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Re: Holley 4780

Depends on you intended use...
If you are looking for a strip style set-up then the carb will be just fine with some tuning.
With your larger heads, cam and hopefully the exhaust to go with it it may be an acceptible carb for your needs.
For a more street oriented set-up it might prove a tad large, again depending on trans, gearing and ect...
Throttle response will be better with a smaller cfm carb if you intend to use mainly on the street.

Since it was 'free', I would give a good once over, install it and try to tune it to your combo - it may be just right with the proper tuning and jetting.

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post #3 of 5 (permalink) Old Oct 1st, 09, 01:42 PM
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Re: Holley 4780

I think that woud be a killer carb for your application!!..what heads are you running??
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post #4 of 5 (permalink) Old Oct 2nd, 09, 01:50 AM
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Steve
 
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Re: Holley 4780

A 4780 is an 800 cfm double pumper.

Sounds a tad big but that depends on your cam, comp, converter, rear gears etc..
If 292 is your advertized duration number so I'd say this carb is a bit big on that many cubes. But there are some decent 350s that will want more than this so my advice would be to rebuild it, and give it a try. You can always sell it.

Stock jetting is 71/85 and shooters are both 31s. Clues to look for are needing to re-jet more than 4 jet numbers from stock and if you fit a vacuum gauge, you should see about 1-2in/hg at WOT. A carb that's too big will see about zero in/hg.

Holley's rebuild kit for all variations of the 4180 is # 37-485.

http://www.summitracing.com/parts/HLY-37-485/

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post #5 of 5 (permalink) Old Oct 2nd, 09, 10:28 AM Thread Starter
Dave
 
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Re: Holley 4780

Wow...thanks for all the great information! You guys are the best! I will rebuild it and bolt it on and see how it performs. Thanks for the feedback!
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