454 Card size

[68_Step]

I just purchased a Chevy 78 C-30 with a 454 in it. The carb on it is a Holley double pump 600, #4776. Is this card big enough for this engine? The engine has headers and "may" have a mild cam installed, not sure about that. As a side note, the engine does not seem to have the power I would expect from it. I know there may be numerous tuning problems, but the 600 carb was what first jumped out at me.

Thanks!

[SanitysBane]

wicked man, u know that the 3/4 77 454 was the fastest thing around in the day. well xpt for the 'vette but it could give it a run for the money. i am partial to the quadrajet so thats what i would put on itplus its a 750 CFM

[stepside454]

I agree with Sanity on the Q-jet, but to answer your question, I say no, not only is 600 cfm not enough, a mechanical secondary is not the right set up .
It depends an awful lot on what max RPM you intend to run it to, with it being stock, with maybe just a lil cam, Im gonna assume youll stay within 5000 RPMs. In that case Id go with either a Q-jet, or a 670 Holley street Avenger(vac. sec. ), the 670 might like a 1"open spacer under it on a 454, or a Demon 725.

[SanitysBane]

if u want more performance i would look at the edelbrock heads that have the tiny combution champers to help that low compressoin ratio out (7.4:1)

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Stepside454: Which Demon 725? Road Demon Jr or the Road Demon?

If I use a Q-jet, will I have to replace the manifold? Isn't the 600 Holley is a squarebore, and the Q-jet a spreadbore?

[SanitysBane]

u could use an adapter, thats what i have

[stepside454]

for your application the jr. would probably be fine. as far as well a q-jet fit, what intake do you have ?

[68_Step]

Stepside454: It is a Preformer Z-0 manifold

[stepside454]

I assume you mean performer 2-O. if thats the case, it is compatibal with both square & spreadbore carbs