axapowell

Anybody change out the Q-Jets to Holleys on their 454 Mags?

A buddy of mine is looking to put Holley 800cfm's (HP 500 carbs) on his 454 Mag 365 hp. Have already freshend the motors with new heads and exhaust. Not really looking for performance gains, but the Q-jets seem to be gas hogs. It already has the dual plane intake, which we would use the conversion spacer to accomadate the Holleys.

Looking for a starting place to jet these things and any real results from the change. Anybody?

Thanks,
Dave

jeff1000man

They are all going to suck gas. Try putting that gas to work by building some engines that will make power with the fuel.

You really don't need those big 800's on there unless you are planning to build bigger engines later. If you didn't do a cam swap, then you aren't picking up much power anyway. Change over to a single plane high rise intake for a little more power on the very top.

Good luck.

Griff

The Holleys will suck even more fuel than the Q Jets at cruise speeds.

thumper038

iTrader: (1)

Yep what they said!

picklenjim

78's or 80's all the way around for a start.

ezstriper

750 would be what I would run..they work well on mild setups..Rob

jeff1000man

I just took a 496ci engine off the dyno. I did a comparison between the 750 holley, and a 900 holley. Maybe a 1% difference.

You have to always remember to figure out how much carb does the engine need??

The 496 that I have didn't make any more real power with the bigger carb, so the engine didn't need it.

That is just more food for thought.