750 cfm carb on a 318

[iw378]

Do any of you guys run a 750 cfm carb on a 318 ? The reason I am asking is that I have a holley 600 now. I pulled my heads off a couple weeks ago because I had a bad exhaust valve
and low and behold my heads have 1.88 intake valves (675 heads). Had a valve job done and now re tuning. I am now at 69 jets in the 600 and it seems to want more. Is a bigger carb in order ?

 

[RustyRatRod]

No.

 

[273]

If your making 400 plus horsepower and squeezing every additional hp is important to you.

Could use a vacuum gauge to check

 

[AJ/FormS]

A little large, for a teener, but
If you already own the 750, install it ,spend a couple of days tuning it, to satisfy your curiosity; then put the 600 back on. But I wouldn't rush out to get one.
A 650DP? Well,now you're talkin. Ilove DPs.
You might need a side of gears to go with that.

 

[UOP]

Large jet sizes are an indicator the carb is too big. If you're way above what the carb came with originally (factory jetting) then the carb you have is already a little big. Not saying you can't run a 750, but I'd stick with a vacuum secondary unit since they tend to "size" themselves to the engine they're bolted to.

That said, I don't think you'll gain much, if anything. The little hp you might gain wouldn't be worth the loss of driveability IMO.

Been there done that.

 

[318willrun]

I've done it with 360 heads and a 340 cam, but it wasn't necessary. It ran good, performed good, but I ended up running a cast intake and thermoquad....