Alright guys,
My buddy has a 92 Formula with a .40 over 350 with flat top/valve reliefed pistons, the bottom end has been balanced and blueprinted, but it's all stock stuff! He will be running vortec heads that will get cleaned up, but other then that, they will be stock! He is ditching the fuel injection and going Carb'd! The question is, what carb to go with? Been told 650 and also been told 750, so I thought I would post up and see what you guys say! Hope to hear some advice! thanx for your time and sorry for the kinda long writeup!

Vinny

 

Good question. I personally think the 650 would be plenty. Yet I see a lot of guys running 750s with this combo. I've researched this a little myself since this is the combo I am wanting to put together. Although, I may end up going with a 400 shortblock so a 750 is a must.

 

what is the compression ratio? if it's lower with stock heads don't go bigger than 650cfm. with higher compression 10.0:1 - 11.0:1 and at least fuelie heads (camel hump heads 202/160) go with a 750cfm.

 

just reread your post. go with a 600cfm no more than 650cfm if all stock.

 

It's been bored .40 over, just uses stock stuff if I remember right! He talked to Holley and they said go 750, so that's what he is gonna do! Thanx for the help guys!

Vinny

 

750 seems a little big to me. he may want to buy a jet kit also.

 

He's gonna talk to them again and go from there!

 

Go with a vacume secondary 750 with 30cc squirters and start off with 70's in the front and 74's in the back with both power valves still in it.

My nova has stock casting vortecs....


Mechanical 750 hp series holly with a 50cc in the front, and 30cc in the rear, 78/88 jetting for a 12.9 afr.... all motor

I will be stepping up to an 830 main body to give it more air on the bottle.

Hope this helps

Dirty

 

He is gonna go with a 750 and the Comp 292 cam! Should do pretty well power and sound wise! Thanx for the help/suggestions guys!

Vinny

 

With that 292 cam make sure his vortec's are clearanced for that much lift. They have valve stem seal to retainer issues when used with cams with decent lift. IIRC they can handle .450~.475 stock.

 

Will do! Thanx for the advice!

Vinny

 

Use this formula

Displacement x Max RPM divided by 3456 = cfm size

For an example:
357 x 6000 divided by 3456 = 619

So a 650 should be plenty