I am thinking about a 350 with Votecs for my old Nova and have some questions. I need power at 1000 rpm so the cam will be extremely mild. Do the normal rules apply about compression and mild cams or are the Vortecs different?

The same applies b/c all that would be different would be a timing change.

The Vortec heads have a more eff. combustion chamber so can be timed back and still make great power.

Anybody else, please chime in here.

pdq67

The vortecs will give you some leeway on compression. Where the old 76cc style iron heads might only tolerate 8.0-1, the vortecs will tolerate at least another point or more. I could give some specific examples if you want from my own personal experience. And really, for a strong street engine, these things don't need much cam at all. Look at the 350 ramjet engine...350hp with something like a 196@.050 hydraulic cam.

Anyone know what pistons Chev uses in their crate Vortec engines? (flat-top, dished)

flat tops pistons you should be around 9.7 to 1 depending on the size of the valve releifs or decking of the block.

Just for a an example, I'm running a true 9.8:1 (190PSI) compression with my Vortecs, and have no ping whatsoever on 91 octane fuel. I also run 33* total timing (20 initial), and all in by 2600RPM.

Silver 69 how much cam you running? I still haven't got any pistons but may go with dished because of my RPM needs.

I'm running a Isky 270 Megacam, it's 221 @ .050 with 108LDA. The tighter LDA helps build cylinder pressure.

I'm also running flat top pistons with four valve reliefs.

I've only run this motor to 6000, and it pulls strong. I think it could go a little higher, but I don't want to push the motor too hard.

Probably a dumb question, but i'll go with it anyway:
Can you have Vortech heads tapped & drilled for the old style valve covers without causing all kinds of problems?

I hate centerbolt covers- I'm looking hard at a set of Vortechs- But am leaning towards some Dart's instead because i can keep my polished alum covers...

Thanks for any responses...
(btw: I know they make an adapter, and i have heard they leak real bad- so no need to suggest that option) ;)

You can, however, you'd have to weld on some extra materia to drill and tap. Otherwise, in my experience, no.

Even though the centerbolts seal much better than the perimeter style, it's still tough to give up your favorite set of valve covers. IMO, the adaptors aren't worth it.

Theres definately not enough material in the valve cover rails to drill and tap for the old style covers. Personally I like the centerbolt vc's...they give a different look under the hood and they don't leak.

I have the adapters and they leak :mad:

Dan.

The Aluminum Fast Burn (Vortech)heads from GM are drilled for both types of valve covers.
Jim

The GM Vortec crate motors use a dished piston, but I don't know if it's a round dish or a D-cup. If the KB piston site ever gets back up, they have charts for compression ratios for their pistons when used with different chamber sizes. They also have some good info on engine building. Their catalog has the same info, and is free for the asking.

Just ordered everything from SalleeChevrolet.com Super prices and they know what they are talking about.