[fiscus]

Anyone know what compression ratio the vortec 350s have?

what are the pros and cons of using a vortec 350 as a base for a buildup (aftermaket cam, intake manifold, and headers) as opposed to using an older 350 with vortec heads?

I know the vortec 350s are roller, but how does that factor in? any other differences?

[BOBCRMAN@aol.com]

First a few Cons= No mechanical fuel pump provision, block and especially the heads are crack prone, known for cold knock problems, virtually no 4-bolt production blocks, needs special intake manifold, exhaust ports do not fit some headers.

Pro's= Roller cam, one piece rear seal seldom leaks, better ports and combustion chamber design,

[club327]

Seeing that I'm in a similar situation as you I now know a bit about Vortecs. Bobcrman is dead right. They have 64cc head chambers which are heart shaped to promote better swirl and combustion. The inlet ports are higher than normal (hence the need for a dedicated manifold and special intake gaskets) and outflow most heads up to about .480" lift (correct me if I'm wrong). The exhaust ports are less effective though and respond well to a dual pattern cam or by fitting 1.6 ratio rockers on the exhaust valves only. You need self aligning rockers or guide plates......but you cannot use both together! They don't have screw in studs. They're also limited to approx'.450" valve lift due to the high valve guide boss - machining these bosses down in height and diameter allows the use of high performance springs and ensure clearance between the guide and retainer. Also you can only use center bolt valve covers. Check out the following sites bud http://www.chevyhiperformance.com/te...98/index4.html http://www.chevyhiperformance.com/howto/97458/ Reading the good things about the Vortecs would make one buy them in a flash. But when you consider the changes needed to run them and their poor durability record, I think there's other heads out there that are more effective over the long run. Rob

[OddRodder]

A little off topic but, is one casting more crack prone than the other on the vortec heads? 906 vs. 062? I have done three sets of 906 heads to various stages and have had no cracked heads yet, am I just lucky?

[club327]

With the Vortecs cracking, I'm just going by all you guys have been saying. All I know about the 2 castings is to avoid the 906 head, which has specially modified and hardened exhaust seats that kills flow at low valve lift.

[Rhansen]

Originally posted by club327
Reading the good things about the Vortecs would make one buy them in a flash. But when you consider the changes needed to run them and their poor durability record, I think there's other heads out there that are more effective over the long run. Rob

I agree, by the time you add it all up you are approaching the price of AFR or comparable head.