[Hobbes9112]

Have a chance to pick up a set of vortec heads and an edelbrock air gap intake for a pretty good price. I have heard good and bad about these heads. Are they worth buying? If so, what kind of cam would I need? Would I have to upgrade the springs? What kind of performance increase would I be looking at?

The block is a 350 bored .08 over (I already know this sounds crazy, but it is what I have to work with). I was going to use some 76cc cast iron heads and an edelbrock performer with a Comp Dual Energy cam #12-208-2. I don't know much about vortec heads and any suggestions would be greatly appreciated!

[DOUG G]

Not sure about if the 906's are good or not. Vortec's are 64cc chambers and about 170cc runners. Really depends on what pistons (compression) and usage.

[Hobbes9112]

I have the pistons that came with the block, but I am not really sure what they are. They are nearly flat, but that is about all I know. My Camaro is driven to shows, cruises, on dates etc., I don't plan to do any racing, but I want a good performing motor that can get up and go when a punk in a Honda pulls up next to me. [img]smile.gif[/img]

[67 Plum]

Hard to tell with out specs.You may have to much comp. with the 64cc heads.The 906 are good heads.

[DOUG G]

Plum, thats where this looks like its going.

Hobbs,look up the piston numbers and go from there.

[JimM]

if your pistons are the normal 4 eyebrow flat tops, use an .040 gasket and you'll be fine on compression if they are 64cc heads.

[kamero68]

The 906 Vortecs were used on the heavier duty trucks and have pressed in hardend exhaust seats which makes them more durabale and resistant to cracking. The down side is, the machining mismatch of the pressed in seats with the bowl walls. The mismatch is miminal and can be blended but these heads dont flow quite as well as the 062s. But again, the difference is very, very slight. I would use them.

, the springs have around 70#s on the seat and if you want to run much more than .450 or so of lift you'll need to up grade springs and shorten the valve guides for retainer to seal clearance.

[ 03-23-2005, 12:25 PM: Message edited by: kamero68 ]

[Chris88Z]

I love vortecs in every aspect. If the deals right scoop 'em up but be prepared to do some machine work if you want to use them in a performance motor. Have the guides cut down, upgrade the springs, and install screw-in studs. After you've done that you'll have a head thats capable of 11's with the right combo.

[travis]

The 906 casting is the only 350 vortec head I have ever seen. I've installed 2 sets and have a 3rd set here for another engine. None of my 906's have the bigger exhaust seat either. The thick exhaust seat, AFAIK, was only used on the 3/4 ton and larger truck 350's, not the 1/2 tons. Also, AFAIK, the only difference between the 062's and the 906 castings is that one was factory installed on the truck engines, while the other one was over the counter only.
One thing you need to check is the deck height of the pistons. A .030 flat top with 4 valve reliefs, .040 in the hole, with .041"x4.166" standard felpro head gaskets will yield 9.4-1 compression...perfect for a wide variety of streetable performance cams. If the block is 0 decked, your compression would be closer to 10-1...still plenty doable with the right cam selection. The vortec heads fast burn style chambers are much more detonation resistant than any old style head.

[Hobbes9112]

These heads are off of a 1997 k1500. How do I measure the deck height. That might be a dumb question, but this is the first engine I have ever put together.

[67 Plum]

With the shortblock assembled you measure from the top of the piston to the deck surface with the piston at top dead center.

[kamero68]

I guess I didnt know what I was talking about even with 20 years experiance working on heads for a living, but here is an article from CHP that seems to agree with my observations.

http://chevyhiperformance.com/howto/97458/

[ 03-23-2005, 12:34 PM: Message edited by: kamero68 ]

[Eric68]

To measure dech height lay a straight edge across the deck and measure the distance between the straight edge and the top of the flat part of your piston when its at TDC.

[BPOS]

Question:

Since the piston will rock in the bore, should you measure the high and the low and compute an average, or should you go with the smallest reading only? Or should you measure at the wrist pin centerline where piston rock has the least effect on the measurement? Thanks.

[Mkelcy]

Originally posted by kamero68:
I guess I didnt know what I was talking about even with 20 years experiance working on heads for a living, but here is an article from CHP that seems to agree with my observations.

http://chevyhiperformance.com/howto/97458/

The "avoid the 906 Head" in the cited article turned out to be wrong information, that even Chevy Hi Performance backed away from. Turned out to be confusion about what the casting numbers meant. The best URL I could find explaining what went on was from Sallee Chevrolet's BB: http://www.sallee-chevrolet.com/Disc...tml?1089732160