Guys,
I've got a fairly stock 350 crate motor on my 71 chevelle. I'm wanting to change my heads on my winter rebuild because I have a horrible flowing 76cc head "Hecto in Mexico" that came with the motor. I was wanting to do vortecs, but they are a touch pricy for my budget and I already have a nice intake and valve covers. My friends dad has a nice set of 70's heads casting 3991492. Which are:
LT1,Camel hump,accessory holes,64cc, straight plug 3991492....70-up................over the counter,Camel hump,64cc, straight or angle plug ...
Could I turn these into a decent set of heads or an I shooting myself in the foot for not going vortec?
PS his price is 100 bucks for the heads. I would need to refresh them however.

Randy,
The '492 (double hump) heads in question come in 2.02/1.60 & 1.94/1.50 valve sizes. The latter can be machined for the larger valves, but most machine shops are pretty "proud" of their work and charge accordingly. I have a pair of these heads and while state of-the-art in the day are out moded by today's standards. Not certain what you mean by "refresh", but you w/probably need: new valve guides, hardened exhaust seats, springs, keepers, valve job, at a minimum.
These costs really add up and when all is said and done you will have a set of heads that doesn't compare w/the newer, better, and probably cheaper Vortec iterations. Check with you machine shop and see if you can pin them down on the actual cost you will incur. Tom

thanks Tom,
I've never worked with heads before. I'm not real sure what the costs typically are to get a set of heads reworked. I'm sure it can get pricey. I've just never actually attemtped to mail down a price.

If you get lucky and don't need guides, your looking at $200 or so for a rebuild/resurface. If its a stock crate motor I wouldn't swap heads without changing the cam/lifters/springs. Just my $.02

Good Luck!!!

To properly work up a set of heads, from junkyard stock condition to full race prep, costs around $650-750, plus port work.

Work they will need:

Clean-up
Enlarge intake valve seats 1.94" to 2.02"
Enlarge exhaust seats 1.5" to 1.6"
Pull out pull-out studs
Mill stud bosses about 3/8" (varies from head to head - correct way to do it is to cut them to some specific distance from the deck)
Drill & tap stud bosses
Cut spring pockets to 1.45" or 1.55" A/R, cutting only as far down as a .030" shim to avoid hitting water
Cut valve guide OD to .530" or .500"
Cut valve guide height down
Drill push rod holes out for push rod clearance
Drill guides & install K-Line liners
Valve job
Deck true
Bolt holes repaired & Heli-Coiled A/R

Parts:

Valves (int & exh), preferably .100" longer than stock
Guide plates
Threaded rocker studs
Valve springs
Retainers
Keepers
Seals (Teflon)
Shims
Spring seats (maybe - depends on springs)


Plus port work.

It's REAL REAL EASY to run up a bill HIGHER than it would cost to just buy BRAND-NEW castings, which will come to you with all that work already done.

Think REAL HARD and CAREFULLY about how far you're willing to go, BEFORE biting off. Take that list to your machinist and see what it will cost, up front. It can be real sobering to go pay a $1000 bill at the shop for a set of heads, and then discover you could buy Darts or Trick Flows or something, for less than $100 more; and had an ALTOGETHER BETTER casting to begin with.

To properly work up a set of heads, from junkyard stock condition to full race prep, costs around $650-750, plus port work.

Work they will need:

Clean-up
Enlarge intake valve seats 1.94" to 2.02"
Enlarge exhaust seats 1.5" to 1.6"
Pull out pull-out studs
Mill stud bosses about 3/8" (varies from head to head - correct way to do it is to cut them to some specific distance from the deck)
Drill & tap stud bosses
Cut spring pockets to 1.45" or 1.55" A/R, cutting only as far down as a .030" shim to avoid hitting water
Cut valve guide OD to .530" or .500"
Cut valve guide height down
Drill push rod holes out for push rod clearance
Drill guides & install K-Line liners
Valve job
Deck true
Bolt holes repaired & Heli-Coiled A/R

Parts:

Valves (int & exh), preferably .100" longer than stock
Guide plates
Threaded rocker studs
Valve springs
Retainers
Keepers
Seals (Teflon)
Shims
Spring seats (maybe - depends on springs)


Plus port work.

It's REAL REAL EASY to run up a bill HIGHER than it would cost to just buy BRAND-NEW castings, which will come to you with all that work already done.

Think REAL HARD and CAREFULLY about how far you're willing to go, BEFORE biting off. Take that list to your machinist and see what it will cost, up front. It can be real sobering to go pay a $1000 bill at the shop for a set of heads, and then discover you could buy Darts or Trick Flows or something, for less than $100 more; and had an ALTOGETHER BETTER casting to begin with.


I " think " his car is just a street peeler he wants a bit more out of.

Under his current heads is a stock mexican crate engine. He already said even vortec heads are out of his price range.

IF he gets lucky and his $100 heads aren't cracked and the guides aren't wasted, matched with a basic rebuild & resurface and a cam they'd prolly wake his 350 up a bit.

I am definatly not going race prep here. I am going for 350 HP. Yes on this rebuild a new cam of some sort will be going in. This thing is dead stock currently. The double humps that are offered look near perfect for bare castings. No surface rust or anything. They certainly need valves and seats and possibly blasted. In the end is it safe to assume I'm loosing 30-40 HP by not going with a decent vortec set up? I'm really cheap here. I'd like to do this converstion on a budget. The vortec heads aren't too bad, but they require me changing the intake and valve covers. Two things that on my engine I really like (Edlebrock RPM Performer and tall chrome valve covers.

Just to let everyone know. I went ahead and got a set of used Vortec heads, intake and valve covers all for a good price! Thanks for the input. Now I just need to open a new forum and learn how to get a touch more lift out of the vortecs.

http://www.nastyz28.com/forum/showthread.php?t=56505

Here's a link with all kinds of good Vortec info. I'm gonna do a Vortec swap too, and I also have a Hencho block and heads. I think a great cam for Vortecs is a Crane Powermax cam with 226/234 duration with 458 and 473 lift. It should clear the guides but you better check. That's what I have in the enigine right now and it sounds killer and runs strong too, even with the low comp I have now and the crappy heads.

I opened a new thread on the subject.
http://www.chevelles.com/forums/showthread.php?p=1531587#post1531587