I need some advice here on my 1987 350 TPI IROC. We just discovered that it has an intake manifold gasket leak. Meaning that we have to get pretty far down into the engine to fix it. Then engine has 120,000 on it, runs pretty well and only leaks oil, doesn't seem to burn it (no smoke at all even on startup) So I was thinking, I could throw a water pump, timing chain/gears and possibly some heads at it. Since it's my daily driver, I am keeping it stock as much as possible. (less trouble that way) I found some Heads that will fit:
1987-1995 305 & 350 Chevrolet engines. Will raise compression on 350 engines .5-1 point depending on pistons
58cc #14101081 GM cylinder heads
Baked
Blasted
Magnafluxed
Resurfaced
New valve guides
Intakes cut for 1.94 valves (were 1.84)
Multi angle valve job
New 1.5/1.94 valves
New springs (110lbs, .525 lift)
New seals
New hardened valve keepers

Now, here is the question. I really can't go into the bottom of the engine. ($$$!) I have good oil pressure (30/60 with 10w-30 and 50/60 with 20w-50) the engine doesn't knock, i get 22-23mpg hwy. But i have heard if I put on new heads I will break the bottom (bearings/rings/rods etc) The previous owner of this car cross threaded the #8 spark plug at some point, new heads would take care of that problem at the same time. Can I do this? Or will it cause me MORE problems than it solves? Any advice on this would be helpful, I'm gonna have to do something pretty soon since in addition to leaking oil, the manifold gasket is starting to leak coolant as well. Also, are there any OTHER things that should be replaced while we've got the top of the engine off? (Oil pressure sending units are already on my list)

 

It shouldn't break anything really. If you drive it like a grocery getter than you'll probably never have a problem with it

But for the price your probably going to pay for some heads, why not just rebuild it instead?

 

The price a lot of these shops selling the 305 heads cut for 1.94 valves is starting to approach the price the aftermarket manufactuers sell their SR heads for. For 100 to 200 more bucks you can probably get a brand new set of World, Iron Eagle, or pro topline Stock Replacements. And if you want the smaller 305 size chamber for higher compression you can get the 305 torquers. Just something to think about.

 

If you do change the heads and timing set, I would consider a cam swap at the same time.

 

One thing I really DON'T wanna do is raise compression. I live in CO at 6500ft and I can run regular unleaded no problem (more compression would also mean more stress on old rings!) I can get the new heads for $400, they are cast iron ( I don't want aluminum) with the above specs. Most days I drive it like a grocery getter, but we also take trips and I REALLY get down and drive it. ( I can put 700 miles on her in a weekend NO problem!) If you know of good heads in the same price range, PLEASE, point me in their direction!

 

Then why not just port your heads and then get them redone?

 

Hope this link works:
http://www.primediapowerpages.com/cg...216&2D101012/1

There are several on that page. At the bottom look at the 67cc pro topline assembled torker heads. They are 3 cc bigger than yours but the extra flow should make up for any loss in compression and ensure not detonation. 530 is a little higer than 400.

If you wanna spend less than 400 then I would do what 85TPI400 suggested and get yours redone before I would buy the reamanufactured heads. Unless of course you can't find a shop to do it for less than that.

 

Those 081 heads are the 305 version of your heads
083 or 217. So with a 1.94 they would be the same as yours.
The ports are the same.

When you install the bigger 1.94 valve in a 305 head the chamber must be enlarged a little so they'll likely be bigger than 58cc's
about 60/62 unless they were milled.
Don't see any increase in flow or compression compared to what you have now.

Look into a set of Pro Topline iron lighting 180cc heads with 64cc chambers. Or port your own heads.

You can repair the sparkplug threads witha Heili Coil.

The 305 (081) heads can be made to flow decent with lots of porting but yours have equal potential.

 

Ok, so it looks like I really am better off having my own heads re-done. Biggest problem will be finding a machine shop that does decent work. But it seems we all agree that whether I redo my own heads, or get another set, provided I stay around the same specs, I won't hurt the bottom end? What do shops charge generally for a GOOD job on a set of iron heads? Anything I should look for? Stay away from? Thanks for all the help!

 

Another option, since you've got it down that far......

Try finding some alum L98 Vette heads...I've seen these go for as little as $400 ready to run. Add a good cam, something along the lines of the ZZ4 roller car ( $125 from GoAutocenter ) and you'll be presently surprised at the difference in power.



HTH

 

I think it would be silly not to install a new cam while you're at it. And heck it'd be a great time to install some headers if you don't have them, since you have to take the manifolds off anyway.

Of course I just added a couple hundred $ to your budget too