ported & polished heads..

[wireman121]

I am looking to get a set of heads ported and polished..

Here is my problem though, I have the heads from a 93 that had 97k miles on it. I also have a crate motor in my car now, came with 0 miles, has about 12k on it now. Should I remove the 12k heads and have them ported and polished, or would it be fine to have the spare heads ported and polished, then just swap them in for the current ones?

I guess I am asking if the 97k is going to make that much of a difference? Also, does anyone here port and polish heads, and if so, how much?

[RidgeRunner]

As long as the heads themselves aren't warped or otherwise damaged, I'd think mileage would be irrevalent assuming you were going to freshen them up with new seals, guides, etc... or make sure everything is in spec.

[SappySE107]

I do port work, and have done a few DOHC sets already. Cost really depends on what you want done. Using the higher milage heads is fine as long as the guides are good. You would want the heads pressure checked and decked and cleaned though to make sure they are up to par and the mating surface is flat.

Using the lower milage heads would mean the valve guides are probably better, but then you would have to be without the car for a while. If you watch ebay, you can get a new set of heads as well for cheaper than the cost of having all the machine shop work done to make a used set good and verified/cleaned.

I have a set of new heads bare that I ported for sale right now for $500. You would need the valves and springs and seals and all that stuff to put on them. Normally I would charge 650 for the same work.

http://cgi.ebay.com/ebaymotors/ws/eBayISAPI.dll?ViewItem&rd=1&category=33617&item=2453265090&sspagename=STRK%3AMESUS%3AIT

[Lyle's GTP]

Was your crate engine a rebuild? If so I would use the spare heads. Because If the heads have been surfaced once all ready you don't want to do it twice if you don't have to. Also the chances of damaging the surface while porting/polishing is very good, so don't take the chance. It's best to have your deck height as close to stock as possible. Unless you want your heads decked for higher compression then it really doesn't matter.
Lyle

[SappySE107]

dont port the heads because there is a good chance of damaging the surface? I don't agree at all. Why does it matter if yor deck height is close to stock, compression important or not?

[Lyle's GTP]

Well because for your engine to preform optimally you must have both decks the same height, to keep the left and right bank cylinder compressions the same. Also your ECU is programmed for a certain compression, going beyond that could send it out of whack. Then there a issues of detonation and valve clearances. Lots of things, it's just a good idea.

Lyle

[SappySE107]

the computer is not gonna care about .1 diff in compression, so don't worry about that. Deck height is based on the block, the heads being decked doesn't change that. You would want to do both heads equally but thats not a problem. Detonation? Not stock, not from decking to make it flat either. Valve clearance is based on RPM and engine wear and rod stretch. Hence the .012" value I gave.

[Lyle's GTP]

Think about the mechanics of decking the head or the block, they are sort of the same. You are making the combustion chamber smaller and bringing the valves closer to the piston in both instances. But by stock rebuild specs, a head can only be surfaced so many times, even with a thicker gasket. Coming from a company which built 50 engines a week. But it all depends what you think is all right. AERA would probably say not a good idea. The company I worked for scrapped heads all the time because they were .010 low on the head deck height, same for blocks. But again that's stock. High preformance is a different story, but you know that already.

Lyle

[Streetrodder83]

From the factory the deck heights on the block are rarely equal. That's why in factory spec. manuals there is usually a range in specs. Having to machine alittle off the surfaces to straighten things up is no big deal. You should be checking piston to valve clearance anyhow, whether the engine is built for stock or for high performance. Even if the heads were milled .010 I doubt it would cause an interference issue.

[Lyle's GTP]

Yes, you're probably right. With this engine yes but others no. But my mistake, what I ment to say was AREA sets deck height max/mins and if you are below that min. you could use a thicker gasket but some time they are too far gone. Shit, I've seen some GM 350's engines rebuilt 10+ times. Some that we get have come back with two of our serial #'s on them.

Lyle

[Streetrodder83]

I can see where your coming from, when you're assembling a large amount of engines you don't want to have to worry about clearancing issues. You just want it to work. When you're putting all your time and effort into one engine you have time to be picky about what you want for tolerances.

[Lyle's GTP]

Yup, but I don't work there anymore. I was tired of being a butcher, every thing was done half assed there. Have you ever heard of Optimax Engine Reman? We were owned by UAP/NAPA Inc. Supplied engines all over north america, for napa, genuine auto parts, bumper to bumper, etc. DON'T EVER BUY ONE, OR LET ANY ONE YOU KNOW BUY ONE!

Lyle

[Streetrodder83]

Yeah, I have heard of them. Don't worry, I trust any of those places about as far as I could throw one of their engines.

[Lyle's GTP]

I'm thinking about posting a detailed warning to everybody about these guy's and AC delco, their engines were even worse. Man do I have stories to tell.

What do you think?

Lyle

[wireman121]

well to answer that original question, no it was a new engine, not rebuilt. had 0 miles on it. SappySE107, if you are interested, I can send you my old heads plus $$ for the new ported and polished heads....old heads have 77k miles on them, and dont have anythign wrong with them....they look like they have under 30k. let me know :-)