Cal Club Autocross Forums

Hey guys,
I just got my built short block and I was planning to transfer the head from my old motor (only 10K miles on the head) yesterday but I noticed a lot of carbon deposits. It's possible that these deposits occurred when I was still using gas and then some white stuff were added from the E85 and now the thing looks like camouflage .

Do you think it bad enough that I need to send the head for disassemble or should I just clean the bottom part as much as I can and use it?
What is really the issue with carbon build ups? Can they really degrade the seal of the valve?
I already spent a lot of money on the bottom end and I would prefer not to spend any more money at this point, that's why I ask if it's necessary...

If it was me, based on your description and assuming you have no reason to suspect that the heads/valves were not operating properly AND there is no indication of burnt valves, I would simply scrape or wire brush the deposits off before installation. The deposits CAN contribute to hot spots, but if all was well previously, things should be fine now as well.

Im no engine builder, but I agree with Ed.

10k is not all that mich. there should be no reason for a refreshing is there is no reason to suspect so.
Though that is more deposits then I would think should be there. you sure its not running lean?

I say clean her up with a wire brish, and call it a day.

is there carbon on the valve seat? or just the face of the valve? (im guessing just the face, other wish it would likley be running poor.)

Clean em. Be careful with the wire brush though. You'd hate to damage the metal that way. I'd try brake cleaner and a scotchbright scrubbie first. Also remember that the part that matters most is the *back* of the valve, not the face. If those look good, you're in pretty good shape.

I am a bit concerned about the second shot though. Is the lower right valve "wet" or is that just due to the camera flash?

Mike

Mike Simanyi wrote: I am a bit concerned about the second shot though. Is the lower right valve "wet" or is that just due to the camera flash?

Mike

There was some oil in one of the cylinders Mike (this is on the old engine).

Christos Adam wrote:

Mike Simanyi wrote: I am a bit concerned about the second shot though. Is the lower right valve "wet" or is that just due to the camera flash?

Mike

There was some oil in one of the cylinders Mike (this is on the old engine).

That could be either a valve seal or more likely worn rings. Did you do a compression and leak-down test before the tear down?

What fuel ... additives ... are you running.

hey this is stan just clean it up and close the valves pour slovent into the combustion chamber if they don,t leak you should be just fine or bring it to the shop and i will do if for you and check it out

Bob Beamesderfer wrote:

Christos Adam wrote:

Mike Simanyi wrote: I am a bit concerned about the second shot though. Is the lower right valve "wet" or is that just due to the camera flash?

Mike

There was some oil in one of the cylinders Mike (this is on the old engine).

That could be either a valve seal or more likely worn rings. Did you do a compression and leak-down test before the tear down?

Yes, I did and the numbers in all the cylinders were very close to each other but very close to the lower spec limit (if I recall correctly close to 137 Psi). This was the stock engine with 130K miles running 17 psi of boost so I wouldn't be surprised if the rings were bit worn.

Mako Koiwai wrote:What fuel ... additives ... are you running.

Just regular crappy cal 91 gas for half of it's life and E85 for the other half.

Stanley Kowalski wrote:hey this is stan just clean it up and close the valves pour slovent into the combustion chamber if they don,t leak you should be just fine or bring it to the shop and i will do if for you and check it out

I need to make sure first that you are not trying to sabotage your big nemesis
Seriously though, thank you Stan! Let me know what I can do tonight and if I have no luck I'll give you a call tomorrow.

I don't recall hearing to many successful engine stories that start with combining old and new parts. As they say pay a little now, or a lot later - just doing the labor twice would suck. I would take it in for service now while it is out, just for the piece of mind.

Only 10k miles, how many "racing"?

Jason Isley BS RX8 wrote:I don't recall hearing to many successful engine stories that start with combining old and new parts. As they say pay a little now, or a lot later - just doing the labor twice would suck. I would take it in for service now while it is out, just for the piece of mind.

Only 10k miles, how many "racing"?

Not that many miles racing Jason.
If I spend money again on the head I want to get a vvt head with oversize valves so in that sense I don't want to invest in the old head which btw I don't think something is wrong.

Christos Adam wrote: Not that many miles racing Jason.
If I spend money again on the head I want to get a vvt head with oversize valves so in that sense I don't want to invest in the old head which btw I don't think something is wrong.

Well it sounds like you made up your mind before you even posted. ;)