SprintCarDriver

Took the vette out to a party this weekend. Thought it might be a good break in on this new engine. :) On the way home, lost a clyinder. :cry Limped home on 7 cly. So disgusted didnt start working on it until last night.
Did a compress test with the following results:
1- 180 3- 175 5- 180 7- 180 :D
2- 165 4- 150 6- 155 8- 165 :eek: Whats going on here.

Leak Down time. 1, 3, 5, 7 less than 1%
2 - 20%, 4 - 60%,(air from the Carb) 6 - 60%(air Everywhere :cry
I'm worried now, burnt pistons, burnt valves. Lets pull the head...
I dont have a digital camera, so no pictures but here is what I have found.
Shined a lite over each valve and saw lite in the passages from around the exhaust valves. So all exhast valves leaking. Remove the exhaust valve from cly. 4 and does not look bent. Did not chuck it up but for the amout of lite I saw I would think that I could see a bend. No marks on the pistons.

Any ideas on how this happened? I do know that that the fuel settings are still not complete but could this cause the valve not seat?
Taking the head to the machine shop tomorrow, just wanted to see what you all might think.

ylose

whoa...that royally sucks dude...no info for ya...but total sympathy..not that it helps...

here is something to make ya smile....
i bet now the shifter ***** price will go up !! :lol: :lol:

SprintCarDriver

which by the way, the pictures are being taken as we speak. Hopefully I will send you a picture tonight. Checking on shipping, should not be much..
You are sending a blank check right? :yesnod:

gkull

Let me get this straight. You pulled the head and the exhaust valves don't return to the seat with spring pressure on them?

So you took out a valve and it doesn't look like bent stem? Well I'll tell you right now I have had bent valves from smacking pistons. You have to pound the valves out because the bent stems wedge in the guides.

My take on what you said is. The person that assembled the heads used incorrect stem to guide clearance/ incompatable metals. Stainless valves need a certian type of guides. Or lack of oil. If you go way tight on PC unbrella seals you can oil starve the exhaust valves.

SprintCarDriver

The valve slipped right out. No extra pressure needed. Here is another tidbit. Put the valve back in and hold it to the seat and still see light. Rotate the valve and still light. Wonder if I hand lap the valves in (like the old days) might help. Maybe the seat angle does not match valve angle? Dont know. Maybe will tomorrow...

john's '81 mouse

Assume you are certain that you had valve rocker arm preload, assuming you have hydraulic lifters, set correctly, and not too tight.

Did you have valves and seats ground during your rebuild? Were the valves hand lapped in each seat, and checked for good seal/contact area before finale head assembly?

Sounds strange, and I can only imagine how disappointed and frustrated you are, but there has to be a reason and explanation for this situation, you just need to hang in there and keep 'digging'.

SprintCarDriver

Heads were completly rebuilt by a machine shop. I did not do any checking as I trust the shop. But apperently something was not correct...

gkull

I wouldn't even screw around! :cuss They would be back down to shop you trust. Because they can't even grind the seats correctly. I can tell you right now you don't lap out daylight shining through.

I had a shop try to tell me the mill boy was new and one of my heads has something like a 20 degree valve angle, But it should be OKAY!!!!!!!!!!!

Yes, Sir I always like to run one side of the motor different than the other. Morons........ they were ported and polished screw in studs and guide plate and dual spring 186 double hump heads. All I was having done was refreshed with new guides and seals. :conehead

ram82fire

It would be very wise to listen to GKULL as he said you cannot lap daylight out !!! Another strange thing here ,,,, how you got any reading at all in a cylinder where the valve does not contact the seat . Induction is the key to power and it really sounds like you have some serious issues to address .

G :D

SprintCarDriver

I agree. And I will be there when he opens. They did put in new valves, think that they didnt even grind in the new ones in? Only makes the third time I have had the top end off since the cam was put in.. Need to put in a zipper!