98Z28CobraKiller

iTrader: (17)

OK. I know that has been discussed a bunch of times but if the slack is on the wrong side of the chain, dot to dot can be a tooth off. Not saying that's it but I know this first hand.

Has the MAP sensor been replaced yet? An SD tuned car will not run with a bad MAP. I know this first hand also.

Reversed cam sensor will give intermitant startup trouble but the tack will work. I know this first hand.

Pushrods too short will cause less overlap and thereby more compression not less.

Bad PCM usually will not power up the fuel pump. If the pump is humming, the PCM is likely OK.

rufretic

iTrader: (37)

Good info, thanks. My pushrods are too long though, not too short. I have 7.4 in there and the pushrod checker tells me I need 7.275 plus .075 preload on the lifters equals 7.35.

qqwqeqwrqwqtq

No, your cranking compression is very low and is not right.

What I meant is the noise of the leaking air is possibly going by the rings and not past the valves, by having compressed air in the cylinder you have enough time to determine where your air leak is.

EDIT-I'm not saying there is anything wrong with the lower end, just that you can't assume the air you can hear bleed down is coming from the valves when it could just as likely be the rings (and would be normal).

The low cranking compression is a problem but I'm not saying it's because you can hear air leak past the rings. Probably not related, just saying that a leakdown will tell you if the cylinder and valves are sealing up well enough. If they are all sealing and you still have no/low compression then the cam timing is way off or the valves are being hung open by too long of pushrods.

-Jim

Pat-Man

iTrader: (3)

Man...it just sounds like your timing is off. Have you double checked your timing chain?

JL ws-6

iTrader: (50)

Just get the FI stuff off the car, and get the thing to start n/a first.

2000_SS

iTrader: (24)

this is probably a good idea.

i also agree with INTMD8, the air is just as likely to be leaking past the rings as the valves. take your intake off and unbolt your headers, turn the motor over until it is in the compression stroke of one of the first 2 cylinders and see if you can feel air coming out the exhaust or intake side...i'm not sure how easy to detect it would be, but it's worth a shot since your intake and headers are fairly easy to remove....just an idea, even if it's a bad one, you STILL gotta take your headers and intake off, so why not, right?

Dark Shadow

i would buy the right pushrods first then see what happends. you know they arnt right and there cheap start there.
i have 7.35 chromoly rods send me a box with a return label and you can have them for free

rufretic

iTrader: (37)

Thanks buddy, I pmed you.

rufretic

iTrader: (37)

Well it looks like it is my valves. I took the intake off, put tape over the intake port and turned it over with no pushrods in, so the valves should be sealed and air just pushed off the tape and out the intake port. So now it is proven my valves are not sealing. I'll be pulling the heads in the next couple days and hopefully it won't be too hard to fix them.

LilJayV10

iTrader: (39)

That sucks man. I know all about putting the engine together and something go wrong. Before you posted this I was going to ask if you ever did a leak down test or not.

Dark Shadow

no prob there just laying around pm'ed ya back!

2000_SS

iTrader: (24)

let us know if it's the VALVE'S or the SEATS.....i doubt your heads are bad, and i base that assumption on nothing....i'm just being optomistic. seats, valves, and valve jobs are relatively cheap.

rufretic

iTrader: (37)

I'll post pics once I get them off to see if anyone can tell why they are leaking. They looked ok to me when I put them on so I'm not sure what to look for.

Rickys S/C Z28

iTrader: (13)

man that sucks but if all you need is a valve job or new seats then that wont cost you very much so good luck

FrankSS

iTrader: (18)

any progress on getting the heads off yet?

rufretic

iTrader: (37)

No, I havn't touched it since I found out the bad news. I've been sick so not really feeling up to it. I'll probably do it this weekend.

Rickys S/C Z28

iTrader: (13)

ok man keep up posted brother!

Pat-Man

iTrader: (3)

Did you post awhile back that you put in a cam with +4 degrees of timing? When you install one of those cams, do you have to retard the timing chain 4 degrees? Someone with some more experience in that please let me know. I was just thinking.

Rickys S/C Z28

iTrader: (13)

find any thing yet?

rufretic

iTrader: (37)

I did today. Got the head off to find marks in my pistons from the valves. I don't get it, I clayed one of the pistons and it didn't look like I had any clearance issues. Now after trying to start it all my pistons are dinged. I guess it's a good thing it didn't start after all. Now I have to figure out what to do about this before I put heads back on.
As for the heads, I can't tell by looking at the valves that anything is wrong. I'm going to poor a little water in them like someone said and see if it leaks through.
I'm going to go take a picture of the pistons to post up to get an idea how much damage I did. I think I can just have the pistons cut to clear, has anyone tried doing that themselves?