tdc after eplacing head gaskets 4.3

i marked my distributor placement, but didn't mark my rotor placement.
if i turn the crank pully to the point where both #1 valve pushrods are at their lowest level, i am at tdc for number 1 cylender, correct? one of the crankshaft pully notches is highligted, but i think it's the wrong one, it was marked on a previous repair.all i'm getting using that one is backfire indicating bad timing, any suggestions? sorry, first post, it's a 94 4.3, and i'm tearing my hair out, thanks

Check this thread out, it's from the Blazer forum in the How To/Technical Info:

http://www.automotiveforums.com/vbulletin/showthread.php?t=881442

Hope it helps

Rotate the motor in normal direction watching #1 cylinder intake valve open then close keep going until the dampner mark aligns to the 0 on the timing tab. The motor is now at TDC for #1 cylinder assuming the dampener hasn't slipped. You can rotate it with the starter but be careful. Hope That helps.

yes, thanks guys, that does help, since there are 2 marks, and i foolishly didn't highlight the mark before tear down, this may help. i'll let u know tommorow, thanks again

yes, thanks guys, that does help, since there are 2 marks, and i foolishly didn't highlight the mark before tear down, this may help. i'll let u know tommorow, thanks again

Forget the timing marks for setting dist.

Two ways to find TDC no 1 compression stroke.

Bring it up to comptression stroke by finger feel for compression.
Then take a brass welding wire and feel for tdc on piston.

Or when the valves are rocking {one closing and one opening} on your opsite firing cylinder no 4 cylinder.
You are at tdc compression stroke on no 1 cylinder.

Then see what timing mark lines up TDC and use that one to set timing after the engine is running.
Good Luck

well, no luck so far. when i adjusted the valves there was no compression. should i turn the engine over for a few seconds to pump up the lifters, or should i just back off each rocker arm nut 1/3 turn on all till it fires up, or what. i am completely confused now. however, i feel i have established tdc on the compression stroke of #1, it lines up with a mark on the balencer, and both #1 pushrods are at their lowest levl equally.

well, no luck so far. when i adjusted the valves there was no compression. should i turn the engine over for a few seconds to pump up the lifters, or should i just back off each rocker arm nut 1/3 turn on all till it fires up, or what. i am completely confused now. however, i feel i have established tdc on the compression stroke of #1, it lines up with a mark on the balencer, and both #1 pushrods are at their lowest levl equally.


You need to check the opsite firing cylinder for the valve rock to get the true top TDC compression stroke.

When valves are all of the way closed on a cylinder .
Back off rocker arms on that cylinder untill you can spin push rods by hand.

i'm fairly confident i have tdc now, but before adjusting the valve lash, should i 'spin' the engine on the starer to 'prime' the lifters or what. or, should this be a new thread?

This thread is good.
You should be able to feel the top of lifter without priming it up.
A good lifter will be spring loaded from borttom to top.

Are you going to adjust valves engine running or before you start it?

well, finally got it started, thanks to everyone, especially mt 2500, now to fine tuning, couldn't have done it w/out u guys. i will post back in a few hours, wish me luck. thanks again

You are welcome.
Let us know how it goes.

well boys, big trouble, water in every cylender. i'm gonna take a compression test tomorrow, an hope i just screwed up the intake gasket. don't know how a cracked block would let water in every cylender. oh, well, i'll see tomorrow but, i did get it cranked.

What was the actual reason for replacing head gaskets? WOuld you explain the problem before you started.

sure, it was overheating. and it was time for a valve job. but it has been a bitch to get it back right. i'm hoping all i did was hoop the intake manifold gasget this time

sure, it was overheating. and it was time for a valve job. but it has been a bitch to get it back right. i'm hoping all i did was hoop the intake manifold gasget this time

Don't take this wrongly by me asking these questions just attempting to help.

What did you find for problem causing overheating? Were the head gaskets or intake gasket bad?

Did you have the heads magnafluxed for any cracks and checked the heads for any warpage? What brand gaskets did you use?

How many miles on engine? What year vehicle.

If you would give us any detail that you think could help diagnosing that would be great. Like you stated hard to believe that coolant in every clyinder.

Hey duh1, I'm in Florence (SC) and know a fellow that's got a good 4.3 if you end up needing one. I think it came out of a ~95 blazer., anyway He wants $600 for the engine and 700r4 transmission hooked to it, just thought I'd throw that out there as an option. I bet there are a lot of busted blocks around here after the temp. last night, we're not used to this. Good luck with the repair.

sorry for the late reply, but it's a 94 auto 4.3 c/k, a tad over 200k miles. a year ago it was overheating, so i did a valve job thinking it would also cure my overheating probs. it worked well for a while but i kept having sensor probs because the guy i paid to do the job sent the sensors to the machine shop with the heads. long story short i broke the cardinal rule here, i did not send the heads to be checked after this last overheating bout. after replacing head gaskets this week water was in 5 of 6 cylenders, commpressio test today ranges from a low of 60lb on #1, 90lbs on 2,3,&4, and betwee 110 to 150 on 5 and 6. so, i'm taking the heads to the shop for magnaflux and warp test, the valves and springs are just a year old so i'm not to worried there, will have them tested though. thanks to all that responded, looks like this one is gonna take more time and money

Just a thought, have you by chance tried retorquing the head bolts. Could the head or intake bolts be streached from being overheated causing your problem? I know on some engines it is required to install new head bolts whenever heads are removed I do not know if this is the case on the GM's or not.

I have never replaced chevy head bolts, but i guess they could streach. also, if oil and water have gotten under the gasket surfaces i don't think retorquing would help. besides if i take it down that far i might as well replace the gaskets and get the heads checked

Best to install new head bolts any more.

There were also a few years that had bad head bolts.
I have saw some break off.
Good Luck