i put a 1994 caprice 9c1 lt1 into a 92 3rd
gen camaro. i never heard the donor engine run, but i got it running in my car and
after i put aluminum heads(stock lt1) and headers on it it began to have a rather
severe valvetrain noise (clatter) after startup? so i hooked up the factory egr
system to see if that was the problem but i got nothing. to add to the noise, once
the engine reaches full operating temp. it wants to die and when you try to restart
it , it spins over slow like the battery is weak and will not crank up till the
engine cools. also i noticed a white vapor emitting back through the maf??? the maf
and o2 are operating fine also..plus , i noticed something strange, my ecm has a
single knock module in it and the engine has two knock sensors??? yeah i know,
lucky me. im at witts end and if anyone can suggest anything at all i would really appreciate it.

pkchevyracer

 

Are the valves adjusted correctly?
All the spark plug wires hooked up right?

If you disconnect the MAF, then start the car, it will run in speed density mode. If the car runs good without it hooked up then you probably got a bad MAF.

There could be a number of things that could cause it but it sounds a lot like the valves aren't adjusted right.

 

i adjusted the valves by spinning them until the pushrod starts to drag when the opposite valve is open. the car will run without the maf plugged in, but ,if i blow on the maf it causes turbulance in the idle and will die?? so i guess i need to replace the maf?? spark plug wires are 100%. now i just wanted to check, but do you think the valves being misadjusted will cause the engine to not want to start after warmup? before i put the aluminun heads on the car would haul *** when i got on it but that was before the exhaust was ran also.but it always has done the nostart after warmup ever since i got the engine running. i think the ecm may be bad, i know the wiring harness is caprice because the dlc pinout is d29 and f body car uses d30. but i dont know if the ecm is correct. the part number is missing and its got a single knock module in it and the car has dual sensors!!!!

 

That's not the right way to adjust valves. Try again.

 

You have the valves tightened to zero lash(or when the pushrod has all play removed). On stock LT1's, the correct adjustment is to tighten an additional 3/4 turn past zero lash. And with the number one piston is at tdc.

 

guess im too use to old school chevys..lol. i will fix that asap but im afraid that will only fix the valvetrain noise, but i will see what happens today and get back, man i appreciate you guys.

 

You have to remember these are roller lifters instead of standard flat tappet lifters. Also, they may be too tight as well, that's how a buddy of mine's LT1 sounded when he had them too tight, he loosened them up, started the motor and then tightened them down until the clatter was out. I have to re-do mine this way since I did mine the correct way and they rattle after putting about 4k miles on since I put the motor in last year.

 

There are two "easy" ways to adjust hydraulic lifters (whether roller or flat doesn't matter).

Method A:
1) Loosen all of the rockers.
2) Put #1 at TDC (doesn't have to be on the firing position). Take out the lash from all rockers.
3) Turn the crank 180 degrees. Take out the lash from any rockers that are now loose.
4) Turn the crank back to TDC (1/2 turn only). Take out the lash from any rockers that are now loose.
5) Turn the crank another 180 degrees. Take out the lash from any rockers that are now loose. There will be (should be) fewer loose rockers with each 1/2 turn of the crank.
6) Turn all 16 rockers down to the preload (I use 1/2 turn, 3/4 is factory recommendation).

Method B:
Remove valve cover, start engine, loosen each rocker to clatter then tighten until noise goes away. Turn down to preload. Go to next rocker. After completing all 8 on that side, shut off engine, replace valve cover, repeat on the other side.

There is a harder way, but A or B will give as good of results as the harder way.

 

well....i did the preload lash and it sounds like a knock coming from rod #1,2,or 3. i pulled the knock module out earlier and havent put it back in yet, but i dont think thats gunna make it sound like a mid engine knock, so i guess im scrapping project lt1 in my 25th car....

 

you're giving up on the LT1 because of this? you can get though it, don't give up yet!

 

well, i do have a buddy with a lt1 from a c6 longblock i can get for 300, but i just dont want to create a money pit...but i dunno...

 

Keep the knock module and knock sensor hooked up. It will run like a dog without them, it won't cause a knock though.

Sometimes even if you do things right with "Method A", you might have one loose rocker, if you just kind of don't double check them. Anyways, try this(Method B): Pull off the valve covers and start the engine but don't rev it up. You will have to take off the alternator and put it back on for the passenger side. See if one or two of the rockers are obviously loose. Tighten it until the knock sound goes away.

 

ok, i'll try that today....