mrnorm_hemicide

iTrader: (17)

Hey Guys,

So I just finished an absolute PITA head gasket swap on my 97 lt1 (i swapped in Impala gaskets), and now I am having a problem with it dying out when started. So, let me give yall some details. I believe it has something to do with over tightened rocker arms. I tightened all the rockers staticly, and fired it up. It ran a little rough but it did idle, and then I shut it off and tightened the remaining rockers that were loose. When I went to start it again it ran for about 2 seconds then died out, like it was starved for air or something. I started it again and held the throttle open a little, and it ran but the SES light started flashing so I shut that sucker down asap.

I'm thinking the SES light was from a major misfire, but I know it has new plugs and good wires, and they're all connected. I believe this to be an issue of overtightened rockers. I think what happened was when I staticly adjusted them I shouldnt have continued to adjust after the lifters bled down. Does this sound like it could be the issue here? Anyone's input here will be very appreciated. BTW these are stock rockers/pushrods/lifters/cam. Thanks.

Sk8phreak88

iTrader: (4)

Valves are too tight. Ya can't just tighten the ones you can, run it and tighten the rest. You've got to set set zero lash and then 1/2-3/4 is the normal preload after zero lash.

http://shbox.com/1/4th_gen_tech2.html#adjust_valves


I my self like the engine running method to set lash, but the first few times it can be kind of scary when you realize you're sticking your hand in a running motor. It can also get very messy, but I seem to have the best luck doing it that way.

enjoi355

iTrader: (3)

from the way you described how you did the rockers, you might have to do them again

heres a pretty good write up

http://shbox.com/1/4th_gen_tech2.html#adjust_valves

heres a good video too

http://www.youtube.com/watch?v=BgIzn2neiuY

enjoi355

iTrader: (3)

o man, lol, you beat me to it!!

Sk8phreak88

iTrader: (4)

Haha.

Badazz 97 TA

iTrader: (18)

wow........

mrnorm_hemicide

iTrader: (17)

Thanks for the input guys, thats exactly what i'm thinking. Like half of the valves are probably way too tight, but since the others were loose when I set lash staticly the motor still had enough air to run and idle. After I tightened the others, the motor now does not have enough valve action to allow it to breathe and thus it dies out quickly. I'll go back, loosen all of them and then do it again. I had forgot that you only need to set them once, cause even tho the lifters bleed down and it feels like they're not right again, when the motor starts the lifters will pump back up and take up the slack. Hopefully its that simple stupid and the motor will run fine after that...

mrnorm_hemicide

iTrader: (17)

Well the gaskets blew. Changed the oil twice and each time it was turned to chocolate milk. I did everything by the book, the head surface was clean and the heads weren't warped. Does anyone have any theorys on why these new Impala gaskets blew so quickly? Do you have to use a different torque spec than the factory f-body spec for these gaskets because they're so thin?

jay7199

iTrader: (9)

you replaced head bolts?

I8ASaleen

iTrader: (9)

What tightening procedure did you use with the head bolts?

mrnorm_hemicide

iTrader: (17)

Used new felpro head bolts. And I used the GM spec and sequence for 97. 22 ft lbs in sequence on the 1st pass, then 80* on the long and medium bolts, 67* on the short ones in sequence on the 2nd pass. Let me guess, this torque spec does not apply to the impala gaskets?

robsquikz28

iTrader: (246)

Heres what the specs are below...but how did you actually tq them to get the degree?

Also did you use arp head bolts or felpro bolts?

http://shbox.com/ci/head_assy.jpg

mrnorm_hemicide

iTrader: (17)

I used felpro bolts, and I referenced a 90* angle to get close to the torque angle. I know what you all will say about that, but I had to take one head off this motor earlier and reused the stock head gasket and my method of torque and it was fine. My buddies have all done the same. I'm wondering if the torque spec changes with a thinner gasket. With a tty bolt I would think the thinner gasket would require more torque to stretch the bolt and make it seal well.

SPEED#1

iTrader: (14)

They are the same. Hundreds of people have used them on here with no probs. You either have warped heads or didnt tighten them enough.

19mike84

make sure you run a thread chaser in the threads for the block. i made that mistake with a friends car once.

mrnorm_hemicide

iTrader: (17)

I figure thats the only way this could have gone wrong. I know the heads werent warped, so the only thing I can surmise was that there was coolant at the bottom of some of the bolt holes and that threw off the torque reading. B/c otherwise I did everything by the book. One things for sure tho, I don't trust the impala gaskets anymore. For one thing, they look like paper compared to the factory fbody gaskets.

RamAir95TA

iTrader: (2)

I don't know if that torque procedure applies to aftermarket head bolts, but I've always done it in 3 step increments with the ARPs. 23lb., 45lb., then a final pass of 70lb.

I'll also assume you put thread sealant on the threads, right?

There's nothing wrong with the Impala head gaskets. There must have been something awry with your method. Thousands of people use those gaskets with no problem, including myself on my 383.

mrnorm_hemicide

iTrader: (17)

The new felpro bolts came with thread sealant on them. Like I said, the only thing I can surmise that went wrong was there might have been coolant at the bottom of some of the bolt holes, which would have threw off the torque reading on them and allowed the gasket to blow, cause otherwise I did everything by the book. I did this job before with the stock gaskets and it went without a hitch. Idk, either way I have to do it again, but this time I think I'll stick with the stock gaskets, I just feel with the aluminum heads a thicker gasket is a little more forgiving.

RamAir95TA

iTrader: (2)

The torque specification is dependent on the type of bolts you use. OEM bolts use the angle method while conventional bolts (ARP, Felpro) use the 3-step torque process. If I were to do it again, I would use ARP head bolts, a good thread sealant, Impala gaskets and the 3-step process as opposed to the angle-torque method.

I doubt a small amount of coolant in the bolt hole can throw off the torque that much to reduce the clamping force to beyond spec.