I blew a head gasket on my bone-stock '89. Using a straight edge from end to end, I have .006" warpage. This means when I lay the straightedge on the head, I can fit a .006 feeler gauge between the head and the straightedge mid-way on the head (between#3 & #4 cylinders). Is this allowable or is the head too warped??? I have heard.003 is allowable on a gas v-8 head.

 

Max overall flatness spec is .012". Max variation within any 2" diameter area must be .0004" or less.

 

Thanks, two more ?'s Should I replace the head bolts and what, if anything, does Cummins suggest to coat the new gasket with. I usually use copper spray....

 

Look the bolts over carefully for rust or necking (bolt will look stretched). Cummins has a neat little plastic card gauge to check bolt length (#382392100), the max lengths are: Short-2.815, Medium-4.807, Long-7.201. Cummins doesn't recommend any coating on the gasket. The bolts should be oiled before installation.

 

This sounds stupid I know

But, I was always told you should take the head bolts, clean them well and then drop or lightly throw them at the concrete shop floor. (hex head down of course) they should make a high pitch metallic "ping".

That means they are good, if they make a duller noise, they've been stretched.

 

I guess it is your decision, but rather than drop the bolts (which sounds like it might work) for the cost and peace of mind I personally would just go ahead and get new ones. Then there would be no question as to the integrity of the bolts.
Tom

 

I agree with MnTom. While I haven't had this problem with Cummins bolts, it is quite annoying to torque a head down, and have the last bolt snap on the last stage of the torque procedure. A big waste of an hour and usually a gasket.

 

I agree with the above posts. I'd replace the bolts too. definitely worth the cost.

I've expereinced the aggravation of having the last bolt snap.

The dropping thing does work though, I've seen it done.

One of those "crude but effective" things.

For peace of mind I'd just replace though.