head/rocker assy. nuts and a compression Q, sorry about the long post Options

[tat2dphreak]

ok, I'm reassembling the heads onto the engine...

Haynes suggests the nuts that hold the heads be 23ft./lb... I'm starting to question my torque wrench... these things are already VERY tight on the studs and the wrench hasn't clued me in on getting close to 23... my question is this: is it possible to get these nuts too tight? will I damage the heads if I keep going until the torque wrench feels like telling me to stop? (IMG:style_emoticons/default/idea.gif)

also, how tight should the rocker assy. nuts be? these didn't seem *REALLY* tight when I took them off... (IMG:style_emoticons/default/confused24.gif)


next: according the all-knowing Haynes 120-156 lbs of compression is normal, 100 minimum... I'm assuming this is with the engine cool... how much compression is good when the engine is warm? should it me more? less?

one last Q: how much effect can carbon buildup on the heads have on the compression?... when I removed one head(the 1,2 cyls) there was bad carbon buildup which cleaned up easily... a little B-12 and some elbow grease with a toothbrush easy... this head now looks much better than the one that I was going to put on that side... this side of the engine had good compression when the engine was cool 130/140 but only 60-75 warm... after the cleanup... would it be safe to use this head again? or should I just use the other one?

[Dave_Darling]

You very definitely want a wrench that reads the correct torque (23 lb-ft) for the heads. You also want to go in steps. I actually start at 10 lb-ft, go to 15 lb-ft, then add 2 each time. Always use the torqueing pattern (Haynes shows it). I also tap the head with a mallet in between the last couple of torqueings. Not sure if that helps, but I've gotten superstitious about it... (IMG:style_emoticons/default/wink.gif)

Overtorqueing by a little bit won't hurt things, as the studs have a whole lot more stress placed on them when the engine warms up. Just loosen them again and torque them to the correct values in the right pattern.


The rocker stand nuts are 10 lb-ft, and should be done with that cylinder at TDC or you won't even get the rocker stand all the way down on the head before you hit the torque spec!

You really, really need a torque wrench that reads down to ~9 lb-ft. Even if it's in inch-pounds and you have to convert, it's worthwhile. Remember, the oil sump retatining bolt is torqued to 9.4 lb-ft and it can break your crankcase and cam if you overtorque it!!!

Compression numbers are generally spec'ed when the engine is warm. Cold I would usually expect less. Fresh rebuilds I would also expect lower numbers on, at least until the engine fully breaks in. (Figure a couple hundred miles or more of "break-in" driving.)

--DD