Magic Headgasket stuff

[MtnGoat]

So, looks like a head gasket for the Deathmobile. Has anything changed in this arena in the 15 years since I've done one, or do I just do the same thing as always?

I never did use any extra sealants, just a new gasket and clean decks.

Comments? Tomorrow (Thursday) is the day.

[James]

That's the way I've always done it - make sure you are not warped (the head - cylinder that is).

[datzenmike]

Flat, smooth as a baby's bum and cleaner than clean. Clean the block bolt holes. A bottoming tap is nice but an old head bolt that has the threads ground off in a strip down the length will work as well. Fill the groove with grease to catch the debris and install into block. Repeat until the grease comes out clean.

I made one for cleaning out the thermostat housing bolt hole after barely extracting a broken bolt.

[defdes]

Great trick there, Mike.

[MtnGoat]

That is a good trick! Will the grease screw with accurate torquing?

So, if my straightedge says bad things...I have it milled and then what for a gasket? Don't I have spacing issues with chain length at that point? No haynes..what size feeler gauge should I be able to slide under it in the low spots..preferably none, but there must be a tolerance.

[datzenmike]

There must be no more than 0.1mm or 0.004" (4 thou) across the total head length using straight edge and feeler gauges.

Head bolts should be lightly oiled before torquing so a small amount of grease shouldn't hurt.

Nissan gaskets from the dealer are hands down the best. (pricey though) My last one was $23 from NAPA, Felpro I believe. If the head and block are flat and clean, bolts clean and oiled lightly on a purely stock motor almost anything will do. If the motor is above stock I would get a better gasket.

The old bolts can be used if un-damaged and clean. Don't forget a dab of oil on the washer.

[MtnGoat]

Thanks mike. If it does need to be surfaced, what do I do about spacing then?

[banzai510(hainz)]

spacing? what does this mean?

I use Permatex coppercote on my head gaskets or nothing at all.

Nissan is the best gaskets if possible. but getting up there in price.

http://olddatsuns.com/620tech.htm

[defdes]

I use Permatex Indian Head Gasket Shellac just around the front cover section.

[James]

I think you are talking about affects on camshaft timing. If its a minimal amount of surfacing - it should be fine. You can adjust the camshaft timing if necessary. There are spacers available for the cam towers if there is a lot of material removed - but its not an optimal situation.....
I have had good luck with fel-pro head gaskets. I agree about sealing around the front cover area - it always wants to leak there.....

[banzai510(hainz)]

http://www.thezstore.com/page/TZS/PROD/10-1151

SilverSeal is another source.

Felpro uses a copperhead gasket as a shim along with the head gasket. I seen these in motors I have taken apart but never used them myself.

I had a heap warped so bad that they had to cut the bottom and the top. Cause the cam would go in straight and the last cam journal was shot.

[MtnGoat]

Ok, looks flat. I cleaned enough to get the straight edge crosswise in two directions and end to end as well.

Valve tops look good, no buildup, plugs look healthy. The two center holes in the block have the pistons at the bottom (TDC) and the cylinder walls look great in those two...no pitting, no ridge, can still see the crosshatch.

OK, still haynesless...

Anybody got the torque specs, including the two small front cover bolts?

Anybody have any tricks they use for torquing? I do the Z and back and forth from inner to outer, with several stages..all down, all snug, then torque em.

I am cleaning the decks right now and will run a tap down the holes in the block a die on the bolts.

[James]

Could you tell where the gasket had failed?
I can look up torque specs later - but if you have standard bolts (no groove in the top) it is less than if you have z turbo bolts. Was your car overheating?

[spoolinitup33]

Can you tell if a head and block are truly flat just by looking at them? Just wondering for my own good.

[MtnGoat]

Hi James, I have the standard bolts, no ring.

I cannot tell where the gasket failed, which disturbs me a bit. On the other hand, it didn't come off clean and it's hard to tell sometimes if the leak wasn't a big one.

I was not overheating and have never had a record of overheating with this motor, the radiator and thermostat are in great shape.

I did find when undoing the bolts that three near the center were not nearly as tight as the others.

Torque specs would be awesome, thank you. I've been a member for a couple days and already think you guys rock. Everyone seems cool and helpful as heck.