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L20b head gasket

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Rebuilding 1978 l20b, bought a fel-pro 21178 pt no re torque head gasket. Had head shaved .10 and block milled smooth along with timing cover. My question is, should I not retorted head after it is run or not, and if I should the spray on copper coat on head and block when I assemble?

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Neither

* it is no-retorque, meaning it needs none after breakin

* Fel-pro PT had built in sealers

 

Of course you should still do the usual L20B maintenance schedule which includes retorque every two year, 24k miles (or whatever your owners manual says).

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Do NOT use spray on copper cote. Nissan didn't use it and you said the head and block were surfaced. Gasket alone will do it job.

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it is no-retorque, meaning it needs none after breakin

Still wouldn't hurt, right? I re-torqued mine to make me feel better.

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No, won't hurt. Do it on a cold engine that has been sitting over night. Loosen only one bolt at a time and tighten to the final torque of 60 ft. lbs. Doing it this way you can do them in any order.

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Don't over think this. Nissan assembled tens of thousands of these engines with dry gaskets and bolts.

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Do NOT use spray on copper cote. Nissan didn't use it and you said the head and block were surfaced. Gasket alone will do it job.

Nissan used a graphite coated gasket. Some aftermarket gaskets are not graphite coated.

 

My rule of thumb is if it is a graphite or "print-o-seal" gasket, no copper coat required. If it is neither, then it gets copper coat.

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Lightly oil the threads.. And under the head bolt washer, and under the bolt head. Dripping off the end of the bolt isnt good but dry isnt good either. When you torque it dry, you lessen the stretch on the bolts due to extra friction, and you also gall the threads in the block.

 

This is exactly why arp gives you lube when you buy bolts and studs from them.if you contact them they can give you a spec thats different than they say in their instructions when torquing using motor oil. Rod companies like carrillo, etc, prescribe a bolt stretch spec, so you can use whatever you like essentially, even though they reccomend that they use their lubricant.

 

This also applies to main bolts and rod bolts.

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An oily rag is good for wiping the threads.

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Rebuilding 1978 l20b, bought a fel-pro 21178 pt no re torque head gasket. Had head shaved .10 and block milled smooth along with timing cover. My question is, should I not retorted head after it is run or not, and if I should the spray on copper coat on head and block when I assemble?

 

You had the head shaved .100" HOLY CRAP!!! That is very extreme and I sure hope you corrected the cam journals with shims to correct chain slap/looseness. Not to mention valve clearance to pistons....of course the .100" could be a typo and it was actually shaved .010" in which all is good.

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Or could be .1mm or 4 thou. 0.1" is 2 1/2 mm

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Probibly .010... I hope.

 

Most shops usually charge quite a bit more to surface more than a clean up, it takes a while for a cbn style surfacing machine to cut .100

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A lot of shops don't square the head when they are surfacing it. Meaning they may take .001 or .002 off one end and then .010 off the other. It's a cheap shortcut they take and it pisses me off that you have to ask for (and pay more for) a squared surface.

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I dont mean to thread jack but is there any good writeups on doing the headgasket for this engine with the tips and tricks included? Thanks.

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Remove battery cables. (trust me)

Remove the hood. Mark hinge locations with felt marker.

Drain coolant. At least half way.

Disconnect the top rad hose at the thermostat housing. Tie out of the way.

Remove distributor cap and wires. Cover distributor with a baggie.

Remove the vacuum signal hose from the vacuum advance line and vacuum source hoses from the intake to the charcoal canister.

Remove air cleaner, disconnect the carb auto choke and idle cut solenoid wires as well as the throttle cable.

Disconnect the vacuum hose to the brake booster at the intake and the smaller vacuum line to the transmission (if automatic)

Disconnect the air pump hose at the pump.

Disconnect the thermostat by-pass hose and the intake water hose (if equipped)

Disconnect the fuel line at the fuel pump inlet.

Disconnect the battery negative cable on head behind the fuel pump.

Disconnect the heater hose at rear right of head.

Disconnect the exhaust down pipe from exhaust manifold.

Disconnect the block vent hose at the PCV valve.

Remove valve cover.

Loosen cam retaining bolt but do NOT remove!

Set engine to TDC compression stroke on #1 cylinder. From here on the engine must not turn or be bumped off TDC so block wheels and place transmission in neutral.

Block the timing chain tensioner so it cannot possibly fall out by inserting a wooden wedge or folded length of garden hose down between the timing chains below the cam sprocket..

Mark relation of the cam gear and the timing chain so it can be put back in the same position.

Remove the cam sprocket retaining bolt and lift away the sprocket... the chain will settle down between the two chain guides and be out of the way when the head is removed.

Loosen/remove all head bolts and the two 10mm bolts at front of head that seat into the top of the timing chain cover.

 

Head should now be free to lift away with the two manifolds. It's more awkward than heavy so get some help. I find this preferable to the aggravation of unbolting them, (and possibly breaking a stud off) cleaning the gaskets off and bolting them back on with a new gasket. (and possibly breaking a stud off or stripping one) Look for and save the two round ring alignment dowels front and rear on the carb side.

 

Clean head and block surfaces cleaner than clean. The head is soft aluminum so go easy. Check head for warp-age. If warped have it fly cut to level it. Avoid removing the cam towers. Head can be replaced now or rebuilt. Clean the threaded holes on the block as well as the head bolts... they are totally re-usable.

 

Install new gasket dry, without dressings or sealers. Be sure the two alignment dowels are in the block. Instal bolts and tighten to 20 ft. lbs. in this order...

 

R A D

7.....8

3.....4

1.....2

5.....6

9....10

 

Using same sequence tighten to 40 ft. lbs.

 

Using same sequence tighten to 60 ft. lbs. Done.

 

Don't forget the two 10mm bolts into the front cover.

 

The rest is the reverse of removal. Have a digital camera and take lots of pictures to show how everything is as you disconnect it for easy reference when putting together.

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