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85GLHT-Omni
02-28-2006, 09:19 PM
I'm almost done with my port and polish job on my 287 head project. Thus far I've assembled the following...

-1985 287 Casting Head, mildlyyyyyyyyy ported and polished, intake and exhust ports gasket matched, bathtubs polished, three of the four cylinders have the normal valve seat to valve seat cracks, about a 4 mil dip from plane between 2 and 3, two helicoils installed for exhaust manifold studs
-New MP Valve springs (with internal dampers)
-used stock valve keepers
-used stock lifters (soaking in mystery oil)
-88 TBI Cam
-New Square tooth Findaza adjustable cam
-used stock roller rockers (soaking in mystery oil)
-used stock retainers
-New backcut MP turbo valves 112.2 mm for G-head

I bought some valve lapping compound, actually two part compound, having never lapped a valve, how much lapping is needed? When do I know I'm done? I also bought the NAPA suction cup lap tool.

Also, what is the prefered sealant to use on the manifold stud/bolts? I've used red RTV before, but is there something better?

In addition, I also ported and polished an exhaust manifold. I'll drill and tap it for the EGT when I remove the boss and TC currently installed on the engine. I'm planning on gasket matching and polishing the intake manifold runners next.

afsautoworx
03-01-2006, 11:16 AM
For the manifold stud/bolts on some engines ive done like my 3100 chevy, they use plumbers pipe "dope" or sealant. Anerobic gasket sealer would probably work too. Dont know about lapping the valve, are they in bad shape?

turbo xtc
04-30-2006, 12:06 PM
all valve lapping is is to make a good seal ever pull a valve out and notice little pits in it? well lap enough to make a good seal is what i do is lap until you hold the valve up and look at it with a flash light and look close you'll see a light rainbow color to it then put the valve in it's seat and push the valve with pressure from your finger then blow in to the port and listen if you have a leak.thats it!but before you check it clean it and the seat off they have to be clean.one other point i get the compound from napa get the grease based kind if you use the lapper and it don't want to move with the suction cup squirt a little drop of machine oil on the compound and what i do is lift the valve off a little above the head and lightly slap it back down.This makes the compound stick to the valve and grinds a lot better and just like a indian rubbing two sticks together while lapping lift it up again and slap it down again.Keep doing that until the pits are gone.Now pull the valve out clean it and inspect it And do it again.You want a line that is about 1/4 inch wide all the way around the valve and it must be smooth all the way around it with the rainbow color when you hold it up in light.I have found out that if you do this in a cold garage the grease based compound is cold then the suction cup will keep popping off so warm the head a little bit not to hot to the touch though but just a little another hint keep the compound room temp once you get a little friction it will stick and work very fast i do about 15 to 20 minutes per valve it takes a little practice and i have even found out kids do it real good if they are pestering you show them how turn them loose on it my son does a very good job at it he is only 12 years old