Help with 862 Heads
#1
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Help with 862 Heads
I found a set of ported 862 heads with 2.05/1.6 valves that I want to buy was told they were done buy MTI but no paperwork to prove one way or the other one cylinder has some damage to it and looking for opinions to weather milling will clean them up. The bad thing is I dont know if they have been milled or not before no markings stamped we can find. Im looking to bump up compression and pistons have 3cc reliefs cut in them.
#3
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Milling will fix that. Every .006 off is 1cc. A clean up might be .006 to .010, which is fine.
You will need the composite head gasket for those heads BUT they are on a HUGE backorder from gm. We have a better solution. Mls gaskets made for the notched deck heads. They are $50 for the set. (plus shipping)
You can email me with any other questions.
You will need the composite head gasket for those heads BUT they are on a HUGE backorder from gm. We have a better solution. Mls gaskets made for the notched deck heads. They are $50 for the set. (plus shipping)
You can email me with any other questions.
#4
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they should measure 4.75 +/- .002" from the deck to the rocker cover surface.
ws6store is correct, that head is notched so you either need a composite gasket or have it welded up.
my preference is to weld them up to use an MLS gasket and at the same time flow some 4043 into that damaged area.
this is all depending on what they are milled to currently and your application.
good luck!
ws6store is correct, that head is notched so you either need a composite gasket or have it welded up.
my preference is to weld them up to use an MLS gasket and at the same time flow some 4043 into that damaged area.
this is all depending on what they are milled to currently and your application.
good luck!
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Surest way to know is to have the chamber volume checked by a speed shop.
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MYALIMONY (12-14-2020)
#14
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You have to replace the seat, 2.00 is all you can put in the stock seat. Just got through doing it the stock head will also accept 1.56 exhaust valves FWIW
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So I put the calipers on the heads today looks like they have been milled .030 so my next question is can .010 more be cut off to clean them up. I don't believe I will have ptv clearance problems my pistons have -3cc valve relief cut in them and cam is 230/234 .601
#17
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A clean up is normally .005 - .006. Id recommend that at most...going more your head deck gets thinner and youll def want to measure for pushrod length. You should be ok with ptv issues with valve reliefs. If not either an adj timing set of pair of cometic .060 gaskets would do the trick.
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scout2000 (07-22-2021)