pistons
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Joined: Dec 2015
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From: In Your PC
It's hard to argue against the mathematics when it comes to engineering ... I'd like to know how the pistons made the jump.
Andrews *did* publish piston clearance warnings for '84 to '86 Evo, including the EV27.
What the warnings said, was
So they were advising notching the pistons which would be cheaper than buying new ... except we have Ebay nowadays.
For me, often "the devil you know is better than the devil you don't", i.e. stick with the original 'known good' pistons unless going for higher compression.
Andrews *did* publish piston clearance warnings for '84 to '86 Evo, including the EV27.
What the warnings said, was
Note: Late 1984-early 1986 EvolutionŽ engines require their pistons to be notched to obtain the necessary valve-to-piston clearance.
For me, often "the devil you know is better than the devil you don't", i.e. stick with the original 'known good' pistons unless going for higher compression.
Last edited by Big Member; Dec 29, 2015 at 07:30 PM.
Thread Starter
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Stellar HDF Member
Joined: Jan 2015
Posts: 2,504
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From: ct
Well it just keeps getting better, I would like to get my **** back from Indy so I can measure up with my pistons , .045" gasket ,27 cam and see what is what. John says definitely valve will hit, one way to find out. So I think I will not buy pistons just yet.
Install pistons with out the rings, no base gaskets, install head gaskets and heads with two snug bolts, measure valve travel without the spring installed ....this the best way ????
Install pistons with out the rings, no base gaskets, install head gaskets and heads with two snug bolts, measure valve travel without the spring installed ....this the best way ????
Thread Starter
|
Stellar HDF Member
Joined: Jan 2015
Posts: 2,504
Likes: 150
From: ct
It's hard to argue against the mathematics when it comes to engineering ... I'd like to know how the pistons made the jump.
Andrews *did* publish piston clearance warnings for '84 to '86 Evo, including the EV27.
What the warnings said, was
So they were advising notching the pistons which would be cheaper than buying new ... except we have Ebay nowadays.
For me, often "the devil you know is better than the devil you don't", i.e. stick with the original 'known good' pistons unless going for higher compression.
Andrews *did* publish piston clearance warnings for '84 to '86 Evo, including the EV27.
What the warnings said, was
So they were advising notching the pistons which would be cheaper than buying new ... except we have Ebay nowadays.
For me, often "the devil you know is better than the devil you don't", i.e. stick with the original 'known good' pistons unless going for higher compression.
Dirt don't hurt
Joined: Jan 2011
Posts: 21,065
Likes: 4,561
From: Haslet Texas
Well it just keeps getting better, I would like to get my **** back from Indy so I can measure up with my pistons , .045" gasket ,27 cam and see what is what. John says definitely valve will hit, one way to find out. So I think I will not buy pistons just yet.
Install pistons with out the rings, no base gaskets, install head gaskets and heads with two snug bolts, measure valve travel without the spring installed ....this the best way ????
Install pistons with out the rings, no base gaskets, install head gaskets and heads with two snug bolts, measure valve travel without the spring installed ....this the best way ????
I ain't seen him be wrong yet!!
Dirt don't hurt
Joined: Jan 2011
Posts: 21,065
Likes: 4,561
From: Haslet Texas
Granted you will have to get the jugs to 10 over but it is best to have a machinist get them to match.
Just a thought.
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Stellar HDF Member
Joined: Jan 2015
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From: ct
Meaning ? Bore the jugs .010" over instead of just honing ??
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Joined: Dec 2015
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From: In Your PC
Perhaps I should have written "might have" as it's not possible to know if that was from Andrews, or just off a template. I think it original came from a Custom Chrome catalogue, e.g. they also use the same disclaimer for Crane Cams. It applied to all cams, not the 27 specifically.
http://www.powersportsnetwork.com/en...tCategoryCode=
Powersportsnetwork are CC resellers ... but same caveats apply to them.
Engineering is ultimately determined by some very old fashioned, simple and reliable mathematics. You can't just assert they might, and worry, you've got to show how. Or how not. John know this. Those are 'good enough' figures I gave you. Again, I encourage to measure your own, not worry, and not spend money you don't need to.
I still say something else must have been going on for contact to happen; skimming, pistons, rod adjustment, thinner gaskets, over revving ... something to fill that considerable gap. It has to have had.
Last edited by Big Member; Dec 29, 2015 at 08:29 PM.
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Dirt don't hurt
Joined: Jan 2011
Posts: 21,065
Likes: 4,561
From: Haslet Texas
Whenever you get new pistons you have to get the jugs machined to match.
If your jugs are worn enough then the stock ( 0 over) pistons won't seal right.
What ever shop you use they will need the jugs and pistons to make sure they match correctly.
If your jugs are worn enough then the stock ( 0 over) pistons won't seal right.
What ever shop you use they will need the jugs and pistons to make sure they match correctly.
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Stellar HDF Member
Joined: Jan 2015
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From: ct
If something doesn't happen soon, I'm getting them and sending to Hillside like I should have done.