TRex w/ Decked 243 heads
TRex w/ Decked 243 heads I have a TRex cam 242/248 .610/.615 110LSA. I am pulling my 241s and replacing them with 243 heads.
edit: I am thinking I will be getting them milled .036 to achieve a 11.1:1 CR How much should I fly cut to maintain proper PTV clearance?
edit: I am thinking I will be getting them milled .036 to achieve a 11.1:1 CR How much should I fly cut to maintain proper PTV clearance?
Last edited by Rangersltw; Apr 27, 2012 at 01:39 AM.
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Verdad Gallardo I just had a thought. If I am not having clearance issues now and then get the heads milled .036. If I fly cut at least .036 Wouldn't that be the same clearance I currently have?
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From: BFE
You should flycut .080 or 2cc
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Bolt them on and clay them.....take what you find and subtract .040" and that will tell you how much you need to cut the pistons to be safe.
Since your bumping up your compression go with a .40" gasket too...stock pistons come .005-+" up out of the hole, so this will give you your optimum quench area and help keep knock down if you get a bad tank of gas
Since your bumping up your compression go with a .40" gasket too...stock pistons come .005-+" up out of the hole, so this will give you your optimum quench area and help keep knock down if you get a bad tank of gas
Lift is not the only thing that should be used to determine ptv clearance. Cam timing events are a big part of this. I agree with claying your set up to be certain. As with any engine modification checking clearances is the only insurance to avoid a problem.
Bolt them on and clay them.....take what you find and subtract .040" and that will tell you how much you need to cut the pistons to be safe.
Since your bumping up your compression go with a .40" gasket too...stock pistons come .005-+" up out of the hole, so this will give you your optimum quench area and help keep knock down if you get a bad tank of gas
Since your bumping up your compression go with a .40" gasket too...stock pistons come .005-+" up out of the hole, so this will give you your optimum quench area and help keep knock down if you get a bad tank of gas
TECH Senior Member
Joined: Mar 2004
Posts: 14,620
Likes: 17
From: BFE
When does max lift occur???? Contact is probable from 10* BTDC to 10* ATDC. So lift (at the range we use) have little to do with PTV clearance. Do not confuse with tappet lift.
If you're going to cut that much off the deck, don't forget to get the shorter Push Rods while you're in there. My new pushrods needed to be shorter by the exact amount I milled the heads also subtracting the .01 for the thinner headgasket from stock thickness.(Not exactly shocking) - in your case, .050 shorter. ( .036 milling + .010 thinner gasket = .046) I suggest starting there.
.080 on Intake. .10 on exhaust. - Exhaust expands more with more heat is the reason. I bet you're already too close to the pistons and just haven't hit yet. If you're heads are going to be off. Don't be lazy. Clay the pistons and KNOW what you need to do.
or just slap those puppies on there and GO! There's always a choice.
.080 on Intake. .10 on exhaust. - Exhaust expands more with more heat is the reason. I bet you're already too close to the pistons and just haven't hit yet. If you're heads are going to be off. Don't be lazy. Clay the pistons and KNOW what you need to do.
or just slap those puppies on there and GO! There's always a choice.
Last edited by 95ONE; Apr 27, 2012 at 01:29 PM.
My overall goal with decking the heads is to be around 11:1 CR. How can I figure out how much I will lose with fly cutting? I will be claying the pistons to check for PTV.