Milled 317s PTV clearance with big cam?
02-22-2012, 02:08 PM
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Milled 317s PTV clearance with big cam? So I have a good deal on 317 heads, there pretty much new and cheap. Currently I have 241s that are semi ported.
I was wondering if I were to mill the 317s down to about 66cc (or whatever a 243 head is) what's the biggest cam that can fit?
I am looking to use a Whiplash II cam which is mid 240s, and around 630 lift 113LSA.
I was wondering if I were to mill the 317s down to about 66cc (or whatever a 243 head is) what's the biggest cam that can fit?
I am looking to use a Whiplash II cam which is mid 240s, and around 630 lift 113LSA.
02-23-2012, 12:35 AM
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I'm not a professional, but I think you will have PTV issues unless you flycut. No way would I try to run that without measuring it. I have milled 317's, maybe a little more than what your looking to do, to about 62cc, and a 226 intake lobe (on a 113 as well) gets you to about 0.065-0.070 clearance, which is cutting it close. The convention I've heard used is 0.080 min on the intake, and 0.100 on the exhaust. Now the profile of the lobe plays into this, but a 245is lobe is probably more agressive than what I have. Even if you were not milled at all, I think that would be cutting well into the safety margin. I would guess that about the biggest you could safely run would be about a 230ish cam in those heads, unless you went to a wider LSA. I'm not sure what your looking for, I would guess a race car only, no street use with a stick that big? From what I have read on those Whiplash cams is they are typically used on larger displacement engines like LS7s.
02-23-2012, 11:45 AM
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I'm not a professional, but I think you will have PTV issues unless you flycut. No way would I try to run that without measuring it. I have milled 317's, maybe a little more than what your looking to do, to about 62cc, and a 226 intake lobe (on a 113 as well) gets you to about 0.065-0.070 clearance, which is cutting it close. The convention I've heard used is 0.080 min on the intake, and 0.100 on the exhaust. Now the profile of the lobe plays into this, but a 245is lobe is probably more agressive than what I have. Even if you were not milled at all, I think that would be cutting well into the safety margin. I would guess that about the biggest you could safely run would be about a 230ish cam in those heads, unless you went to a wider LSA. I'm not sure what your looking for, I would guess a race car only, no street use with a stick that big? From what I have read on those Whiplash cams is they are typically used on larger displacement engines like LS7s.
So milling them down to 243 chamber size and flycut pistons should work?
I would ideally go with a set of LS3's since my bore is over 4.00 but Im replacing alot of stuff so I'm tight on budget and found these 317s super cheap locally
Anyone else has any input?
