Asmodeus

64cc LS6 heads, stock MLS gasket (0.052 compressed), stock valves.

I want to install a 230/236 .612/.602 108+2 into it. (XFI/XER)

..and remove my LSK lobed 228/232 112+2 for more DCR, a little more low end torque, slightly earlier peak power, easier on my springs, better balance of my head's intake/exhaust flow ratio, and I believe to be better valve events for my head's flow.

Compared to the previous cam, I would have an earlier IVO which the stock size valves like more than the bigger valves, earlier IVC to shift a bit earlier (I'm paranoid about spinning bearings right now), 48 degree EVO which is 2 degrees later than my previous cam for more low end torque, and a later EVC for more overlap.. I'll be sure my exhaust is up to the task. The heads are about a 74.5% avg intake/exhaust flow ratio above .300 lift, so I chose a 6 degree split vs the typical 4 degree most people use in LSX engines. I will be going from 6 degrees overlap to 17 degrees though, I kind of wanted that lower.

Am I cutting it close? In the clear? Not a chance? I know I should measure to be sure.. but if people have done more under essentially stock heads, I'd prefer to just plan ahead

(My other option if I have to flycut is to mill to 59cc, run a .040 cometic, and shove a 236/244 111+3 in there and see what the budget port heads will do, but I'd rather not)

john563

iTrader: (17)

Is that cam spec out by patric G? Cause the one I'm waiting on is almost exact,but its on a 111lsa+2. Right now I have a tr224/112 and tsp stage 2.5 5.3 heads and ported fast 90/90

slowbrakiller

iTrader: (10)

heads milled?

Asmodeus

No, this cam is specced out by me I've spent many hours this week trying to understand what different valve events do, and how to move them around based on engine requirements.. finally put it all together to actual cam specs using a spreadsheet.

Trying to find out if that tight LSA will fit, and also want to see if my logic is flawed.

And the heads are not milled, 64cc chambers. They are patriot's stage1, I think they do clean the surfaces up, so I guess they COULD be 63c.

JPH

iTrader: (2)

its closer but will clear with stock unmodded heads. you mill=you flycut

edcmat-l1

iTrader: (10)

Cant see puttin anything close to that size in without checkin. Simple matter of 2 checker springs and a dial indicator. Cheap insurance......
BTW have fun tunin that thing with 17 deg @ .050

mudflap1989

iTrader: (4)

Yeah, I think that it will clear as much as most big cams clear these days (MS4, Vindicator, G5X3, etc.). The 106 ICL is hurting you on the intake side. I believe that you lose somewhere around .003" for every degree that the ICL is advanced. But I think that it will probably clear, might not quite be the 0.080" as suggested, but many people are running clearances under 0.080".

I really just suggest flycutting and milling the heads, especially since you are concerned about DCR. It's really not that big of a deal. I'm a gambling man but i've took that gamble and lost before and I would much rather spend the time to cut the pistons, than spend 20 times a much time putting a new motor in.

Asmodeus

T-Rex is a 242/248 on a 110+0.. my ICL is 4 degrees earlier but my intake lobe has 12 degrees less duration (divide by 2 for the leading edge for 6).. so in all practicality this should clear by .003*(6-4)= .006 more than a T-Rex, even with all my advance, right? Assuming the stock gasket and unmilled heads, right? but I do have the LS6 heads.. What does a T-Rex clear by on 243's vs 241's or 853's? On the 64cc vs 66.67cc's heads?

Maybe I'm all worng with my math.. but I have my clearance at .012 TIGHTER than a T-Rex straight up in a 241 headed car..