AmericanOutlaw1315

I have a 2004 GTO LS1. Stock bottom end. 121,376 miles on it. Absolutely no problems. Doesn't use oil or anything. I just recently upgraded the transmission with one built by Monster Transmissions. One piece driveshaft and a 10" 3200 stall torque converter.
I seen a killer deal I could not turn down. I purchased Trick Flow 215 heads with BTR .660 Double Springs. I was told they have 62 cc. But the machine shop that checked everything out marked the combustion chambers to be 58cc.
So I am trying to decide on a cam for the engine. Without having to flycut. I already have a Low Lash Solid Roller. 236/244 .646/.646. 114+3. Equals a 230/238 duration at .10 Hot Lash.
I know the GM MLS head gasket is .051"
I was wondering if I could run a .075" or do I need to plan on either flycutting or getting a different cam?

Darth_V8r

iTrader: (4)

I ran a 237/245 112.5+2 LLSR on a 59cc 346. Was very tight but cleared. Based on that yours should clear but narrowly

AmericanOutlaw1315

I appreciate the insight. Is there a minimum ptv clearance I need to have? I plan on putting clay on my piston and checking.

dr_whigham

iTrader: (49)

229/236 112+2 on AFR 205's at 59cc.... They were a 15* valve angle. Yours are even better at 13*

Darth_V8r

iTrader: (4)

Treat 0.055 as a HARD minimum for PTV. Figure you'll lose 0.035 of that to rod stretch. With LLSR, since you'll gain lash with heat, your clearance will actually improve with temperature. Just do not rev until it is fully warmed up.

Edit -- gain in lash reduces effective duration, which improves PTV clearance (added for clarity)

AmericanOutlaw1315

Yeah I figured the 13.5 valve angle will help. Plus that's a good point after it warms up. I just figured I'd run a thicker MLS gasket. Put clay down and take a measurement to see just how much ptv I will have.

Darth_V8r

iTrader: (4)

you definitely should. Just think of the clay as your worst case scenario. If you have 0.055" cold, then you're good to go warm. Just until the motor warms up, if you rev, you'll see about .035-0.40 rod stretch, and that's when you can have a ptv. That's really your big risk. on a hydraulic valvetrain, I consider 080 my minimum, because I"m not going to grow lash as the engine warms up.

AmericanOutlaw1315

Well guess we will see. I would definitely let the engine warm up before taking off in it. But at the same time if I have to flycut. Then I'll jump off that bridge when it comes.