facex

iTrader: (1)

Just looking for insight on piston to valve clearance. I've got two adjustable pushrods and some checking springs on order, so I will be checking the clearance, just wondering if anyone had an educated guess. Stock 2001 LS1 with a Thunder Racing TruTorq Level 2 223/230, receipt says .612/.608 115 LSA, but it is advertised as .609/.604 115 LSA. I did not receive a cam card, so I don't know the exact specs. I am adding some Advanced Induction 226cc 243 heads, milled .030", and going to be using a GM MLS gasket. Does anyone foresee any problems with this? I am going to check PTV just to be sure, but if anyone has experience with this, your thoughts are appreciated. Thanks.

On a side note, I am running the cam only right now, with 7.425" pushrods. With the heads being milled .030", would I be ok with 7.4" pushrods? Or would I need a bit shorter? Again, just theoretically speaking here, I will measure to double check.

Tainted

iTrader: (9)

ProBably 7.4

ejbta2

You need around .08 piston to valve clearance. I just built a motor and that's what they said I needed for my build. That may be a standard but I don't know for sure. You might call Texas Speed they will sure help you for sure, they did me.

JakeFusion

iTrader: (7)

80 thou is what is recommended, but you can go less. Is it as safe? No. But most cam only setups shops sell are much tighter than that (sometimes 20 thou). I'd feel queasy about anything under 50 thou.

We'd need to know what ICL the cam is installed on. I'd say anything above a 111 ICL will easily clear with a 223 lobe and stock valves in the 243s.

The swag formula is as follows:

Freedrop (.150" on stock heads) - piston depth - .080 + gasket thickness = total Lift clearance @ tdc

Tappet lift @TDC Lobe CL (Comp lists these in their master catalog) x rocker ratio = Valve Lift @ tdc.

If your valve lift at TDC if more than the clearance then you have to flycut. But you see the variable there of .080. Plug in the absolute minimum you are willing to accept .050 or .060 and then you'll see how much clearance you could have at worse case.

Sales@Tick

iTrader: (3)

If you're having Advanced Induction do your heads, Phil can pretty much tell you in a very close range of estimation of where your P to V will end up with his heads and depending on which valves you're utilizing. If they're larger than stock you've taken away even more of your available P to V that you did have before.

JakeFusion summed it up nicely though and posted the correct way to estimate what the P to V can be. I say estimate and can loosely and in the context I did because cams are not always 100% ground the way they were specified to be, and what we're doing is just an estimate. There can be slack in the timing chain that will skew the measurements, there can be a variance in the cam itself from what it was meant to be ground and several other variables that can play a factor in the available clearance.

JakeFusion

iTrader: (7)

Yep. It gives you a rough swag though. If you come in at 20 thou. Probably not good. If you come in at 70 thou, you can probably run it without much heartburn.