dirty2kTA

iTrader: (3)

-already tried the search with no luck.

i pretty sure i have seen a formula posted before to calculate piston to valve clearance.

can someone give me some information on this.. i want to know if a 236/236 .585/.585 112 cam will fit in a stock cube. the heads are tsp ls6's.

brad8266

iTrader: (23)

Should fit without a problem.

There is no formula to calculate PTVC, you have to measure it yourself if you want to know.

Xtnct00WS6

iTrader: (8)

If you find the formula...post up!

That cam should be fine if your LS6 heads aren't milled, you're using stock valves, and if you don't have a thinner than stock gasket.

JPH

iTrader: (2)

there is a formula, but it is never right. computers can't measure all the variables, just numbers. just put the cam in and check it, that's the only way to know for sure.

brad8266

iTrader: (23)

Well a formula that doesnt work is worthless. Might as well be no formula. I just checked mine by claying it, gave me piece of mind.

JPH

iTrader: (2)

i agree, i always check my stuff first hand also.

dirty2kTA

iTrader: (3)

what are the varius methods for checking clearance..

i assume once the heads and cam are in you could roll the motor over by hand, but it seems like there is better way..

i have experiance with heads/cam installs. i did the job about 4 different times in my last car, but clearance was never an issue. the shop assurred me of clearance.

brad8266

iTrader: (23)

I like using the clay test. Google piston to valve clearance and you will find out how to do it. Or do a search here, I posted a thread about it after I clayed my setup.

The Alchemist

iTrader: (19)

So when you say 'you clayed the heads' do you put a peice of modeling clay at a specific thickness on the piston, rebolt down the heads and then manually turn the motor over, repull the head and check to see if the valves left an eyebrow in the clay?

I get that, but can you buy clay at a predetermined thickness? I'm guessing you would need it be pretty uniform thickness in order to be an accurate measurement.

My issue is a little different. I've got a TR 224 on a 112lsa but my heads are milled, and I have 2.05 intake valves, and I'd like to go down a thinner head gasket, but don't want to throw an intake valve threw a piston...

brad8266

iTrader: (23)

You only need a piece of clay about 1/4 inch thick, you put it on the piston top and then assemble the top end and crank the engine over a few revs by hand and then you measure the thickness of the smallest part of the clay that the valve went into. The valves will go into they clay if it is 1/4 inch thick. You want the smallest part of the clay to be at least .100 thick on the intake valve side and .080 thick on the exhaust valve side. Cut the clay into sections with a razor so you can measure the thinnest spot. This is the minimum PTVC that you want to be safe. If the PTVC is smaller than those values then you will want to either go with a thicker gasket or get a different cam or swap heads.

Irocss85

iTrader: (1)

Brad you got the numbers mixed up. you want .080" on teh intake side, and .100 on the exhaust. the reason for the difference is the exh. valve gets hotter then the intake valve due to the incomeing air/fuel cooling the valve down.
anyways I got some pics for you from when I did mine. you want modeling clay because it will not "spring" back up after the valve has compressed it. somewhere around .25" thick is what you want. too much and it'll stick to the head and peel up when you lift off the head. I cleaned the piston top really good, and oiled the combustion chamber and valves so the clay would not stick to the clay. carefully cut the clay down the deepest part of the indentation and remove the outer half. you can use either feeler gauges, or the point of a dial caliper to measure the depth. also, you'll want to use either checking springs in place of the valve springs so the plunger in the lifter doesnt colapse and give you a false reading, or just do like I did. use modified stock lifters that have solid internals, and NO plunger movement. I dissasembled some old stock lifters and filled them with epoxy and reassembled. then just add your preload.





that should help you picture what your goin to do. I used some putty instead of modeling clay. its not as easy to work with, but it still works just fine. you can get modeling clay at hobby stores. wish I would have known that before. couldnt figure out who the F@@@ sold that stuff.

brad8266

iTrader: (23)

Yeah my bad i listed it backwards, dyslexia kickin in. I knew what i meant, I just typed it backwards, i do that all the time.

Irocss85

iTrader: (1)

I know, Im constantly swithcing letters around while Im typing. see what I mean? I left that just to prove my point. I think the backspace button gets used more then the return key.lol.

Xtnct00WS6

iTrader: (8)

Here's how I did it. https://ls1tech.com/forums/showpost....64&postcount=6

dirty2kTA

iTrader: (3)

thanks X

ExceSSive

iTrader: (13)

Found this interesting http://www.centuryperformance.com/piston2valve.asp
http://www.compcams.com/technical/Ca...106-07/381.pdf

2. Check piston to valve clearance.
Insufficient clearance will render the engine inoperable. A minimum clearance
of .100” on the intake valve and .125” on the exhaust must be maintained.
Keep in mind that when you advance or retard the cam, it dramatically
changes clearance. Also, most of our High Energy Cams™, Magnum
Cams, and Xtreme Energy Cams™ are ground with 4 degrees advance already
in them. Always check clearance with the cam degreed in the correct position.
For instructions on checking piston to valve clearance, see our camshaft
installation sections on page 378.

ALLBOTTLE

iTrader: (13)

There is a formula you can use if you have all of your motor specs.

Freedrop - piton depth - .100 + gasket thickness = total Lift clearance @ tdc

Tappet lift @TDC Lobe CL x rocker ratio = Valve Lift @ tdc.

If your valve lift at TDC if more than the clearance then you have to flycut.