sixspdss

iTrader: (1)

im building an ls1 block with a ms4 cam and ls6 ported heads. i got a new block that's been rebuilt with flat top Hypereutectic pistons. it has stock stroke and stock rod length and i was told with this heads and cam package it should clear ok. well we put ls7 lifers in with stock length pushrods, put clay on the pistons and turned it over by hand and took the heads off and sure enough both valves kissed the piston. there should be .080 clearance from piston to valve. now the seat on the ls7 lifters are .020 higher than the stock. but even so it would still be to close with stock lifters... so i guess the only thing is to flycut these pistons. how much can you flycut these pistons? im not boosting or shooting nitrous

garygnu

what size valves ? measure how thick the top of the piston is .contact Texas Speed and the piston manufacturer to see how deep to fly cut the pistons .

JustAFooL

iTrader: (45)

Seems like I've heard of people cutting them .010". That may be totally wrong but for some reason I think I remember seeing a thread not to long ago with someone asking the same question and that was the response.. Maybe someone will chime in and say whether I'm right or totally wrong.

sixspdss

iTrader: (1)

the valves are 2.00"/1.55". im going to call texas speed tomorrow and see whats up

poltergeist 02

iTrader: (65)

.080" is safe, and people have done as much as .100".

A.R. Shale Targa

iTrader: (2)

this ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^

97camaro383

iTrader: (31)

Any numbers or track times with your setup?

poltergeist 02

iTrader: (65)

Not yet. I just changed setups in November and the weather usually doesn't let up until April around here.

JustAFooL

iTrader: (45)

I think I missed a decimal point..

sixspdss

iTrader: (1)

actually im just going to skip flycutting the pistons and just go with a different cam. so if anybody is interested in the ms4 cam just shoot me an offer...

JakeFusion

iTrader: (7)

Flycutting isn't so bad. I'd go about .110" max.

LivernoisMotorsports

iTrader: (1)

If this is a freshly rebuilt engine why does it not have the correct pistons in it for the heads cam you are running?(don't know if you bought something second hand or if you had something built) If it has the "wrong" pistons in it why not get the correct pistons as opposed to modifying the wrong ones? Why sacrifice the camshaft you wanted to run? For a street car you are looking for .080"intake and .100"exhaust. .040"piston to cylinder head.

studderin

iTrader: (28)

I cut my stocks .100, (cutter sliped going 75-80, so matched them all)
Ive heard people going .120,
a stock piston is not going to fail from flycutting,you will melt/crack a ring land.
Somone cut one in half to get a sectional thickness, it was plenty thick in the crown. it was years ago

M1SERY

I cut mine .100 for clearance with the MS4, milled the heads down to 59cc running a .045 gasket spraying 175 shot on it . Usually on average 3 10lbs bottles a month, with no problems. These cams don't mph very good at the track on N/A unless you have all the supporting mods to go with it . I have the biggest cam out of all my buddy's and they all out preform me. Wish I would have got a custom grind for my set up. Mine was a budget build and I already had the cam so that's what I used.

.125 is max on fly cutting, that's what I found with my research

Happy Wrenching

sixspdss

iTrader: (1)

Yup I talked to Martin from tick performance and I am now going with a custom grind cam so I don't have to flycut pistons. Ms4 cam is now for sale.. $350 shipped