anthony.fatica

iTrader: (10)

I see all this talk about flycutting on here and was wondering why not just turn the face down on a lathe? As an ex-machinist i always had better results with turning round parts rather than flycutting. Does finish have something to do with it or are they usually ground smooth after? And what finish number is required? I'm curious because I'm looking at putting L92s or LS3s on my LS2 and I have been reading about some PTV clearance with big cams on these heads. I have access to both a bridgeport and a lathe (even an old shaper which gives a great finish) and may end up having to do this...Thanks in advance to anyone with some input!

85MikeTPI

iTrader: (9)

The entire piston top? You lose strength, compression and quench cutting the entire piston top instead of just fly cutting valve reliefs..

anthony.fatica

iTrader: (10)

Ok that's what i wasn't understanding. So you just fly cut reliefs and not the entire top to shorten the piston? I don't know where so don't ask, but I saw a video of someone flycutting a piston and took off the entire top so that's what confused me...

Tainted

iTrader: (9)

Lol no. Flycutting is only putting valve reliefs into the piston. They make a tool for it already. Its called a Isky racing piston notcher I believe

machinistone

We only face the top of the piston in the lathe in order to reduce compression height in custom applications, for valve reliefs we mount the pistons in a special vise and cut the valve reliefs with indexable flycutter. Sometimes we use the CNC to cut special dishes or reverse domes in the crown as well.

bww3588

iTrader: (49)

Agreed, if you try to take enough of the top of the piston, your going to seriously thin out the crown. Also, you will lose probably .100 or more on compression height. A piston .100 in the hole will create a turd for an engine

anthony.fatica

iTrader: (10)

Thanks for all the clarification. I doubt with this build I am going to cam it that big that I need to do so, but for future builds I may or may not start getting into that. As crazy as it sounds because building an engine is a headache in its own, it's still my stress relief learning about different builds and I want to get a little deeper into things in the future. Thanks again guys! Appreciate the input!

Tainted

iTrader: (9)

if you are wanting to use LS3 style heads on a 6.0 engine a good "general" number for cams to stay under is 234 on the intake duration, and using stock rockers I wouldnt push past .630 lift.

anthony.fatica

iTrader: (10)

Ya, I did some reading around over the weekend and it seems like TSP really has it figured out with their 231/236, .641"/.615", 112 LSA as being the largest that will work with their ported heads so I was thinking right in the region of what you said...


Edit: Meaning not as big as their biggest for these heads, I was a little unclear on that