Irocss85

iTrader: (1)

ok, lots of questions I'll # them. answer as many as you can for me please.

1) how far can/should I cut the notch's in the pistons? I know I have to check how much I'll need, but basically how much is max so I dont poss. go too thin.

2) if alot, does that mean 100shotn20 is out due to the piston strength goin into the toilet?

3) if I cut them to max depth now while I have the tool, so I have the option to choose a diff. cam later w/o having to recut them deeper, how much will the lower scr/dcr hurt power now? for instance say I only need additional .010" to be at spec, but maybe max recomended depth is say .030", why not cut them deeper so I dont have to do this all over again if I change the cam later?

4)can someone figure out my dcr for me now before I mill the heads or notch the pistons so I can tell if Im far off high or low?

853 heads-milled only .003 to clean up sealing surface. stock valves. lightly polished chambers only.
stock short block, MLS gaskets (.054?)
custom cam as follows.
235/242 112+2 LSA LSK int. lobe/XE-R exh. lobe
valve timing at .050 ---- open --- close
intake ------------- 7 btdc --- 47 abdc
exh. --------------- 55 bbdc --- 7 atdc
ICL 110 deg. (will be degreed in to make sure)


5)what is ideal dcr for 93octane (generally, on a good tune)?

6)will be degreeing in cam, and if need be will buy an adj. timing set. if I can retard cam 1deg to be in spec for PTV, would that be the same as the cam being ordered as 112+1 as far as power goes or would that really be too minimal to matter?

7)what should be the installed height be for the springs with that cam? PRC duals BTW. how is that determined?

TIA for any of the above questions you can answer.
chris

JZ'sTA

iTrader: (23)

First off you probally don't need to flycut.
Next your SCR/DCR will not change much at all from flycuting the pistons.
Depending on how much you flycut will determine the difference from stock, but the difference is minor.
A 100 shot should still be okay.
I don't have my DCR calc handy, but it will be decent, not great by anymeans, but better then some of the bigger cams out there.

Irocss85

iTrader: (1)

well, thanks, but Im trying to see how much room I have to mill the heads for better quench/dcr and with that Im sure (I think) I will have to notch the pistons.

hammertime

iTrader: (1)

1) I've heard of people who removed .080, but you shouldn't need to remove anywhere near that amount.
2) 100 shot should be fine, but it can't hurt to touch any notches with a cartridge roll to smooth any sharp edges and prevent hot spots from forming.
3)how many cams do you want to swap, when a 10 minute jet change will net you 50 more hp? Its really hard to say how much more clearance you might need, but if you have any idea what durations you might want, you could cheat a little by adjusting the IVO open point of your current cam to the IVO of the 'potential' cam, then checking clearance. Do the same with exhaust at EVC points, and that should give you some idea. Add .010 to those for insurance, but even that is not fail safe...especially as lift rates continue to increase.
4)piston .007 out of the hole, 66.5cc chambers and .054 gasket is giving me 10.36 SCR, 7.73 DCR. If you can mill to 61cc, run .040 cometics and add no more than 1cc for valve clearance, you can raise that to 11.36 SCR and 8.45 DCR. somebody please confirm
5) 8.5 - 8.7 DCR for 93 octane with proper tune
6) would be best to mock it up and measure before and after retarding, but you probably wouldn't gain much at all, and you'll lose DCR and low-end power you might not be able to give up with a cam that size.
7) since you are looking at LSK lobes, I've read that they should be shimmed such that they are within .050 of coil bind at max valve lift - should be a minimum and maximum height published for the springs you select though

1stz06

iTrader: (18)

I was going to run the G5X3 and LG recommended that I cut .080. I thought that was too much so I passed and decided to build a 427.

Irocss85

iTrader: (1)

i would do the same if it were an option. yes im jealous.

Irocss85

iTrader: (1)

thanks for all the info. why is the dcr soo low on this cam on what would be a stock engine? I will get the cometics and mill the heads if it will have THAT kind of affect.

if I advanced the cam another 2deg. instead,for a 108 icl, how much would advancing the cam help dcr and power?

Irocss85

iTrader: (1)

anyone else care to run the #s to see if hammertime's #s are accurate? also, hammertime, you said mill to 61cc, do you know how much material that is to remove? .030? .020?
Im goin to have ETP set up the valve installed height's.

also, since Im goin with thinner head gaskets and miling the heads, Im goin to have to get shorter pushrods too right?