SOM_of_a_Beach

Currently in my car:
160 T-stat
SFC’s welded in
Aluminum Lower Control Arm’s
Pro5.0 shifter
Lou's short stick
3.73 gears
Front sway bar removed
Whisper lid
K &N Filter
Borla Catback Exhaust



What I have in my living room:

AJE K member
AJE A arms
5.3 Liter Heads (stage 1.5 done by TEA)
Comp Cam (232/240 @ 114 LSA)
Weiand intake (hand ported by TEA)
Weld Drag Lites
Direct port pro fogger race kit (NOS/Holley)
Bottle warmer, Purge kit, Blow Down Tube, etc.
Holley Blue Fuel pump
Kooks stainless steel headers
Battery Relocation Kit
BMR Battery Relocation Kit

(I am gonna sell my borla to get the money for x pipe and true duals)

Okay sooooooooooooo, I was told my piston need ot be fly cut. Can some one tell me why I have to do this? I would like to understand the technical portion. Also, one person qouted me 12 hours of labor for fly cutting, is this correct? I am thinking if different pistons will run me the same as the fly utting then why should I even bother. Please help me understand.

Ive seen the pictures of fly cutting and have read that if it is too thin than it wont handle nitrous etc etc. Any information is appreciated. Also feel free to post up links that I could refer to.

Thanks,

Crystal

SOM_of_a_Beach

please help me understand, or post links to more informaiton so I can educate myself. thanx

94form2000z

iTrader: (10)

The reason you'd have to would be to keep the piston from hitting the valve as if that's not obvious. Depends on the specs of your cam and whether or not you milled the heads at all.

pdd

iTrader: (3)

do a search bro. i just flycut my pistons last week and have a few pics of it on a thread here

SOM_of_a_Beach

I did a search, read the first 3 pages worth and didnt really snawer my question. I understand the obvious..to prevent a piston from whacking into something. But what makes it necessary is it the type of heads I purchased or the cam that makes fly cutting necessary? How long does it typically take and are there any alternative (i.e. purchase of another piston if the price is equivalent to that of the fly cutting)

Thanks,

Crystal

racer88

Crystal, the amount of lift you have from the cam. Cam specs could be ie; .608 .613 in the intake and exhaust. Too much lift on milled heads becomes a clearance issue as the above guy mentioned of pistons whacking the valve. That's why on some pistons they are dished to allow for the lift when it comes to valve clearance. Without cutting yours it's evident there isn't enough clearance with the lift of the cam he picked out for you.

It's techincal stuff, I would really look into forged racing pistons that will work with your set up. You are going to eventually need that with higher compression especially with nitrous.

pdd

iTrader: (3)

I flycut my pistons in about 2 hours. when you mill your heads that brings them closer to the pistons. so by cutting the pistons this allows more room between the piston and the valves

2MuchRiceMakesMeSick

I considered it but then I though, why spend money on something thats going to break. When mine goes ill go forged and buy them notched.

pdd

iTrader: (3)

[QUOTE=2MuchRiceMakesMeSick] why spend money on something thats going to break. QUOTE]
why would they break? unless your spraying huge nitrous shots at them

BLASTER

iTrader: (4)

I think flycutting would be cheaper to do than replacing all your pistons.

So if you understand the reason that you flycut is to avoid hitting the valves with the pistons, what is unclear?

Your cam duration, advance, LSA, CC and valve size dictates you P to V clearence. Your combo incorporateds 5.3 heads which have small CC to raise compression which means that the valves will be closer to the piston and since your cam is of moderate size, your P/V clearence will be compromised.

Dustin 98TA

Its not necessarily the lift alone that will make P/V issues. Its a combination of lift and duration. With a low duration and high lift, you could probably get by, when you raise the duration the valve stays open longer and the piston could possibly hit it.
The only sure fire way to tell is to clay it and see what you got.

NLang

iTrader: (12)

Lift isn't at all a determining factor. It's how long the valves are held at a certain lift (duration) as well as a valve timing that causes the interferance. Generally, 8* before (intake valve) and 8* after (exhaust valve) the piston reaches top dead center is where the valves will be closest to the piston tops.

Squintz Palladoris

iTrader: (1)

FYI Piston to valve cearance can be checked without claying the pistons. You can get some weak springs specifically designed for checking clearances and valetrain geometry. Once you figure out if you need to fly cut (and if so how much extra clearance you will need) you put the proper valvesprings back on.

Brad

Beast96Z

iTrader: (21)

#1 dictates your camshaft spinning in the motor. When it turns it lifts....
#2 your lifters/pushrod, which presses your
#3 rocker arms
#4 the pressure from that presses your spring/valves open
#5 is the piston. It's coming up while the valve is open. If it is open to long,(dictated by the size of your camshaft), it will hit the piston. This is where you would need
#6 a valve relief or fly cut. (dictated by the orange mark on the piston. By cutting into the piston, you make a place for your valve to go instead of it smashing into it.
Due to the angle of the valves to the pistons, diffrent size valves will bring you closer or further away to the piston. So, if your heads are milled, your bringing your valves closer to the pistons, if your valves are bigger, your bringing them closer to the piston, and if you install a larger camshaft, you are holding the valve open longer and pushing the valve down further, so it has more of a chance to hit the piston.

Did that help any?

pdd

iTrader: (3)

great pic and defanition beast

Beast96Z

iTrader: (21)

I was bored and wanted to try my hand in the paint shop.

Squintz Palladoris

iTrader: (1)

That was the best reply I have seen on this site man. Next to Try a search on this subject lol.

Good stuff man you really must have been bored!

Brad

SOM_of_a_Beach

Thank you very much, that was actually very helpful. BTW, the lift is .595/.608

Have you guys ever heard of diamond pistons? I was told they would make a direct fit and are inexpensive.

Thanks,

Crystal

SouthFL.02.SS

Crystal, just do yourself a HUGE favor and get a cam that's a bit smaller. The TSP 233/239 or a FM13 or FM14 on that setup will kick ***.

You can pick up the 233/239 from Texas Speed for $310 right now.

Do this and there should be no need for flycutting.

Beast96Z

iTrader: (21)

If your heads aren't rediculously milled, then you shouldn't have a problem anyway. Do you have any more specs like cam advance(usaully a+1,2,3,4 after the LSA number on the cam, the actual LSA, and how much if any, the heads were milled?