How to fly cut the pistons ?
05-29-2003, 07:02 PM
#1
TECH Junkie
Thread Starter
iTrader: (12)
Join Date: Jul 2002
Location: Austin, TX
Posts: 3,422
Likes: 0
Received 0 Likes
on
0 Posts
How to fly cut the pistons ? Hey guys i clayed my motor and even doing that put nice marks in my pistons so I need to fly cut my pistons does anyone know where i can get the tool to do this?
Marc
Marc
05-29-2003, 07:41 PM
#3
Re: How to fly cut the pistons ? DEAR GOD NO!!! DO NOT GET SHORTER PUSHRODS!!!
Stop and think about what you are doing (draw it out if you have to). You have a GIVEN distance (7.400") from the top of the lifter to the pushrod cup in the rocker arm. That distance is FIXED, it can't be changed. Now if you put a shorter pushrod (7.350" is the next smallest) look at what you have. When the pushrod is sitting on the lifter, it will be 0.050" short and WILL NOT be touching the rocker (yes...hydrolic lifters will pump up but I'll get to that in a min). So now, you have slop in the valve train. It WILL make noise, it WILL damage things, and you WILL loses a CRAP LOAD of HP.
Now, I mentioned the hydrolic lifters pumping up. If that 0.050" slop is in the lifters given range of make up, then the lifter will pump up, close the distance and BANG!!! First time you drive the car you will scrap it. If its not, then the lifter will pump up all it can, and then you will be back to having slop in the system.
This is not the way to lower your lift levels. This is like......"Hey...I need to lower my car so I will let all the air out of the tires"....its STUPID! (sorry if that offends you but its the truth.....).
There is a tool out there (I think isky makes it) that you can use to fly cut your pistons. It's a fancy grinding stone. Call Thunder Racing, I think they have it. It goes into the head (in place of the valve) and you turn it with a power drill.
Another option is to take a small grinder with a small grinding bit and make the "fly cuts" in the pistons. This can be done with the engine assembled. You need to fill up all the holes everywhere with rags/towels/tape/etc. to keep grit out of the engine. After you get finished, make sure you really clean everything up. My machinist told me this one....it’s an OLD OLD OLD school trick. I personally would not feel comfortable doing this one
(don't trust myself) but it will work (know a number of people who have done it).
I had this problem (p-to-v clearance) when I did my heads/cam in my Z28 . The heads were milled 0.020” and had larger valves (2.08/1.60) so I had to either fly cut or go with a smaller cam. I decided to go with a little smaller cam (TR224 vs. TR230) since I didn't want to go cutting into the stock hypereutectic pistons.
Good luck,
Chris
Stop and think about what you are doing (draw it out if you have to). You have a GIVEN distance (7.400") from the top of the lifter to the pushrod cup in the rocker arm. That distance is FIXED, it can't be changed. Now if you put a shorter pushrod (7.350" is the next smallest) look at what you have. When the pushrod is sitting on the lifter, it will be 0.050" short and WILL NOT be touching the rocker (yes...hydrolic lifters will pump up but I'll get to that in a min). So now, you have slop in the valve train. It WILL make noise, it WILL damage things, and you WILL loses a CRAP LOAD of HP.
Now, I mentioned the hydrolic lifters pumping up. If that 0.050" slop is in the lifters given range of make up, then the lifter will pump up, close the distance and BANG!!! First time you drive the car you will scrap it. If its not, then the lifter will pump up all it can, and then you will be back to having slop in the system.
This is not the way to lower your lift levels. This is like......"Hey...I need to lower my car so I will let all the air out of the tires"....its STUPID!
(sorry if that offends you but its the truth.....).There is a tool out there (I think isky makes it) that you can use to fly cut your pistons. It's a fancy grinding stone. Call Thunder Racing, I think they have it. It goes into the head (in place of the valve) and you turn it with a power drill.
Another option is to take a small grinder with a small grinding bit and make the "fly cuts" in the pistons. This can be done with the engine assembled. You need to fill up all the holes everywhere with rags/towels/tape/etc. to keep grit out of the engine. After you get finished, make sure you really clean everything up. My machinist told me this one....it’s an OLD OLD OLD school trick. I personally would not feel comfortable doing this one
(don't trust myself) but it will work (know a number of people who have done it).I had this problem (p-to-v clearance) when I did my heads/cam in my Z28
. The heads were milled 0.020” and had larger valves (2.08/1.60) so I had to either fly cut or go with a smaller cam. I decided to go with a little smaller cam (TR224 vs. TR230) since I didn't want to go cutting into the stock hypereutectic pistons. Good luck,
Chris
05-29-2003, 07:45 PM
#4
Banned
Join Date: Sep 2002
Location: Azle/Saginaw, Tx
Posts: 5,581
Likes: 0
Received 0 Likes
on
0 Posts
Re: How to fly cut the pistons ? there's a guy here with a 98 SS with a pretty big cam and heads but i don't know how much taken off (milled) and he just compensated with 7.35" pushrods and he has no abnormal stuff such as noise or bad performance. i wouldn't want to start cutting the stock pistons either. if you're having problems i guess i'll go ahead and order myself a set of short rods just to get it overwith.
05-29-2003, 08:19 PM
#6
Banned
Join Date: Sep 2002
Location: Azle/Saginaw, Tx
Posts: 5,581
Likes: 0
Received 0 Likes
on
0 Posts
Re: How to fly cut the pistons ? Louis? how much to do this, what is involved? can you assure me that their wont be any particles in the motor? and most importantly, how much? i'm running bigger, and milled heads so i'll probably need it. how safe is it on stock pistons?
05-29-2003, 09:27 PM
#7
TECH Junkie
Thread Starter
iTrader: (12)
Join Date: Jul 2002
Location: Austin, TX
Posts: 3,422
Likes: 0
Received 0 Likes
on
0 Posts
Re: How to fly cut the pistons ? I might just buy the tool since I plan on opening my own shop but how much is it if ya'll do it I might just have to let ya'll do it. My combo was 5.3 heads milled .030 with a X 1 cam.
Trending Topics
05-29-2003, 09:48 PM
#9
Re: How to fly cut the pistons ?
there's a guy here with a 98 SS with a pretty big cam and heads but i don't know how much taken off (milled) and he just compensated with 7.35" pushrods and he has no abnormal stuff such as noise or bad performance. i wouldn't want to start cutting the stock pistons either. if you're having problems i guess i'll go ahead and order myself a set of short rods just to get it overwith.
05-29-2003, 10:02 PM
#10
Banned
Join Date: Sep 2002
Location: Azle/Saginaw, Tx
Posts: 5,581
Likes: 0
Received 0 Likes
on
0 Posts
Re: How to fly cut the pistons ? that's why he did...to much lift for the milled heads. like .588 lift with .030"(i think) heads. his duration was actually more than what marc is running
05-30-2003, 07:22 AM
#16
TECH Veteran
Join Date: Aug 2002
Location: Hartsdale, NY
Posts: 4,055
Likes: 0
Received 0 Likes
on
0 Posts
Re: How to fly cut the pistons ? Thunder Racing has a set up for flycutting pistons...
It is a head specially machined to take out the valve seats. The piston cutter is inserted in the head and placed on the block with a few bolts in. You spin the cutter by hand or with a drill until the head is flush with the deck...repeat for all valves...
They rent it out so call them.
It is a head specially machined to take out the valve seats. The piston cutter is inserted in the head and placed on the block with a few bolts in. You spin the cutter by hand or with a drill until the head is flush with the deck...repeat for all valves...
They rent it out so call them.
