Flycutting VH pistons for cams- Needed?

Post by **elwesso** » Thu Nov 30, 2006 3:12 pm

Just wondering if we came up with any definite if by running a cam with .5" lift we need to flycut the pistons...

Im just seeing if a cam upgrade would be possible without removing the motor and the heads... I mean, if i could remove the valve covers and put in new cams without doing anything else except valve springs, thatd be grand...

Post by **Ezekial** » Thu Nov 30, 2006 6:34 pm

what are all the cam specs?

Post by **elwesso** » Fri Dec 01, 2006 9:13 am

whatever defrag recommended!! im not a cam guy, 280 degree with .5" lift...

Post by **defrag010** » Fri Dec 01, 2006 2:25 pm

I actually haven't been able to measure stock pvc, but by how shallow the chambers are setup and how small the valve reliefs on the pistons are, I would plan on it. To make it easy, iskycams sells a flycutter that you can use with just a drill. It's on their site somewhere (iskycams.com)

Post by **elwesso** » Sat Dec 02, 2006 11:02 am

but i would stil have to take the heads off in order to do that, right??? I dont see any other way....

Post by **Ezekial** » Mon Dec 04, 2006 3:14 am

yeh heads would have to come off ...

Post by **Q45tech** » Mon Dec 04, 2006 6:41 am

The oem flycut depth is there for the rod stretch that occurs.......higher rpm than oem limiter will increase rod stretch so new rods on a high mileage engine are always a good idea if you increase lift.

Also what will an extra 0.110 " cut do to piston longevity?

It isn't as simple as you think if durability is a requirement.

If I spent $5,000 on up grades I would want the engine to last another 200,000.

Post by **elwesso** » Mon Dec 04, 2006 7:23 am

thanks for the reply tech... What do you think then, would be necessary to accomodate the extra lift? Are you saying NEW oem rods would be sufficient, or slightly shorter custom made rods would be needed?

Post by **defrag010** » Mon Dec 04, 2006 6:33 pm

I would worry about rod stretch on an aluminum rod race motor that lives its life at high rpm.. but for a street motor with forged steel rods, stretch is negligible on rods that haven't overheated. The valves are angled (don't know exactly which angle), so the amount of lift over stock isn't going to be .110". The VH pistons have a thick enough dome to take alot of flycutting.I remember measuring that part of the pistons when I measured the spring pad depth on the cylinder heads (~1/2") but I don't think I included it in my master spec thread. You can flycut .080" at the angle of the VH valves without having to worry about the thickness of the dome surface of the piston.

Flycutting VH pistons for cams- Needed?

Flycutting VH pistons for cams- Needed?

Re: Flycutting VH pistons for cams- Needed? (elwesso)

Re: Flycutting VH pistons for cams- Needed? (Ezekial)

Re: (defrag010)

Re: (elwesso)

Re: (Ezekial)

Re: (Q45tech)

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