I am going to be flycutting to clearence my soon to be setup... here are the head #'s, for ref. they are patriot LS6 stage 2.

2.02" Intake
1.57" Exhaust

I would guess 2-1/4" cutter?

How do I determine the correct cutter size? I will most likely be using my stock 853 casting heads so what size guide do I need? 8mm?

Thanks for the info!

 

If you dig under my name, I have been through this whole thing.

You need a 2 1/8" cutter for int. The pilot shaft should be the dia of a push rod. 5/16" I think. Make SURE the pilot tool is not loose in the hole. It will bounce around causing the tool to chip teeth off of it.

My ext cutter is 1 3/4".

 

And there are no stupid questions here. Well at least not this one.LOL

 

A few pics for ya.

 

what H/C are you running? Do you have a donor head I could use. I will be running ported LS6's. Can I use the same diameter cutter for both cuts using the larger on both?

Your PM's are full

 

PNT-218 .. 2 1/8'' Intake valve cutter
PNT-134 .. 1 3/4'' Exhuast valve cutter
NP - 516 .. 5/16'' PILOT



http://www.iskycams.com/pdfcatalog/2004-05/page17.pdf

 

Cool pics. I'd never seen the cutter.

There are some stupid questions.............I've asked a bunch of them

 

5/16"? I thought it was 3/8". Dang it, I don't even remember what one I ordered now.

 

how do you know when to stop cutting? im going to assume you have to have some sort of measurement so you dont mess with the compression and as to not damage the piston? then what about all the debris dropped into the cylinder.

 

These were 5.3's. I got the donor from TEA, You CAN not use the same size cutter for both. They would over lap.

 

There is a collar on the tool that you set according to how much you need to cut. Ya stop once it bottoms out to that point..

I took duct tape and covered the top of the piston. This covers the ring gaps.

 

Yeah the intake cutter won't even fit in the chamber of the head when you insert the guide through the exhaust side.

 

thanks for all the info. I think I'll try it so i can get the setup i want.

 

Yep, I like those numbers...

...Remember to go twice as deep as you actually need. If you need .030, dont just cut .030. P to V isnt closest right at TDC, the pistons is slightly downbore. Since the valves are on an angle, theyll move over a bit laterally. Thats why you need to cut deeper than you normally would, and then check afterwards.

 

very awesome thread. I have my set of original 99 ls1 factory heads that I guess I will sacrifice to my fly cutting cause...

They however have stock size valves, and the heads I now have (Patriot "LS6 style" heads) with welded up 59cc chambers on the car have 2.055 intake valves so the cutter I went with for that is 2 1/8" which I assume will not obviously seat itself properly in the factory head.

Is this going to be an issue?

Also, the exhaust cutter I went with is 1 7/8" and the exhaust valve is of course just shy of 1.6

(just FYI it is a custom grind cam, and the lift is well above .600")

Any and all help is appreciated, thanks!

 

Lift doesn't matter. It's duration and LSA.

 

bring piston to top dead center. tape off deck surface, and either use gasket, or layers of tape to simulate your new head gasket thickness and include if your milling the heads. in my case, I millled the heads .033 and used a .040 head gasket. so the stock head I used as the tool simulated .033 of that diff (unmilled right?!!!) and made the tape thickness added up to the rest of the .040" cometic gasket I used in the end. so the tape thickness owas .007". after tapeing, cut tape away to reveal the area to be cut. you want the cutter to rest on the piston, not the tape so you get an accurate cut. now bolt on the tool (old head with cutter in it) and let the cutter sit right on the piston. install the feeler gauge under the collar and on top of the valve guide and tighten down the lock collar. I then measured the distance to the tip of the cutter (valve tip sorta) for a referance # that I could double check when I was done cutting, to ensure the collar didnt move on me, creating a deeper cut then I wanted. after cutting insert a vacuum into the ports to suck up most of the shavings before you pull the head off. then immediatly vac. off the rest to keep that **** from getting anywhere else. then sand off the sharp edge around the cut and wipe clean with a paper towel and some cleaner.

another tip is to spray the cutter teeth with wd40 before bolting on the head. the cutter will operate smoother, and you'll get a nice smooth cut. heres more pics.



measuring the depth of the cut to keep consistent cuts in all the cyl.s. you'll find some of the valve guides will be a few thousandths off. an easy way to see if there all the same is the width of the cut at the bottom. the deeper the cut is, the wider it is. some of mine werent as wide as the others after the first go around.






hope this helps you fella's.

 

Thats experience I couldnt of gotten if it wasnt for your post. It'll help a hellova lot. Pics are awesome too. Really appreciate it, thanks alot.

 

May be a stupid question, but does flycutting lower your compression ratio?

 

yes. but only slightly. and you can more than offset that by milling the heads, which is the benefit of flycutting.