high compression setup

[bszopi]

w...t... f...

[gectek]

those are really popular to fly cut with. they work reasonably well. just set the depth with your drill and you are golden.

[robertisaar]

i can honestly say i've never seen flycutters in place of valves until today...

[gectek]

there are companies that sell the stick on blades and there are ones that sell the modified valves.

[IsaacHayes]

Gotta use a junk head and modify it to work properly.

http://ls1tech.com/forums/generation-iii-internal-engine/1005655-piston-flycutting-engine-car.html

[gectek]

no you dont
why a junk head?

[IsaacHayes]

Well, as that thread shows, spinning a bit/valve could mess up the valve guides, and also if you look at the thread he had to grind the hell out of the valve seats so the cutters would sit right.

[gectek]

well that is that style. and the valve spins in the guide anyway. just use some lubricant and i do not think it would be a big deal. if you use the correct blades, they stick to the valve and do not mess anything else up.

[geldartb]

well even if it required using a junk head i still got the heads off my old 3400 and the pistons are currently mounted in that block so none of this would get done on the engine in the car, just swap pistons when im done cutting them.

what im thinking would work right. the valves are in the same place, and i could build a setup out of sheet metal or something the same thickness of the headgasket ill be using to do this.

pretty good writeup from LS1tech. the guy seems like he did his homework on that.

got any links for the stick on types. i found the lindy tools site and its $75 for the cutter and 25 for the guide rod.

http://www.etsupply.com/edgetools/index.html

[IsaacHayes]

Why do you think you need to cut reliefs for your valves? Or are you wanting to do that to lower compression??? Dave is the one who needs to cut reliefs due to his long duration...

[gectek]

flycutting would not change CR much at all. it would help, but at that point you could just get the pistons machined for a better overall look/design. If you run a larger cam with more duration and such, then i would def flycut first if you still want to use stock pistons. otherwise the diamonds can be ordered with valve reliefs already.

[Superdave]

those are pretty neat, never thought about doing it that way.

[ForcedFirebird]

Rotating the valves in the head won't ruin anything. How do you think valves have been lapped since the dawn of re-seating valves? Even a valve seat machine has a pilot that goes into the guide to keep the facing of the seats accurate

You have to figure if you do a valve relief, you are going to lose about 2-5cc's of material depending on the depth of cut, but how safe is the ring lands going to remain on the already thin castings after valve reliefs are cut?

Off topic, but an easy way to know if your valve seats and valves are concentric is to spray the valve with some runny lube and drop them in the guides - if they hit the seat and bounce, they are good, if they thud, you need to recondition either the valve angle or the seat sealing angle.

[geldartb]

Bradon, what is your intake valve closing ABDC ? I'm wondering what the 12.52:1 compression will be actual with your cam.

well heres the numbers from Ben

IVO 6 BTDC
IVC 42 ABDC
EVO 53 BBDC
EVC 1 ATDC

[IsaacHayes]

That's not enough to run 12.53:1 compression. That won't bleed it off enough IMO. With .070 quench and 11.51:1 though you'd be fine though. I have 33 IVC and I'm going to shoot for 91 octane as that's all we have. It ran ok on 93.