Ls1 fly cutting pistons
Thread Starter
Teching In
Joined: Apr 2016
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Ls1 fly cutting pistons I am wondering if anyone can give me some insight on my situation. I have an 02 ls1 I have the ms4 cam and 243 heads my heads will be coming back from the shop in a few days I'm going to measure ptv clearance first thing but from what I have learned is more than likely I will have to fly cut to be safe. My question is can I use a different ls head other than 243 or 241 head to use the lindy fly cutting tool? What I mean is or the valve angles the same? Or do I have to disassemble my heads and use the lindy tool in them to fly cut??
11 Second Club
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I am wondering if anyone can give me some insight on my situation. I have an 02 ls1 I have the ms4 cam and 243 heads my heads will be coming back from the shop in a few days I'm going to measure ptv clearance first thing but from what I have learned is more than likely I will have to fly cut to be safe. My question is can I use a different ls head other than 243 or 241 head to use the lindy fly cutting tool? What I mean is or the valve angles the same? Or do I have to disassemble my heads and use the lindy tool in them to fly cut??
TECH Junkie
Joined: Nov 2013
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From: White Bear, Mn
Here is a nice easy way to measure.
Piston to valve measuring
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Verdad Gallardo Ive done this, but never in the car. Oooof, that will suck. I brought my pistons up to TDC using a deck bridge and indicator. Now...depending on camshaft, you might have the least ptv a few degrees off of tdc, but I’ve found that tdc works fine. Use the empty spare head. Use a little oil in the guides, with the cutting tool. A 1/2 drill will tend to chatter less than a 3/8 drill will. I have used both, and the results are the same, after you debur the cut piston with 300 grit sandpaper. Some folks will tape up the area after finding the cylinders tdc. I have taped up before, but I have also not taped up and simply cleaned well. The chips and dust will get down into the area above the top ring and is hard to clean. I use a shop vac and compressed air. Set the stop on the tool, and then use a new sharpie to mark, or use tape below the stop, to see if the stop has moved during the process. Take your time. First one is a little unnerving, but after you get it, you’ll find it’s not too bad.
I was going to fly cut mine then i bought tfs heads and clayed it. Theres far more ptv with the tfs heads. With 243s i would have had to cut unless i wanted less than desirable compression, even then it would have been tight.
Banned
Joined: Mar 2018
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Something worth mentioning that I'm surprised no one suggested.
The Cutters on the Lindy tool can sometimes touch the piston if you install the head with the piston at TDC. Thats not good.
Sometimes you may need to install the head, start the drill that drives the cutter and with the cutter resting on the collet rotate the engine to TDC.
Depends on the engine, piston, deck height, valve angle, head gasket thickness, Some people think you don't need a head gasket to flycut, this makes the clearance less.
The Cutters on the Lindy tool can sometimes touch the piston if you install the head with the piston at TDC. Thats not good.
Sometimes you may need to install the head, start the drill that drives the cutter and with the cutter resting on the collet rotate the engine to TDC.
Depends on the engine, piston, deck height, valve angle, head gasket thickness, Some people think you don't need a head gasket to flycut, this makes the clearance less.
I ran the MS4 with stock 241’s and had no issue with PTV clearance. You should definitely check the PTV clearance but I doubt you are going to have to fly cut unless someone milled an excessive amount off your heads.
Wouldn't want to do this job in the car though. I had mine on an engine stand. I slipped a large clear bag over the engine before cutting. I cleaned up after each cut and then taped the hole up before proceeding.
Banned
Joined: Mar 2018
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Also not suggested. Smear a thin layer of grease around the cylinder so when you bring the piston to TDC it fills the gap above the top ring. Gap full of grease- no metal gets in. Grease will also burn off fairly quick when the engine is started.
Thread Starter
Teching In
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I appreciate the comments I'm going to fly cut. So I can run smaller gasket and maybe mill a bit more. The machine shop just put bigger valves in heads. 2.02 . 1.57. So I'm going to get the right size from lindy . So should I do it with my headgasket on? I'm assuming I will have to use my good heads to do it since I will have bigger valves then an old junk ls head?
