question on flycutting.
12-02-2006, 04:30 PM
#1
question on flycutting. about to flycut my pistons. just wondering if there's a easier way/less time consuming to figure out how deep in the hole the pistons have to be to cut each one. if I figure out #1 like this method, can I then figure out how deep in the hole that piston is and repeat that depth for each piston?
also any other instructions/writeups on how to flycut? Im pretty sure I got it all down now, but just would rather see how others are doin it to make sure Im doin it correctly before I start. not really something I want to learn as I go ya know.
this link does not work anymore.
http://www.ffhp.net/tech_Isky.htm
quote:
Best way to measure actual clearance would be to mock it up with solid lifters, test springs and a degree wheel. Then start from about 45* BTDC and measure the distance of the valve from the piston with a dial indicator (push the valve down until it contacts, noting the difference on the indicator). Going in steps of 2-3 degrees should let you home in on where it is the closest.
quote:
also any other instructions/writeups on how to flycut? Im pretty sure I got it all down now, but just would rather see how others are doin it to make sure Im doin it correctly before I start. not really something I want to learn as I go ya know.
this link does not work anymore.
http://www.ffhp.net/tech_Isky.htm
quote:
Best way to measure actual clearance would be to mock it up with solid lifters, test springs and a degree wheel. Then start from about 45* BTDC and measure the distance of the valve from the piston with a dial indicator (push the valve down until it contacts, noting the difference on the indicator). Going in steps of 2-3 degrees should let you home in on where it is the closest.
quote:
12-02-2006, 08:00 PM
#2
Forget about solid lifters with test springs. Theyre so little tension that theres no way itll compress the lifter plunger. Dont torque down the rocker, only tighten it tilla ll the play is removed, then on to measuring. Go from -20* to +20* measuring every 2*.
12-02-2006, 08:37 PM
#3
You have the best way. The solid lifter is a good idea, JUST IN CASE. It would suck to find out something like, "Well, we THOUGHT it wouldn't compress" LOL!
But yeah do that. Then you can just go ahead all the way around your cam so that you can know the EXACT specs on your cam, instead of just the claimed specs.
But yeah do that. Then you can just go ahead all the way around your cam so that you can know the EXACT specs on your cam, instead of just the claimed specs.
12-02-2006, 09:03 PM
#4
well Ive already degreed it in. perfect as advertised in the card. and, I already made some solid lifters. I have test springs, but I felt like N4cer, what if? didnt want to take any chance of it not being exactly accurate. guess it wont be soo bad to do that checking/graphing. just take meausurements in steps, ploting them down on paper.
but Im assuming it'll be safe to just repeat whatever depth the piston is at while at the closest point to contact?
but Im assuming it'll be safe to just repeat whatever depth the piston is at while at the closest point to contact?
12-03-2006, 10:28 AM
#6
but if you have a solid lifter and you torque the rocker down, it will keep teh valve open instead of preloading the hydraulic lifter. The valve wont ever close and it will skew your measurements. You either need an adjustable rocker, or simply finger tighten the stock rocker until all the play is take up.
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12-03-2006, 04:58 PM
#8
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Cut it .080" and if you are still worried about it, change cams. Thats plenty for most any cam and head milled up to .030. The difference between .050 and .080 as far as compression isnt worth worrying about.
Brandon
Brandon
12-03-2006, 10:53 PM
#9
nah, Im not changing cams. I like the specs on this cam or I would not have ordered it like this.
I think your misreading my questions though. I am goin to cut the relief until I have .080 clearance on the intake, and atleast .100 on the exh, the question was where should the piston be in the hole (how far down from TDC should the piston be) when I make the cut.
Im pretty sure Im goin to be in the .100" depth for my cut. I mocked it up with the stock Push Rod, and stock gasket, and before I had the heads milled, and came up with .028 clearance on the inake side. so after milling .030 off of the head, and subracting for the thinner gaskets (stock .054 vs .042 mr gasket = .012 difference) I'll need to cut .094" to clear by .080". so I'll round up to .100 for my first but, and reclay it to see how that went.
I think your misreading my questions though. I am goin to cut the relief until I have .080 clearance on the intake, and atleast .100 on the exh, the question was where should the piston be in the hole (how far down from TDC should the piston be) when I make the cut.
Im pretty sure Im goin to be in the .100" depth for my cut. I mocked it up with the stock Push Rod, and stock gasket, and before I had the heads milled, and came up with .028 clearance on the inake side. so after milling .030 off of the head, and subracting for the thinner gaskets (stock .054 vs .042 mr gasket = .012 difference) I'll need to cut .094" to clear by .080". so I'll round up to .100 for my first but, and reclay it to see how that went.
12-03-2006, 11:47 PM
#10
Originally Posted by Irocss85
I think your misreading my questions though. I am goin to cut the relief until I have .080 clearance on the intake, and atleast .100 on the exh, the question was where should the piston be in the hole (how far down from TDC should the piston be) when I make the cut.
12-04-2006, 08:03 AM
#13
Always cut at TDC. You have to cut MORE than the what you think you might need to compensate for any lateral movement of the valve as the pistons moves down bore. IE. Even if you cut .080 at TDC, you may only gain .050 clearance at the moment of least P to V clearance.