Will I need to flycut pistons?
Thread Starter
TECH Regular
Joined: Dec 2005
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From: Kailua-Kona, HI
Will I need to flycut pistons? Just wondering if I will need to flycut my pistons with this setup:
Ported LS1 stage 2 heads - UNMILLED
Stock thickness head gasket
TSP 228R cam (.588/.588 - 228/228 -114)
1.8 roller rockers
Just wanted to make sure that this will work no problem. With the 1.8 rockers it will bring the lift of the cam up to .623, so I just want to be safe.
ALSO,
Can I get some recommendations for the 1.8 rocker arms? Harlands?
Thanks.
Ported LS1 stage 2 heads - UNMILLED
Stock thickness head gasket
TSP 228R cam (.588/.588 - 228/228 -114)
1.8 roller rockers
Just wanted to make sure that this will work no problem. With the 1.8 rockers it will bring the lift of the cam up to .623, so I just want to be safe.
ALSO,
Can I get some recommendations for the 1.8 rocker arms? Harlands?
Thanks.
With 1.7's id say youd probably clear just fine, but with the 1.8 theres just not enough anecdotal evidence out there to say one way or the other. Measure using a checker spring from 15* BTDC to 15* ATDC checking with a dial indicator every 2* or so. Thatll give you a good idea on how close you come.
Here is a link to assist in the flycutting learning curve.
https://ls1tech.com/forums/generation-iii-internal-engine/709183-how-flycut-pistons.html
R/
Frat
https://ls1tech.com/forums/generation-iii-internal-engine/709183-how-flycut-pistons.html
R/
Frat
Thread Starter
TECH Regular
Joined: Dec 2005
Posts: 444
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From: Kailua-Kona, HI
Why would you NOT go with 1.8's?
You should not have any piston to valve clearance issues with that setup!
Here's a short lesson on valve timing and its relation to piston to valve clearance for anyone curious
That's a diagram of a random cam I found online. The basics of the valve events are the same though! People wonder why I tell them that amx lift is not the most important thing to consider when wondering about piston to valve clearance. Here's why! You see at the peak of the red curves (when the cam is at max lift), the piston about half way up/down the cylinder. That's not where you have piston to valve clearance issues, since your valves are only open ~.600" (of course that varies on the cam and rockers). You have clearance issues when the intake valve is chasing the piston after TDC (see the red line ramp up right before TDC?). So if your cam has a nasty aggressive lobe on it and gets off the seat with fast ramps and big low lift numbers, you're more likely to kiss pistons. The opposite goes for the exhaust. That piston is chasing the exhaust valve as its closing.
So....if you've got those real aggressive lobes and big duration, you're more likely to kiss pistons and valves together. That's where valve reliefs come in to play.
Again, that's the abbreviated version. Don't nit-pick
Here's a short lesson on valve timing and its relation to piston to valve clearance for anyone curious
That's a diagram of a random cam I found online. The basics of the valve events are the same though! People wonder why I tell them that amx lift is not the most important thing to consider when wondering about piston to valve clearance. Here's why! You see at the peak of the red curves (when the cam is at max lift), the piston about half way up/down the cylinder. That's not where you have piston to valve clearance issues, since your valves are only open ~.600" (of course that varies on the cam and rockers). You have clearance issues when the intake valve is chasing the piston after TDC (see the red line ramp up right before TDC?). So if your cam has a nasty aggressive lobe on it and gets off the seat with fast ramps and big low lift numbers, you're more likely to kiss pistons. The opposite goes for the exhaust. That piston is chasing the exhaust valve as its closing.
So....if you've got those real aggressive lobes and big duration, you're more likely to kiss pistons and valves together. That's where valve reliefs come in to play.
Again, that's the abbreviated version. Don't nit-pick
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COMP - FAST - PACESETTER - DIAMOND RACING - EAGLE SPECIALTY PRODUCTS - CALLIES - COMETIC GASKETS
RAM CLUTCHES - MOSER ENGINEERING - KOOK'S HEADERS - ARP - GM BOLTS AND GASKETS - MSD - NGK
POWERBOND - ASP - AND MORE!
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Thread Starter
TECH Regular
Joined: Dec 2005
Posts: 444
Likes: 0
From: Kailua-Kona, HI
You should not have any piston to valve clearance issues with that setup!
Here's a short lesson on valve timing and its relation to piston to valve clearance for anyone curious
That's a diagram of a random cam I found online. The basics of the valve events are the same though! People wonder why I tell them that amx lift is not the most important thing to consider when wondering about piston to valve clearance. Here's why! You see at the peak of the red curves (when the cam is at max lift), the piston about half way up/down the cylinder. That's not where you have piston to valve clearance issues, since your valves are only open ~.600" (of course that varies on the cam and rockers). You have clearance issues when the intake valve is chasing the piston after TDC (see the red line ramp up right before TDC?). So if your cam has a nasty aggressive lobe on it and gets off the seat with fast ramps and big low lift numbers, you're more likely to kiss pistons. The opposite goes for the exhaust. That piston is chasing the exhaust valve as its closing.
So....if you've got those real aggressive lobes and big duration, you're more likely to kiss pistons and valves together. That's where valve reliefs come in to play.
Again, that's the abbreviated version. Don't nit-pick
Here's a short lesson on valve timing and its relation to piston to valve clearance for anyone curious
That's a diagram of a random cam I found online. The basics of the valve events are the same though! People wonder why I tell them that amx lift is not the most important thing to consider when wondering about piston to valve clearance. Here's why! You see at the peak of the red curves (when the cam is at max lift), the piston about half way up/down the cylinder. That's not where you have piston to valve clearance issues, since your valves are only open ~.600" (of course that varies on the cam and rockers). You have clearance issues when the intake valve is chasing the piston after TDC (see the red line ramp up right before TDC?). So if your cam has a nasty aggressive lobe on it and gets off the seat with fast ramps and big low lift numbers, you're more likely to kiss pistons. The opposite goes for the exhaust. That piston is chasing the exhaust valve as its closing.
So....if you've got those real aggressive lobes and big duration, you're more likely to kiss pistons and valves together. That's where valve reliefs come in to play.
Again, that's the abbreviated version. Don't nit-pick
PS the cam runs really strong and with the spray the car feels like it was built to run on the juice.
I strongly recommend this cam fro NO apps. I am sure that you guys make a NO app cam, but this one suited my fancy so I ordered it on a 114 centerline and here we go.
I should see a bit more power when I install my Magnaflow, electric cutout, and bottle heater, so I'll let everyone know how that goes. Then I'll swap the heads and re-tune. Hoping for 550+ rwhp on the spray!
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Joined: Feb 2004
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From: Lexington, KY
I'm no expert either but have always heard the same thing also; if your running agressive profiles, it's best to stick with 1.7's. If you look at TR's websight they say not to run 1.8's with most of their cams due to the agressive ramp rates. I think it has to do with valvetrain geometry, the mass of the moving parts, and the required spring pressures. Not to say that some poeple don't get away with it.
