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Hey guys hoping I can get some input for my 370 build my ls1 crapped the bed but am reusing a lot of stuff from it for my 370 build . I talked to Texas speed several times and I've been told my prc 2.5 heads that were milled .20 for the tsp v3 cam are going to be an issue if I wanted to get a bigger cam because of ptv clearance. I wasn't sure if anyone knew of another company that offered a cam that will work with my prc heads that are milled .20 that will be a better choice for my 370 I want to squeeze out every little bit of power I can out of it . I don't want to have to get new heads because I like the fact that I'm bumping up compression with my prc already being milled. Any advice would be appreciated
Hey guys hoping I can get some input for my 370 build my ls1 crapped the bed but am reusing a lot of stuff from it for my 370 build . I talked to Texas speed several times and I've been told my prc 2.5 heads that were milled .20 for the tsp v3 cam are going to be an issue if I wanted to get a bigger cam because of ptv clearance. I wasn't sure if anyone knew of another company that offered a cam that will work with my prc heads that are milled .20 that will be a better choice for my 370 I want to squeeze out every little bit of power I can out of it . I don't want to have to get new heads because I like the fact that I'm bumping up compression with my prc already being milled. Any advice would be appreciated
What pistons are you going to be using? Most forged pistons are going to have generous valve reliefs so PTV should not actually be a problem.
Ah ok, so those are not really LQ9 pistons, those are aftermarket 4.030" flat tops. It's confusing when you say LQ9 pistons because that implies that you're talking about the OEM 4.0" bore LQ9 piston.
Regardless, if you see yourself going to a bigger cam later and you're already tight on PTV, you are really going to want valve reliefs in your pistons. A bigger cam with the same or better PTV will have to make such compromises in the valve events/lobe design that may not even be worth it IMO.
If you're stuck on using those pistons, there are some online calculators out there that can help you figure out what the PTV should be before you buy anything. You may have to take some measurements, but at least you'll have a more educated guess before you buy another cam and hope it fits.
If you have a dial indicator like pictured below and know how to use it, I can show you the procedure for measuring "valve drop". That will allow me to tell you exactly what camshafts will fit.
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Last edited by CAMMOTION PERF; 04-07-2017 at 12:03 PM.
Hey Blackfbird, Tick has DSS forged 4.030 flat tops with nice deep valve reliefs for $399 shipped, I just bought a set to pair up with a 6.0 block I've got laying around, the pistons are far superior to what you're looking at for not much more money, just sayin. P.S. ptv won't be an issue.
That would be a bad move IMO, the top of an oem hypereutectic has the structural integrity of a potato chip and if you go cutting into it .025-.045" or more there's a chance they won't survive. All you would have is a crappy piston with a weak spot, do it right and get slugs with valve reliefs and have all the ptv you want. Those valve stem style piston cutters are old school for cutting forged pistons, not cast junk
Exactly. If it's a 370 you should most likely have a valve relief. You could essentially run anything you want, from a clearance perspective.
With my heads being milled .20 by you guys for the v3 cam what would be the minimum I would need for valve clearance to run say an ms4 cam? Like would a -5cc piston be sufficient?
.050 int. .080 exh. Thereabouts. Get some clay, put it on the piston head and roll through, take the head off, carefully cut away half of it and measure the thickness. there's a better way than that if you have the tools but the clay method works and is easy. The valves are closest to piston in the overlap phase, exh. closing and intake opening , 10* before, 10 after the exhaust stroke is completed , those aftermarket pistons generally have more than enough clearance for shelf cams you're interested in but you should check anyway.
That would be a bad move IMO, the top of an oem hypereutectic has the structural integrity of a potato chip and if you go cutting into it .025-.045" or more there's a chance they won't survive. All you would have is a crappy piston with a weak spot, do it right and get slugs with valve reliefs and have all the ptv you want. Those valve stem style piston cutters are old school for cutting forged pistons, not cast junk
I used these to cut .050" reliefs. They cut really smooth and it's super easy to do. They cut with no jerking and grabbing. Cut each valve relief in seconds. Good for NA but I wouldn't use n2o or forced induction with piston that has been cut. I know of guys who went as much as .100 on a NA engine with no problems.
That would be a bad move IMO, the top of an oem hypereutectic has the structural integrity of a potato chip and if you go cutting into it .025-.045" or more there's a chance they won't survive. All you would have is a crappy piston with a weak spot, do it right and get slugs with valve reliefs and have all the ptv you want. Those valve stem style piston cutters are old school for cutting forged pistons, not cast junk
I've had the heads in our LS3 milled .075" and used the Lindy Tool to flycut the factory pistons .100".
I've had the heads in our LS3 milled .075" and used the Lindy Tool to flycut the factory pistons .100".
And now you have a week set of brittle pistons? Piston crowns on forged pistons are reinforced on the under side to compensate for valve reliefs, cutting into a cast piston that has NO reinforcements just doesn't sound like such a good idea, people run across the freeway at night too. Hope it works out for you.
04-05-2017, 04:17 PM
Replacing tsp v3 cam for 370 build? 
