GT5point0

So heres the complete setup:
Block is a stock bottem end, from an 88 LX.
Heads are TF TW with a port to 2.08
Cam TFS stage 2, .544"/.563" lift and 224/232 duration @ .050"
TF track heat intake manifold
1.6 RR's.

So Ive heard now on here i prob will experience ptv problems, would pulling out my cam and going with a different one make it so i dont have to flycut the pistons and stuff like that or what would be the best alternative to elimanate this problem, the engine is fully built and on an engine stand right now, i can do mechanical work, thus building the engine but cant do machining work to pistons and such. I figured if i could crank the engine and here no noises of things hitting then everything should of been good. So let me know what my best option here would be because if i could swap a cam and be fine and still ahve good performance then let me know what would be the cam i should go with and what not

Thanks

jwog666

i would remove 1 head and put some modeling clay on the top of the piston, then reinstall the head and valve train, then rotate the engine 2 turns, remove the head and measure the thickness of the clay where the valves contacted it, if i remember right you want at least .040" clearance vertically and at least .025" radially,but that was with a solid cam


edit: only use a small ammount of clay where the valve reliefs are

GT5point0

thanks anymore advice if i do have clearnace issues, would changing the cam to another cam make it so i for sure wont have issues?

jwog666

well, if you take your measured clearance and its too tight by lets say .010" then you would get a cam with roughly that much less lift. but you really shoud measure the clearance so you can buy the cam the the max allowable lift

GT5point0

by crankingi t over by hand like i did there isnt anyway that i could possibly bend the valves?

5spd GT

Peak lift has nothing to do with piston to valve clearance. That camshaft places thepiston well over 2.00" down the bore at peak lift.

That camshaft has issues of clearance, typically on the exhaust side.

Advancing or retarding the camshaft can gain you a bit, butit compromises your performance and powerband.

Advancing the timing opens the intake sooner and closes the exhaust sooner. That will gain you some clearance on the exhaust valve, but you will lose clearance on the intake valve. Retarding the cam causes the timing to open the intake valve later, and closes the exhaust later. You'll gain clearance on the intake, and lose clearance on the exhaust. So changing the cam timing won't result in increasing clearance on both valves.

GT5point0

anymore advice i would like to get as much help as possible becasue i was going to put the engine in this week now this has become so frustrating that i have everything put together and ready to go and if i do put it i dont wanna risk breaking stuff which now i think is going to happen.

PJC Racing

Clay the piston first to verify if you have clearance problem. David (5spd GT) gave you good info if there is a clearance issue. If that doesn't work, you could change the cam, but due to timing event you could make the issue worse if you don't how to select the proper valve events. Your best bet, if there is a clearance issue, is to get a custom cam. Or you could also flycut the pistons.

But you really need to clay the piston and make sure there is a clearance issue. If there is, I would recommend going with a custom cam, this would ensure you have the proper timing events to clear the piston anda custom cam will have more power/drivabilty potential.

Joel5.0

You have a set of heads that usually provide more clearance than the typical inline heads, there's no other way around for you, other than checking for PtV. BTW, you need to make 2 roller lifters into solid, and check for PtV with them at zero lash and some clay on the piston.

mjr46

like everyone is saying check ptv and use converted roller lifters..I take out the spring inside and shim with washers for proper height and then set up valvetrain on number 1 and check accordingly using play dough