MLP00Z28

iTrader: (4)

Has anyone put 317's on a 3.90 bore with overseized valves without having any problems, lets say 2.02 and 1.6? I am planning on doing this but I want to know if there's enough valve to cylinder clearance. Ive seen 243 heads go with those valves on 3.90 bore but dont know if 317 angle is the same. I'd like to get 2.08 and 1.6 valves. By the way I've got big cam and wiseco forged 3cc relief pistons. thanks

MLP00Z28

iTrader: (4)

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405HP_Z06

iTrader: (11)

2.02/1.6 are not an issue in those heads on a 3.9" bore. I would discourage the use of a 2.08" intake valve on the listed bore. This small bore will significantly shroud this large a valve. Some say that a 2.05 is too large for this bore.

MLP00Z28

iTrader: (4)

Hey aaron wassup, always helping me jaja, I've seen 243 heads with 2.08/1.6 and my 317 heads are gonna be ported and angle milled so this should help a bit, I'm more worried about PTV clearance with this large valves than piston to cylinder wall clearance, still thinking on this since my ported has never put 2.08 and 1.6 valves in 243 or 317 on a 3.9 bore. I may go with 2.02 and 1.6 or maybe assemble my shortblock, get measurements and based on the results order the valves. By the way I'm milling the heads, thats why im worried bout PTV. thanks

Any comments are welcome

405HP_Z06

iTrader: (11)

PTV clearance will depend on the cam. I would almost bet that you will have PTV issues with a 2.08 intake valve. My suggestion to not use a 2.08 valve was based on the extreme valve shrouding that will occur on a 3.9" bore. You will have a more efficient engine with these heads and a 2.02 or 2.04 valve max ported on a 3.9" bore than the same with a 2.08 valve.

MLP00Z28

iTrader: (4)

Thanks for the advice, my cam is a Trex and I have forged pistons for 6.098 rods and 6.100 rods, based on stock engines I've seen they're .006 out of the hole so I calculate .008 out of the hole with my rods. I need about 61cc chambers to achieve 11.50 CR but I really need to assemble the shortblock and measure everything, I am really worried about milling them that much because I am almost sure I'd have PTV problems, so I may weld the chambers, what do you say?

MLP00Z28

iTrader: (4)

Anyone know where can I get 2.02 and 1.6 valve seats?