"Valve pocketing" of pistons

[Grelland]

Guys,

I do not have much experience from engine building but I have searched some obious sites for advice, but have not found any good how-to's yet.

My issue is that I have come across a set of used Scat wedgeport 44x37.5mm heads, and the previous owner states that he run these with pockets machined in the pistons to clear the valves. He has been running a quite agrgessive JPM cam and 1:1.5 rockers.

My question is how do I safely measure/verify whether I need to do the same to my pistons?

I dont want to end up bending the valves trying.

I was thinking of trial assembling everything with "huge" copper rings on the barrels, to make sure I have enough clearence, and then use clay to verify, but is there a more elegant methoid out there?

The rest of my engine is roughly as follows:

Oxyboxer case
76mm stock wbx crank
5.4" scat i-beam rods
94mm wiseco pistons
Mahle barrels
FK8 cam
TP lifters
pauter 1:1.3 rockers

Any advice highly appreciated.

[nicolas]

no, the big shims work but i would set it up with the shims i would eventually use. use light springs and stop were it hits. be sure to measure the lift up to that point. compare to the the whole lift and cut the difference plus 1mm in the head. this is still a lot of work, but unless someone has a better approach this is how i would do it.

[Grelland]

no, the big shims work but i would set it up with the shims i would eventually use. use light springs and stop were it hits. be sure to measure the lift up to that point. compare to the the whole lift and cut the difference plus 1mm in the head. this is still a lot of work, but unless someone has a better approach this is how i would do it.

Thanks. This is some work, but now I have an entire winter ahead of me, so this should be doable

[LGK]

Hello,

With an FK-8 and 1.3 rockers you will never run into issues with your setup.
You're looking at between 12.5-13.2mm lift@valve maximum depending on your geometry.
Go ahead and start mocking up your engine as it is supposed to be,put light springs and check when turning the crank.Use some clay on your piston and check after 360° roatation where you are.
Believe me you won't ever come close to your valves with this setup,or your heads should be flycutted A LOT ?

Best rgds Steve

[Grelland]

Hello,

With an FK-8 and 1.3 rockers you will never run into issues with your setup.
You're looking at between 12.5-13.2mm lift@valve maximum depending on your geometry.
Go ahead and start mocking up your engine as it is supposed to be,put light springs and check when turning the crank.Use some clay on your piston and check after 360° roatation where you are.
Believe me you won't ever come close to your valves with this setup,or your heads should be flycutted A LOT ?

Best rgds Steve

Thanks Steve. Just the kind of advice I was looking for

Roy

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