Valves Hitting Pistons In High Comp Motors

[Paul-]

hi currently building a 4k tighe 104 and hoping to get 8.3 dynamic compression just wondering if anyone has found that the increased lift and machining so much iff the cyl head that the valves end up hitting the pistons , i am planing to check the clearance before final assembly and will post up my findings then but just checking if anyone has done this before thanks

Edited September 4, 2009 by Paul-

[irokin]

You're barely even scratching the surface as far as lift and shaving goes. Definitely check but I can't say I can think of anyone bending valves in a K motor.

[altezzaclub]

Just do it, then put the head on w/o a gasket and turn it by hand.

 

Cam timing affects piston/valve clearance a lot, so if you have one of those wonderful variable cam gears make sure you try turning it w/o the gasket at both ends of the cam timing range you expect to use.

 

You will need the gasket thickness to allow for stretch in pistons & rods, some chain slack and a bit of valve movement.

 

If the pistons touch the valves (you can put a bit of plastosine on the piston to see the clearance) you might solve it with cam timing (you just can't run the cam there) or mill an eyebrow out of each piston. Usually inlets hit, not exhausts.

 

Chase up Rob here in Orange (rob83ke70) he's a mechanic with stacks of 'rollas, and will be a mine of information for you!

Edited September 6, 2009 by altezzaclub

[philbey]

What static comp are you looking at (i can't be bothered putting the details into my comp calculator.....)

 

Like irokin said, that shouldn't be a problem at all, there's plenty of people running big cams and lift on K engines here. Myself being one of them.