aaahhh i see what yours sayin..if they had vavle reliefs in them then its probaly wouldnt be a problem

I think it is about 12mm of clearance using 90 pistons, or so I have been told. I haven't actually measured it myself. I think with the 89 pistons you get a little under 8mm clearance, but don't quote me on that I haven't measured it out myself

Any cam combo can work it's all about tuning your engine management. Placement of cams is a big thing too, especially for overlap, and how agressive your timing would be..

If people do chose to use stocker 248/248 cams, and can't achieve any more lift in cams with the 89 pistons, you could always get larger valves up to .040.

see thats y we luv vinny

8mm, from the valve closed to the piston or what? Cause isn't stock lift on the S13 cams like 9.3mm~?

Also wouldn't OS valves give you even less clearance because now that the valve is bigger it's edge is closer to the piston? Correct me if I'm wrong

...

That would be closed. From valve at top of pentroof to top of piston. 89 pistons arent a wise investment.
If you enlarge the valve that would leave less clearnce so even using 90 pistons if you were to enlarge the valves .040 you would be stuck using 240 cams. Or if you use 90 pistons with no valve enlarge ment you could get away using 270 duration cams. Or at least that is that I have been told.

You also have to consider where the valve opens in stroke 1, and where it opens in stroke 4. You are dealing with more play, but then you have to worry about valve overlap at higher rpms.
I wouldn't quote me on this though I should be checking this as fact not here say.

soo 90 pistons wit bc 264 cams n .5 mm over size vavles shouldnt have An issue with clearance?then should b jus enough room 2 not have a bent vavle correct?

Yes and no.
It will work with the cams not with the oversized valves. It could bend a valve at high revs.
You would probably have to step up to titanium retainers and springs, get to much valve float it could bend a valve.

So 90 SOHC Pistons and BC 264's would work w/ stock Valve Size? Would a full Supertech head be enough to prevent valve float and bent valves at 8k? Lighter Valves and Retainers and Stiffer springs, that should be more then enough eh? Then a good P & P to top that off.

thats what im thinking jus with bc head wit p&p head i have should do wonders with a good tune..if not i'll suck it up n put in je 11.0.1 pistons wit vavle reliefs.. !!speakin of reliefs could you take those 90 pistons n get vavle reliefs put into them???

with this set up n good ecu tuning i should b able to break the myth that kade cant make 200+ in N/A form....

I believe Greaser is using stock valve sizes with SOHC pistons and the Brian crower cams. Yeah I think a P&P to top it all off, with retainers is the right way to go.


It would weaken the piston strength.

so u think .5mm over size would really make that big of a difference??waht about jus on the exhaust side..???

so having forged pistons with the reliefs already in them you think would be weaker than cast??or would the forge be the way to go?

240 kid how did ya build go??