Adding valve reliefs when there are none

[danz]

id wait until you have everything together and clay it before you lose sleep over how to mod the piston.


edit; the sweetest way ive seen people do the mods ur looking for is to grind teeth into the valve like little blades and use that!! i think it was rushi that did that, iirc...

[cyanide]

Yes, after reading though multiple builds including yours, it seems like the newer OBD1/2 heads had a favorable valve angle, so no work was required. Since Rushi was using the old PM3 casting, he was already at a disadvantage.

I will be claying the motor with my cut head, so I can see what's going on inside the bore.

[The_Beave]

Favorable angle compared to what? I have always been under the impression that the VTEC valve angle is much worse for flow than any of the non-VTEC heads.

[cyanide]

Compared to the older heads, when considering piston to valve interference.

You have seen my port work; The valve angles won't be that much of a problem for me

[The_Beave]

heh

True.

[DocHudson]

the sweetest way ive seen people do the mods ur looking for is to grind teeth into the valve like little blades and use that!!

This is the best thing to do. This is what we do to 1600 blocks using PM0 pistons (30.7mm CH with a fair amount of mid dome)

What's good about it is that you don't waste too much material on the piston. Once you've made the raw cuts, just clean up the surrounding areas of the new reliefs and get rid of sharp edges.
You might want to open them up just a hair for insurance against possible piston rock.

Clay also. And account for rod stretch.


Add: If i'd want to take it a bit further, I'll cut a junk head up to just one chamber then cut that piece again in the middle to get a clear side view of one intake and exhaust valve seat. I'll mock it up to the block set to tdc so i can see all the way through.

I've actually seen this in 2sohc's lab LOL