Head issues

Finally! I have had time to get back to work on the commando race engine thats been on the back burner too long.
Whilst doing the pre assembly check of the squish band clearance between the pistons and head I found left pot had the required .050" clearance but only .038" on the right, also it had some dodgy helicoil inserts under the exhaust ports, one of which was crooked.
So after removing the old helicoils we put the head onto the milling machine for a bit of work.




As I dont have boring facing head I used the face cutter to "carefully" remove the required 12 thou.
Then as the threads under the ports had already been bodged the option was while the head was set up to tap out the old holes to 1/2" UNF and screw in some blank bronze inserts then tap them out accurately to the required 3/8 BSF





The most time consuming part of this operation was setting the head up accurately.
Freddy

A couple of more pics, JS carillo rods



JS pistons beside Maney pistons

Who's stolen the Flywheel ?

Chamber volumes match , no doubt . Now .

Fly wheels are just overrated! chamber volumes will be sorted later

Wow--that head looks like it will be over 10-1 with a standard head gasket. What camshaft do you plan to use?


Tim Kraakevik
kraakevik@voyager.net
'72 Combat, '74 RH10 850

The CR will be closer to 12:1 with .040" head gasket and running the JS stage 2 cam,

Hi Fred,

I have JS piston's and rod's in a standard 850 up in Sydney. That compression ratio is sharp, from what I read on Jim's site, he does deeper valve pockets for high lift and or compression upped engines. Are you planning on cutting the valve pockets, after a mock up of course?
What fuel is planned for your race engine? Should be a kick ass engine with that pork chop flywheels!

Cheers Richard