vintage motor head shims

[glenng]

I've got an old vintage hydro I built 20 years ago. I ran it about 15-20 times on 20% and put it away. It was too heavy and too slow to race but did run well and jump up on plane quickley. Radio gear has been updated and aluminum doublers have been replaced with carbon fibre. The motor is an old .65 O.S. vrm disc valve it still look's like new on the inside and outside. I'd like to run the boat again on 50% nitro. The engine had one .0085 shim-do I have to add more shims? how much would you suggest? Thank's, Glenn

 

[Mike Hughes]

Well that would depend on what the head clearance is at now. I would set it some where in the .012 range. You need to measure the piston to top of the sleeve at TDC and than measure the headbutton depth. Subtract the two and you will have the clearance.

Mike

 

[glenng]

Well that would depend on what the head clearance is at now. I would set it some where in the .012 range. You need to measure the piston to top of the sleeve at TDC and than measure the headbutton depth. Subtract the two and you will have the clearance. Mike

Thank's a lot Mike, Button depth .202/piston to top of sleeve .2065 + .0085 shim= .013. I'll re-measure a few times to be sure and put it back together. Appreciate your help! Thank's again, Glenn

 

[Mike Hughes]

I would go with that. Close enough.

Mike