Originally posted by Top Gun 777
On some brands of engines ( actualy most of them), to have engine running longer and better it is the best to lap it before initial start. I am always doing, regardless the brand.
Well I am against to use Cogate or other sustitute to real lapping compaund and using rotory tool ( any kind of power tool) is realy dangerouse because it is hard to control fitting condition.
am using old hand lapping method-lapping compaund 1500 grid from Clover ( oil based) and lapping tool for piston. I am sugesting to don't lap sleeve-only the piston.
I can give you my numbers for fitting piston to sleeve after lapping is done- for 12 Novas engines it is 3.1-3.0 mm ( initiay it is 4.3-4.5m) and for 21 engines it is 4.2-4.3 mm ( initial 5.7-5.8).
To mesure this fitting I do following- I clean piston and sleeve with denaturated alchol and fit piston inside sleeve with slight force till it got stock on the top and then mesure the distance from the top of the sleeve to the top of piston.
There is to thing needs to be taking care of-wash everything very good after lapping is done ( if any lapping compaund will stays there it will ruin intire engine within a second) and second thing is try to do everything possible to don't make ellips on piston.
Unfortunatelly I don't have digital camera to put pic of my lapping tool, but I made couple of them for my friends and may be they can put pics of it.
Good luck and be patient.
Edward
Well said Edward, I dont know all those numbers at all but I just know Colgate and WD40 should stay in the bathroom and garage, not the engine!
