....the pistons have been in there for 20 years, lol ( they have 4 divots on the top ).
*** #4577 (front ) and CMT (rear ) of crank = Forged Steel, SMALL journal, 3.25" stroke (arent the SMALL journals the best, and forged is great too?)
*** #3884520 , # gm26, #H1 6, # gm32, # G286 = 60cc chamber, 1.72" intake and 1.5" exhaust ( all the info I could find ).
Thanks, if I should upgrade, PLEASE offer advice ---
Small journals are not as strong as large journal cranks - small is better ONLY in that they have less surface area, and thus less drag on bearing surfaces, which makes them desired for some type of engine uses - But, not usually blown unless it's a dedicated match race engine.
The smaller surface area concentrates the loading in a smaller area and increases the forces the bearing surface is subjected to during rotation. The surface is also exposed to higher bearing surface speeds due to it's smaller dia. A large journal crank spreads the load over a greater area and surface speeds are lower, which is easier on the bearings.
The heads are to small to work well with the flow needs of a blower motor.
If the pistons have '4 divots' on them, they are probably lower compression cast units - not something that will hold up well in a blown motor ...
You need to study blower set-ups and engine buildups for this type of use.
It is necessary to build a lower end that will hold up to increased pressure and HP output.
As well as an upper end that takes advantage of the blowers flow capacity.