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Synchro909 · 10-19-2019, 11:53 PM

I've seen a couple of A engines with B cranks. The clear distance between the main bearing bolts (2") is the limiting factor for journal size. The main bearing journals on the B crank have to be reduced to less than that to fit. So that I can leave the journal as large as possible, I'd prefer to use insert bearings from where ever. It would be larger than the original A specs but much smaller than the B.
I'd be looking for a good touring engine, not a racer so cross drilling wouldn't be required.
If A con rods were used, there is also potential to grind the crank to give a longer stroke. That would give higher piston speeds but more compression and torque. How far do you go for a hobby car and how many $ do you have to spare?
I have never built such an engine but I wonder whether the A main bearing caps would be good enough or should they be remade? Any info on that?

10-19-2019, 11:53 PM	#12
Synchro909 Senior Member Join Date: Jun 2014 Location: Melbourne, Australia Posts: 7,496	Re: Model B crank in Model A I've seen a couple of A engines with B cranks. The clear distance between the main bearing bolts (2") is the limiting factor for journal size. The main bearing journals on the B crank have to be reduced to less than that to fit. So that I can leave the journal as large as possible, I'd prefer to use insert bearings from where ever. It would be larger than the original A specs but much smaller than the B. I'd be looking for a good touring engine, not a racer so cross drilling wouldn't be required. If A con rods were used, there is also potential to grind the crank to give a longer stroke. That would give higher piston speeds but more compression and torque. How far do you go for a hobby car and how many $ do you have to spare? I have never built such an engine but I wonder whether the A main bearing caps would be good enough or should they be remade? Any info on that? __________________ I'm part of the only ever generation with an analogue childhood and a digital adulthood.