I had this hesitation problem with an A14 B310 Coupe I used to have some years back. It only arose after I fitted extractors and 2" exhaust (Otherwise Std engine).

I tried all sorts of things including slightly drilling out jets (I thought maybe the exhaust was more efficient and causing lean out). I think now it was probably the exhaust system was too big for the engine/carb combo.

To clarify my GX120Y engines are the twin carb/large oval port/double valve spring heads (although I no longer have the carbs/manifolds).

I'm wondering if maybe yours is the earlier 1200 GX and that maybe they had this crank?

I think I know the crank you're referring to and they look much nicer than the norm. I understand they're lighter. Was on here not to long ago.

I've got two GX120Y engines and neither has this crank. Ditto B310 A12. Someone also said they had seen A14 cranks like this but the one I've got is the plainer design.

My thoughts are that it's from early 1200? Or maybe early 1200GX? I've only ever seen one in the metal but origin is unknown.

Here is link to prev post. Crank Link

I believe the clutch plate will be Datsun 510/1600. Same for drive shaft output.

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Now that I see the broken end on the countershaft I recall seeing it on here (or a link to ebay or similar). It would have taken some considerable force to snap that end off or perhaps welding the gears to the other end buggered the temper in the steel.

I'd actually have thought it would split the front of the (alloy) gearbox case before snapping that off assuming something went through the gears to cause this. How's the condition of the bearing housing in the gearbox casing?

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Very nice (apart from the damage obviously).

I think 60L would be good but wouldn't be fussy. Is this 60A?

Those ratios aren't quite as close as the Option 2 56A I've been using but sound good. What engine is it behind and how has it handled?

Should be relatively straight fwd to replace the damaged gears given they're standard. What caused the damage - failed bearing or??

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Contacted Albins - they don't do kits for 60 (or 56) series boxes.

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Can any one tell me more about Albins or put me in touch. Sounds like investigating depending on cost.

I understand A series engines remain popular in highly modified form in Japan.

Does anyone know what gearboxes they run behind them there?

I know you can adapt Toyota T50's etc but their standard ratios are no better than Datsun 56 or 60 series.

Also interested to hear views as to any readily available boxes which have reasonably close ratios standard? (Can then worry about how to adapt.)

I need close ratios and 4 speed is fine. Running a 'peaky' 1300 racecar which only comes on cam above 6000rpm. I've tried 56A C/R boxes which were very good while they lasted.

I'm picking you'll end up with comp ratio of about 5:1 with that combo. A14 crank in an A15 might work?