351c dizzy shaft size...

[JimNiki]

I've noticed on ebay that many of the no name cheap distributors come in 2 sizes.

They are described as "old" and "new", or generally speaking 12.5mm and 13mm.

Does this refer to the newer aussie blocks made from 79 onwards?

I'm 99% sure that the block I sourced to replaced my original cracked block was an "old" one.

I've noticed that all the good distributors from the US do not mention this and have basically only the one sort.

I measured the shaft on my dizzy and it says 12.99. So I take it as being the 13mm variety...

Can I assume that this is near enough to the original spec of 1/2 "?

Does this mean I can safely just order my dizzy from msd or pertronix and as long as it is for a 351c, then it will fit.

cheers...Jim.

 

[Don C]

The shaft size for 351C's, at least in the US, is 0.531". The older flat tappet Windsors are 0.467" and the newer roller cam Windsors are 0.531", but the gear outside diameter of all Windsors is smaller than the 351C's.

 

[JimNiki]

I measured 12.99mm at the base of the shaft... 0.531 inch as you mentioned equates to 13.47mm.

If the shaft is tapered for a tight gear fit, does it sound reasonable that the ID of the gear itself would be 0.5mm bigger?

I suppose that part isn't important as the gear will already be on it and there is only one gear size for a 351c.

My biggest concern was whether the shaft was big enough to fit over the oil drive shaft.

The newer aussie blocks which went to electronic dizzies made it impossible to fit an early dizzy into a newer "black" block.

I read that it was for emmisions reasons.

 

[Don C]

I know that Summit Racing also sells 0.500 gears for Clevelands, 400Ms, and 429/460s, but I never knew why, until now.

If the distributor comes with the gear already mounted I would check the clearances.

 

[JimNiki]

I think I'm about to buy a pertronix plug and play billet flame thrower 111 from summit...

Anybody have any reason why I shouldn't get one?

Thanks to your undecisive govt, our dollar is still very strong, so if I'm going to get one, now is the time.,,