Weist pin sizrs

[Jim]

Is there any difference in the wrist pin end of a 21-a con. rod and a con.-rod from a 59-a engine? ( I don;t have the pn. ). In other words are the two wrist pins the same O>D>? Thanks in advance. Jim

 

[Ken/Alabama]

Yes

 

[Bored&Stroked]

If you're talking about the con-rod little end - they are both designed for the standard .750 flathead pin - no difference that I know (as far as the ID of the little-end bushing). Now the real question is . . . what are you trying to do???

 

[Jim]

I'm thinking of building a 284 ci, using 21-a rods and a offset ground 4" merc crank. I was just asking about wrist pin or rod little end sizes. Thanks for the comeback. Jim

 

[Bored&Stroked]

Hey Jim - just built a really stout 284 cubic inch engine . . . using the combination you're talking about. If you run the 21A rods, try to find a NOS set (instead of having an old set rebuilt). You'll be further ahead in the long run. Also, if you can find a set of STD Cadmium Silver rod bearings (Heavy Duty Truck and Bus) - I like them a lot more than the harder "copper" style ones. Good luck! If you need any help, just PM me.

B&S

Here is a very detailed thread on all aspects of the build - on the HAMB:

https://www.jalopyjournal.com/forum...iolet-hot-1941-42-merc-flathead-build.862832/

 

[Ol' Ron]

I would have the big bore of the rod increased .001/.0015 for this conversion. I ran many engines with thes 21A rods in the stock car. Another thing is side clearance of the bearing and Rods. for street I'd run .010/.012" on the rod and .020" on the bearings. My friend Ron Horrell just retied the 296 I built for him 15 years ago. Has many hard miles on it,need alittle refreshing. Also, if the crank grinder put's a larg filit radius on the crank check the for side clearance. I have all this in my book.