Help with T3 heads

[Oldrat]

Would a head marked

13 02 21 60
     R5


Be a direct replacement for a head marked

13 02 21 60
     R12


Anyone know the difference or relevance of the R5 & R12 numbers

Many thanks

Brian

[Antietam Classic Cycle]

If you could post some nice clear photos of them, that would help. Shots of the intake mounting, exhaust port, sparkplug area and combustion chamber area in particular.

[guzzisteve]

I believe that the R # is a casting # as in which mold it came out of.

[Antietam Classic Cycle]

I thought the R stood for "revisione", i.e. R5 would be the 5th revision of the mold using the same basic casting. <shrug>.

[guzzisteve]

Think you are correct, been a long time since I looked into this. Just remember it was a casting code.

[Oldrat]

Thanks gents, that makes a lot of sense.

[Antietam Classic Cycle]

Thanks gents, that makes a lot of sense.

Still doesn't answer your question though. Differences between an R5 and R12 could be fin shape near the plug, valve sizes, port diameter, diameter of the intake manifold bolt holes, etc.

[guzziownr]

850 T3  build date March 1975: