> Not entirely true ... original engine was 1991 cc , the TR3B
> was upped to about 2200 cc
Well, if you're going to get picky about it, 86mm liners (giving a
displacement of 2138 cc) were available as a factory option (or dealer
retrofit) from fairly early in the TR3 run. And even the TR4 was available
with the 83mm liners, again as an option.
Even the "service oversize" 87mm liners only get you to 2188cc. To actually
hit 2200, you need the 89mm liners available as racing parts (eg British
Frame and Engine) (which actually take you to 2290cc).
> if it is DM2 that is for the TR2,
The DM2 was used for all TR3, and well into TR3A production. Apparently the
DM2 and 25D4 units were actually used interchangeably until the early TR4
(according to Lucas documentation anyway); as some of them had exactly the
same specifications. For example, model 40735 (which is a DM2) is listed
for 63 TR4. Model 40795 (which is a 25D4) was introduced in 1962 with
exactly the same specifications.
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