Subject: Re: [TR] WTB a TR-3

From: "Randall" <[email-masked]>
Date: Thu, 7 Jan 2016 17:25:54 -0800

> The fully synchro box is a nice upgrade............

Agreed, but it's an easy retrofit to the earlier cars.  And unless they put the car up on a lift, not likely to be spotted by a
concours judge.

> I can't feel the difference in what is supposedly a 10% power 
> bump 

What 10% power bump?  From what I've read, many if not most of the later 3As were delivered with the "optional" 86mm liners instead
of 83mm (and 83mm remained an option for the TR4 & 4A).  According to the last edition of Practical Hints, the 86mm TR3(A) engine
(which is indicated as being standard) was rated 105 bhp @ 4750 rpm; while the 83mm engine was rated 100bhp (same as given in
earlier versions of PH).  The TR4 owner's manual gives 100 bhp @ 4600 rpm (presumably for 86mm), so the specified power actually
dropped.  

The drop in power rating was probably just due to "truth in advertising" laws; but might possibly have been related to the slight
change in combustion chamber shape, which lowered the compression ratio slightly.  I'm not certain that happened at TR4
introduction; but the TR3 SPC I have shows a different part number for the 86mm head than the TR4 SPC does, leading me to believe
there was some difference.

Randall

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