T3 Engine numbers

Technical Big Block Tonti and Loop Frame models
1

I’ve recently bought a T3 engine as a spare and to ‘do up’ (that’s ‘refurbish’ to anyone south of Warrington).
Is there any way of making sure it is actually an 850 T3 engine short of ripping it apart ? The engine number is VD103774. I can find frame number listings but nothing for engine numbers.
If it has 83mm bores and an oil filter in the sump, would that make it a T3 if the engine number can’t be verified ?
The carb inlets have 8mm bolts and are the VHB30 type so it’s nothing exotic, and not a T4 as the number in my 1980 T3 is 111701 and allegedly the original engine.

Further to this, is stripping the engine and rebuilding it something an average mechanic can do, or are there bits I should definitely be thinking of farming out to the more experienced ?

Any and all help appreciated.

2

I would guess the engine is a 850-T3 but i cant find any VD engine numbers more then 5 numbers long, they run between VD11111 & VD26537, for the 850-t3, As for rebuilding the engine it is well within the realms of a good DIY mechanic, BUT if the engine is well worn then deep pockets are required to do a propper job! all the best with it, Chris.

3

I have just done some more research regarding the engine number and apparently the T series engine with a 6 number serial number originates from the USA and engines with 5 numbers are from Europe . I got the info off a forum so i don’t know how accurate this is, but if anyone else knows better then please pitch in, hope this helps, cheers Chris

4

thats the frame number series though isnt it? engines were a separate series of 6 figure numbers, which just to add to the confusion the Americans used as their ‘frame’ number, added to the frame on a separate plate… I think the club dating officer has a self-compiled list of engine numbers so he may be able to give you an idea of the date of the engine…

5

Yep sounds like a T3 to me. Bores should be chrome plated?

6

Thanks for the replies, everyone.
I’ll rip the top end down over the next couple of days and have a look at the rings and bores. They should give me a fair idea of the life it’s had.
If the bores are u/s (or chrome) is it worthwhile to upgrade to 88mm bores ? HMB do a set that bolts straight in - anyone had any experience with these or converting an 850 ?

Cheers

Stuart

7

This is exactly what i have just done to my 850 le mans because of the difficulty of getting new 850 pistons and cylinders, i decided to go with the 950 conversion from stein dines who’s service, quality of parts and price was excellent, the other route you could take if your pistons are OK , is get your cylinders nicasil plated, that costs about £235 for the pair of cylinders if they are not damaged to start with at Langcourt in weston-super-mare, cheers chris.

8

Thanks, Chris.
Just had a look at Stein Dinse and it looks similar to the HMB kit, only cheaper :wink:
Did you have to do any work on the heads or are the standard heads OK with the larger bore ?

Cheers

Stuart

9

Hi, i went with the le mans 950 conversion which came with high compression pistons, (To suit my le mans heads),you will have to go with the standard 950 kit unless you change the heads to le mans heads (which are like hens teeth!), with fitting this kit the only issue is re jetting the carbs, the 950 cylinders fitted straight into the crankcase as the cylinder spigots had been turned down by the manufacturer so no messing about with machining the crankcase, the heads are fine as they are and don’t require any modification. cheers Chris.