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Evening all.

This is an odd request for which I am sorry.

Having got my TR sorted to a point, well I'm happy with it, I have turned my attention to my Spitfire which I actually bought before the TR and sort of lost interest in when the TR arrived.

Well I have learned a lot about "restoring" old Triumphs and one thing I have learned is that it is important to know what you have! to that end I have been trying to find out just what I have bought.

This is where I am getting a little confused, I thought I had bought a mk4 but now I am not so sure, the very battered vin plate looks a bit odd one side pop riveted the other side screwed on the numbers indicate a 1972 UK built car FH43378 that agrees with the licence plate number, the trim number indicates a black interior which it has. The paint is stamped as 96 saphire blue.....to my mind the colour of the car is French Blue? which is odd as I believe this colour was not used until 1973.

The engine number is YC67581HE this is where it gets very confusing from my research this engine number it would seem to refer to a 1500 Spitfire or rear wheel drive Dolomite 1500s I assume the engine was at some stage replaced?

On the plus side the chassis looks very good and despite the odd bit of bodywork welding which looks to have been very well done it seems like a nice little car. should I be worried or just get on with it?

 

Thanks all David

 

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I think your engine is indeed RWD Dolomite.

It could have had plenty of paint and mechanicals replaced from donors over the years.... just indicates a colourful life :)

....... Andy 

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Those 4 pots tend to destroy their cranks before they have done 70,000 miles if driven gently, and I have killed two of them before even reaching 35,000 miles.

Dolomites rusted so quickly they were a good source of replacement engines back in the day!

Neil

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That's a nice way to look at it. Must say I have only driven it up and down the lane but it does seem to go very well for little Spit. 

Will look at Rimmers (got them on "speed click"

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David, my blue Spit already had a Dolly engine when I bought it - and it was only 7 years old at the time (1988). I suppose it's possible that someone's built a 1300 in a 1500 block. Even though it's badged as a Mk4, I wouldn't worry about the engine unless you decide you prefer Triumph's rev-y 1300 to the torquey 1500. That's more down to driving style. (Torque for me every time!)

Cheers, Richard

PS: Why do the 1500's (stroke = 87.5mm) have a reputation for going through the bearings and destroying the cranks, compared to the 2500's which were stroked even more (95mm)? The bearings are the same size, right? Was it just infrequent/no oil changes by 2nd, 3rd, etc. owners on a cheaper car?

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On 1/16/2020 at 1:49 PM, Spit_2.5PI said:

David, my blue Spit already had a Dolly engine when I bought it - and it was only 7 years old at the time (1988). I suppose it's possible that someone's built a 1300 in a 1500 block. Even though it's badged as a Mk4, I wouldn't worry about the engine unless you decide you prefer Triumph's rev-y 1300 to the torquey 1500. That's more down to driving style. (Torque for me every time!)

Cheers, Richard

PS: Why do the 1500's (stroke = 87.5mm) have a reputation for going through the bearings and destroying the cranks, compared to the 2500's which were stroked even more (95mm)? The bearings are the same size, right? Was it just infrequent/no oil changes by 2nd, 3rd, etc. owners on a cheaper car?

One theory I heard which actually makes some sense is that when the centre pair of pistons are going over TDC at high rpm, the crank is pulled upwards towards the block and the bearing clearance at the bottom of the main cap is increased.

This leads to an effective drop in the oil pressure at this point in the crankshafts rotation and starves the big ends of oil. The solution I was shown was to cut a groove around the inside of the main bearing housing so oil feeds around the back of the main bearing where it can enter through the hole in the bottom half of the bearing. This maintains oil pressure apparently more effectively than cross drilling the crank.

The straight six has massive crank counter weights which probably counteract this problem.

Neil

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That's a nice theory Neil, thank you. I'd always wondered why Triumph stroked the 1300 to 1500, not 1650cc.

(We've built a 1650cc engine to go into the Atlas. I wasn't planning to explore the upper rev range anyway!)

Cheers, Richard

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