ET: Engine (Twin) Older engine in the Later frame rapide

[Andrew Lawton]

Sorry if this is a simple question im new to Vincents.
I have seen a few rapide's with a older engine to the frames eg 1949 engine in a 1951 frame. Is there any reason for this?There is one for sale at the min with this conversion.

 

[Simon Dinsdale]

Imaging this. It is 1968 and your only family transport is a 18 year old Vincent sidecar outfit and the worn out engine gives up on a Friday afternoon.
Your options are :
1. Try and rebuild the engine over the weekend so you can use it to go to work on the Monday morning, using Spares that are virtually non existent or badly made.
2. Buy a replacement engine from the local scrapyard or Conway motors etc for £5 and do a swap.

In those days matching numbers was never a consideration.

Simon

 

[Sakura]

Imaging this. It is 1968 and your only family transport is a 18 year old Vincent sidecar outfit and the worn out engine gives up on a Friday afternoon.
Your options are :
1. Try and rebuild the engine over the weekend so you can use it to go to work on the Monday morning, using Spares that are virtually non existent or badly made.
2. Buy a replacement engine from the local scrapyard or Conway motors etc for £5 and do a swap.

In those days matching numbers was never a consideration.

Simon

I think I must be still stuck there. The only importance I can attach to matching numbers is monetary, or in the case of a historical or other important machine. As most road post war Vincents were basically the same is it really important?

 

[Andrew Lawton]

Its not the matching numbers I'm thinking about. Its the fact most of the bikes have the older engines in?
Just thought they might have changed something and the older engine was better?

 

[vibrac]

"Basically the same" is all you need to know. If your intention is to ride it and not count rivets or expect a windfall when you sell it my advice is to concentrate on its actual condition.
The things the Vincent is not short of, power , parts and people with information to advise you

 

[Andrew Lawton]

Brilliant thanks people. Like I say im new to this and just trying to learn as much about these as I can.
Many thanks

 

[Simon Dinsdale]

As VOC Machine Registrar I see later frames with earlier engines and also the complete opposite, plus bikes which are non matching engine and frames from the same year. There doesn't appear to be a preference to the enthusiastic riders as long as the numbers are factory stamped and not "corrected" in the search for maximum profit.

Simon

 

[Albervin]

Andrew, there were major differences in frames between 1947 and 1950. It was not unheard of for a rider to take his bike to Vincent and ask for an upgraded frame e.g. a Series C frame with longer "swing arm" and rear damping. To do this properly he would also have bought a set of girdraulic forks. Then there was crash damage repairs as well.

 

[Bill Thomas]

I think it was more a case of , What ever you could get your hands on ,
Some of us picked up a Comet Engine and Gearbox, And slotted it into a Twin frame,
So we had something to ride.
Some even put the Engine in a Norton Frame !.
Just remember these are old bikes and need a lot of looking after.
If your Bike has Girdraulic front forks, It might be an idea to fit an Hydraulic Steering Damper,
They are only about £50 plus a few home made brackets.
Good Luck, Bill.

 

[Bill Thomas]

Before you Buy anything, Give Simon the Engine and Frame Numbers, Just to make sure they are OK.
Cheers Bill.