Grey Flash 2751

This rather long-winded term (from the 1950 Spare Parts List) is, in actual fact, referring to what is commonly known as the “inlet manifold”.

After sending photos out for comment I was informed that both the 32mm carb and the adaptor appeared to be original and that I was very lucky to have them as they are almost impossible to source.

Peter Johnson commented: “The carb came with many other original parts and I suspect/believe it is the original item. The manifold is cast iron… It was cracked when I got the bike, so we constructed a jig and re-welded it with cast iron rods and re-machined the clamp area to the correct diameter…”

Now as the restoration proceeds, we are looking at this cast iron adaptor more closely (Bert reckon SG Iron).

I ran what we know past buddy Franc Trento – he’s a veritable mine of Vincent racing parts info having carefully assembled the Ehret Black Lightning and rescuing it from being restored to death. Franc believes 2751 should be fitted with an early pattern fabricated steel adaptor, as per his old BL.

We needed to take Franc’s comments seriously. I ran our quandary past David Dunfey and he confirmed that his Grey Flash is fitted with a fabricated steel adaptor, the same as the Ehret BL.

In both these photos we can see that the adaptors are fastened to the cylinder heads by cap screws (5/16″ BSW).

We’re not really able to get to the bottom of why the bones of 2751 came with this later adaptor. It does appear to be an original Vincent part, and a racing part too. Could it have originally have been fitted to a Black Lightning?? One clue is a stamping on top of the casting.

Could it have originated on the front head of a BL? When the parts of 2751 were gathered up in New Zealand, might the original adaptor not have been present and this damaged one been included in its place? We shall probably never know… We’re going to leave it as-is – a future owner might be able to get to the bottom of this. If any readers of this blog are able to shed any further light I’d be very glad to hear from them.

Finally, there was the issue of how to attach the adaptor to the cylinder head. As we know, equal length cap screws were employed with the fabricated steel item, but this one featured a stronger, stepped arrangement. After some consultation it seems likely that studs (rather than unequal length cap screws) and special thin walled 0.445″ nuts would have been used. Bert rigged this fixing up to see whether it would work.

Then the tank was seated on the UFM – the first time these original components had been re-united in many decades.

This is all looking very good indeed. We’re aware that the adaptor may not be original to 2751. We’re also aware that it is something special and interesting so it’s going to stop where it is! There is a story there and we don’t know what it is – if anyone is able to comment further then come on down!! 💁🏻

12/12/2020
Since I first published this post I have actually been offered a correct-type early fabricated steel adaptor. It seems highly likely that 2751 would have left the factory fitted with this type of adaptor and, due to the special finishes employed on this early Grey Flash, it would have most likely been dull chromium plated. After careful consideration I have decided not to change this part but leave the later cast item as-is. Some might poo-hoo this stance but I would like to reiterate that we are not trying to achieve a generic level of finish and, in the process, erase the racing pedigree of the machine and the DNA of the men who raced it. The finished restoration will feature untreated scars and some non factory parts as a homage to its history and to enable a unique story to continue be told from hereon. This makes the bike even more interesting in our opinion.