Mongrel TR6 engine?

[Bodiam]

Been looking for reasons why my recently-purchased TR6 PI is running unevenly. Made some improvements with the usual suspects, but have found that the engine number is a CP, while the commission number of the car is CR. However, the throttle bodies have twin balance pipes, which I believe were fitted to the CR engine. I'm now concerned that the mismatch of throttle bodies with the rest of the engine may make it very difficult to get the engine running smoothly and would be pleased to hear any observations anyone may have.

 

I have also looked at the identification numbers on the cylinder head to see if this too is a mismatch with the block, but the numbers on the casting (V3207, 25EZ, 312388/, 188 1) don't seem to appear on the table on the TR Register Technicalities CD, so I'd appreciate any help anyone can give me to identify the head.

 

I'm also beginning to wonder if the recon Metering Unit fitted after the engine was reconditioned is the correct one, but I understand I can figure this out by looking at the number and colour code of the springs, so I'm keeping my fingers crossed on that.

 

Many thanks in advance for any help.

 

John Doyle

[Steves_TR6]

The engine in my six is 'bespoke' too.

 

Perhaps your best course of action is to try to trace its history?

 

Start with a check with the registrar, or post your registration on here and see who knows what about it.

 

Hth

[Bodiam]

"Bespoke", eh? Wish I'd thought of that, sounds so much better than "Mongrel"!

 

Thank you for the suggestion, I'll certainly follow that up.

[Alec Pringle]

Hi John,

 

312388 was a saloon (2000, 2500 or 2.5) or GT6 head, at least that's how it will have started life.

 

Since then, 40-odd years ago, it might well have undergone more than one transformation . . . . what it might be like internally, your guess is as good as mine without further investigation.

 

I wouldn't go rushing into inspecting the metering unit - open one up and it can get costly, unless you know precisely what you are doing.

 

As already suggested, try tracing history first, it's very well worth the effort.

 

Once you've found out as much data as you can trace, time for a good rolling road.

 

Cheers

 

Alec

[Bodiam]

Hi, Alec,

 

Thank you for your advice, you're right of course, a lot can happen in 40 years.

 

The engine was rebuilt by Coventry Classic Engines in 2006, but not refitted to the car until 2009, since when it has done less than 500 miles. Unfortunately, CCE don't have records going back that far, so I guess I'll have to start at the beginning and see what I can find out.

 

Thanks again for your help,

 

John

[Bodiam]

Well, I've done some detective work with the PO and a number of companies who have supplied parts for the car in the past, and I'm as sure as I can be, without taking it to pieces, that I have a 150HP CP engine with 150HP road cam and MU. The head has apparently been ported and polished in the past.

 

So, it appears the only mismatch is that I have 125HP CR throttle bodies on a 150HP CP engine and I wonder if anyone has any experience of whether this may cause any problems?

 

Thanks in advance for any advice.

 

John Doyle

[OldBob]

Hi John,

 

main differences between CP & CR throttle bodies is the twin balance pipes on the CR ones and singles on the CP's. I'm pretty sure they have the same butterfly diameter.

 

The throttle mechanism between the two types is different though, the CP one is simpler and less prone to wear. Wear or uneven adjustment can cause the CR mechanism to allow the butterflies to open out of sync. more easiy than the CP system so this would be the first thing I would check on yours as you have uneven running. .It is possible to re-furb ths CR bodies to accept the CP mechanism

 

If you look on the pics on this web site you can just make out the different mechanisms and you may be able to identify which are fitted to your bodies.

 

http://www.prestigeinjection.net/manifold.htm

 

regds

Bob

[Bodiam]

Hi, Bob,

 

Thanks for the very helpful information, I'll get my throttle synchronisation checked and see if that may be a problem.

 

Assuming the throttles are properly synchronised, is there any inherent reason why having CR throttle bodies on a CP engine would cause running problems, does anyone think?

 

John

[Bodiam]

On top of everything else, found the distributor had incorrect cam, giving 14 degrees of advance rather than 7. Sorted out by Martin Jay, so now thinking about a rolling road session. Does anyone know of a good one reasonably close to the Stafford area? Thanks in advance for any help.

 

John Doyle