Carb Options????

[Sparky Brum]

Dear TR6 enthusiasts,

 

I am about to embark on a special journey that only ever happens every now and again (but usually during a mid life crisis or when the kids have left home). That journey involves purchasing a TR6, one of life's last few pleasures for the middle aged man! This will be my second TR6 as the first had to go due to mitigating circumstances surrounding the nice people at HMRC!.....say no more! Sadly my knowledge of anything technical to do with engines is extremely limited as most of my cars have been covered in plastic only accessed by those with special screwdriver sets that demand £120 an hour!!! My New Years resolution is to learn the basics and make sure I buy the right car this time. Having spent the past few months looking at various models I have discovered that the majority of them have varying types of carb set up all offering varying levels of power and benefits. Pre 73, post 73, triple SU's double SU's blah blah blah!!! As such I would be extremely grateful if somebody could give me an 'idiot's guide' to the pro's and cons of the options out there! Any help would be greatly appreciated!

 

Regards,

 

Sparky!

Edited December 14, 2010 by Sparky Brum

[zogabu]

Hi Sparky,

 

Why consider only the carb option ?

 

Two years that I am the lucky owner of a 1973 PI TR6 (CR model) and since I have replaced the Lucas pump by a Bosch one, I have encountered absolutely no problem.

 

PI makes the car very enjoyable, even if I have no experience of carb TR6, I would not switch for it.

 

Guy

[poolboy]

You'll probably be better off keeping things simple. The stock dual 175 Zenith Stromberg CD carbs as originally found on North American models or the equivalent HS6 SU carbs provide adequate fuel for an unmodified TR6 carb'd engine would be in that category.

Pay no attention to the photo below. That engine is not stock.

Edited December 14, 2010 by poolboy

[Mike Goldthorpe]

Hi Sparky,

 

Why consider only the carb option ?

 

Two years that I am the lucky owner of a 1973 PI TR6 (CR model) and since I have replaced the Lucas pump by a Bosch one, I have encountered absolutely no problem.

 

PI makes the car very enjoyable, even if I have no experience of carb TR6, I would not switch for it.

 

Guy

 

 

I'll second that. Bosch pump in mine - hardly any problems over the decade + I used the car as primary transport. Go for PI.

[RobinTR6]

The PI is great when it works but more toublesome if it goes wrong. Having had both I can really say theres a lot in it. The Su's were certainly less thirsty. I suggest you read Roger Willams book on the subject and see what you think of the opinions on here, then decide. If you find a great car at a sensible price that may decide for you.

 

Robin

[TRTOM2498PI]

I have x2 CP 150BHP TR6 PI models, both running Bosch pumps. I have driven through Europe, Alps, Lemans in 35 degree heat, without complaint. Provding they are set up correctly, they will give no trouble. I have also completed X4 Round Britian Reliability events, 2000 + in 48hrs, Lands End to John O'groats without any issues. I averaged 23.1mpg driving it hard over a weekend, so economy is not too bad given motorway driving consisted of a genuine 80mph + (GPS) driving too. Overdrive is essential though. Performance is also good from PI models, again, providing car is set up well.

 

Cheers

[YankeeTR5]

Hi Sparky,

You don't mention your location, so maybe all you have is access to carb equipped cars. If so, I'd stay with the stock two carb setup if only because if you don't you will have to live with someone else's armchair engineering of an engine. Some get it correct, others spend bunches of money and don't.

However, if you live in a geography with plenty o' PI, go that route. Reliability appears to be an issue for worn/older setups and you have the right technicians (if in the UK) to set things up properly and, frankly, pretty inexpensively. With PI, you also get the benefit of a better camshaft with a power band into the high 5K's to low 6,000 rpm. The carb models, if still equipped with a stock cam, have a power peak at 4300 rpm and bog down pretty quickly beyond that. The PI model appear to have a completely different dynamic (ie are way more fun).

So, in order of what I would do:

PI...twin Zenith Stromberg's, Triple SU's/Zenith's. Although, if the car was setup properly I'd most definately swap position 2 & 3.

 

Also, outside of carbs, I'd have overdrive as my primary feature in a search.

[PJM]

Definitely overdrive, carbs or PI depending on where you are. Get to know your local TR area members for advice and assistance, go with the best you can afford and one that has been driven regularly not left standing. Let us know where you are and we shall see if we can help.

[Sparky Brum]

Cheers for all the replies guys (albeit I'm still non the wiser). I'm located on the outskirts of Birmingham (UK) so may well see what the local group have to say over a pint!

[Clarkey]

Sparky you have pm

[Clarkey]

Sparky

Have a look at Marko's website www.classic-marques.co.uk.

I went to see him when I was looking and it was a very valuable visit.

also get yourself a copy of Roger Williams The Essential Buyer's guide for the TR6 well worth a read,

Best of luck in your search

[RobinTR6]

Read the book first, listen to the forum, then look at cars so you alreday have some knowledge. it works.

 

Robin

[88V8]

....my knowledge of anything technical to do with engines is extremely limited

 

I'd stay with the stock two carb setup if only because if you don't you will have to live with someone else's armchair engineering of an engine

I think this is very good advice. Buy a standard car.

 

As regards carbs or injection, petrol injection is fine when it's working well, but can be a time & money pit if it's not.

 

Twin carbs are much simpler. I like twin SUs, but that's because I'm used to SUs. Some say Strombergs are just as good.

Most carb cars come from the US. The only problem with this, in addition to perhaps being left hand drive, is that some were strangled with emissions equipment that really dropped the power output. Someone on here would be able to tell you what to avoid.

 

Carb cars are also cheaper to buy than those with injection.

 

The advice to make sure you get a car with overdrive is also good, as they're pretty miserable without, and fitting overdirve to a car that doesn't have it is neither cheap nor simple.

 

Having said all that, what really matters is the condition of the bodywork & chassis. That can really eat your money. All cars have their peculiarities when it comes to rust, and Roger Williams' book will tell you what to look out for.

http://cgi.ebay.co.uk/Restore-Triumph-TR5-TR250-and-TR6-NEW-/190481010416?pt=Non_Fiction&hash=item2c598d8ef0

 

Ivor

[poolboy]

Ivor, I really don't believe that anything attached to the ZS carbs were strangling them or robbing performance.

No, if anything it was the compression and the tuning, but not the carbs per se.

[Willie Felger]

Hello Sparky,

 

I participated in a similar discussion about 6 months ago and received wide-ranging replies and some strong views.

 

These depended on the love/hate relationship with the TR6 injection system. I'm of the latter view, but no matter!

 

I bought a CP series abandoned project where the injection system had not been touched and was full of crud. It was obviously going to cost a lot of money to sort out. As I don't like the injection system in the first place I bought from Goodparts in the USA a manifold to fit 3 SUs.

 

I used 3 HS6 carbs and modified the original throttle linkage to fit underneath them, and have chokes on the front and back carbs using the standard cable set up. The fuel pump is a Facet solid state one in the boot via a Filter King under the bonnet and all stainless braided hoses.

 

Result? For the price of a Bosch pump and 6 injectors I have a sweet and clean-running engine that makes me grin every time I fire it up. The whole set up is very neat and looks pretty damn awesome too - I'll take a picture and try to attach it later.

 

There are only two tricks: One is to use only carbs with the float chamber on the right hand - i.e. the front side - so it clears the steering column. Two is to feed the heater water through the manifold's pre-heating tubes.

 

In my humble opinion, every injected TR6 I have heard sounds as if it is running with the choke out and smells like it too, to the point where I try not to follow one in my TR3A in a convoy.

 

I can't speak for its performance or economy yet, but speaking to a member who did the mod some time agao (with his own beautifully made manifold) it is much more economical and performs as well or better.

 

Whatever you decide, good luck with it!

 

Best regards

 

Willie Felger

 

Camb Follower

 

1972 TR6

1959 TR3A

[Andrew Smith]

.............I'll take a picture and try to attach it later.

I'm sure Willie won't mind me posting a photo of his 6's triple SU set-up - one which I may consider in the future..........

 

 

Cheers

Andrew

Honorary 'Camp Flower'

[Willie Felger]

Thanks Andrew - you're a proper toff!

 

A later piccy would have shown it complete with the linkages but this will do nicely and gives you the general idea.

 

I'm still driving my 3A, although I have stooped low enough to be seen in a Benny hat to protect the log'oles, instead of a proper flat 'at. My Clayton heater (from Holden) is brill and looks after the rest of the bits.

 

Have a Merry Christmas - and a big hug for the Memsahib.

 

Willie

[Andrew Smith]

Willie,

 

If you mail me the latest photo I'll replace the one above - I would like to see the linkage in any event.

 

As you know, you can't beat a 'proper' flat 'at.

 

Merry Christmas to you and Sue, and we’ll see you in 2011 when you move down this way – you know it makes sense!

 

Cheers

Andrew

[Andrew Smith]

Willie,

If you mail me the latest photo I'll replace the one above - I would like to see the linkage in any event.

Cheers Andrew

Hi Sparky, and interested others,

 

Willie has emailed me these more recent photos of his triple SU set up and asked me to post them with his commentary:

 

 

This photo shows the general layout and the throttle and choke cables. The central throttle cable uses the standard TR6 item onto a home made bracket bolted to the centre carb:

 

 

This view shows the other side with the metering unit removed and the dizzy mounted on the US carb version's low pedestal and drive gear. The filter King serves as a pressure regulator and filter. I have the same on my TR3A. I have yet to replace the garish and odd-lenghth HT leads with something less untidy:

 

 

This is a general view from the intake side. The centre choke linkage is removed but a home made bracket is vital to hold the main carb jet firmly in place:

 

 

Cheers, and here's hoping 2011 is good to us all!

 

Andrew

Edited December 31, 2010 by Andrew Smith

[roy53]

strange this far in and no mention of webers! which when set up are less trouble and dont lose settings through use. Of corse only my views though.Good set up pi is just fine.

ROY

[Andy K]

Hi there.

 

Thank you for sharing all this with us. I have been thinking about doing this as well, but had no idea if it was OK for a RHD car because of the steering column. Two questions though.......

 

Do you think there is enough space for 3 x HIF SUs, and what about a one-piece air filter?

[Steve Knight]

( quote ) I bought a CP series abandoned project where the injection system had not been touched and was full of crud. It was obviously going to cost a lot of money to sort out. As I don't like the injection system in the first place I bought from Goodparts in the USA a manifold to fit 3 SUs.

 

I used 3 HS6 carbs and modified the original throttle linkage to fit underneath them, and have chokes on the front and back carbs using the standard cable set up. The fuel pump is a Facet solid state one in the boot via a Filter King under the bonnet and all stainless braided hoses. Willie Felger ( quote )

 

Hi Willie, I understood the USA heads had the inlet ports cast closer together - except for the very late imports that reverted to UK spec heads. Is this manifold made especially for the UK, or does the USA part fit regardless ? Can you see that the ports line up correctly. Regards Steve Knight.

[Denis]

I say PI! That's the whole point of the SIX (and the 5 of course)! It was the first British car (I'm told) to have Petrol Injection and it's what the designers designed it to have!

 

By all means add a more reliable German pump (to go with it's Germanic styling) if you must! To me it should all be the original classic equipment, to get that 'vintage' period feel! My PI system has had very little attention over these past 38 years, and those that have occurred are quiet understandable considering I never ever had it serviced by a Dealer.

 

I once saw a TR6 that had been so 'Updated' with discs and telescopic dampers at back and differant wheels and loads of modern stuff...Why not just go buy a modern sports car? UCK!

Edited January 3, 2011 by Denis

[Tom Fremont]

For the record only, this set-up using vintage Weber 40 DCOE 18 carbs from the '60s, never truly "rebuilt" has worked flawlessly on the engine below for 90,000 miles. P.I. cam. 24 mpg ( Imperial ) overall, 30/31 mpg highway with O/D. Calibration done via seat-of-the pants by yours truly with lots of advice ( some of it good ). Spark plugs clean after 12,000 miles. Oil consumption 1 U.S. quart / 4000 miles on X-country trip in 2009. 1/4 mile in 16.2 seconds taking it easy on the clutch.

 

I'm sceptical that any less than 6 throttles will deliver comparable performance .

 

 

Appearance-wise they're hard to beat, and of course " period " too. Here's a view of the U.S. TR250/ TR6 national club convention 2010 Best of Show car engine:

 

[Denis]

For the record only, this set-up using vintage Weber 40 DCOE 18 carbs from the '60s, never truly "rebuilt" has worked flawlessly on the engine below for 90,000 miles. P.I. cam. 24 mpg ( Imperial ) overall, 30/31 mpg highway with O/D. Calibration done via seat-of-the pants by yours truly with lots of advice ( some of it good ). Spark plugs clean after 12,000 miles. Oil consumption 1 U.S. quart / 4000 miles on X-country trip in 2009. 1/4 mile in 16.2 seconds taking it easy on the clutch.

 

I'm sceptical that any less than 6 throttles will deliver comparable performance .

 

 

Appearance-wise they're hard to beat, and of course " period " too. Here's a view of the U.S. TR250/ TR6 national club convention 2010 Best of Show car engine:

 

 

They certainly look impressive, and a nice snug fit too! My bog standard (stock) UK CP PI 'Six' used to return 31 mpg on leaded fuel (101 octane) which is what it was designed to run on, and when I took it to a Dragstrip in 1976 I got a best s/s 1/4 mile et of 15.37 at 84 mph!

 

Edited January 4, 2011 by Denis