Relative merits and demerits of standard and non standard fuelling systems - discuss

[GDPR]

I have been given official sanction to restart a discussion on the different fuelling systems.

I think most of you are aware of my stance on this, with a preference for standard carburation and ancillary systems, and a liking for a well designed efi system for efficiency purposes.

One of the problems as I see it is Triumph fitted a system to comply with a stringent emissions requirement, and the skills required to maintain these systems are being lost in antiquity, although not all of us are dead yet.

I would invite you to put forward your arguments to your personal preferences, and why - but please be open to fair and equitable discussion, and the right of the individual to express an honestly held opinion, and to others to challenge those views without it being taken as a witch hunt....

So whats your poison and why?

[wilf]

Me ? Strommies, but that is because my interest is in making the car run as well as I can keeping it as standard as I can, with some precautionary mods like electronic ignition, header tank and leccy fan. I have done the performance thing on far quicker cars than a Stag could ever be, played with all sorts of carbys and efi things, now I like tuning what the makers originally fitted. So for me, seeing what Triumph pretty much intended under the bonnet is fine.
Just my personal thing.

[martin]

I'm pretty much with Russ, and Wilf, the Strombergs were the original fuelling system, and if reasonably maintained are reliable, and pretty much as economical as you're going to get with a 40 year old engine design. sometimes, they're not properly looked after, which is a shame, as anybody with a mechanical bent, and a little patience, can learn enough to keep them in good fettle, with an ounce of professional attention on occasion. I don't just say this 'cos I'm old - though I am. Martin.

[mikethemechanic]

Hi- I use standard set up so underbonnet appears as it should but have 'thought' about injection,how about two metro single point injectors on the standard manifold tower,one e.c.u. controlling each unit so only other additions are higher power fuel pump ,crank sensor and temp sensor ? easy fit relative to multipoint syttem.

[Seaking]

I do like the http://www.pattonmachine.com efi stag set up looks so neat and standard looking.
pity with import costs make too expensive.

[Firept]

Russ.
First thing I have to say is that with a pair of well sorted Stroms you can get close to or some times better than 30mpg, there are a number of modern cars with smaller engines that would be proud to say they can achieve that so whats the problem? If you want out and out tuning and power then fully EFI it but what is the point of that the car was designed as a 1970's grand tourer and it does it with style.
I do however agree with Glenn above in that a dual injection similar to the one from Patton Machine (I think Rover 600 series used similar) you can get a smother engine and no need for the choke control (Anti theft device!!) you may even get better fuel consumption. but If I want power ,smooth 6 speed automatic, and other mod cons then I would buy a modern car. Each to their own and I admire those that take and modify and tune but why do that to a grand old lady?

Paul.

[davidf]

For myself, I stick with strommies for 2 reasons - one is originality, the other is that I understand them, and haven't a clue about EFI! I have said this before, but I will repeat myself - while there are plenty of original Stags around, I take an engineer's interst in the modified Stags, even though I would not go that route myself.

[GDPR]

Fair point Paul, although efi is a definite route to efficiency the Strombergs were the weapon of choice by the manufacturer. My 2.0 twin cam Honda CR-V with variable valve timing gives the same power output as the Stag, but no matter what I do I cannot get better than 26.5 mpg which I can easily exceed with a 45 year old design V8. Rover 600 used Hondas PGM-FI system which was good but definitely not frugal - customers frequently complained that the economy nowhere near matched the claimed figures. The Metro SPi system suggested by Mike is ok, but Rovers MEMS efi was not the most reliable system, and to fit 2 almost lunacy - apart from the standard Stag manifold not split in such a way thatthe o2 sensors needed for closed loop in each exhaust would be sharing the exhaust gasses from 2 systems they could suffer from MAP sensor lag - I think that might dial in some unwanted problems!

The Patton system from what I have read is superb, and allows the engine to be otherwise pretty much untouched, and because the Stromberg bodies remain, the engine breathers still work as intended. Maybe on my trip across the pond next year I could split a set between the family and bring it back at minimal expense - admittedly I'd have to get it to Canada first...

[KOY 23]

Speaking as a carb tart, having had Strombergs, Holley, weber and now mulipoint EFI. Why, I keep asking myself. I had no probs withStrombergs, late 20's on a run, no leaks. The rot started when I was offered a 4 barrel Holley, supposedly correctly jetted, it drank fuel, pressurised crankcase, had to fit oil catch tank to sort a problem I never had before. I should have invested in rolling road sessions to sort it but the Weber kit had just been announced so I thought my money would be better spent on that rather than improving the Holley, which I thought was too big for the engine.

Initially I was pleased with the Weber, economy was back to the high 20's, performance was similar to the Strombergs. I kept the same breathing system that i used with the Holley, so had no issues there. Then I heard reports of weak mixtures and knowing dangers of this, I spoke to the supplier who immediately referred me to Webcon, who advised jet changes. Meanwhile I had bought an Air fuel ratio meter which confirmed it was running very weak. With the help of this rolling road sessions and Webcon I got the jetting correct. Performance improved and I was happy with the carb, as it offered improved performance and similar economy to the Strombergs but was easy to adjust.

Whichever carb was fitted, my car was never easy to start and warmup, always requiring a different mix of choke and throttle.

i have always thought EFI was the way to go and may be an insurance to keep the car on the road if emissions are tightened up, so the offer of a set of manifolds was too good to miss. The conversion had its problems and many times over the last winter I asked myself why did I start this. Now I have a fully mapped EFI and ignition system. The car feels much more powerful, starts immediately and runs smoothly whilst warming up. Consumption should be better.

Hopefully I have got where I want to be but the Strombergs are still in the loft.

John.

[therat04]

My strombergs were pretty well clapped out so as a temporary measure I fitted a weber carb, i intend to do up my stroms and refit them but the ease of setting up and excellent mpg and performance from the weber i will probably take my time refurbishing the strombergs.....Steve

[Staggard]

I think john's story ( KOY23) is not unusual being the donkey and carrot syndrome, the promise of better things ( Eg proformance economy ect ) but then you can easily become involved in the money pit. So my summery ( if it aint broke dont fix it ) ( if it is broke then why not fix the thing that has been working well for years and looks authentic ) The flip side is with my Bonneville that has Amel's fitted as original equipment, even after overhalling them you could not bring God to get rid of the flat spot's and the refusal to tick over so they were replaced with a set of Makuni's needless to say it flew and ticked over like a dream. My point is that the originals did not work, but IMO the strombergs do and if they don't ( on you'r car ) save money and fix them. Graham

[flying farmer]

My first carb on a Stag engine was a holley because the engine I bought had no carbs and I had a spare 390 holley.

It was a simple carb to jet, just took a while keeping an eye on fuel consumption and the feel of the engine. The fact I was doing 12,000 miles a year in it meant it got done fairly quickly. Getting rid of the flat spots took longer, but an article I chanced upon when on holiday in the states about setting up carbs too big for your engine worked wonders. (it was a magazine aimed at the drag racing fraternity)

I went to efi for more power and economy. My original set up using a modified Stag inlet manifold gained an extra mpg or two, but not really any extra power, hence my later fabricated manifold which did both.

My first experience of the Strombergs was when I bought the first Stag. It was never brilliant at starting when very cold and was as flat as a fart.

Despite the receipts from the previous owner and reasonable MOT emissions it turned out one carb was set too weak and the other too rich, correcting this worked wonders.

I reused these carbs on the Estate, the engine of which had been run on injection for years. As I always fit a lambda sensor to the balance pipe of all my cars with a jack plug in the interior (easy to swap my mixture analyser between cars), it showed the tubular manifold and straight through exhaust system did not seem to suit the carbs at all.

A flooding problem lead me to rebuild the Stombergs, it also became apparent that the needles and jets were knackered.
Not suprising after 115,000 miles.
What was suprising was fitting new needles and jets lead to the mixture analyser sitting in whatever part of the mixture range I chose to set it from idle to 6500rpm despite the different exhaust system, and since the rolling road run that prompted the rebuild showed a power output of 162 bhp despite a VERY rich mixture over 4000rpm, only 3 bhp behind the same engine with the correct mixture on its first injection system.

Fundamentally I think it is possible to get most forms of carburation to work properly, just don't expect them to work perfectly out of the box, you need to budget for a rolling road session to do the job properly.

MOT emissions only cover the idle mixture, it can be set up well here even if the carbs are knackered, and tragically far out on the rest of the rev range.

Neil

[Westfaling]

I had strombergs on my first Stag. It was only 6 years old but the carbs still needed adusting every few months to keep it running well.
When I needed new carb(s) to replace the US spec strombergs on my current car a Weber was cheaper than a pair of Stombergs - bit of a no brainer. If the cost had been comparable (for new carbs) I'd have stuck with strombergs for originality.
Nick

[KOY 23]

Neil.

Thank you for your detailed and knowledgable response, I always learn something new from reading your posts.

By the way, what shape should a fart be?

John.

[milothedog]

Strommies for me, I think they are part of the character of the car. As some have already said if I wanted EFI, Etc I would buy a car that had it.

I do greatly admire those that set to and achieve these mods though, Flying Farmer, Stagdad, Koy23 spring to mind but it's not something I have an interest in and like to keep my car almost standard.

I think maybe for me it would be like being back at work again as I worked side by side with the R&D team on a few projects, at least then I got paid for it


Ian