triple webbers for series one 4.2 L FHC

[guyjohnwood@aol.com]

Dear all,

As part of my restoration, I have been advised to add these for my fast road engine rebuild, along with long bore manifold.

However, I have been warned that webbers = petrol smell in the car ( I have a FHC ). Any views on this? Extra fuel consumption I can live with but this bit about fuel vapour / smell of fuel is worrying.

regards to all who offer advice,

Guy

[Heuer]

Avoid them like the plague! Increased fuel consumption, constant smell of petrol, hugely expensive and time consuming to set up and unlikely to bring any real power benefit. Also although 40 DCOE's were fitted in period only the larger 45's are now available which are too big for the E-Type. Read these guides from our KB before making a decision:

Weber Set up Guide 1: http://dl.dropbox.com/u/8496016/Weber%2045DCOE.pdf
Weber Set up Guide 2: http://dl.dropbox.com/u/8496016/Weber%20Wisdom.pdf
Tuning DCOE Carburettors by Kimble & Trindal: http://dl.dropbox.com/u/8496016/Tuning% ... uretor.pdf

On the plus side there will be no end of people wanting the triple SU's off you and many Weber owners will be delighted to do you a swap!

[abowie]

I put a 45DCOE on my MGB. On that engine, which revved happily over 7000 RPM, there was a power improvement on the dyno and I personally loved the Weber induction noise. Petrol smell was never an issue.

As David is alluding to above performance improvements on the long stroke slow revving XK engine may be much harder to find. Unless I was building a race engine that I intended to run at high revs for a lot of the time I personally would stick to SU's.

[Heuer]

For improved performance EFI is the way to go. E Type UK sell an upgrade and I have driven it - superb!

[Moeregaard]

Webers are great carbs if you're going for b*lls-out horsepower, but for a roadgoing E-type they are not worth the hassle.

[tinworm]

Webers are dirty old things and work best flat out I have found - any other speed they are not much fun.

regards Barrie

[JEP41]

For what its worth

I Love my Webers on the e-type and have a set of 40DCOE's for my 3.4 litre C-Type engine. When set up correctly they perform perfectly. The key is to finding somebody who knows how to set them up. Once set up they are very reliable. I have just had my webers reset on the rolling road after ten years of excellent service. The only reason I elected to check them was an engine removal to replace the gearbox. I do not get a strong smell in the cockpit of petrol but when the bonnet is lifted I get a lovely smell of hot engine with a slight fuel smell which is nectar to the nose. 8)

[44DHR]

For what it's worth too, I run triple 45 DCOEs on my 1967 Series 1.

Yes, they have to be set up properly - which I do myself - and I don't get petrol smells in the car. I do get plenty of comments on the visual set up when the bonnet is opened and when people hear the induction noise through the Pipercross socks.

If you read my adventures on Running Reports with my trips down to Monaco through Italy in 2012 and last year down to the Black Forest and Switzerland clocking up over 2,000 miles each in those two runs there were no faults or hesitation with this set up - totally reliable.

As I have always said about people's preferences - My Car - My Choice of what I do with it !!

regards,

Dave

[44DHR]

Thanks for the three articles - very interesting as I have not seen these before as I am not a member of the E type Club.

I would not avoid anything "like the plague" just because things are a challenge and need a clear understanding of the issues to be resolved. I have set up all manner of carburetors over the years in my hot rod era, particularly on american V8s with Holley 4 barrel carbs. There are two guiding principles in that the fuel delivery is only one part of the equation as you also need other elements such as good ignition, (spark and timing), with a good exhaust system to get everything to work, plus you need to size the carburation choke size to the engine and the intended use. Many a schoolboy error in clamping on a massive carburetor which results in a very low airflow through the required workings and wondering why she no go fast. I tend to select the smallest possible choke size, (the main venturi), to get the best possible fastest flow through the carb without limiting the required overall air capacity for the engine speed desired.

I tend to run my systems rich and use the fuel to cool the charge - especially on supercharged systems - and although there is an obvious higher fuel use, the reality of what were are using the cars for, this is the least of our worries.

Looking at the second article, "Weber Wisdom", there is an error in the chart showing the various "recommended" settings. On my 4.2 E type triple weber DCOE 45 system I almost follow the Haynes Techbook settings, but the correct size for the auxiliary venturi shown in that Techbook is actually 3.5, not 4.5 as shown in the second article guide of various recommended settings. The first article by Mike Cassidy shows the correct 3.5 figure for the venturi. I use this 3.5 size, but all my settings are the same, but I go up a size to 170 on the main jets from the recommended 165.

Another misconception stated above about the DCOE 45 being "too big" for the Jaguar engine is that it is not the barrel size, (40 or 45), which determines the airflow, but the main venturi which is a seperate component fitted in the barrel. A DCOE 40 barrel can take up to a maximum 36mm main venturi, which some people use for road use in the Jaguar engine, as shown in the second article guidance, but if you want to go to a 38mm main venturi, (or up to a maximum 40mm), you have to go to the DCOE 45. The DCOE 45 can go down to taking a 28mm main venturi, so the carb itself is certainly not "too big". I personally believe you want 38mm as the size for the main venturi for road use, provided you have a suitable auxiliary venturi to match it. The auxiliary venturi which is like a circular nozzle in which the fuel mix is dispensed into the airflow, then into the main venturi and then through the butterfly throttle and into the engine.

You certainly don't want to run lean on these engines, but on our European runs we are cruising at 80 to 90 mph for several hours at a time - until I have to stop for fuel !!

So please don't dismiss the Weber setup for the E Type. Some things are inherently beautiful and give us wonderful pleasure when correctly functioning - perhaps like a woman - but equally, if we gave up on things because they are difficult, frustrating at times and hard to understand - where would we be without them !!!

Cheers,

Dave

[christopher storey]

My own experience of DCOEs has been restricted to siamese port engines ( BMC A and B series ) and thus what I can add is of limited value, because the airflow in such engines does not behave the same as in one port per cylinder engines, but for me, the most difficult thing about setting up DCOEs has been the choice of emulsion tube . It is this which is the most critical component on a road car, because it very largely controls the transition between off throttle/light throttle/wide throttle conditions . A good choice makes the car perfectly pleasant ; a bad choice creates an absolute pig!

I should like to know what tubes Dave has used to get good results

[44DHR]

Chris, you are correct in that the emulsion tube is a critical component to get right and I use an F2.

There seems to be a good consensus of opinion on that size, as looking at the second article listing of various recommended settings, the F2 seems the popular choice.

regards,

Dave

[Heuer]

Webers don't automagically give you more power. The best example of this is the Lotus ?lan which, up until the S4, was fitted with a pair of Webers and replaced by a pair of Stromberg's. For years people whined on about how the iconic Webers were the only game in town and how cars fitted with them were faster and more valuable. It is only with hind sight people have begun to understand that the only thing they were faster at was going up in flames! Lotus knew what they were doing and it is now generally accepted the Stromberg equipped cars are actually a little quicker than their more exotically equipped brothers. Lotus could not get the message over however and public pressure made them revert to the old setup.

On the E-Type they are fun to play with but provide no performance improvement below 5,500 rpm on a road car.

Note: the reason for the fires was due to owners removing the air filter during service or because they liked the induction roar. Unfortunately the propensity of the Webers to puke fuel vapour during backfires and the location of the dizzy immediately underneath was not a happy union.

[Simon P]

Webers are all well and good, but real men run Dell'Ortos.....

:D

[Moeregaard]

One more advantage to running SUs instead of Webers is that they have dashpots to polish. It's always fun to open the bonnet at the filling station, only to have some econobox driver point and ask, "What in the hell are those?!"

[44DHR]

Guy,

I trust in reply to your original request for information, these responses have been informative.

From people who don?t run or have working experience of Webers, to those who have, the comments are all valid. The point I said at the start, it is your choice what carburation you choose for your car, but whatever that is, provided there is a good understanding of their operation and function there is no ?bad? carburation as such. Webers by their very ability for all their functions to be modified and assembled for the useage required, do need a clear level of ability to get them to work correctly, unlike some other stock or standard carburation requiring less sophistication. Webers don?t inherently leak, smell, backfire or catch fire any more than any other carburation provided they are correctly assembled, maintained and understood. I just have a mechanical fascination with all objects and these provide a further enhancement to me on my particular car. I could also polish the carbs, but just polish all the lovely brass fittings.

Sure, my Weber set up will use more fuel than the standard SU?s and I don?t claim they give any more power or go make the car go any faster in road specification than other options, they also don?t have such efficient air filtering and re-cycling of the crankcase gases as what Jaguar perfectly designed as standard, but it is my preference for the visual looks of the 6 highly polished ram pipes with no large air box dominating the area and have a definite aural induction sound, which I personally like.

All choices are equally valid and each has their own merit. You pays your money and takes your choice !!





Regards,


Dave

[JEP41]

Dave,

I agree with your views 100%. I love my webers and have a spare set of 45 DCOE's sitting on the bench for my next project so far undefined? If I worried about fuel consumption I would drive a Ford Fiesta 1.2 8)