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Here are some messages covering that subject.

This is a very popular subject. Especially the S2 Stromberg to SU conversion.
From: "Jan White"
Subject: Triple SU's
Date: Wed, 21 May 1997 21:49:24 -0400

My '68 series 1 1/2 has the two strombergs. I was wondering if there is any real power gain if it was replaced with the triple SU setup. Does anyone know if its worth the cost, I've heard its about $1000. Is the performance gain worth it. Are there any tuning considerations when using the triple carb setup? Timing, plugs, etc. Where is the best place to look for the manifold and carbs? Hemmings? Any third parties. Any general info would be appreciated.


From: "pat harrington"
Subject: Triple S.U.'s
Date: Wed, 21 May 1997 21:12:04 -0700

The dual stromberg setup was used on all Federal Spec cars from late 67 onwards. These are the E-types with the poorest performance and probably the most tuning problems. The dual Strombergs are nothing but constant trouble, being difficult to tune and keep in tune. Yep, your best bet would be going with the triple S.U. setup. These carbs are the model HD-8. They can be found on many other vehicles besides the E-type. The Rover "P" series also ran these carbs, and occasionally they show up in Pick-a-Parts. The S.U. carb is a very simple instrument with only two moving parts. Once the function of the "Constant Depression" carburetted is understood, You should be able to tune and sync the triple carb setup in about 15 minutes. This setup will provide more horsepower, with less trouble. The 4.2 engine has no problems gulping the additional fuel/air mixture. If racing setups are your bag, three Weber 45 DCOE's work very well, but are tough to tune. Mikuni and Solex also have side draft carbs for this application. You will need: 3 HD-8 Carbs, triple carb intake manifold(s) (3.8/4.2 either will work), linkage, fuel lines, and some other misc. stuff. If your car has the x-over rail from the exhaust manifold,

You'll have to block that off or get a proper non-smog manifold. The smog goons in your state may have laws against these alterations, or they may not be sharp enough to know the difference. You may want to research this topic before you start taking your intake apart, and buying parts.

The cost for everything from the cylinder head out (which is what you'll need) will cost at least 1,000.00. then you'll probably want to rebuild each carb and detail the whole set-up so it looks good. The result will be a much more reliable and better performing motor car.

Good Luck
Pat Harrington

From: David Lowenstein
Date: Thu, 22 May 1997 10:09:44 +0000
Subject: Re: Triple SU's

Jan -

There's been a lot of discussion on this subject over the last few months. I recommend you check the digests from late January (which included my discussion on the subject) and late March (including a very useful post from Larry Schear). BTW, I get my car back tomorrow after having the triple SU for dual Stromberg swap completed. I will give you an immediate answer to your question about power gain on Monday!


Dave Lowenstein
Washington, DC

From: Mark McChesney
Date: Thu, 22 May 1997 09:42:11 -0400
Subject: Re: Triple SU's

I think the cam profiles were changed on the S2 motors (less carb/less cam for smog). Does anyone know for sure? This would have an effect on any performance gains you might see from the SUs. Be careful, this is how it all starts. If you do new cams, you should do headers, and then there is porting and if the motor is making more hp you'll need 4 piston vented brakes, and that suspension kit from GTJ would be nice... It never really ends :-/

Mark McChesney

From: Steve Patchel
Subject: Re: Triple SU's


There has been much written on this topic by people much more knowledgeable than me.I can only relate my experience, the PO retrofitted with 3 SU's to my 70 S II and its really quick. Fuel consumption is about 15 MPG.

Only down side is getting the car through the California Smog Test. If you live in a location with tight smog test do be careful. It took a lot of work and expense to finally get my car through the test.

Hope this helps

Steve Patchel
70 ots

Date: Thu, 22 May 97 08:49:06 PDT
From: LLoyd
Subject: carbs/cams/H.P.

As I recall, the 2 carbs to three switch makes about ten horsepower increase. I don't imagine it would be noticeable except a the top end. Oh - and this is replacing the cams also...


Date: Thu, 22 May 1997 11:07:26 -0500
From: Dann Poindexter
Subject: Re: Triple SU's

Since someone brought up the subject of cams...

The cam profiles are different. I am switching to the 3 SUs setup and changing the cams. The set of cams I was interested in, I had read about in an article about a light blue SII FHC that was raced in England, the article tittle was "Fire in the Belly". I donít remember which Magazine. I have misplaced my copy of the magazine, and if anyone remembers the article or has a copy or remembers the name of the company that produced the cams or .... I would be greatly appreciative.

Dann Poindexter

Date: Thu, 22 May 1997 17:20:45 -0300
From: Bill Spear
Subject: twin carbs to triple

I too have a '68 OTS which I switched over to triple Solexes. I am very happy with the performance, although as noted you can expect a decrease in milage. In an engine swap years ago I wound up with a '64 engine which might have had the proper cams in it, although I didn't feel there was a great deal of difference attributable to the carbs between the engines. Oddly it seems to me that fuel consumption is much higher at loafing low speeds. When blazing away out on the highway it improves. Go figure. Someone out there probably knows why this is. I have never had the slightest tuning problems with these: they seem rock steady. I would guess that triple SU's would be about the same difference in street applications and be easier to find someone to look at if needed while touring. Also they would likely be easier to find complete with all the odds and ends. On the other hand there is a Walter Mitty sort of boost seeing all those side drafts lined up just like a Le Mans D Type :~)

Pat suggests the 45's...I was advised to gt 48's and did. Maybe milage would be better with smaller ones? At any rate it doesn't seem to suffer from over carburation..

Also of course, don't lose all the gear for the Strombergs. California or not, sooner or later, you or someone else is going to need them.

Bill Spear

From: pat harrington
Subject: Tri-power and Cam profiles
Date: Thu, 22 May 1997 16:06:24 -0700

The Article "Fire in its Belly" is from Classic and Sports Car 6-95.

The Cam Profile run in this Series 2 was done by the owner. It is 460 thousands lift and 270 thousands duration. This is not the stock profile. According to the factory workshop manual, the stock profile for a U.S. Federal spec 4.2 smog motor is no different from the earlier cars.

The lift is shown to be .375. The duration is not listed. The car tested in the article also has a lightened flywheel, improved fuel system, and an uprated oil pump. Horsepower is listed at 306bhp, as opposed to a stock series 2 of about 190-200 bhp. He was running a triple S.U. setup.

Commonly known logic tells us that More fuel and CFM of air = more power. There is an excellent book called "S.U. carburetters, tuning and techniques" Which is highly recommended for anyone contemplating any carburation changes. There is a whole chapter devoted to carb. choices. Remember, the U.K. spec series 2 ran 3 S.U.'s as they were'nt subjected to U.S. smog regs. While the 265 BHP claimed by Jaguar is totally false, The pre-smog/triple carb cars produce a lot more H.P. than the dual Stromberg models.

The Road & Track test car for 1964 whomps the 1969 car fair & square in the period road tests. I took my 3.8 down to the street legal drags in Pomona CA, and it ran a brisk 15.55 in the 1/4, with a speed of 92 MPH. I seriously doubt the smog motors would approach a 17 sec. time.

The benefits of triple vs. dual carbs is a complex question, which would require a serious cost/benefit analysis by anyone contemplating this changeover.

Good luck & Happy Motoring

Pat Harrington

Date: Thu, 22 May 1997 14:21:50 -1000 (Hawaiian Std Time)
From: Antony Clarke
Subject: Re: Tri-power and Cam profiles

In view of all the carb chatter I thought I would I would repeat my question of a few months ago that went unanswered..

I am restoring a 64 XKE OTS car with a great looking engine that has triple dual throat WEBER 40DCOE carbs that look like new. I have never fired it up and it is not ready yet. Does anybody have any experience with these and any comments on performance, problems, expectations etc.??


Tony Clarke
XK150 DHC 1960
XKE OTS 1964

Date: Thu, 22 May 1997 19:54:55 -0500
From:James A. Isbell
Subject: Re: Tri-power and Cam profiles

>I am restoring a 64 XKE OTS car with a great looking engine
>that has triple dual throat WEBER 40DCOE carbs that look
> like new. I have never fired it up and it is not ready yet.
>Does anybody have any experience with these and any
>comments on performance, problems, expectations etc.??

I have two of them on my 1800 cc Water cooled VW in my Formula Atlantic race car.

I am surprised that it only takes three of them to feed an engine that is more than twice the size of mine. But then, maybe I am over feeding mine...#8-) It does suck up alot of 115 octane.

They are hard to set the idle mixture on and the only way I have found to do it is with a Colortune. If you dont get them set properly it will idle rough. That isn't a problem with my car since once its rolling it never gets below 2000 rpm anyway. The rough idle sounds real tough, but probably not on a street car.

You can buy a book on Weber carbs at most racing shops that will help you tune them.


Date: Fri, 23 May 1997 14:15:25 +1200
From: John McDonagh
Subject: Re: Tri-power and Cam profiles

A friend of mine had triple 45DCOE Webers (and other hot bits, cams etc) on his MK2 when he was racing it. It was very fast - over 220 hp at the back wheels on the dyno. My virtually standard 3.4 Mk 2 made 120 on the same dyno which the dyno owner said was about normal.

Expect horrific fuel consumption - like single figures. Also just remembered a 3.8 E-type with triple webers and other gear was timed here at 172 MPH during a speed trial in the 1960's. It was a roadster - not sure if windscreen fitted or not for that speed.

John McDonagh
Department of Accounting Finance and Property Studies
Lincoln University
New Zealand

Date: Thu, 22 May 1997 17:36:15 -0700
Subject: Re: Triple SU's


A friend asked me today if I knew of anyone who would be interested in an early Series 1, 4.2 engine. It is complete with triple carbs (including choke linkage), water pump, flywheel and pressure plate (no bell housing), no starter or alternator. He said it was in very good material condition. The head shows no signs of corrosion and the cylinder liners are excellent. In his opinion, the engine and head needed only minimal work.

He also said he would provide a set of AE bearings and a set of original Hepolite rings with the engine.

He's asking $1800. The engine is in Southern California.

Jan, I realize this is more machinery than you need, but the total price for 3 carbs, a manifold and cams could make this a worthwhile package and you would have a spare engine, too.

The owner is building a new shop, is not on the net, and is difficult to reach by phone on a regular basis. If you or anyone else is interested, send me your phone numbers and I'll have him get in touch with you.

Regards, Dick Cavicke

120 OTS, FHC
65 E-type OTS

From: "Jan White"
Subject: Triple SU's
Date: Fri, 23 May 1997 01:32:59 -0400

Thanks to all of you for the fine feedback on the Stromberg/SU conversion question! One thing I failed to ask is whether the conversion has any impact on originality or resale value.Would the car be more desirable with triple SU's, or would it have a negative impact on value because its not original equipment? I don't plan on ever having this beast judged, I'm just going to have fun driving it, so it really doesn't matter to me, but you never know, some day I may be a PO! Thanks again for all of your input!

Jan White
68 E-type OTS
65 Corvette Coupe 327/365hp (4 speed)
88 Corvette Roadster (Auto, ugh!)
70 BMW R-750 (2 Wheeler!)

From: "pat harrington"
Subject: Jags, Webers, and Going Fast!
Date: Thu, 22 May 1997 23:01:47 -0700

About Webers: I recently had the extraordinary pleasure of chatting with Lee Mueller of the V-12 E-type factory racing team of the early/mid 1970's. He ran the car for the Huffaker crew. Anyway, we got chatting about Webers, and this is what I was told.

Webers are not tuned merely by turning screws. They must be jetted for the specific application.

Expect a big decrease in MPG.

The DCOE carb is for racing, not touring, and perform best at high RPM's

They are noisy. The intake will become much louder.

There is a big difference in quality of associated componentry. The Webers must be perfectly sync-ed, and a cheap linkage will throw them off balance.

This conversion is BIG bucks. Expect about $1500.00 on up for 3 new carbs and quality hook-ups.

Tuning should be left to an expert familiar with Webers.

It was a true pleasure speaking with Lee, he is truly a remarkable man, having survived a heart transplant AND dealing with the factory Jaguar people. I was truly inspired by his knowledge, experience, positive attitude and kindness.

Good Luck to all

Pat Harrington

Date: Wed, 28 May 1997 07:11:32 -0500 (CDT)
Subject: Re: Triple SU power

On 05/27/97 23:04:24 you wrote:
>Re: '68 Series 1 1/2
>Also, someone mentioned the 265hp rating of the 4.2
> triple SU setup was totally false. Does anyone know what
> the actual (gross) horsepower rating is for this engine?

Actual is around the 210 bhp on th dyno....

kind regards

VICARAGE JAGUAR............. Specialist Jaguar Restoration Anthony Parkinson - Owner
Florida Tel 1 305 866 9511
fax 1 305 866 5738
Web Site:

From: "John T. Horner"
Subject: Re: Triple SU power
Date: Wed, 28 May 1997 07:32:51 -0700

> From:
> >Also, someone mentioned the the 265hp rating of the 4.2
> >triple SU setup was totally false. Does anyone know
> >what the actual (gross) horsepower rating is for this
> >engine?
> Actual is around the 210 bhp on the dyno....

Is that a rear-wheel reading on a rolling road dyno or a flywheel reading on an engine stand dyno?


Date: Wed, 28 May 1997 07:53:12 -0700
From: Dan Buringrud
Subject: Re: More Triple SU Questions

Jan White wrote:
> Re: '68 Series 1 1/2>BR> >
> Pat Harrington mentioned that if I switch to a 3 SU setup
> that the cross-over rail from the exhaust manifold will
> have to be removed and plugged. Is this just a pre-heater
> and can remain or must it be removed in order for the
> engine to be properly tuned.

The reason that crossover pipe has to be removed is because the new intake manifold for a three carb manifold will not have anyplace to connect it. Actually you only need to replace the rear exhaust manifold, which is what the crossover pipe connects to. Assuming, that is, that you can find one for sale by itself. Possibly someplace like Jaguar Heaven in Stockton, CA. See George's page for the number and address! If I've mis-stated any details, I'm sure they will be promptly corrected.

Dan Buringrud
68 OTS
Also hoping to go to some 3 carb setup in the future

Date: Wed, 28 May 1997 20:30:25 +0200
From: Stephan Perthes
Subject: Re: Triple SU power

Isn't it like that:

265 bhp = SAE (US) PS
210 bhp = DIN (Germany) PS

My Series 1 2+2 4,2 litres (3 SU HD8 / US re-import) has a German license of Oct 1995 saying "150 KW" (Kilowatt) = 204 PS. 1 KW = 1,36 DIN-PS.

Any more guesses ? There are a few Jag friends around here also wondering

'66 E-Type 2+2 S.I 4,2

. From: "Larry J. or Linda L. Story"
Subject: Re: Triple SU power
Date: Wed, 28 May 1997 18:24:16 -0600

We got about 260 hp at the flywheel after a complete rebuild, including carbs and no exhaust installed on our '67 series one engine with 9:1 pistons. I'm sure that figure dropped severely after the engine was installed in the car.

Larry S
. '67 E-Type roadster

From: "Jan White"
Subject: Triple SU Conversion
Date: Wed, 28 May 1997 21:27:29 -0400

I have been talking with a few folks about what I need for the Stromburg/SU conversion. I still am unsure of exactly what I need. If anyone could answer the following questions:

  1. Linkage - What is different about the two setups? Can I use all the existing linkage from the firewall back? Is the SU linkage normally mounted on the intake manifold? Are there any additional brackets, clips, springs, etc.?

  2. Can I use my existing triangular air box that sits atop the air cleaner? Is it the same one except for the adaptor plate for the 3 trumpets? Is the air cleaner the same?

  3. Will I need new fuel lines, if so can they be fabricated or is there some type of original equipment fittings.

  4. Are the radiator/cooling hoses radically different? Are they available aftermarket, or can I just jerry rig it so it works.

I am attempting to find as few sources for as many pieces as I can. Any help would be greatly appreciated. Thanks!

Jan White

From: "pat harrington"
Subject: S.U. conversions and E-type videos
Date: Wed, 28 May 1997 21:43:30 -0700

To convert a dual Stromberg car to S.U's you will need:

  • Carbs 3 HD-8's

  • Air filter (coffee can with the two snorkels)

  • Linkage

  • Rear exhaust manifold

  • Intake manifold from a 4.2 or triple manifolds from a 3.8

The upper cooling hose might work. (I'm not sure if it's the right length)

Your best bet would be finding a used assembly from an E-type or Mk10, or 420G. Just order everything from the cylinder head outwards and an air cleaner assy. The linkage should hook up to the firewall pivot on the rt. side of the firewall. The triangular air box looks like it should work with the triple feeder trumpets.

The E-type documentary is available from Classic Motorbooks 1-800-826-6600.

I hope this helps

Pat Harrington

Date: Thu, 29 May 1997 11:26 +0200
Subject: RE: S.U. conversions and E-type videos

Just a warning boys, the intake manifold and enriching device on a Mk 10 or 420 G are different from the E-type. The intake manifold is turned upwards on these cars and with it in an E you can't close the bonnet. I know as I have been there. The enriching device is the standard electrical one on a Mk 10 and on the E a manual one, this wouldn't matter much I suppose, most people prefer the manual and it would be more original.


From: "David Lowenstein"
Date: Thu, 29 May 1997 10:59:17 +0000
Subject: Re: Triple SU Conversion

Jan -

I just completed a dual Stromberg to triple SU conversion on my 67 S1.5 OTS. I can answer some of your questions. However, it sounds like you may end up a little confused, because some of my responses conflict with others who have responded as well. The reasons for some of these differences may be that my car originally had the tricarb setup (a PO swapped it for the Strombergs), whereas fitting a tricarb to a newer car may require different pieces. I am assuming you have the 4.2L motor:

> 2. Can I use my existing triangular air box that sits a top the air
> cleaner? Is it the same one except for the adaptor plate for the
> 3 trumpets? Is the air cleaner the same?

Perhaps others have had a different experience, but I found that the air box in addition to the trumpet connector had to be replaced. With the trumpet connector, you should try to find one from a 4.2L tricorn motor. The 3.8L trumpet connector looks very similar, but has a smaller breather pipe. If you're only able to find a 3.8L trumpet, it can probably be modified by reaming the hole in the plate, and fitting a larger pipe, but I suspect that would be a real hassle. Similarly, the triangular air box looks the same for 2-carb and 3-carb 4.2L cars, but the different trumpet connectors have different mounting points. It appeared possible to rework the mounting connections to allow my existing air box to mate to the new tricarb trumpet, but instead I traded my air box with a guy who had the correct one and needed mine. The air cleaner is the same (at least on a 67 - newer cars this may not be true).

> 4. Are the radiator/cooling hoses radically different? Are they
> available aftermarket, or can I just jerry rig it so it works.

You will need a new upper radiator hose (the one which connects to the header tank). All the good E-type parts houses will have it.

I did not have to replace the rear exhaust manifold since my car originally had the tricarb setup. I can't say for sure it won't work, but I was warned to stay away from a 3.8L intake for a 4.2L conversion.

I wholeheartedly agree with Frans that you also stay away from tricarb SU setups from any car other than an E-type. I avoided learning this the hard way when my mechanic demonstrated for me the pitfalls of trying to use the 420 tricarb setup. It doesn't fit without some really unpleasant modifications (at least on a 67 S1.5).

Once you're finished, this conversion is really worth it. The car is noticeably faster, idles more smoothly, and sounds better.

Good Luck!

Dave Lowenstein
Washington, DC

67 E-Type OTS S1.5 driver
71 Olds Cutlass Convertible
79 Triumph Bonneville
Keeping parts guys in business nationwide

Date: Sun, 01 Jun 1997 11:03:26 -0400
From: Chris Veenstra

I have a set of triple Weber carb's that came off my old TVR. I would like to put them on my '67 XKE to replace my triple SU's. The Weber carb no. is #50 101.

Will these carb's work on my XKE and what jets do I need to use? Where do I get jets and other parts for these? Where can I get a manifold, or a manifold conversion?



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