View Full Version : Weber DGV Carb Conversion for 78 MG Midget 1500

02-12-2009, 11:46 AM
Hello all of my fellow MG owners! I was just wondering if anyone has done the Weber DGV carb conversion for their midget and if you had any problems or the need to re-jet upon getting it tuned in? I have replaced my original Zenith Stromberg with the Weber DGV and cannot get it to run with the choke all the way off. I can shut it off about halfway and beyond that it wont run. First thing that comes to mind is "jets". Any thoughts?
I appreciate any feedback!

02-12-2009, 04:25 PM
Start here ;

If you cant get it to run good after adjusting the Idle mixture screw.

Proceed to here be fore you do anything else.

02-12-2009, 04:59 PM
What jets are in it now? Was it from a kit set up for a 1500 or what?

02-12-2009, 06:21 PM
Good point I was asuming it was one of the peirce kits.
Also you need to make sure you dont have any leaks at the intake manifold mating surfaces before you mes with the carb. The ears for bolting it to the head are probley not the same thickness as you header - exhaust manifold and the washers end up not being able to make up the differance in thickness. Spray some wd40 around the gasket mating surfaces and see if there is a change in RPM if so you have a leak and need to address it.

02-12-2009, 09:13 PM
I have a DGV. I bought Nigel with a worn and neglected Zenith, and after spending too much time and money on it...basically, I got desperate for <span style="font-style: italic">anything </span>that would let me get on the road sooner. The Weber worked right out of the box for me...just a little twiddling with mix and idle, but it sure didn't seem to need new jetting.

I bought it as a kit for the 1500, with manifold etc., so I assume the jets are adequate for it. If you bought it with carb+manifold, yours should be too.

I'll echo what Chris said: First <span style="font-style: italic">make sure </span>you have no vacuum leaks, <span style="font-style: italic">especially </span>if you have the Pierce intake. It may require you to grind a bit on the exhaust manifold to make clearance for it, and shim up the mounting clamps so it holds snugly. It took me several tries to get the manifold to sit tight and flat to the head; even when it looked all right.

Having done it, though, and even though Nigel's been running over a year on the Weber, with no attention paid to the carb <span style="font-style: italic">at all</span>...I wouldn't do it again. Knowing what I know now, (thanks in large part to the guys on this here forum,) I would have gone with an SU4 bolted onto the 1500 manifold instead. Nigel's Zenith was thrashed beyond rebuilding, and used SUs can come cheap--much cheaper than a Weber. For all a Weber's complexity and fine-tune-ability, it doesn't have the economy or the responsiveness that an SU has for a Midget. (I don't have any firsthand knowledge of this, or even hard numbers to back it up--just the word of many Spridgeteers that have tried and compared both.) A Weber also doesn't have the engineering elegance and beautiful simplicity of an SU. Which is odd, frankly, considering the Italian origins of the Weber. But you have the Weber, so enjoy it, 'cuz it's better than no carb at all! :driving: (Just don't expect 30 mpg and lots of low-end torque.)

02-18-2009, 10:43 AM
Hello all! I really appreciate all of your feedback. I didnt want to do it but I took it to a guy that knows MG's inside and out in my area. I hate the idea of "someone else" working on it and possibly having the joy of getting it running right. I purchased the Weber DGV from Moss for the 1500. It was the manual choke kit and came with the Pierce manifold. I used new manifold gaskets and some additional gasket sealer and honestly couldnt find any air leaks. So right away I was leaning toward the jets. I honestly dont know what jets are in the Weber when its off the shelf. When it comes to the "guts" of the carb I become really ignorant. I should know today what the problem is as I seen him pull it in to the shop yesterday and start bending over into the engine compartment. I do have my original Zenith and manifold still and if worse comes to worse I can always get that rebuilt by University Motors and put it back on. Yet the idea of spending the money on the Weber was to fix the headaches that came with the Zenith (my head still hurts at times). I will let all of you know what this guy comes back with. If he tells me I have a air leak Im gonna kick my own butt.

02-18-2009, 11:26 AM
I thought the kitted versions of the Webers were pre-jetted to the point where it should be pretty darn close out of the box. My '63 has a Weber kit on it and although it's okay, I'm hoping to get the original SUs back on and tuned soon.

02-18-2009, 11:33 AM
One thing I've come to realize about myself is that I don't have to know everything about my car and that sometimes getting help - even paying for it can speed up the process immeasurably. I've had my carb to the shop twice as well as numerous friends to gather round and help - some in person and some online - I've even had a friend do some offsite repairs/ fabrication that I couldn't - like U-joints. Of course for me the big offsite project was the body/paint. I suppose I could learn everything but I'd rather be done and drive - I think you made the right call, sometimes it's just not worth the aggravation!

Besides you gotta know that at car shows I'm still going to say "yup, I did it all myself." :driving:

02-18-2009, 01:31 PM
THey tend to ship them a little rich after all rich isn't really going to hurt the engine but lean.. I would guess it won't need jetting and just a float adjustment I bet its to high and Idle mixture and idle speed screw adjustment.

02-18-2009, 02:29 PM
Hey MG buddies. You know I stopped at the mechanics today to see how things are coming and honestly I sit here with a very uneasy feeling about things. This guy was recommended by a lot of the british car owners and shops around yet Im not seeing anything to promising. I went and looked at the car which had the hood up and I see the distributor in a million pieces and nothing done on the carb. This car ran excellent for years and the car did run ok with the choke on when I put on the Weber its just I couldnt get the thing to run with it shut off because of it being to lean. He started mentioning there was no spark which is news to me and explaing the mixture screw at the base of the carb. Im thinking, "Did you bother to read the breakdown I typed out for you when I dropped off the car?" I had the mixture screw adjusted way out and it still wouldnt run. Maybe I just need to sit back and stay out of it till he's done but when you see things like that I cant help to get a little concerned. Especially knwing I could get a bill for making the car worse then it was before I dropped it off. Anyway, I had to vent. God willing it all works out!

02-18-2009, 02:54 PM
whatever you do - don't sit back - it's your car - it's your money. Don't ask me how I know. BTW make sure it's the right mechanic - as opposed to just the right shop

02-18-2009, 03:24 PM
I don't let anyone else work on my hobby cars. I don't know much but I'm learning a ton every time I launch into something. I can't afford to have a pro work on it but beyond that by the time you've worked on it for a while you know more about THAT car then most any "pro". What you don't know can be learned from the books and great sites like this. I like the tinkering and satisfaction although the frustration can sometimes start to outweigh that I'll admit. Tuning Webers is actually pretty tough I've learned, lots of potential places to tweak it (main jets and idle jets on two different circuits-primary and secondary, emulsion tubes, then the mixture and idle screws...)but all those variables make it hard to get spot on.
Being new to SUs I was shocked at how simple they are, elegantly so. I'm looking forward to getting mine back on in place of Weber!

02-19-2009, 11:24 AM
Well gang, todays mission is Im going to the shop and flexing a little muscle without creating to much trouble. I agree with "jvandyke" when it comes to others working on my hobby car. I just felt I was at a road block with the tuning of the Weber and everybody kept saying take it to this guy. He is without a doubt an old school british mechanic so maybe I need to respect his process a bit. I am going to try and pick his brain to see if ultimately there is a process in his head that will lead to this thing running great again. I guess there is some jelousy on my part not having "my" hands in there as I always enjoy working on these cars and learning new things. These forums also have proven to be a real blessing. It has made me want to go to one of these MG rally's to just hang out and talk to others. Thanks to all of you guys who left feedback.

02-19-2009, 12:06 PM
It seems that many "old school british mechanics" would scorn the Weber in favor of an SU setup, from what I've gathered so far. Maybe the Weber is better than the Zenith though. As for working on your own stuff. See the other thread I started about "OT bad wrenching experience". Ugh.
Even so, it's my birthday Monday, I just happen to have this afternoon, all day Friday and some of Monday off, what would I like to do more than anything else? Tinker with the Midget!!
(but I'll probably end up working on the Dodge's brakes)

02-19-2009, 04:18 PM
The carb should have worked out of the box not perfect but it should have been able to run the engine. I'm confused as to the spark problem was it not running at all when you dropped off?

02-19-2009, 05:10 PM
Hello Texas Bugeye and others. I stopped at the mechanics and had a bit of a relief when I saw him sitting down and carefully working on the carb. I went over things with him and apprently the few days it was sitting outside his shop before he pulled it in to work on it, something happened with one of the wires at the coil and he wasnt getting spark. Odd thing is I had no trouble with it when I dropped it off. I guess things happen. There is progress with the car. He ran the choke cable up to the drivers area and reworked the throttle linkage so it would advance better then the way I had it. I noticed he is making parts that work a bit better then what was given to me with the carb setup. He pulled my platinum spark plugs out that he totally is against in these cars and put in the regular champion plugs and said he will have her running later today. It sounds like he has plans to work with the timing and if need be make some jet changes. The thing that was a bit of concern was how much this was all going to cost as he has been in it for a few days now. He seems honest and commented he has only 2 to 3 hours actually in it. At $75 an hour it can add up. Im going to leave ho\im be tomorrow but the hope is Monday I hear something and I can get it picked up without a hole in my wallet. Well see. More to come.

02-19-2009, 10:19 PM
He pulled my platinum spark plugs out that he totally is against in these cars...Did he happen to mention why he's against 'em? Just curious; I'm running "Bosch Platinum +4" (or some nonsense like that) currently in Nigel. Back when I was wrestling with my Zenith, they were the only plugs that wouldn't <span style="font-style: italic">constantly </span>foul. When I swapped the Weber in, I never bothered to change the plugs back to stock. Think I should?

02-19-2009, 10:50 PM
That sounds reassuring. If he gets it spot on for $200 or so and you get to enjoy the car pretty much trouble free for a while then it's good money spent I'd say. Although I hope he's the "teaching" type in that he'll share what he did and why so you get to learn something for your $$ too!

02-20-2009, 08:13 AM
It appears things are not as side ways as they sounded in the begining good for you hope it al works out and your on the road soon!Ask him about the plugs as to why he is angainst the platinum units. If he swapped jets make sure you get the numbers of them for future ref.

02-20-2009, 08:29 AM
This is what I put in my truck, which gave me a 1.75 MPG increase. Any help in that department is a blessing!
They paid for them selves on one trip to Oklahoma and back on fuel savings.


This is what I put in the "B" and increased idle speed before I lowered it, by 150 RPM. Other than that? https://i58.photobucket.com/albums/g273/PJ161/A-Icons/confused0031.gif


02-20-2009, 09:22 AM
Wow! Talk about your exposed electrode! Spark everywhere! Being Iridium maybe it can stand out there in the heat pressure changes. Sort of like standing on the sun! Must be some tuff stuff. Anybody else try these?

02-20-2009, 09:54 AM
What I failed to mention was, the fuel cost savings was when gas was $3.50 a gallon. Now it would take two trips like that for them to pay for themselves. They say their supposed to last a 100,000 miles? We'll wait and see just how true that statement is.
The Champions are about 9 bucks each and the NGKs are about 10. Not cheap, but they seem to preform a little better than conventional plugs.

02-20-2009, 12:00 PM
Hey gang. I will ask about the plug issue in greater detail and let all of you know what he says. He did sorta explain his thinking already but honestly my mind was on the carb more so at the time when I should have been listening. I do remember it made alot of sense what he was saying. I also will find this web page that spoke of why the new generation style plugs need to be in "newer" cars and stay away from the oldies that like things to be simple from an operation stand point.

02-24-2009, 05:49 PM
I just completed a successful conversion on my 76 Midget 1500 using the Pierce kit. I also added a header and freeflow exhaust.

I had to add a crankcase breather to overcome the increased cranckcase pressure. It was pushing oil from the dipstick tube. This went on the blanking plate where the mechanical fuel pump was.

I am using a Carter 4070P high volume low pressure pump along with a Holly regulator to keep it down around 3 to 4 LBs.

Next is to go drop by and see Mike Pierce this week to insure proper jetting and adjustments (he and his brother Warren are racing friends and the shop is only 10 miles from my place).

I'll try to keep you posted.


Tracy Drummond
Healeys, Midgets and Miata's Oh My!

George Zeck
02-24-2009, 07:50 PM
Midget78 -

My name is George Zeck and I live in Avon Lake, OH. I just put on a Weber onto my 1275 this summer. Went on easily. I did have to re-do the choke cable and make some minor adjustments. It was running in &lt; 2 hours.

I did add the spacer plate - I had some vapor lock issues (might still have - I last drove it in Oct). Your pretty brave to drive in it the last week of Cle weather. It's been bleeping cold.

Email me privately and maybe I can answer a few Q's.

Good Luck -

George Zeck
Emerald Necklace MG Club

gzeck2 at yahoo dot com

02-25-2009, 10:45 AM
Hey Tracy. You know I also had the issue with the oil blowing out of the dipstick. Actually I didnt even realize it until I stopped working on the car and notice the puddle under the car. Its like the polish way off changing the oil. I put a "T" on the line that runs from the bottom of the air cleaner to the valve cover. I went to Auto Zone and purchased one of those $15 air cleaner filter units that tighten onto hose or pipe. That allowed me to regulate the amount of air being pushed into the crankcase and putting to much pressure in there making the oil blow out. I have yet to drive the car to know if that will fix the oil blowing out under driving conditions. I also seen on the net a guy who drilled and tapped the intake manifold, put a hose barb on it and ran another hose to the intake manifold with an inline PCV valve. I guess that works also.

02-25-2009, 11:00 AM
I also seen on the net a guy who drilled and tapped the intake manifold, put a hose barb on it and ran another hose to the intake manifold with an inline PCV valve. I guess that works also.

This is what I did. Documented somewhere here. On a Weber with Pierce intake. On my 1098, there is only a hose from the valve cover to the air cleaner (stock), most have a timing chain cover thing and later have a gulp valve too. I was loosing oil (from a tappet cover "drain pipe"), not enough vacuum on that valve cover line from the Weber's "Longflow" style foam filter housing. So I drilled, tapped the intake on the outboard side right below the carb and moved the valve cover hose there. Oil leak gone immediately. During the process I discovered that the fitting on the valve cover was loose so it could be I would have been alright had I just tightened that up but I was already done.
My only leak now is from the oil filter adapter housing.
I do wonder if I'm sucking too much oil into the intake but I'm not fouling plugs so I'm going with it for now.

Here's the thread (https://www.britishcarforum.com/bcforum/ubbthreads.php/ubb/showflat/Number/492765/Searchpage/1/Main/48895/Words/intake/Search/true/Re_1098_vent_tube#Post492765)

BTW I used a barb fitting and restricted the opening (with a piece of vacuum tube cap with a tiny hole snipped in the end). Metered orifice approach vs. PVC