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'75 Mark III, 33K miles, given to me for rehab. I have time, some experience, tools and a few $$. But will need ongoing advice from you who have done this. Interior/top will need rip-out and redo. First: Trying to see if/how engine runs. PO took autochoke off the Stromberg carb. Need source for carb, OR, can this be replaced with some better version, e.g., Bosch side draft??
So far, have good spark, engine turns over, fuel pump works, but no carb system. Will also have to steam clean birds' nests out of gas tank. Or, as my son suggests, can/should that be replaced with modern fuel cell tank?
Welcome to the list. As for your problems, they don't sound like anything that you can't handle . . . and if the problems are beyond the expertise on the list, then there are some excellent professional mechanics who CAN DO THE JOB. Their experience and expertise are well worth the money and our time. 33 K original miles. Fantastic!!
Something in your original message you stated that you have a "1975, Mark III, with a Stromberg carb". Note 1975-79 were Mark IV (powered by a Triumph 1500 cc engine) and were aspirated by a Zenith Stromberg Carb. The Mark III (correct me if I am wrong on these years 1968-74) were powered by a 1300 cc engine and were aspirated by a pair of SU carbs. Stand at the front of the car, open hood and if the carb and intake is on your left (passengers side) then the car has the 1500 cc engine with a ZS carb.
Your car may still have all of the regulation smog equipment on it. How would you know? First thing I did was purchase a Haynes shop manual and literally read it cover to cover to familiarize myself with the car. This may have been the source of some of the "hard starting problems" - which is what I assume was the previous owners reason for removing the autochoke. Do you still have the old autochoke? If so there is a published method (on the Web) to "reset" the autochoke. You may want to get in touch with your local MG club to see who has a Midget that they are parting out.
Carburettors . . . like opinions and ******** everybody has one. All opinions will differ. Almost certainly the Zenith Stromberg (ZS) provides the least power. Some opt for dual Skinner Union (SU) carbs and others for Webers. All a matter of opinions. This is all I will say about the subject.
About the fuel tank. As of last summer, there were NO aftermarket fuel cells. The only replacement which I was able to locate was a factory original. The cost, to the best of my recollection, was ~$250.
Interiors can be replaced with relative ease (relative to how big you are when crawling around in the cockpit). Several major suppliers will sell you everything you need. This is a weekend job. You may want to also replace the rubber diaphragm on the bottom of the seat when and if you replace the seat covers. The diaphragm prevents you from "bottoming out."Finally, if the car has been sitting for years you would be well advised to replace hoses and gaskets. Note if you have a 1975 then your fuel pump is an AC-type. This is a mechanical fuel pump. It is expensive to replace ~$65, but cheap to rebuild about $5-10. The rebuild is dead easy.
For your information Weber does offer two choices of carburetors for the 1500cc Triumph motor. The DVG which is a down draft model and designed for street conditions, offers choices of electric, water and manual choke for approx. $500. The other option is the DCOE which is a 2 barrel side draft racing carburetor and costs approx. $700.
I'm not sure what the emissions laws are in LV, but I would suggest checking into this before considering the Weber conversion. I know for a fact that the DCOE model is not compatable with any emissions systems and does require some engine modifications including replacing the exhaust manifold with a header, replacing the distributor with a full mechanical advance version and inserting a fuel pressure limiter. The DCOE should only be used with an engine than is in excellent mechanical condition or the result could be negative. Adjusting the DCOE can be time consuming and expensive if you are not familar with the operation of this type of carb.
So therefore I would not recommend the DCOE unless you are serious about building a racing motor. Hope this helps.
I just converted the carb on my 1500 with a Weber downdraft. Now I have a serious pressure build up in my crankcase. While the car is at idle oil seeps out around the dipstick, plus if you remove the stick and rev the engine slightly oil will hit you right between the eyes. What do you think may cause this?
You do not mention how you hooked up the PCV system when you changed over to the Weber. On my B, the intake manifold did not come with a connection for the tube running from the tappet cover to the old intake manifold. This provides your negative pressure in the crank case.
I had to machine the intake to accept a threaded coupling to attach the PCV system to. I suspect that you have a similar problem. The basic kit is made to fit several applications and must be modified to work with any particular model.
The points that Rick has raised about the Webers are excellent. The emissions laws vary by locality. The original equipment will always pass emissions - assuming that you do not have a "kindred spirit" who determines pass/fail.
The following is an internet address for my particular favorite among MG mechanics. John Twist owns and operates University Motors near Grand Rapids, MI. He runs clinics during the month of February - excellent!! You can find him at:
http://www.universitymotorsltd.com
I wonder whether he would sell you a re-built carburettor, it would be like new based on the quality of his work, on the condition that you include the "choke-less" ZS carb.
Its not always true that "original" equipment will pass the stupid smog checks. I rebuilt my 76 to absolute stock specs last June, now a 76 is still tested for 2 more years here. they do a rolling-road type exhaust test, no under hood inspection at all. They failed me. I went home and re-tuned the Stromberg so lean that engine would hardly run. Went back. They failed me again. I ordered and replaced the stock setup with a webber, removed the EGR and air pump, plugged holes in head with screw in plugs.
They passed me without a problem. Go Figure......
The stock stromberg was not worn out and was "rebuilt" along with the rest of the engine, actually ran fine but have to admit that the webber does have more top end and the progressive 2bbl sounds neat.
For what its worth I think the oil burners I seem to follow every morning on the way to work are the ones they should hassle instead of those of us trying to keep a classic on the road.
I'm glad to hear that you were able to get the Weber to pass emissions inspection. Some state laws require a check on individual equipment along with static and dynamic tests. I disagree with the state checking under the hood for all emission components present, because if it can pass the tail pipe test then who cares what's under the hood.
Your car is an example that emission systems can be intact and functioning and producing more polution than a car without. Just my opinion.
I generalized my statement "way too much". It is obviously true that a stock carburettor will not gaurantee that a car will pass emission tests.
I profess to be a chemist and I should know these things! The only reason that I could imagine that a stock system should not pass emissions is that the catlytic converter is not functioning to its maximum capacity. The tailpipe test is, probably - I'm guessing, a carbon monoxide test.
Seems like a chemist/MG enthusiast should be working on this problem . . . . hmmmmm.
But find your findings of carb replacement interesting. Do you know the figures and the gases that your cars are tested for. Over here in England our cars are tested for Carbonmonoxide and Hydrocarbons through the tailpipe.
If they are fitted with a Cat then Oxygen and Carbondioxide but that does not affect any pre 82 MG it only affects MGF and RV8 over here. Do you run your cars on unleaded? Do you have any figures?
For info, Nevada does tailpipe test with these rqmnts:
| 2500 RPM test | Standard |
|---|---|
| CO% | 2.50 |
| HC (ppm) | 500 |
| Dilution (CO+CO2 %) | 6.0 |
| RPM | 2800 |
| Idle Test | Standard |
| CO% | 2.50 |
| HC (ppm) | 500 |
| Dilution (CO+CO2 %) | 6.0 |
| RPM | 1600 |
I will have to have this one checked before licensing. Hope it passes.
Re my original entry: Have read the book and studied pictures again and I have the Single Zenith-Stromberg 150 CD4, manual choke version. Checked with local autoparts store today. None available to buy. Was able to get rebuild kit and will try that. I am not getting fuel at the carb, so also bought replacement mechanical fuel pump (no rebuild kit was avail for the stock model) for $32.00 My son wanted me to go electric version, but I worried about my ability to install, since they 'warned' that it must be installed via oil pressure switch connection. Well, will just see if I can get some fuel flowing to start with !!
To follow up, our emission test here is no longer a tailpipe deal, my car would have passed the idle test just fine. They also check for CO and HC levels but am not sure as to the exact values pass/fail. That was the test in place until last summer.
Now they have a simulated driving test on a rolling road, my failure was at the 30-35 MPH road cruise and de-accelleration test. Now I would suppose if I had a huge stock of needles for the carb and played around long enough I could have gotten it passed but its 20$ a try.
I know the failure was in HC's being excessive in engine overrun which I am not suprised about. No where near the precise control of that with a carb vs computer control fuel injection, seems to me that the state wants all the classics off the road on a daily basis here. If I could not have gotten it passed I could have gotten an exemption for more $$ that would limit me driving to shows/club/events.
Trying to fight this seems a loosing battle. However since the webber passed their test I am still on the road.
You will probably not be able to find components for the drive train at the local autoparts store. Don't get me wrong. I am proud to support the local guy with grease under his finger nails, but he can't afford to carry those parts. You will, however, find a few bits here and there. Chris Kotting keeps a list of what "american" parts will fit.
http://www.iwaynet.net/~ckotting (last time I checked)
I found a few electrical components at NAPA as well (flasher relay etc).
As I understand it, you have a re-build kit for the carburettor. It will consist of diaphragms, gaskets and jets for the carb. However, it will not contain parts for the choke. If you are missing the choke you must purchase a replacement. You may be able to do it through a local club. From the www.mgcars.org page here is your local contact: