Hello,

I looking around for a recomendation on a mechanic in Los Angeles. I have a 72 250 engine 130.923 with Dual Zenith Carbs.

Currently it run fines at running temperature but above or below it backfires and has poor acceleration from a dead stop. It also seem to be eating alot of fuel.

It's out of my league to DIY so I need a mechanic with experience and the patience to work on this old carb.

Thanks

Adrian

I don't know a shop in LA, but steel yourself for the news that you probably will need more than just an adjustment. You probably have the dreaded vacuum leaks.

Lots of information on this forum, and I have some information that I can send or fax.

Good luck.

__________________
Chuck Taylor
Falls Church VA
'66 200, '66 230SL, '96 SL500. Sold: '81 380SL, '86 300E, '72 250C, '95 C220, 3 '84 280SL's '90 420SEL, '72 280SE, '73 280C, '78 280SE, '70 280SL, '77 450SL, '85 380SL, '87 560SL, '85 380SL, '72 350SL, '96 S500 Coupe

Why do you think it's a vacuum leak?

Let me explain some other issues about this situation. Basically I was having some more serious work donw on this car when I lived in SF. The guy who was doing it basically was holding my car hostage and was taking forever to finish the job. By this time I had moved to LA and he still wasn't done. So eventually I went to SF and got the car int he condition it is currently in. It did not have this problem before.

Her'es some notes from the Haynes book that describe some of the problems I'm having.

Excessive Fuel Consumption:
Worn or Loose fuel inlet needle valve
Incorrect float adjustment
Accelerator pump stroke incorrect
Fuel injection nozzle in carb throat requires alignment
Choke valve plates not fully open
Automatic choke heater coil not functioning correctly

Difficult hot start:
Float chamber vent valves require adjustment
Float chamber vent valves require cleaning

Engine stalls when cold and clutch depressed:
Fast Idle speed too low.
Incorrect choke valve plate gap
Vacuum regulator incorrectly adjusted

I don't know you may be right about a leak but I'm also certain that they guy that was working on it is not as familiar with making these kind of adjustments as he thought he was.

If you have some better information on diagnosing this problem I'd like to hear it ;-)

Because hese are the classic symptoms of a vacuum leak.

Basically, the surfaces of the carb(s) warp because of excessive heat, probably because one or both of the heat risers are stuck in the open position. This opens up gaps where the surfaces (top plate, fuel block, body, and intake manaifold) meet and causes a loss of vacuum, which causes the carb to run lean, which causes a carb backfire under acceleration when the engine really wants gas. I am not sure of the physics of the backfire, but it certainly happens.

The vacuum leak in effect puts the carbs out of adjustment, since one is getting more air and fuel but it is not getting to the cylinders that needed it. These cylinders run rich, hence the poor fuel economy.

I have personally experienced this on several 250C's, and there a number of posts on this forum that started out looking for advice on how to adjust and rapidly moved to vacuum leaks.

CTH will pick up this thread pretty soon and explain it much better. In the meantime, I am happy to fax or mail you an excellent article on the subject.

Chuck

CTH will pick up this thread pretty soon and explain it much better. In the meantime, I am happy to fax or mail you an excellent article on the subject.

Chuck

yeah I started reading the many backposts on Zeniths and 250's

So I take that there is some hope ;-) The car runs great on the highway and gets the expected fuel economy there but in the city it's a pig. oink oink

Try "Hans German Auto". If I remember, he's on Lankershim in N. Hollywood. I used to take my 250C (with the dual Zeniths) there years ago when I lived in N. Hollywood. Lot's of grumpy old German mechanics there that know their stuff on the older cars. Got mine running tiptop. Probably one of the few places locally that has the sync tool especially made for those pesky Zeniths. Once mine were set up properly, I never touched them again except for keeping them clean.

I also had the good fortune to pull a freshly rebuilt pair of Zeniths off a wreck at one of the Euro "pick your parts" salvage yards in Sun Valley. Paid .50 admission and got out the door with them on the manifold for a whopping $35.00. Some poor guy spent big $$ to rebuild these carbs. When I pulled the valve cover I saw the cam was completely shot with almost flattened lobes! Bring a light tool box with just the essentials and comb through the wrecks for bits. You can make out like a bandit. Decent burritto's from the "roach coach" out front too!

STS

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Sounds good.. wish I lived closer to that part of town. I may check out Hans anyway especially if they've got the experience. Not that it means much but the best MB mechanic I had in SF was named Hans. There's a couple of places within walking distance of where I live but they might be wiley.

I don't trust mechanics who aren't old, german and grumpy ;-)

__________________
MB 72 250 M130.923 114.011 170k The Beauty

Is it this guy?

Hans German Car Repair Inc
5434 Laurel Canyon Boulevard, Valley Village, CA 91607
(818) 985-6626

__________________
MB 72 250 M130.923 114.011 170k The Beauty

Must be him..probably moved for more space & service bays. Busy place. I left the valley in 94'. They had just changed my area's name to "Valley Village", separating it for a new zip code from N.Hollywood. I lived just 2 blocks from L. Canyon on Burbank.

I gave all my 250's receipts to the new owner when I sold it so I can't provide any more info. It's got to be the same place, just moved.

Good Luck

STS

If you find the carbs are worn out There used to be a weber conversion that was quite popular.You can search for those.Good luck Michael