Tough maiden voyage - 1970 250 Automatic

[BWhitmore]

When replacing the stud on the manifold be sure to coat the threads of the stud with a sealant to eliminate a possible coolant leak. The crumbling gaskets is the source of the vacuum leak.

[vwnate1]

# 1 : remove the combined manifolds from the engine and lay a straight edge across the mating surfaces, these some times warp causing vacuum leaks .

When Installing an InLine manifold, you need to get it in place and lightly install the bolts/nuts, then apply the final torque beginning with the two center bolts then working out wards, left to right tightening the fasteners from the moddle outwards .

This is critical as long "log" typ manifolds creep as they heat and cool so how they're tightened is how you prevent leaks and cracks .

I don't know about Mercedes but American InLine engines never have a fastener at the outer end, only a locating pin and much grief is caused by un trained people installing bolts or studs/nuts in those two positions .

[barry12345]

I used to make some of the gasket set components under each carb. I do not think I made the thick ones though. It is nice to have the heat risers working but not easy sometimes.

I am not a fan of kitting these carbs initially. As too many problems are caused by them sitting and gumming up when the gas evaporates. So I introduce laquer thinner to clean them out on the car first. I always assume that they were probably working well enough on the engine sourced from. Or the ones existing are going to be gummed up as well. From sitting.

I feel so strong about this and the old zenith carbs. If I an going to let them sit on a car. At least run it out of gas to the carbs to reduce the amount of gas left in the bowls. Before stopping the use for periods of time.

\Ideally then is to separate the fuel line in the area of the drivers foot well just where it transisions at the firewall area. Under the car. Run the carbs out of gasoline and feed them with a quart of laquer thinner. Using the starter to pick up the thinner and move it into the carbs. Best approach then is just stop feeding the thinner in and let the engine run out of it as fuel. What little thinner left in there will evaporate and leave no residue in the process.

I have had decent running zeniths get a lot better with just the laquer soak alone. I was leery initially about the float but never had an issue with that and the thinner. The thinner is fast acting on the gas residue. What I call a carb with average gumming problems takes about twenty minutes usually. Engines run pretty well on the laquer thinner afterwards as well. .

I was hostile over all the carbs I had kitted or paid to have kitted before I developed what I still use on many smaller carbs today. I have eight zenith cars at this time. Six are on m130 engines and two spares.

I turned a wooden adaptor on the lathe to cover the area of the throat. Kind of a bowl that uses the original large o ring for a seal. I must have been excessively fussy then as I also painted it. My balancing device has too small a foot print. Aquired used and probably sized for motorcycles.

It of course will not fix a real problem but all too often with these it is just a miserable buildup of gas residues. A test I use is pull the adjustable needle screw low down on the carb. If no gas comes out at a reasonable flow. The carb is gummed up. On several occasions absolutely nothing came out initially. You have two carbs so you expect equal flow by comparison. I do not know if the thinner is more or less aggressive than commercial carb cleaners. I do know it is a solvent I really have grown to like over the many years though. There is also a bolt on the intake manifold up towards the front of the manifold. I have had two cars I worked on that it was leaking air in. It takes very little to upset the fuel to air ratio. Putting the the first cylinder into a partial miss. So always spray a little wd 40 on it to check. What I like about what I use as well it is a semi dynamic test that verifies that idle fuel passage is really clear. You of course can do the same thing with gas in the carb.

I wish I knew more about cars but it is just a hobby to me. I do have in my memory what a really good m130 engine should sound like at idle.

They can be really smooth. People have mentioned and I agree the ignition system needs checking. I am not certain anymore but timing it is done at about 3500 rpm. The distributor shaft bearing seems prone to wear on many even way back. I think there is a provision for lubrication that was probably ignored. So the conversion to electronic makes a lot of sense.

Last but not least. Somewhere at some time I read a carb in storage on a car longer term. That may not be that long on these particular carbs. Should be filled with light oil.

It may just have been luck of the draw. When I drove Mercedes cars with zenith cars as everyday transportation. I cannot remember having any amount of real carb issues. On my fintail I did have one re kitted by a Mercedes tech on his recommendation. Although it did seem fine to me. The guy must have had ears like Bugs Bunny.

How long ago? Kit and labor 25.00. Including removal installation and set up. He had a small dealership that he ran totally with just a helper. He wore a suit under his coveralls. His place was fairly busy. A Dutch guy with a Mercedes dealership. Many of them did a lot of their cylinder head work in house back then.

I am not a safety nut. Yet the old braided fuel hoses should be replaced to prevent a gas fed fire under the hood episode. I fought one in my parents garage many years ago. Not Mercedes though. They really get looking pretty ratty anyways.

[Number400]

I have made my peace with the Zeniths. It took a few tries to understand them but now I have rebuilt two sets, one that was really gunky and rusty.

Onto the manifolds. I struggled and got some but not all of the upper manifold bolts off but one of the under bolts is rounded off so I went on to the exhaust manifold bolts. Some are hard to reach but I loosened them all a bit to make sure I could. I got two of the exhaust bolts off and have some penetrating oil on the other ones. More wrenching tomorrow but I am taking my boards on Saturday and should be studying.

I really hate not being able to drive this car yet but happy that I am getting to the bottom of the issues and will clean and fix things along the way and it will be more reliable because of it. Anyone have a line on those thick gaskets?

[Number400]

Can anyone one confirm 186-141-03-62 the correct part number for those insulating flange manifold gaskets? 1970 M114 motor. I wrestled the manifolds off which was quite a feat considering the exhaust and AC compressor are still mounted.

Think a 2012-2018 Pruis motor mounted sideways will work? That or the drive train from my 07 Tacoma. Ok, I will stop.

[Number400]

Well, I jut learned that the heat risers/exchangers have no bearing on vacuum leaks as they go nowhere, it just fins and the flaps so they have nothing to do with my low vacuum and engine stalling. Since the revs did pick up when spraying carb cleaner between the carbs, I am hoping that the new intake/exhaust gasket will solve the issue there.

[Number400]

Hooray! My gaskets finally arrived. Should I be concerned that my intake and exhaust manifolds are not quite flush? Is that worth getting machined or will the manifold gasket take up the difference. Its not much but there is a slight edge.

[Number400]

Actually, I just loosened up the nuts that hold the manifolds together a bit and I will mount on the car, then snug those down. Just loosening them a little, the mating surfaces fell into line. I initially made them quite snug to get the stud holes they form to be round.
Anyway, thinking/typing aloud so I don't do anything stupid and crack them due to poor installation practices.

So start in the center and tighten towards the outside. Once all are torqued in that order, then snug the nuts that join the manifolds.

I just built my smoke machine today and looking forward to getting the car back to running soon and with no vacuum leaks.