New carb for twin cam six Can it be done?

[DieselBone]

I was wonding if anyone ever replaced the solex carb on their 2.8 twin six. I'm sick of that thing, and I'd like to replace it with a holley. I saw a 76 280C on ebay with that conversion, I asked him about it, but he said he bought the car like that. I'd like to change mine over. Does anyone know how, or know of someone that did it?? I'd like to be pointed in the right direction. From what I have heard, you use a holley 4 barrle?? I think the smallest they make is a 390CFM?? But it can't be a bolt on. Another thing is I don't care about the smog stuff, I don't need it. Thanks guys!

[Russ114]

i've been researching for a while.

theres a few 320/280 CFM carbies called "Economasters" made by holley (i think!) which are apparently a good carbie to bolt straight onto the manifold (with the use of an adapter plate)

i'm about to do it myself, do a google apparently theres a few good webbers that work too (something like a DCOE)

[Catrinus]

The Weber carb you want is a 2bbl. The model # is DGAS. Do a search on this site -- lots of stuff has been written about it. I swapped mine last year and have been quite happy with it. It's pretty much a bolt-on (the kit comes with a set of adapters which mate up not only the intake manifold but allows you to use the stock air filter as well). There is a different linkage that comes with the set. I think a new kit is $400-600 and well worth it as the original Solex 4A1 was a POS, even when brand new. Again, do a search on this forum and hold onto your hats because this is a pretty universally-despised carb. The Weber is amazingly simple, especially in comparison with the Solex. I can't figure out why MB would ever put such junk on their cars. I can see why they went to F.I. pretty quickly with this engine.

Catrinus
73 280C

[Catrinus]

Sorry, I forgot to tell you the FULL name of the carb:
Weber 38 DGAS

[DieselBone]

Catrinus,

Thanks, I tried searching and nothing really came up. I'll try a bit harder. Where did you get the 'kit'?? I'd be willing to try that for sure. Any difference in power?? Mine is 76 280C from cali, with all the good stuff on it I think if I get rid of that solex and work on the valve train a bit, I'll be in business! Thanks!

[Mark DiSilvestro]

Several years ago, I saw a Rochester Quadrajet bolted on, in place of the Solex, on a grey-market BMW six. Try a search for 'JAM Engineering'. They sell carb kits that replace the Solex.

Happy Motoring, Mark

[ctaylor738]

I bought a used JAM kit for my 73 280C. It uses a Holley 4360C four-barrel and works very well. It bolted right up to the existing manifold with a new gasket. The kit is pretty low tech - the most advanced piece is the adapter ring so the stock air cleaner can be used.

What exactly is your engine doing? As you know the 76's had the most complex emissions setup, but also the latest and greatest version of the Solex. Your carb may be fine, and other issues may be causing problems.

Mark is right - you can adapt just about any small four-barrel to work on this engine. If you have a few extra bucks, Holley also makes a throttle body injection setup that IMO would be the way to go.

[DieselBone]

Where should I start??? It is a 76, I haven't had a lot of problems with it running, just the idle was bad at times, and didn't want to start hot. I had a 73 280 motor laying around, so I swaped carbs, and took most of the emissions 'stuff' off. Mostly because the carb didn't have those hook-ups. Really the car ran much better after that, hot start wasn't a problem anymore. Idle was pretty good too, and a cold start still sucked. I'd really just to put something on there I know, I know holleys. Its not that the solex is that complex, its just I don't want to put up with it anymore. The overall engine I think is nearing a rebuilt, it has a lot of blow-by, more than my 300D and valve train is starting to make noise I don't like too. It could be just an adjustment. I have the option of buying a 250C parts car, and just do an engine swap, but from what I have heard, those carbs aren't easy either. The parts car does come with NOS fenders, and for the whole car he wants $300.00 which I think is a steal!

[DieselBone]

But right now with a good engine, I think either the holley 4, or the injection seems pretty good. I assume its TBI????

[ctaylor738]

Believe me, I sympathize.

Is your cold start problem a) getting it to fire initially, or b) keeping it running after it starts? Is it c) worse if the car sits for a while?

a. Bad accelerator pump and/or choke plate not closing completely
b. Cold idle speed adjustment, or choke gap adjustment incorrect
c. Warped top plate allowing fuel to evaporate.

If the valves are making a lot of noise, the chances are pretty good that you have a flat spot on at least one of the cams.

Before I condemned the engine for blow-by, I would see if the vacuum passage is clear. This runs down the left side of the cam case into the intake manifold. You need to remove the valve cover to check and maybe remove (with a giant screwdriver) and clean the small orfice in the passage.

The swap from the 250C is not as easy as you would think. You need the whole exhaust, and to move the battery to the other side. Fuel lines, heater connections, throttle and transmission linkage are different. The transmissions are different. The M130's are famous for carb troubles as well.

[grimgaunt]

as long as you can adapt the mounting flange pattern on the intake to a readily available carb you should have no problems.
Some I would recommend are - Weber 32/36 DGV style, Edelbrock 1406 (probably overcarburettion for a 2.8 six since it flows 600 cfm) and the best of all (if you have patience) a Rochester Q-jet from a early - mid 70's GM

Another option if you're handy with a soldering iron is the MegaSquirt EFI setup

[nachi11744]

Hello,
The simplest route would be the Weber 38 DGAS conversion that will have plenty of cfm for this engine. It was used on the Ford 3 litre V-6 Essex engine from the late sixties/early seventies, the only qualification being that the float bowl has to face forward, ie the direction of travel
The Solex(nee Pierburg)4A1 has a nasty reputation, but I think it has got more to do with the cheap quality material the huge castings are made from. The top cover warps due to heat and overtightening of the carb securing nuts and that creates air leaks and causing the choke flaps and secondary airvalve shaft to bind, screwing up virtually all running conditions. This is not just on MB engines, BMW used the 4A1 as well, I have two warped examples from a 1980 E12 525 displayed in my *horror house* hall of fame
Have a good week.

[Russ114]

Originally Posted by grimgaunt

Another option if you're handy with a soldering iron is the MegaSquirt EFI setup

any hints for this on a carbied car...?

i've been looking at a megasquirt lately for when the injection on the 450 dies.

[grimgaunt]

the route I would go (and have been planning for a while) would be to keep the original setup for injectors (ie- keep the intake and the injectors), remove the wiring and control computer.
The D-jet ones will be easier in this regard than the k-jet since the throttle plate is not there . Use the original (or a new) throttle position switch, bank fire the injectors using the MSquirt

[250 Coupe]

Not sure if our engines are even fire but this looks cool.
http://www.holley.com/HiOctn/ProdLine/Products/C950/C950TB/950-19S.html

Michael