M10 Carb Conversion and Fuel System Questions

[stanhayward]

Hey all, some of you may have seen my thread about how shitty my M10 is running in my 85 318i. Basically all the fuel injection stuff is fucked. This leads me to think about converting to a single 32/36 weber carb. It'll be cheaper than fixing the fuel injection system, the cold start injector and idle controller would be over $750 to repair. I realize they can be deleted, but I'd prefer a complete fix. That also leaves me the possibility of selling/installing this engine down the road into a 2002.

This leads me to my fuel system questions. Did the early 318s also get the dual pump systems that the early 6 cylinder cars do? If that was the case, could I just delete the second pump and run the low-pressure feeder pump for the carbs? If I'm whistling Dixie just let me know or if you have other suggestions I'd be happy to hear them.

[stanhayward]

http://m.ebay.ca/itm/330938627035?cmd=VIDESC&gxo=true

This is the kit I'm talking about for a 2002. If there are any incompatablities please let me know.

[SkiFree]

-The jetting that comes in that kit is not correct for your engine (or just about any M10), so plan on buying a number of jets.

-You'll need to source a fitting for the brake booster from an early single-barrel M10 manifold.

-Air filter is the tall style and may not clear your hood.

-32/36 is a progressive carb with different sized ports, so jetting/tuning can be a bit challenging for a first timer.

-Current fuel pump (or proposed alternative) wouldn't be useable for a carb'ed application.

and a number of other things, but that's a quick off-the-cusp reply.

[stanhayward]

-The jetting that comes in that kit is not correct for your engine (or just about any M10), so plan on buying a number of jets.

-You'll need to source a fitting for the brake booster from an early single-barrel M10 manifold.

-Air filter is the tall style and may not clear your hood.

-32/36 is a progressive carb with different sized ports, so jetting/tuning can be a bit challenging for a first timer.

-Current fuel pump (or proposed alternative) wouldn't be useable for a carb'ed application.

and a number of other things, but that's a quick off-the-cusp reply.

So long story short, not the best idea ever?

[SkiFree]

No, totally do-able. And being I like carbs, think its a great idea. It's just the ebay item you linked to I wouldn't consider a complete "kit".

[LJ851]

Is that a water heated manifold like stock? You will need to fab custom throttle pieces to actuate the carb and maybe coolant hoses for the manifold as well.

[TobyB]

So long story short, not the best idea ever?

Not really, no. You'll lose performance and drivability and cold-start-ability.
It'll smell like gas. It may not idle as well(!!!) And by the time you're done,
it'll cost about what fixing your EFI will.

But it'll work, be easily- tunable, and probably less likely to die on you entirely.

End of the day, it kinda comes down to personal preference. If you like carbs, do it.

t

[SkiFree]

Is that a water heated manifold like stock?

Yes, it's patterned to fit the water jacket from the early single-barrel manifold.

[CorvallisBMW]

What exactly is wrong with your FI setup? You could buy a whole new m10 harness with ECU for about $50, have the injectors cleaned for $20, buy a used but functioning fuel pump for $20... Not that there's anything wrong with going carb'd, but I'm guessing you'll spend far more time and money to convert the fuel system than to fix it.

[stanhayward]

What exactly is wrong with your FI setup? You could buy a whole new m10 harness with ECU for about $50, have the injectors cleaned for $20, buy a used but functioning fuel pump for $20... Not that there's anything wrong with going carb'd, but I'm guessing you'll spend far more time and money to convert the fuel system than to fix it.

Unfortunately it's not that easy, the PO narrowed it down to the whole idle control system and cold start injector. I don't remember the whole backstory, but basically they were not original and that's where the problem was coming from. I've already done a complete tune up of the ignition system, filters and oil and it still idles at 250rpm if I'm lucky. After trying to start, the exhaust smells very rich. Given that the ignition system is okay, are there any other theories as to what it could be?

[stanhayward]

No, totally do-able. And being I like carbs, think its a great idea. It's just the ebay item you linked to I wouldn't consider a complete "kit".

Andrew, do you guys have all the parts to make a complete kit? I overlooked how much M10 carb stuff Ireland does.

[CorvallisBMW]

You can replace the ICV, have the injectors cleaned, replace the plugs, cap, rotor, distributor and fuel filter, replace the cold start injector, replace the ECU, check for vacuum leaks, etc. There's a lot of stuff that can be just checked just to verify it's operating properly before trying to convert the entire fuel system.

[SkiFree]

Andrew, do you guys have all the parts to make a complete kit? I overlooked how much M10 carb stuff Ireland does.

If you get a complete 2002 single barrel manifold to poach the water jacket and booster fitting from, I've got the other needed parts (just did one the day before yesterday).

[stanhayward]

If you get a complete 2002 single barrel manifold to poach the water jacket and booster fitting from, I've got the other needed parts (just did one the day before yesterday).

I'll keep my eye out and I should be in touch soon.