engine and drivetrain 32/36 with 292 and 10:1

[ash00]

Hey gang,

Does anybody run a 32/36 with 10:1 pistons and a 292? Too much or to little carb?

[Benjamin A.R.]

I went from a 32/36 on stock internals to a 38/38 open plenum with stock internals and it made a big difference in performance. On that basis, I'd say a 32/36 isn't enough, but many folks will say a 32/36 is plenty. Does gas mileage matter? Weirdly, mine actually improved when I did the switch, but I think that's because my mixture screws were stripped out haha. That could also explain the huge difference in performance... hmm Either way I really like the 38. The linkage doesn't ever bind.

[ash00]

I have the dcoe 40s and just can't get them to run right no matter what. I forgot about the 38s!

[zinz]

I have the dcoe 40s and just can't get them to run right no matter what.

 

Most of your carb problems are ignition related....

 

Where's your timing set?

[ash00]

I just dialed it back to 0 deg, but I'm shooting for 10deg advanced.

[zinz]

By the way... my car has IE's 292 and had a 32/36 when I bought it.  I run Solex 40DDHs now and would NEVER go back to the 32/36.  I get better mileage with sidedrafts than I did with the 32/36... If I don't get 25mpg or better on the highway, I know something is amiss. I adjusted my advance curve a bit last week (using the 123Ignition distributer) and got 21.7mpg during 4 days of stop&go commute traffic.  (believe me...I'm not babying it either).

 

What seems to be the trouble with your setup? Give the details right up front, so as best to help out... Matched carbs? Jetting? Ignition setup, timing, etc...

 

Hope we can figure something out for you... Sidedrafts can be a challenge, but well worth the wait.

 

Ed

[Benjamin A.R.]

Oh and don't forget you could get a lynx manifold and use a single sidedraft if you want!

[zinz]

I just dialed it back to 0 deg, but I'm shooting for 10deg advanced

 

Are you talking about static timing?

 

Are you using a timing light? If so, how many degrees at what rpm?  Which distributer are you using?

 

Most importantly... what is it that isn't running "right"?  hesitation? no power? poor idle? lean-popping? running rich (black, sooty/wet plugs?

 

Depending on which dizzy you are running, the standard school of thought is to set timing "all-in" at about 3200-3400rom.... read this http://www.bmw2002faq.com/topic/141041-dcoe-advance-ignition/

[ash00]

Its all sorts of symptoms including weak spots in the rpm band, high idle...I think Im giving up to easy! It's been about 10 years since I messed around with these, but that link will help out. I think I have a tii distributor, but I'll go through this and sort out the timing First thing. Mine was set at 2k rpm, but I'll have to get the timing light out and start from there. Then I have to sort the linkage again as well.

Thanks for the link reference! I'm going to give it all a shot tonight

[zinz]

Don't give up!! ...and definitely don't switch over to a 32/36.  Well, I guess you could...please stay out of the left lane, though.  Or, maybe I could interest you in a nice minivan?

 

10 years...???  That could be part of the problem. The innards could have some varnished fuel mucking up the works. When do you think they were last rebuilt? I'd run a bottle of Techron thru it right off the bat (amazing stuff for cleaning fuel systems) Really, if they were mine, I'd rebuild them, just to know where I was starting.  ( basic carb rebuild is really not difficult)

 

Weak top end could be ignition timing (easiest to check), or you could be lean at high rpm (first check fuel level, then explore a different air correctors, or mains, or a combination)  Can you buy fuel with no ethanol?  I would highly recommend that.. you'll get better mileage and your fuel system will thank you for it, as well. (alcohol is not kind to the internals of our cars)  Alcohol-free fuel may possibly cure your lean spot...maaaaybe. (there is no good source for non-alcohol fuel in my area and I had to richen every circuit of my Solexes...pilot, main and air correctors.)

 

Like you say, check your timing with a proper light ( I doubt you can run as much advance as me because I only have flat tops) but at least go with the all-in at 3200-3400rpm.

 

Do you know how to synchronize these Webers?  Do you have a synch tool?  This is critical to proper sidedraft performance... If you don't know how to synch them, I would ask around and find someone with experience... If you want to try your hand at it, don't turn the synch screws too much when adjusting; they only need small inputs and make sure you denote your starting point, so you can always return to it, as a default.

 

Also check for vacuum leaks. While the engine is running, spray carb cleaner all around the carbs and intake manifolds...anywhere there is a gasket and especially the throttle shafts.  If the engine changes speed during this exercise, pinpoint where you are spraying and determine if you can tighten a screw, or nut, or new gasket, or something to cure the leak. 

 

Sooo...what's the trouble with your linkage?

 

Also... here's some good reading:

 

Weber tuning manual - http://www.lainefamily.com/images/WeberTuningManual.pdf

 

http://www.bmw2002faq.com/topic/57374-dcoe-tuning-help/

 

http://www.bmw2002faq.com/topic/157017-dcoe-tuning-on-new-engine/

 

http://www.bmw2002faq.com/topic/37307-40-and-45-dcoe-weber-jetting-info/

 

Lots of trouble shooting tips in this race set up problem http://www.bmw2002faq.com/topic/133588-need-dcoe-help-ofest-update/

 

Good luck!  Keep us posted!

 

Ed Z

Edited February 24, 2015 by zinz

[roadhog0]

Ran a 32/26 on my motor (300 cam, 9.5:1) when I had the 38 off it for some work and down low the thing ran about the same, but you opened it up and the thing was starting to starve. Mind you I also didnt have the secondary jetted right for that motor... But the 38 is MUCH more fun! I dont get good mileage with it though, still working on that.

[TobyB]

 

 

I just dialed it back to 0 deg, but I'm shooting for 10deg advanced. 

Well, THERE's your problem!

 

hee

 

t

 

who ran both a 38 and a 32, and liked the 38's throttle response, but discovered that lap times were more dependent upon JETTING than carb body choice!

[ash00]

Yup! I found my old weber book, got my current settings and am starting from scratch with Pierce manifolds on speed dial! Thanks for the references, and I'll chime in with updates!

[Rocan]

A 32/36 with a 292 and just stock pistons you will run out of flow by 5000rpm. Below that it will be a bit more progressive, but you really do want a 38/38 if you like to wind it out, otherwise the cam is going to waste. 

[ash00]

Hey guys, thanks for the help so far. I've ordered a rebuild kit and some baseline f9 emulsion tubes, 32mm chokes, and a dvd set.

Getting back into timing, at 3500rpm, what should be the advance?