I am about to put two Dellorto DHLA 40H carbs (like Weber DCOE) in my '87 E30 M10B16 BMW (Pierburg 1B2 is not cooperative :-).
I now have vacuum advance connection from the distributor to the carb. Where to connect that hose now? There is no constant vacuum anywhere? Will I have to drill 4 holes in inlet manifold connect them, and take vacuum from there? Will that have any negative effect ?
The vacuum advance is a fuel economy thing, and it's not usual to use it with twin two choke side draft carbs which are hardly fitted for economy. ;-)
Nedavno Dave Plowman (News) pise:
| The vacuum advance is a fuel economy thing, and it's not usual to use | it with twin two choke side draft carbs which are hardly fitted for | economy. ;-)
So, no modifications necessary? Engine will work fine with no vacuum advance?
I was thinking maybe distributor with only mechanical advance (the one I have has both mechanical and vacuum).
Yes - it should do.
It's possible a different advance curve would produce more power with different carbs. A tuning firm should be able to advise.
I used to plug the vacuum advance into one of the manifold runners (not all four, in my case). Seemed to work fine. Mileage with Solex 44PHHs was only 1 mpg under that with twin SUs. If you're worried about pressure stability, put a (small!) vacuum reservoir between the runner and the distributor somewhere to smooth out the pulses.
Your distributor already has a mechanical advance. While it might (or might not) work better with a different curve (different springs and/or weights), there is no need to replace it outright.
JRE
Nedavno JRE pise:
First I bought at eBay two Delorto DHLA 40H carbs, and then I found inlet manifold with two Solex (do not knew which, will see when it gets here) carbs and a distributor, so I bought that too :-) I will have to see if there are any openings in manifold.
I knew that my distributor has a mechanical advance, but it also has a vacuum advance, and I think that I saw somewhere on the Internet that there are distributors with only mechanical advance (for M10 engine).
I guess I will see when I mount it how it works, and report here.
BTW how to connect cold start system? My Pierburg has combined electric and water operated choke. I guess on Solex/Delorto/Weber sidedraft carbs it is manually operated?
On all but the coldest day you'll get away with just pumping the throttle pedal a couple of times.
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