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Hi all,

I got finally meself a '82 320/6, yay! It seems to run fine, but once the engine has warmed up it hesitates a somewhat when you start accelerating in lower rpms. Also I think the top end is a bit numb.

As I've never had one these before I'm not sure what's normal and what's not. What are the things I should check to ensure the mixture and ignition timing are in working order? Previous owner had a Weber 38/38 DGAS recently fitted and engine maintenance seems to be up date too.

I have an E21 320/6 with weber conversion but then the 38 DGMS (difference is that i have a manual choke).

The mixture setting is very simple. You have two screws with a spring in it at the base of the weber. Both on different side. They are equally twisted. I have set the CO at 1,5 and it drives very good.

Igintion is set at the standard value of the 320/6.
I have recently had the engine running at 6500 rpm and it goes very good. The M20B20 engine is never a very powerfull engine on low revs so the power begins to come from 2500 rpm.

Once the engine is warm, set the mixture screw at between one & a half and one & three quarter turns out, from the fully screwed in position. Careful not to turn the screw in too hard initially. (ooh, err mrs!) Once mixture is set, use the other screw to set the idle. You can set with a CO meter but I found that it's easier to do by this method on a worn engine. You can also check the colour of the plugs to confirm whether the mixture is correct or not. Ideally the electrode with be a light tan colour. It'll be dark or sooty if running too rich and almost white if running too lean. Hope this helps.

I had some time to tinker around (and drive!) the car today . I tested starting acceleration at different rpm's with both part and full throttle. The hesitation is more noticeable under 2k rpm and gradually lessens until after 3k rpms it's gone.

Things I checked, with pics:

1) Emissions - CO was 1.8 at idle which is okay I guess?
2) Plugs - Looks Ok.
3) Air hoses - Valve cover breather was disconnected from air filter box and box connector blocked - Does not affect my issue I think?
4) Carb - has a cracked hose - What does this do?

The cracked hose is your problem.
This hose operates a membrane that gives you a richer mixture by minor vacuumvalues.

This means that when you have minor vacuum you wil get more fuel to richer your mixure.

I replaced the hose and the hesitation is mostly gone!

I feel that it is still running a hair rich though. CO was measured to be 1.8 at idle, if the ideal value is 1.5 how much should I turn the screw (in the weber 38)? Maybe 1/4 turns anti-clockwise?