Distributor Wear?

[sheldo914]

The dwell angle on my 74 2.0L varies by just over 2 degrees from idle to 3,000 rpm and and the contact gap is just under .012 inch at 48 degree dwell. My manual notes these conditions indicate a mechanical fault in the distributor. I figure it's best to pull the contacts and upgrade to electronic ignition. Are there any other parts I should check or replace with the dizzy out?

[Dave at Pelican Parts]

Uh, Brian--you mean the FI trigger points? The ignition ("contact breaker") points can be replaced with the distributor in the car. I never did, 'cause I always replaced the condensor at the same time, and that is a *real* pain to do without pulling out the dizzy...

Check the points for wear, and check the points plate for wear and wobbles and so forth. Then check the distributor shaft for play. Too much play and you might wind up needing to get the dizzy rebushed. I don't know where you can get bushings for it though.

The electronic points-replacement gizmos should be less sensitive to shaft wobble than the points. So you may be able to get away with not rebushing the dizzy for a while if you go pointless. Don't know how long.

Hope this helps!

--DD

[sheldo914]

Thanks all. I'm guessing the "mechanical fault" referred to is cam wear and/or bushing play as suggested. I'm guesing cam wear will be a non-problem with electronic ignition and it sounds as if bushing slop may be non-trivial. I'm still a little suspect on the vacuum retard and centifigul advance system and was considering pulling the dizzy for a cleaning and inspection. Now I think I'll just instal the electronic ignition without pulling the dist and see how she runs.
Thanks for the input. This BB is great. I have several more questions to throw out after I address the dozen other threads that apply to my car. Next thread to follow is the '74 2.0L that passes CA smog at idle but is filthy rich at 2,500 rpm (my problem as well). Looks like the advice is pretty consistent with standard 914 EFI trouble shooting. I'm thinking that EFI analyzer rental might be the ticket after refreshing the vacuum system and dialing in the ignition.

Speaking of tickets, I recently complete traffic school on the web in under 2 hours at www.trafficschooltogo.com. I've got a few tips to "speed" through it if anyone is interested.