Quote:
Originally Posted by benzboy
hey all. I cant seem to get my car running properly.
a little about the car
1973 911 E 2.4 mfi.
I did a top end rebuild. heads redone with all new valves seats seals ect. throttles tested and in great condition mfi pump bench tested and set properly. the only upgrade I done was going from a stock 84mm piston to a 85 mm je piston.
ok the problem
I got the car to idle very nice. but when I give it gas, I get backfiring and sometimes flames through the stacks. I never had a car with points before. I replaced the points and think I got it to the correct gap. .012inches or .30 mm. I read hundred of threads about checking dwell. some say its not important some say check it . I ordered a dwell meter. should be here I a few days. whats the best way to hook it up? I do need the car running to check dwell right?
im going through the CMA. so far air filter and plugs are good. next step is dwell and ignition timing.
a few notes. I did notice my plugs are very black and sutty. which means im running rich. would that also have anything to do with possibly the points and dwell not being set??
also with at idle I timed the car at 5 degrees atdc. when I set the idle with vacuum hose off at 2000rpms, im at about 22btdc. that seems hight to me. I didn't check it at 6000 rpms, just because of the popping and sometimes flmaes shooting through the stacks.
sorry for such a long post. im sure this has been covered before. but this is driving me crazy. been working on this for a month or so.
thanks
tony
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dwell is just a more accurate way to set the point gap, set the gap on the wide side of spec which will have the dwell on the low side.
It sounds to me as if there is a timing issue, but w/ mfi it could be mfi timing, ignition timing or cam timing you need to be sure that all are correct