My 2 Liter carb'd car is extremely hard to start. Once started it runs very well except a bit rich. Attempts to start will crank the engine over and just before starting the starter seems to quit - sounds as if the engine tries to turn backward stopping the started motor rotation.

Could this be a defective starter switch. Timing seems correct and it is set for 29 degrees BTDC. Running Pertronix ignition. I've trouble shot the unit as their tech service recommends and all checked out

ALL parts are new, starter, battery, ignition switch, Engine rebuilt. Hell the whole build is new.

Engine and car are a delight to drive but this start issue is a major problem. Not reliable to take anywhere.

Appreciate the brain trust input to solve this problem. Thanks all

sounds like a timing issue.

bet it will start better if you go back to the original spec on timing... around 29 degree's

If my guess is correct... I'll bet you have over 34 degrees in it now.

Yeah, that reversal is a Hallmark of over advanced timing. Just turn her back a notch.

starter will be working hard in that case,try retarding the dizzy while you are cranking (using remote starter switch ) and see if you get a faster cranking speed.
Good luck.

Could it accidentally have been timed to the wrong mark on the fan
Was the fan ever changed out as different years can have different marks
I’d check it again. Pull a valve cover. Verify tdc and verify the timing mark.

Maybe borrow another timing gun from a friend

I had an adjustable timing light. The Rheostat was not accurate
Two other timing guns showed me it was wrong and I had used it to mis-time the race car

New adjustable ones are digital and less likely to mis-calibrate

With all the input received I am now thinking that my timing light may be at fault. It is a vintage Craftsman brand in what I thought was good shape. I'll buy another digital timing light and redo the 3000RPM and 29 degrees BTDC. We did start with a TDC location. I'm back in Florida as of yesterday so won't get to this until first of May. In the meantime looking to buy the new timing light.

I'll continue with this approach and hope all goes well. As for the fan marks I can say this car, being a barn find from a used Porsche parts reseller, I cannot verify it is original to the car. If I still have issues we'll get that sorted out next. I'm practiced enough now to get the engine, complete with carbs and tranny out of the car in 50 minutes.

Thanks ALL for the valuable input

good luck on it though...

my now dead old timing light was a craftsman too
it served well for my father and for me.... until it didn't

Could be a spark timing issue, but we just went through a similar problem with a carbureted Alfa spider. Alfa idled good, ran good and pulled good. The Weber 40DCOE is equipped with the "starter circuit" which is a carburetor within a carburetor. Problem turned out being 3 out of 4 accelerator pump jets were clogged. An overnight soak in Berrymans did the job.

Prior she would take a shot of Ether to get her going when temps were below 50 degrees, not a few pumps and vroom and any temperature.

Persistence pays off. Car now runs as it should. Determined that the ignition switch was bad. No voltage at coil Positive in the start position. New replacement switch installed and it started right off.

Timing was spot on and it drives even better than before.

Thanks all for the help