Another timing curve question

yellow rose said

I'm with Rusty in that you may need to leave the ignition alone for a bit and start working on the carb.

I'm 255 at .050 on 340 inches and my junk will idle at 750.

I think you need to spend some time cleaning up the idle circuit.

Did you mention what carb you have?

Click to expand...

I don't know of anyone running the Mini-Express that would idle anywhere near that low in a 440 or 451. Mine had a few degrees taken out during the regrind (original was 278, now 272). 107 centerline, in at 105.

Working on the carb too, although only one thing at a time ;) It's an old #4780 (800 DP). Eventually I'll get tired of screwing with it and get something more modern and adjustable!

Already have 3/32" holes in all four blades, the only way I could get enough air in and keep the transfer slots square on both the primary and secondary. If I could run more than 22 initial timing I could probably reduce or eliminate some of the holes - but I still need to keep the t-slots close to square.

Incidentally I know from watching the wideband gauge that the PV is opening way too late (I'd originally followed the common and stupidly wrong advice of half the idle vac). I just picked up an 8.5 and 9.5 at O'Reilly so will be putting one of those in for my next test run.

It's been said that 90% of carburetor problems are in the ignition. Or was that the other way around ;)