I am trying to eliminate a stumble from my 272 Y block, with a points setup. Model of Distributor is unknown. I have a 4 barrel edelbrock carb and the ECZ 9425-B intake. It seems to run rich in the low rpms causing a nasty stumble. I just set the points which were slightly off and truck does run better, but I would like to eliminate that from the equation. Anyone used something like this?
http://www.ebay.com/itm/FORD-Y-Block-272-292-312-BLUE-Small-HEI-Distributor-Coil-Spark-Plug-Wires-90s-/191520502735?hash=item2c9782f3cf&vxp=mtr
The price is right... and its got an adjustable vac advance which i don't seem to currently have. Or am i further ahead to spend a bit more and get something that's well known such as an msd or pertronix setup?

 

The seller has 100% positive feedback. I would be comfortable buying one and trying it.

 

Yeah I am just looking for something that's a known good to eliminate my issues. Or at least eliminate something to check. The more I research my issue, the stumble and my running hot seem to be related. Truck was getting some backfires out of the drivers side, this seemed to get better after we adjusted the points, but I still have a low RPM stumble and a bit of one in the higher ranges under load.

 

What does the timing do at off idle? How much advance with it all in and at what rpm? Is it steady or jumping around? How much advance does the vacuum advance give? What about vacuum gauge readings? Once again, steady, vibrating or drifting?

 

off idle stumble is typically #1...carb adjustment (fuel enrichment issue- ie not enough) and #2 ignition timing advance....

The point gap/dwell should be set to match the power band of the engine....gap is set initially with a feeler gauge then adjusted with a dwell meter to match the engine power band.....the narrower = higher RPM, wider= Lower rpm..

but 1st, get the carb working right then get the ignition advance working correctly, then fine tune the points.

 

I'm of a different opinion Beechkid. We were always taught in school to make sure everything in the ignition is right before attacking the carb. You can't adjust a carb right if the ignition has problems. I do agree on the most common causes of off idle stumble though.
But you can't just guess at timing. Base timing only tells you so much. You need a tape on the balancer or better yet a dial back light. And a hand held vacuum pump. There are specs for stock engines in the old motor's manuals. Of course with todays fuel formulations those are only guidelines. But you still need to know at what rpm the centrifugal comes in, at what vacuum reading the vac. advance starts in and what at all in, plus the amount of total each provides.
And the best, and quickest place to start is with a manifold vacuum gauge. That alone will tell you a lot if you know what to look for. Basically this: low is a tired engine or retarded timing, a dipping or sweeping is generally a low float level or something similar and a vibrating needle is valve problems. Plus you might have a vacuum leak causing or masking many problems. You can't adjust the carb if there is a vacuum leak.

 

Agreed, look at them like as a kind of scan gauge for early iron they are an essential part of the kit, like a grease gun and voltmeter or a test light, etc.

 

I agree....just was assuming that the ignition system was in good condition, etc.