any one know what plugs I should use when converting to HEI distributor?

 

The same ones you were using before the conversion. You can open the gap up a bit more but don't go wild. I typically set mine to .045" gap.

 

I agree. Your choice of brand and heat range should be based on other things beside the HEI. The HEI will successfully fire a larger gap. Oldsmobile typically specified .040" prior to HEI. After HEI they went a bit wild by specifying .080". This proved to be overdoing it. Later they were shown at .060". Your gap should depend on your engine's configuration. Higher compression pressures require smaller gaps to fire consistently. Larger gaps aid combustion, but when they won't fire there is no combustion. If your plugs are doing well before HEI you can just widen their gaps some after HEI. If you want to widen them a lot there are plugs manufactured with longer side electrodes intended for HEI. For example AC R45S was used before HEI and R45SX was used with HEI. There may be some trial and error involved to determine what works best with your particular engine.

 

Agreed. When going from points to HEI you can easily, and cheaply try to use your existing plugs by opening the gap.

If you aren't happy, you can move up or down a heat range or two depending on how the plugs looks after some miles.

I agree that .045 seems to be the median where a lot of us run our HEI plugs.

Some people swear by the rapid fire style plugs, even claim they provide a smoother idle with HEI. I don't know that I buy into them, but AC Delco is having a current rebate on plugs, so if you wanted to try, it's cheaper now.

 

I have run 0.080" plug gap for the last 30000 miles, and I'm on the second set of plugs. I use the Bosch WR9FPZ (called 4223 by Rock Auto and others) with no issues whatsoever.

 

I had the rapid fire plugs, they foul easier if anything. They don't make them for the Olds V8 anymore, mine burnt in the Olds 4x4. I also have a set of Bosch Platinum's, pretty sure they are also discontinued. I see this is the same ones as Seff mentioned above, a few are available still. I might stick them in the Olds 260.

 

I would make it a requirement, not an option that the gaps widen. the voltage has to overcome the dielectric strength of the gap, which is insulated by non-conducting mix. hei reaches that point a bit earlier assuming the base timing is the same due to the voltage rise characteristic. AND, hei can cause side arcing.

I dunno if an ignition profiler tool is available anymore, but they graphically showed the spark characteristic. old tools for old guys.