I am going to be installing a Petronix system in my 1972 Cutlass w/350. What spark plug should I be running? What size ignition wire?

 

Stock stuff works just fine.

 

Yep, no need to change the plugs and wires from factory since all you are doing is replacing a mechanical switch with an electronic switch.

 

Which Pertronix system are you installing? As long as it's a points replacement the gap stays the same, if you're installing an HEI large cap open it up to .045.

 

The better of the 2 pertronix 1181LS

 

Sorry, I didn't realize there was a complete electronic distributor available.

If the distributor is being replaced with a large cap unit as Eric noted above, then you will need new plug wires as the points style 7mm wires have different cap terminals than the 8mm (or larger) HEI wires. I used Accel wires for 30+ years (some don't like yellow wires), and recently switched to Taylor Spiro-Pro wires that are black. Any quality wire should work, though. As I said, the Accel wires worked fine for 30 years - I changed them because when I tried to remove the boots from the cap, they were hardened and all cracked.

You will also need to connect to a full 12 Volt source as the points use a resistor wire to reduce the voltage.

You can use the same spark plugs, and you can open the gap as Eric said, or leave the gap as-is. The narrower gap won't hurt anything, but it won't take full advantage of the higher spark energy from the new distributor.

 

Don't exceed 045; it just wears parts out more quickly.

 

We still don't know which Petronix system the OP is installing. People seem to forget that the GM coil-in-cap HEI was NOT intended to be a performance ignition system. The high voltage and wide plug gaps were intended to satisfy the then-new EPA requirement that cars comply with emissions standards for 50,000 miles without any maintenance or tune up. HEI and the wide gap were intended to fire crappy, crusty, ancient plugs with the lean mixtures required by the rudimentary emissions control systems. If the Petronix system is just an electronic points replacement with a standard voltage coil, you DON'T want a wider gap, you want the OEM gap. If the coil has a higher than stock voltage and you've upgraded the rest of the system (plug wires, for example) to accommodate it, then you can widen the gap, but it's not like there will be some magic 20HP increase as a result.

 

Agreed. I've said many times over the years that I saw absolutely zero difference in performance or drivability when swapping from a well tuned points distributor to a well tuned HEI distributor. The only difference has been no need for routine points adjustment/replacement.

 

I'm using my stock OEM points distributor and adding the petronix. I was going to put in a HEI distributor from a 1975 olds motor, but elected to stay with my original. I had already purchased spark plugs for the HEI and I'm wondering if I can use those plugs.

 

What plugs did you buy? Knowing that will help us to detemine if they are compatible with your points conversion.

 

I hope you don't get left on the side of the road like I did a couple times. I would trust a good (and I mean good) set of points and condenser any day. I used to really believe in Pertronix when I had my 54 until I came home on a flatbed twice. No more that most of us drive our cars a set of points is going to last for several years.

 

ONLY buy the 1181LS! Do not buy the 2 piece 1181.

 

With the system pn you edited in yesterday, I'd use the stock plugs at the stock gap.

 

Try the Breakerless ignition design. Only uses one wire, easier install and is the design of choice for many that choose to ditch points.