Pertronix on 72

[xs-cash]

Can I put a pertronixs electronic ignition on my 72 -350 with the stock alternator and voltage regulator ? Or will the original alternator and external voltage regulator not supply enuff power ?

[Old_Gold]

You should have plenty of power, but will need to remove the resistance wire and bump the supply voltage up to the full 12 volts.

Jim

[Already Gone]

Originally Posted by Old_Gold

You should have plenty of power, but will need to remove the resistance wire and bump the supply voltage up to the full 12 volts.

Jim

I put a Petronix complete distributor and 50k coil on my stock 72 C10 with 350 and auto trans, 4 years in no issues except tach doesn't read right but pretty sure that's a tach issue. Which resistance wire you talking about?

[xs-cash]

Thanx for the replies

[elkniks]

Originally Posted by Already Gone

I put a Petronix complete distributor and 50k coil on my stock 72 C10 with 350 and auto trans, 4 years in no issues except tach doesn't read right but pretty sure that's a tach issue. Which resistance wire you talking about?

The wire from the firewall bulkhead to the factory coil was a resistor wire on my 72. I think it is meant to drop the voltage to prevent burning up the points. It took me a couple of years, a couple of carburetors, and a whole lot of head scratching to figure that one out (pre-internet days).

[davischevy]

Originally Posted by elkniks

The wire from the firewall bulkhead to the factory coil was a resistor wire on my 72. I think it is meant to drop the voltage to prevent burning up the points. It took me a couple of years, a couple of carburetors, and a whole lot of head scratching to figure that one out (pre-internet days).

What were the symptoms running with the resistor wire still in place?

[Old_Gold]

I had another truck that I did an HEI upgrade on without knowing about that wire, and kept killing modules. Also, with lower voltage, you're not getting all the spark power available with the new set up

Jim

[Oldironside]

After I bought my truck I learned that the previous owner installed an HEI still using the resistance wire. The resistance wire was blank metal because the insulation burnt away the whole length of the wire. The wiring harness was toast. If using the original resistance wire when using HEI, there is a good chance for fire in the engine bay.

[elkniks]

Sorry for the late response. It would backfire up though the carb when you hit the gas hard off idle.

[davischevy]

Originally Posted by elkniks

Sorry for the late response. It would backfire up though the carb when you hit the gas hard off idle.

That is what mine did. I thought for the longest time is was vapor locking, because it was worse when I ran the AC. Turns out the AC was pulling the voltage down below the minimum.

[Hotcorner]

I put a pertronix on a 74 F-350 and had to wire directly from the ignition switch to bypass resistor wire. Worked like a charm.

[davischevy]

Originally Posted by Hotcorner

I put a pertronix on a 74 F-350 and had to wire directly from the ignition switch to bypass resistor wire. Worked like a charm.

What he said.

[elkniks]

Yep, that was a tough lesson for me... This was back in the late 90's and I had no idea about the resistor wire. Changed carburetors about three times, pulled timing cover to check cam timing, all kinds of stuff. Then one day I overheard the guy at the local speedshop telling a customer about the resistor wire. I replaced mine from the bulkhead plug to the coil and it fixed it. I think it was a red wire that actually said resistor on it.

[davischevy]

I knew about the resistor wire, and I checked when I installed the Pertronix. The wire had in excess of 11 volts so I thought I was good. I completely over looked the fact that the AC could pull the voltage down.

[xs-cash]

Put the pertronics in , no issues , put to 12 volts too, thanx for the replies guys !

[Bob B.]

It will work fine, but you might want to consider an electronic voltage regulator if your truck has a separate voltage regulator, not inside the alternator. They hold the voltage more constant than the mechanical relay type, and that's always better for electronics. Auto Zone sells a good one:

https://www.autozone.com/batteries-s...715/130005_0_0

[Subdude59]

Posted via Mobile Device

[RustyBucket]

I put a small cap, mechanical tach. drive H.E.I. in my buddie's '64 Corvette several years ago. Looks stock, seems to work good, & wasn't much money on ebay. Non tach. drive ones are cheaper yet.