[brewcity]

Hi guys,

I upgraded my engine with new intake and 4 barrel carb. I also added a MSD/Procomp Ignition Kit (ignition system contains an MSD Street Fire Capacitive Discharge Ignition, MSD Street Fire Universal Wires, MSD Blaster Coil and Bracket and Procomp 8000 Pro Billet Series distributor).
I need to know hat type of spark plugs to now use. The engine had the original AC Delco plugs. Any suggestons on what to use?
Thanks so much for the help!

[.gearhead.]

What heads? What compression? What fuel?

[brewcity]

Originally Posted by .gearhead.

What heads? What compression? What fuel?

Sorry...stock heads on a 327, but will be replacing with either double humps or aluminum 2.02's very soon. Not sure on compression, unleaded fuel.
Thanks for the help!

[DOUG G]

I'd stay with the same plugs....why fix what ain't broke ?

[brewcity]

Originally Posted by DOUG G

I'd stay with the same plugs....why fix what ain't broke ?

Good point! I just didnt know if I needed a "beefier" spark plug with my new ignition and distributer, along with the new intake and carb (and heads later on).

[DOUG G]

MSD 6al and ran AC 45's for a long time... find any where,cheap,and worked.
I only changed due to new heads being angle plug and boots hit headers.

[Steiner]

Only thing to change is maybe your gap. You should be able to go out to at least 0.045", maybe more on a low compression 327 with that much ignition.

[Steptoe]

Damn near every engine is different..stay with the stock or drop down 1 or 2 heat ranfes give them a goo for 100 or so miles then pull them.....
Read the center electrode...it should be burnt like over heated steel...blued off about .5 to 1mm from the tip if in the right heat range.

[ace's68]

I ran the R45 plugs in my 327/210 with dual plane, 4bbl, headers and hei.
I think the plugs were actually R45S or R45SS I forgot the difference but it was one of those two.
My gaps were about .050" or so.

[Steptoe]

The plug gap is not what is critical...
In the HT circuit there are 2 gaps...
1/ in the dizzy going from the rotor to the cap pins
2/ The plug gap
It is the total of these to that is critical to the spark.
So if the rotor or cap pins are worn the plug gap gets closed up
Too much gap anf the HT curent will follow the route of least resistance...which can be anything from arcing in the cap, arching around boots on the cap, blowing holes in the HT leads, or just leaking, to arching around plugs and boots....and even cause partial cross fire between cylinders.
Leaking may not be obvious, if dont have access to occiloscopes etc, inspect on a dark night.

[Steiner]

Originally Posted by Steptoe

The plug gap is not what is critical...
In the HT circuit there are 2 gaps...
1/ in the dizzy going from the rotor to the cap pins
2/ The plug gap
It is the total of these to that is critical to the spark.
So if the rotor or cap pins are worn the plug gap gets closed up

Maybe it's just me but it seems odd to say plug gap is not critical and then in the same breath say plug gap and rotor/pin gap are critical.

Also, the original poster said he has replaced every piece of the old points ignition with a new CD ignition system, coil, and distributor so worn parts are most likely not an issue.

Good info otherwise.