spark plugs

[preaction]

1947 WDX with 230ci engine in its original state, I removed the spark plugs and installed were champion UJ-12 plugs. I cant seem to find a spec for other than gap at .025. The owners manual does not list a replacement plug.

[Dutch]

Maybe some other more experienced guys will chime in here with what they are using. I have a shop manual for B1 trucks that says all models used A5B autolite plugs gap ranged .028-.032. Going to autolite's web site they say the old A5B number is replaced by the 303 model. If someone has better info I would love to know too.

[Tom Petroff]

Here's what I have recorded if it helps;

Spark Plugs [14mm, 3/8" reach, 13/16" hex]
Autolite# 295 (MV Trucks) GAP=.025
AC# R45 (Civilian Trucks) GAP=.025 (6v), GAP=.035 (12v)
BOSCH# WR9EC (Super Plug) GAP=.035
NGK# BR6S (traditional plug)GAP=.035
Symptom - Engine miss at higher rpms (replace).
Torque Spark Plug = 30 foot pounds

OPERATING SPECIFICATIONS
Ignition Timing - 2 Degrees BTDC
Firing Order - 153624
Distributor Rotation is clockwise. To retard timing, turn distributor clockwise, counter clockwise to advance timing.

TGP

[Dutch]

Tom-
I haven't done all the cross references you did but I did do the NGK, The autolite 303 crosses to the br6s but the autolite 295 you list crosses to a b4
Also interesting, you have timing at 2 degrees btdc, the book i have says 2 degrees atdc. Do you find it runs better with earlier timing?

[Tom Petroff]

Yes It runs much better.

I'm not sure if that wasn't a misprint or the fact the gasoline is better.
But any engine running at TDC or after is going to be Lazy.
TGP

[preaction]

Thanks Tom

I have the original owners manual for the 47 and it states the gap but not a plug type. Also is there been anyone who has put a petronix in one of these engines.?

[bilfman]

I put in a pertronics it works great fires up instantly. Well worth it in my opinion. Ran that for over a year and just recently installed an hei converted distributor from langdons stovebolts, wow what a difference. That dizzy really woke up the engine.

[wayneh]

I put the pertronix in mine this year. It works as advertised. I used their 12 volt coil and took out the resisor that we have in series with the point systems.

Wayne

[CSCameron]

I did the swap too. Went to 12v, put the Pertronix ignition in as well as their 40k volt coil. Works great!

They warn you to not leave the key on without the engine running. If you do, it supposedly will burn up the ignition unit. Not a problem for me so far...

Clark