432 Spark Plugs
 

I should be going to pick up a 1964 GMC 4000 here in the not too distant future and I was wondering what spark plug I should get for it. It originally had a 305 in it but that has been replaced with a 432 as I have been told. Also I have read that a 432 is a Magnum motor with out the designation. Is this true? How do I tell if it is or isn't a "Magnum"

Re: 432 Spark Plugs
 

Its listed on the Jolly data page as magnum and I think they are a rare breed too.

Re: 432 Spark Plugs
 

The 432 is a magnum engine that was introduced in 1973, basically a 401 with the 478's longer stroke. The spark plugs are a short reach tapered plug, If I'm not mistaken it's an AC R43T which is an old number so it needs to be crosslinked to a current number, this was a common lug used back then and shared with other GM engines

Re: 432 Spark Plugs
 

Awesome thank you. That's exactly what I was wondering. I read over on stove bolt about different plugs and was in the dark about the vintage of the 432 so I thought I would ask. Does this look right? http://m.autozone.com/external-engin...&showymme=true

Re: 432 Spark Plugs
 

I actually have the correct set of AC Plugs with the newer superceeded number at home, Out of town right now but I'll be home Thursday and will get you the number. Also forgot to mention how to determine a magnum engine. It's all in the Cylinder heads, intake and exhaust manifolds. The ports are much larger and the intake manifold will always have a trapezoid base pattern on the manifold but there were non Magnum intakes on 1960-65 401 and 478 engines that also had the trapezoid base but those manifolds were a high rise a nd the Magnum intake is flatter. It safe to say all 432 engines were Magnums.:ok:

Re: 432 Spark Plugs
 

The spark plug that supersedes the R43T plug is an AC Delco 10 plug. It is important you use this particular style plug because it has a tapered seat and very short reach that was only common with the larger 379,432 and 478 V6 engines built from 1973-74.:ok: