[steve25]

A more important question might be what heat range you need in whatever brand plug you use which is determined by how much HP you think the motor will make?
I have ported 2 sets of these Heads and the 288 Intake cfm that they are said to flow out of the box was not showing up on my bench with both sets of heads!

Let's say that things have changed and they do now flow 288 out of the box and let's assume your running enough valve lift to average 275 cfm out of that 288, so 275 cfm could make you 565 hp in a well thought out motor and in terms of a AC Delco brand plug I would start off with a plug of a 42 heat range with a extended tip for a base line.

[mgarblik]

Once you determine what you need for basic dimensions on the spark plug I may be able to help. If they are indeed 3/4" reach, 5/8" hex, gasket style plugs, I have a large selection in Autolite, Champion and NGK I can fix you up with. PM me or give me a call if that is the style they use.

[Hillard]

Originally Posted by mgarblik

Once you determine what you need for basic dimensions on the spark plug I may be able to help. If they are indeed 3/4" reach, 5/8" hex, gasket style plugs, I have a large selection in Autolite, Champion and NGK I can fix you up with. PM me or give me a call if that is the style they use.

Thanks Mike. Yeah I've never run these heads before so I was just looking to see what style others have used before and then play with the heat range from there, probably staying on the cooler side. Having just taken a quick look they appear to have a tapered seat to me, but I've been working on other things trying to get this ready for Norwalk. So I could be wrong about that, I'll have to take a closer look. One head is still off the engine so it really won't be hard to make sure I have the right length, etc.

[Hillard]

Originally Posted by steve25

A more important question might be what heat range you need in whatever brand plug you use which is determined by how much HP you think the motor will make?
I have ported 2 sets of these Heads and the 288 Intake cfm that they are said to flow out of the box was not showing up on my bench with both sets of heads!

Let's say that things have changed and they do now flow 288 out of the box and let's assume your running enough valve lift to average 275 cfm out of that 288, so 275 cfm could make you 565 hp in a well thought out motor and in terms of a AC Delco brand plug I would start off with a plug of a 42 heat range with a extended tip for a base line.

I understand all of that about the heat range, etc. What I'm looking for is a part number so I know what reach I should use. A quick glance looks like they are tapered seat but certainly a longer reach than say a R45TS. I can figure it out, I was just trying to take the lazy route.