Who makes the shortest spark plugs. Presently I am using Accell header plugs. They do not have the selection of heat ranges that I would like.

I have a couple of really tight areas caused by using Pro Topline heads and Hedman LT headers.

 

Not sure if these are the shortest ones but I've had good clearance with Autolite race plugs with different sets of headers.

 

What is the recommended plug for these heads by Proline? I need specs on Thread reach, Thread dia ( probably 14mm ) and whether they have taper or gasket type seats. I have a Master NGK catalog that might have something of interest but need to know a baseline plug to cross reference. Accel CRef not in catalog.

 

Is THIS short enough?

PS: Don't think it will work..probably too cold...and freakin' expensive!! But it's dammned short. 14mm x .750" gasket seat with 5\8" hex.

 

That would be short enough...... threads look too long though. Seriously, need to match AC R-43T or R-42T for later small chevy. The current Accell header plugs are on hot side for heat range and are extended tip. Would like to have more options. The Topline staight plug heads are hard to get plugs short enough for. Boots get to close to pipe.

I'll check actual thread spec.

I tried the original plugs from 305 to verify tip in chamber and they fit fine till I tried installing them after headers were bolted on. Mad dash to parts store for header plugs. Had to take what they had. Hotter than I like and expensive.

 

Using Accell #574S shorty plugs.... 14mm taper seat, .460" reach 5/8 hex. They are a little warmer than I like. Also are projected tip, would rather have regular tip.

Other reference numbers are AC R43TS, R45TS.

 

Stop chasing plugs and get some fiberglass spark plug boot cover things. They aren't cheap, but they work. You can get them at napa for like $15-8 for a set of 2.

 

Need more than boot covers...cannot get AC or Autolite to even start threads...it is that tight.