Spark Plug Protrusion into Head?

[AnthonyG]

Thx for all the work on this tubman! Much appreciated!

[flatjack9]

On a set of Offy heads I used spacers with the N5C plug measuring a total of .210 consisting of spacers and a second spark plug gasket.
as noted by Tubman, plug depths will vary from cylinder to cylinder. Quality control is not the best.

[tubman]

Ya' know, after thinking this over, the "N" series Champions (or equivalent) may just be the correct plugs for these. Add and extra plug washer, and everything should fall into place, eliminating the need for spacers, etc. Don't really know if it's the optimum solution, but that's the first thing I'll try when I use these heads. I do know I want all of the threads engaged that I can with aluminum heads.

[flatjack9]

An extra plug washer won't be near enough. Read above.

[GOSFAST]

Originally Posted by flatjack9

An extra plug washer won't be near enough. Read above.

"Nailed" that one Jack, probably need a "hundred" or so! Don't have the time to figure the exact number out??

Thanks, Gary in N.Y.

P.S. I would think after 120+ replies and over 3200 views some sort of decision would have been made at this point??

[flatjack9]

I've made my decision to use spacers and one extra plug washer totaling .210. Makes for a good fit.

[AnthonyG]

I had a friend make copper spacers for the 3/4” reach plugs. .19” thick plus the existing compression gasket works on mine. Used Autolite A3924 Spark Plugs dimensions for ref. Which r recommended for the Edelbrock heads. Reinstalling head & think all will work ok. Fingers crossed

[Bored&Stroked]

You will have no issues . . . should be a good solution

[AnthonyG]

Thought I’d show what the spark plug w .19” spacer plus supplied compression washer looked like installed in head. I like it. Thx all for good discussion & all the knowledge!

[Bored&Stroked]

Threads look great - just make sure that 'extended tip' doesn't hit the valve. I don't tend to run extended tip plugs (due to very high valve lifts) - just something for you to check!

On the other hand, if you're going to rev the heck out of it and don't have a tach - then run extended reach plugs. When you FLOAT the valves, they'll hit the plugs and close the gaps, which acts like a 'mechanical rev limiter' . . . ask me how I know these things! LOL

[AnthonyG]

Lol, got Bored&Stroked, should have added the plug is not the ones I’ll be using, just a 14mm 3/4 reach I had measured for depth of thread. I’ll be using the recommended Autolite 3924 used in the Edelbrock 8BA heads

[Bored&Stroked]

All good my friend . . . I think you are on a solid tract . . .