Navarro 8ba Heads

[tubman]

Originally Posted by KiWinUS

Here we have original unmodified heads with correct and recommended H10 spark plug. Sharp script , Sharp block letter NOS Ford 81 head and an older Edelbrock 8ba. Also for those that remember from years past spacers were sold to prevent plugs fouling which pulled the plug up into the spark plug holes shrouding the plug and they worked.

I thought the intent of installing aftermarket heads on these engines was to increase performance? Addressing plug fouling this way has no place here. Your first two pictures are of the biggest mistake one can make with aftermarket heads, and that it to try to use the "recommended H10 spark plug" (your words) in them. Just about all of them are made to use longer reach plugs because aluminum is not as strong as cast ion and requires the extra threads. Edmunds takes 1/2 reach plugs, Edelbrocks take 3/4" reach plugs, and so on. Why would the manufacturers make heads with 3/4" of thread just to put in a plug with 3/16"? The goal here is combustion efficiency and maximum flame front travel. You'll get neither of those with the plug waaaay up in the head.