Navarro heads and spark plugs

[hombres ruin]

Originally Posted by tubman

Gary's problem was with plug reach, the very thing you are asking about, so I felt a "heads up" was in order. I sure hope that they have cleaned up their act; "GOSFAST" seemed to be quite disappointed. Have you tried a 1/2" reach plugs? Champion "L" series or equivalent. If they're not long enough the next step up is 3/4" reach; Champion "N" series or equivalent.

Thanks Tubman.. i will give the L series a try.. also I contacted mike from H&H about the plugs for the Navarro heads and he said Autolite 216… so I don’t know what’s the deal

[flatford8]

Not that I know Jack Schitt about aluminum heads.....but, can the top of the spark plug hole be surfaced deeper to make the “ almost but not quite long enough reach” plug work? Or that you should have to go to that expense after buying the heads in the first place.
For what it’s worth.....the last three sets of Autolite 216’s I’ve purchased, an electrode has pulled right out of one in each set........Mark

[tubman]

Originally Posted by flatford8

Not that I know Jack Schitt about aluminum heads.....but, can the top of the spark plug hole be surfaced deeper to make the “ almost but not quite long enough reach” plug work? Or that you should have to go to that expense after buying the heads in the first place.
For what it’s worth.....the last three sets of Autolite 216’s I’ve purchased, an electrode has pulled right out of one in each set........Mark

This is NOT a good idea, as aluminum needs longer threads than cast iron. The guys who designed these heads (way back when) knew what they were doing. I can see doing this when the heads (like Offenhausers that need a non-existent 5/8" reach plug) have problems. Edelbrock and Edmunds take a 1/2" reach plug, which seems to be sufficient.

If one of the principles at H & H is advising the the O/P to use Autolite 216's (which are obviously WRONG from his own pictures), then I guess he's going to have to resort to trial and error test fitting. Both myself and "51 MERC-CT" have posted good examples of what the relationship between the bottom of the plug and the inside of the head should be; strive for it.

I guess I now know why I asked "Who is Mike Hermann?".