Thread: Choosing the correct spark plugs Chev 400 w/ Alum heads...

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I was just wondering what I need to know about choosing the correct spark plug for my SBC 400- 40 over w/ alum heads and about 10 on compression. I found out that the Accel shorty header plugs that I was using were too short when I took the heads off. By this I mean the "reach" was not long enough to actually reach the combustion chamber, but it still worked. I actually need a 3/4" reach plug. I don't know how to figure the hot or cold requirements that I need. Any help would be appreciated.

in an AC plug you'd be a r43ts or I think R-43-TSL for long if I remember correctly

Just use plenty of Anti-seaze....

who is the manuf. of the head. i have iron eagle after market
and they recommend r46ts maybe ur head manuf. has recommendation

The heads are actually a reprodustion of a Dart II head. There made by PBM-I think there a chineese knockoff but they flow well. They are 2.02/1.60,

I think that u can can run a colder plug in a aluminum head
too but if i am wrong some 1 correct me so i would run a
r44ts or a r45ts. the 45 are probably your best bet.

Thanks for the replies guys but those plugs your suggesting are all .460 reach plugs...I need a plug w/ .750 reach or it doesn't make it to the combustion chamber. I've been cross refrencing these w/ sparkplugs.com. Any other ideas....can I just get a plug with that reach? Talking to the local parts counter "fools" is frustrating if you don't have a part # I'm sure you have all dealt w/ them before. They only know what the computer tells them.

It would be a R 44tsxl

The XL is extra long reach....
I suggested a 43 because of 10:1 compression.... I would start there.... if they foul from being too cold ...step up to a 44...but I think 43 is where you want to be....