J head ??

[n8ling]

I've found these heads # 4027596. My question is are they J heads, did not find any markings, and is there any advantage to them opposed to my stock #3769974 76 360 heads
Also if the are more usefull would machineing them up my compression............just looking for a little more power

 

[GoodysGotaCuda]

J's will have a "J" stamped between the spark plug holes and also a stamped J on the underside of the head.

 

[388dart]

the only advantage is they will have the hardened exhaust seats for unleaded gas - otherwise exactly the same.

 

[340mopar]

The "974" heads are unleaded compatable.

 

[D-mailman]

'J' heads are '915' castings. Last three numbers are 915. Terry.

 

[340mopar]

There is also a "587" 'J' head, 1973 340

 

[C130 Chief]

Bear in mind all production heads with hardened seats were hardened by induction. The hardening only went a few thou deep, allowing for perhaps one resurface at best. If the heads have been rebuilt before, you should figure the cost of insert seats regardless of castings.

 

[n8ling]

Thanks fella's I think i'll just stick with what I got

 

[D-mailman]

C130Chief, yes only a few thou deep. Hardened seats are the way to go. Only '587' heads I have seen were 'U' castings. Never seen a 587 'J'...anyway...they are a good place to start. Same castings really. Terry.