more head combo questions

[mikerallye]

What is the compression on stock 73 340? What is a "J" head? Can I up compression by changing to another year or type head? thanks

[moper]

'73 when measured typically is in the 8.2:1 range. J head is stock open chamber 1.88 intake design. Same as all others. Best way to gain squeeze is closed chamber such as Magnums. I dont like using the smaller LA port closed chambers on 340s. You cna also lose .4 by runnign the MP thin head gaskets.

[Chryco Psycho]

not much you can do , the 340 /360 headsa are approx the same volume & the smaller 318 heads don`t help the flow , the 318 /302 casting would be the best to use

[Rob C]

Mike, to up the ratio, theres the above mentions. Though I think the "302" head is a bad move. One left out, and I'm not the biggest fan of, is milling the head. You can go .060 on the heads deck for a big bump up for pump gas.

I'd rather see a Magnum head swap or a milling of the head.