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There is no douth that you can build a 340 to run low 12 but at what street cost with 91 octane. My friend would like to take his Duster for a round trip of about 300 miles without always looking at the heat gauge worring about detonation. We are using cast iron J heads with 65cc chambers.For those of you saying you can do what we are looking for --What convertor, what cam, what CR you running.

I was told by Hughes that I need to be around 9.2-1 or lower should have no more than 160 cranking presure.

I feel it can be done much easier and safer and have better street manners with more cubic inches.

What CR can you run with cast iron heads and not be on the borderline for detonation?

Thanks

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i run 12.22 with 3.91 gear 28" slick, mix race gas and 93, 360, stock crank and rods, home ported J's milled to 60cc, 11.25cr, 205 cranking psi, single plane ,750 Holley, small solid 244/256 at .050, 4,400 dynamic stall , i do back off the timing to 30 total and run only 93 on the street seems to run almost as strong as track prep, runs nice on the street this way for the last 10K miles. I feel your leaving a lot on the table with this build if your not going to up the CR 160 cranking psi is pretty lame