[carpoor]

My father is trading his 72' SS 454 Chevelle for a 66' GTO convertible this weekend. The car has what sounds like a 66' 325 HP 389 in it. (based on block and head stampings/castings)

Is there much difference, other than the casting number between the two? If it were mine, I would track down a correct long block. But, his goals are to just have a nice driving car. He isn't overly worried about matching numbers, etc.(He's been on a convertible kick for at least 7-8 years now, finally found the right deal recently)

The car supposedly runs good, but needs a lot of detailing under the hood. (a little crusty in the pictures I've seen) My goal is to remove the front dog house and pull the engine/transmission. While it is out, I want to replace the cam with an 068 or something similar, new timing chain, gaskets, valve springs, etc. Just to freshen it up and make sure it will serve the old man well. I plan on doing a firewall forward refresh too while I have it apart.

[Baron Von Zeppelin]

The spring rates are the only real difference between 092 and 093.
Pretty identical otherwise.
Except in retail value.

[carpoor]

Thank you, that is what I needed to know. I wasn't sure about combustion chamber sizes, the information I have found online lists the 092s as 70cc, and the 093s as 68cc. Does that sound correct?

[Jerry H.]

You are correct. The 092's will actually run better on today's gas. And all 389 blocks are the same; no difference in the big car block and the GTO block. Casting # is even the same. The only difference in the stamped code.

[GRX]

x2 on slight spring & chamber size differences.

[carpoor]

Thanks for the replies everyone. Now just need to decide on the Summit 2801 cam, or the Melling 068 replacement.

[jonathonar89]

I did a fairly stock 400 rebuild and this is the cam I'm running. It runs really well on the street and have been daily driving my setup. Just another consideration. http://www.lunatipower.com/Product.aspx?id=2354&gid=297