Jim, The following is some info from GM on the 67 L30 and L79 engines. I'd be much is a carryover from 66. It's more than just compression and timing.
The 325 (L79) came with an aluminum intake and Holley (R-3601A for A.I.R. or R-3607-1A without), 275 (L30) intake was cast iron and Quadrajet. L79 came with the 12-bolt rear 3.31 std. ratio, L30 was a 10-bolt 3.08 std. ratio L79 was advertised with 11.0:1 compression, L30 is 10.0:1. L79 cam is .2981 lift, L30 is .2600 intake/.2733 exhaust L79 cam duration is .306/.306, L30 is .280/.288 (intake/exhaust - excluding ramps) L79 pistons were on-center pin bore offset, L30 was .055-.065. L79 pistons were Aluminum impact extruded, L30 were cast aluminum Dale McIntosh TC Gold #92/ACES #1709 67SS/67 Elky > -----Original Message----- > From: [EMAIL PROTECTED] > [mailto:[EMAIL PROTECTED] On Behalf Of J. Brady > Sent: Wednesday, February 26, 2003 9:01 PM > To: [EMAIL PROTECTED] > Subject: [Chevelle-List] compression confusion please help if you can > > > Gang, > > My '67 327 had to be bored .030" over, and now I will > be needing to get new pistons for the block. After > checking my trusty Chilton manual, it shows that the > only differences between the 325HP 327 and the 275HP > 327 (mine) for that year were the compression and the > timing. If, when selecting new pistons, I buy the > ones that would go with the 325HP 327, will I > instantly be gaining the HP? I know there's some > controversy regarding running higher compression with > today's pump gas, but I had hardened exhaust seats > installed in my heads to help get around that. Is > there anything else I would need to do? For all > intents and purposes, the 325HP motor supposedly runs > 11:1 compression, where mine runs 10.25:1. > > Thanks in advance, > > Jim > '66 Malibu > ----------------------------------------------------- To Unsubscribe please visit www.chevelles.net/list.html To start a new topic, send mail to: [EMAIL PROTECTED]
