GCD1962

It's probably not a Covette engine, but I'm trying to figure out the engine (it was replaced at one time) in my '68 Chev Impala wagon. ID is
KO124DP.

richbopp

IMHO that number dosen't look like a block casting number. Are you looking at the pad on the driver's side rear below the distributor close to the bell housing?

GCD1962

I was looking at the stamped numbers on the front pass side pad

JohnZ

It's a '68 307/200hp, made at the McKinnon Industries plant in Canada on January 24, 1968.

GCD1962

Thanks John - What was the 307 based on? A larger 283?, or a smaller 327? What made it a 307. This one seems to have plenty of power for a heavy wagon, so I'm assumming it had been modified.

JohnZ

The 307 was based on a 283 bore (3.875") with a 327 crank (3.25"); they made millions of 'em.

ghostrider20

John what was the point and reason behind the 307? Why not just use the 327? In keeping with GM, and simplicity, what did this combo offer that the 327 could not? Or was it just a marketing thing to offer something new?

Did GM just want to empty out the junk drawer before going to the 350?

The 302 IIRC was designed to be under the 305ci reg for CanAm?

Mark

ghoastrider1

these engines arent worth "upgradeing" either are they?

JohnZ

Emissions regulations were now in force, and the smaller bore of the 307 was better for emissions (lower surface-to-volume ratio) than the 4" bore of the 327.

The 302 (327 bore, 283 crank) was created strictly for compliance with the 305 c.i. SCCA regulations for the Trans-Am racing series.

SilverC1

The 307 is basically the opposite/reverse of the 302, in both construction and "temperament":

302 has the bore of the 327 but with the shorter stroke (crank) of the 283 - basically a bored-out 283 with high-revving capability, and intended to be just under the 5.0 liter (which works out to 305 c.i., as stated above) limit for the Trans Am series (as used in the original Z-28). Ford of course created their own Boss 302 engine for the Mustang, for the same reason, with AMC (Javelin) and the Mopar folks also following suit.

307 has the smaller bore of the 283 but with the stroke of the 327 - intended for low-revving but reasonably torquey passenger car applications.

I have heard it argued that the 307's were built to use up 283 blocks, but whether this is true or not I have no idea. They made a heckuva lot of these, after all, over a long period of time. But unless that was the motivation why not just make everything as a 327? (I hadn't seen the post above mine before submitting - the emissions argument makes sense.)