[blubomber]

One more note on the motor

The YH code 428 360 hp engine is a small valve design. They produce decent power and lots of torque but are not really muscle car motors despite their displacement. They are 2 bolt mains. These cars usually came with a 3:08 rear end.

The YK code 428 is a true muscle motor with drilled in valve stems, large valves, higher compression; 10.75:1, long branch exhaust manifolds, larger exhaust pipes, competition cam, high capacity oil pump, stronger distributor advance springs. Listed at 390 hp they were probably more like 430 hp. This is a differnt engine than then YH motor espite their identical displacments.

These YK motors were not available to the A body or Firebird cars due to the GM restriction on 400 motors or smaller for all A F body cars except the Corvette. This was lifted for 1970 to combat the large engines used in Ford and Dodge/Plymouth cars. In 1970 you could get the 455 in mid-size GM cars. This situation has restricted the limited the disireability of the 428 for muscle cars. 455's are more desireable in general. You can get year correct 455's for $650-$850.

[blubomber]

One more note. In '69 the YH code 428 became the standard engine in the Bonneville replacing the 400 which was the base motor in '67 and '68. The YK code 428 was optional.

Other 400 cid were also optional but it is fairly uncommon although I have seen 1 or 2 400 cid 2bbl cars. These were special ordered most likely because the owner wanted to save some money on fuel since they used regular v. premium gas.

[smaman]

Thanks for all of the helpful information guys. Doug, what website did you get the #5 thru #1 values from? I go to nada.com but it's always nice to see other opinions.