Correct motor for a 74 z-28

Jimmer · 03-25-2012, 07:03:18 PM

Looking to buy a 74 corvette engine, should it be the same motor as the z-28? I was told it was, it needs a rebuild and is said to have the original heads, block and heads he is asking $250, is it worth it for a donor for a z-28 car? Thanks.

COPO · 03-25-2012, 07:22:56 PM

The 1973-1974 L-82 equipped Corvette was rated slightly higher at 250 horsepower and 285 lb-ft of torque. The Z28's L-82 was detuned by 5 horsepower and 5 lb-ft of torque, not because of a difference in output but more than likely due to internal politics at Chevrolet - it probably didn't want the lower priced L-82 Z28 documented as having the same output as the higher priced L-82 Corvette

Orange71 · 03-25-2012, 07:27:58 PM

The de-tuned condition was usually the more restrictive exhaust manifolds. Same as the earlier LT1 difference of 10 HP...Corvette's 370HP vs 360 HP of the Z28

Z28PILOT · 03-25-2012, 07:45:32 PM

Quote:

Originally Posted by Orange71

The de-tuned condition was usually the more restrictive exhaust manifolds. Same as the earlier LT1 difference of 10 HP...Corvette's 370HP vs 360 HP of the Z28

This is correct , the vettes near straight exhaust pipe configuration and ramshorn exhaust manifolds are said to have favored the vette by a few HP

Yes , thats a good choice , about as close as you can get . The Camaro had a special carb number , short snorkle aircleaner , its own alternator part number for a Z28, the Camaro had a alum dist , the vette has an Iron Dist with mech. tach drive. Vette had its own water pump.

I think the oil pan was a different part number , as the corvette dip stick was on the opposite side of the engine from the Z28 ...I believe

Sounds like a great buy.

Gary S · 03-25-2012, 07:48:49 PM

Quote:

Originally Posted by Orange71

The de-tuned condition was usually the more restrictive exhaust manifolds. Same as the earlier LT1 difference of 10 HP...Corvette's 370HP vs 360 HP of the Z28

Correct.
The Corvette L82 engine was the same as the Z28 engine in 1973-74. The Corvette LT1 engine was the same as the Z28 engine in 1970-72. The advertised HP numbers were due to the difference in exhaust systems between Corvette and Camaro.
Early Corvette engines had an option for "transistorized ignition" that Camaro didn't have, but from what I've seen, that didn't change HP numbers.

The Corvette engine will have a different engine code stamped on it, but it shares the same parts as the Z28 engine.

twozs · 03-25-2012, 07:51:59 PM

Quote:

Originally Posted by Jimmer

Looking to buy a 74 corvette engine, should it be the same motor as the z-28? I was told it was, it needs a rebuild and is said to have the original heads, block and heads he is asking $250, is it worth it for a donor for a z-28 car? Thanks.

well the corvette had 2 small block motors that year .everyone is assuming its automatically a L82??? the L48 ( although Chevy doesn't call it that in the corvette , its the "standard motor" ) which is not the Z28 motor and the optinal L82 . you need to find out which it is . look on the block stamp pad forward of the head on the passenger side . the Z28 motor is the same internally as the L82 ( its just not called the L82 in the camaro, but im done with that crusade !) . the L48 is the lower HP of the 2 corvette small block motors in 74 . still probably a nice foundation if in good shape and should have 4 bolt mains . i think the crank and rods are cast on it ( standard motor) as opposed to forged on the L82

Z28PILOT · 03-25-2012, 08:07:28 PM

Two Z's has a great point !!!! ...I was assuming you were talking about the L82 . And maybe you are assuming the same aboiut the seller

You better confirm its the 4 bolt main L82 engine with the seller. He may not know the diff between the L48 and L82

twozs · 03-25-2012, 08:50:09 PM

hell , it could even be a wheezing 270 HP 454 ci motor at this point . all we know is , it came in a 74 vette .

Jimmer · 03-25-2012, 08:51:34 PM

Thanks for all the excellent points and comments!

Jimmer · 03-25-2012, 09:03:54 PM

I just spoke with the owner, and he said that the number was on the back of the motor, and he looked it up and said that the only way to tell what motor it is , is to pull the oil pan. He said that he bought a crate motor and used the intake and carb on it. He said that the previous owner said that the motor was tired. How hard would it have been for him to pull the pan? He said he did the research to find out what motor it was, but doesnt want to pull the pan?! Sounds fishy, how can I find out what motor it is by a number? Thanks!

Gary S · 03-25-2012, 09:22:43 PM

If it is an original engine, you don't need to pull the pan or any other parts. All you need is the engine code stamped on the front of the block ahead of the passenger side cylinder head. Get that number and post it and someone can tell you exactly what that engine started life as.

twozs · 03-25-2012, 09:39:59 PM

anything south of the first cylinder is a date code and tell you nothing about what the application was for that block in 74 . the pad stamp is the key and if its gone treat it like any other " date coded " 350 , unless you can tear it down and find the forged internals . i do believe the L48 did have a 4 bolt main as all 4 bbl 350s had back then . the difference was the forged crank and rods and aluminum pistons in the L82 / Z28 motor . he is really not asking a ton of money for it sooo..

Jimmer · 03-26-2012, 08:41:48 PM

Found out it was only a L-48, 2 bolt main motor, probably not worth it to buy.

fdeluca532 · 04-28-2012, 10:29:25 PM

Quote:

Originally Posted by Jimmer

Looking to buy a 74 corvette engine, should it be the same motor as the z-28? I was told it was, it needs a rebuild and is said to have the original heads, block and heads he is asking $250, is it worth it for a donor for a z-28 car? Thanks.

I have a 1974 z28 block, oil pan,pistons and rods. the block is at machine shop getting cleaned and checked for cracks.I want 150.00 for all this stuff.plus shipping. quikzus@yahoo.com