Kazbob69

Need some help on this one, found this I'n a barn working for AT&T. Bought it because it was number matching big Block 4 speed car. The heads and intake were missing but everything else is there. It's been sitting since 78 last tagged and was purchased from an estate sale. What is wierd is the name plate says 390hp, 10.25.1, 500ft lbs. Sure you could say someone changed it but this car still has the am fm radio and the interior looks to be unrestored and clean. I pulled the engine and it's 4 bolt main, pink rods, steel crank and has factory gm pop up pistons. Block casting is for 73 454. Have tons of pics, would like some help on this one. This is the 14th vette I've owned and probaly would not of purchased it except for the fact it was big block car as I've liked the chrome bumpers better. Thanks Bob

Mike Ward

Very nice, but what's the question?

GREGG-73

Stay in tune...

GD70

I'm guessing the data plate was changed, and maybe the engine was rebuilt to 1970 454 specs?
Glenn

bobbarry

X2

The fact the engine is partially disassembled indicates the owner in the '70's would probably have changed things out.

Mike Ward

What's the above got to do with an LS6?

bashcraft

And when did they start putting pink rods in big blocks?

Kazbob69

Sorry, did chevy install any 454 390.hp engines I'n 73 corvettes? I found an articles I'n an old car craft mag that said they did but only a few. Thanks

Kazbob69

Sorry, just wanted some input. Thought i would try the forum for help. The pink rods were from an engine builder I'n the 70s. I will give you his number so you ca correct him!

bashcraft

Pink rods came in small blocks.

Mike Ward

No. None. Zero.

The 454/390 gross HP was in 1970 and called an LS5.

The LS6 was a one year only engine installed in '71s and was rated at 425 gross and 325 net HP.

The 1973 version was an LS4 and rated at 275 net HP.

Kazbob69

Hot Rod magazine in its March 1986 issue selected the 1973-74 Corvette LS6 454 as one of the "10 most collectable muscle cars" in the company of the 1968-70 Chevelle, 1970 'Cuda, 1970 Challenger, 1966-67 Fairlane, 1968-70 AMX, 1970 Camaro Z28, 1968-70 GTO, 1968-69 Charger, and 1967-68 Mustang. The big-block Corvettes were the only muscle cars produced after 1970 worthy of the list.[26] Copied this off the web! This is the reason i am asking the question about the engine.

Mike Ward

Misprint. They meant LS4.

Not too good at predicting the future of collectible cars either. The '73-'74 big blocks are the least valuable/least collectible big block Corvettes ever made, and probably always will be.

Maybe they meant '71 LS6.

Kazbob69

Have a Cousin I'n Canada that used to drive down and tow Vettes up the back roads to his house I'n the 70's. The last one he pulled up was a blue 69 mako shark, He must of picked up 15 just I'n okla alone. Name is Eddie owns a mushroom farm. Big guy! Had his own body shop to restore them. Yes i know Canada is a big place but he loves Vettes. Thought you might know him! Thanks Bob

gbvette62

Don't believe everything you read on the internet, or from Hot Rod Magazine, either.

There was no LS6 after 71.

GM Corporate built policy prohibited building anything that would not run on No-Lead regular gas, after 1970. This would make it impossible for there to have been 10.25:1 engine in 73. It wasn't until more recently that they where able to run higher compression ratios, because of computers and higher grade fuels.

The 71 LS6 was rated at 425 hp/475 torque, and only 9.00:1 compression. The only 73 big block was the aforementioned LS4, that was rated at 275 hp/395 torque and had the lowest compression ratio of all 73 Corvette engines at 8.25:1.

You say you've owned several Corvettes, so I assume you know how to identify an engine the engine stamp pad. 73 454's will have one of the following engine suffix codes; "CWM" = LS4 4 speed, "CWR" = LS4 auto, "CWS" = LS4 auto (Calif. emissions) and "CWT" = LS4 4 speed (calif.). If the car started life as a 73 LS4 big block, the 5th digit of the VIN will be a "Z" ("J" is a base 350, and "T" is an L-82 350). The original block casting number was 3999289.

Kazbob69

Checked numbers on block came up 73 4 bolt main, just the gm pistons being pop ups and the plate showing the 10.25.1 got me wondering. I checked the production run and know they didn't make any with anything close to what's I'n it. But thought I'd ask just I'n case. Thanks for the info!

Mike Ward

Don't think I've had the pleasure of meeting him, and yes Canada is a big place.

Kazbob69

Thanks for the help! Looks like my 72 gets a big block!

yankee phil

I bought a 73 454 vette back in 78 with exactly the same ID plate on the consul ,390 horsepower,500 ft lbs torque. Bought the car off some spoiled housewife that was divorcing and liquidating at the time so I don't think she would have switched plates. I walked a built 69 440 GTX top end (60 on) so I don't think it could have been the 275 horse power motor in it,and it was a numbers matching engine that had definitely not been worked on . I too was surprised years later to find the 454 was only suppose to have 275 hp. It was redlined (on the tach) I believe at around 56 or 58 hundred RPM with a distributor driven tachometer and it pulled to the redline no problem. Actually with the factory side pipes on it pulled like a bat outta hell in first gear and when I cut them off to clean up the side the car definitely slowed down with out the extra breathing,I don't think the smog headed engine would slow up so dramatically as this engine did,but I could be wrong on that. Good luck finding out,I'm curious as hell if anyone has an answer for you.

bashcraft

That plate means nothing. Either it or the whole console had been swapped.