LancePearson

actually, for the engineering of it that's not all that bad mpg. My 76 whose carb has an incorrect gasket in it (that way when I bought it recently) is going in at 7 a.m. to have the carb rebuilt gets right now about 14-15 highway mpg and less than that around town. With five weeks ownership, hard to say but I'm getting it squared away with new plugs, wires for the plugs and carb done right to start with then we'll see. Reading the threads, the BB with auto and 3.08 or 06 rear ends should have power enough to overcome the more highway friendly rear end. My Mfour speed is a 3:36 rear end stock I believe, has no A.I.R. pump, l48 small block. I doubt I'll do what others have done, bore it out to 383 or 396, cams, heads, headers and skip the cat. converter. but if I did I know you can get well over 400 hp and then some from them. I'm not going to drag though so I will probably just put a high flow cat converter on and keep it clean. It won't blow you away with acceleration with it's 1976 dumbed down compression, etc. but it still moves the car along and with the 255's on all four corners it goes around corners as I've said elsewhere like an Octopus with 16 arms at nice speeds. I'm pretty satisfied but love this forum as there is so much broad knowledge to learn to begin to make effective choices. I noticed that the first gear is good to get it going, second is a reasonably long gear with my transmission and rear end and third gear has an enormous range of speed to it. Love third gear.

Thanks again for the responses...you're educating a newbie

LancePearson

I said my M four speed 1976 L48 had a 3:36 rear end...that was the auto...mine is supposed to be 3:55 according to two sites. My error.

Lance

Split User

When I bought my 72twenty five years ago, the previous owner had changed the top end of the motor. He put rectangular port heads with the LS-6 intake. That was nice, but they also put the LS-7 cam in it. It sounds beautiful and rattles the car a bit, but the cam is far too much for the 8.5:1 compression. They also put the L-88 carburetor on it.

I also got all the original parts with the car. My question to those of you who know, what changes should I make to the engine now that I am going to rebuild it.

I think I want it stock looking again. So, I am thinking about 9.5:1 compression. Not sure what cam to run. I am just trying to get the horse power up a bit as long as I am going to go through it.

Any Ideas?

TimAT

Just swap the pistons for some that will bump your compression to 10.5:1 Still a touch low for the cam, but it will wake it up- and it'll look just like it does now. And run on pump gas.

gcusmano74

Not necessary to spend a jillion dollars. Have the distributor recurved, and the carburetor rebuilt by Cliff Ruggles or Lars Grimsrud (spelling uncertain). Add a K&N air filter and a tuneup and you will be pleased.

skytop

I love my '70 454 B.B. vert with manual trans. In the summer, with the A/C on and the 500 foot pounds of torque instantly available, the Vette is my magic carpet ride!

jr9170

Iceaxe

Talk about pulling a thread from the grave....

Frank Pope

1972 Corvettes with LS5 454 engines do not have 4 bolt mains! They ar still strong motors, but many individuals have not recognized this in their postings. With that said, as I am the original owner of a 1972 BB 454 and have played with the motor from day 1. The smog pump was the first thing to go, and I changed the pistons raise the compression. The Open chamber oval port heads work fine with some pocket porting and the addition of 2:19 intake, 1:88 exhaust valves. As for the cam, I have a comp cams hydraulic roller with matching springs and roller tip rockers. This is topped off with an Edelbrock Torker 2 intake and a 770 CFM Quick Fuel mechanical secondaries carburetor. On a chassis Dyno there is 351 rwhp. This equates to 439 hp at the flywheel. I hope this has been helpful.

Mr D.

If you want 1970 rated 454 HP in a 1972 car just rebuild the engine to 1970 Specs. No need to re-engineer this, GM did it for you.

MelWff

and once again the thread is pulled from the grave