Yellow79

its a long one, but good reading (i think) for the big block lovers out there. ive got an older friend who helps me with most of my technical motor problems. known to be the best engine builder in town and most of the surrounding areas too. well lately hes been pushing me to convery my '79 sb to a BB setup, and even though its tempting i hate the thought of losing a lot of my handling performance. the motor is a built up 454, and is a little too wild for pump gas at the moment. bored .030 over, with a cam that kicks in at 4 grand, and 14.5:1 compression. came out of his chevelle, and its the strongest running motor ive actually ever gotten the pleasure to experience. recently, I find out its a coded LS-7 chevelle block, the same type of motor that was supposed to go into the '70 vette and a handful of chevelle SS 454's, but was axed at the very last minute for the vette line. wouldve been the most powerful production motor to go into a corvette in history, but since they axed the idea, it left the '70 chevelle ss454 in a position where it outran the best corvette had to offer in 1970. so that thought of finally creating what chevrolet never did go through with intrigues me, and just may be enough to make me take the leap. that and LS-7 badges would look real neat on the side of the hood :lol: hes asking 3000 for the long block, it needs a rebuild and some lower compression pistons installed. i trust this man fully, ive known him for a few years now and he knows his way around all motors, but is really known for his ability to make BB chevys run on the street. as far as i can figure it would cost me a total of around 5000 for a completely rebuilt motor with new, lower compression pistons and a slightly less aggressive cam to match. hes estimating about 650 horse at the crank and torque to match, i have no doubts that the rebuilt motor would do that, even with the lower compression. after doing some math, it runs just about dead even with what im going to have invested in a current project motor when all is said and done. with all that layed out on the table i have only a few problems bothering me.
1. ive already started this aforementioned 400 small block buildup. its sitting in my garage and stares me in the face screaming "Build me!" every time i go to start the car up.

2. i would really, really like to preserve my handling. even if it cost a couple grand in aftermarket parts, i wouldnt mind if that is what it takes to get it to handle like it does now- iron headed small block on the factory 20+ year old suspension.

3. the various mental pictures of parts of my car flying embedding themselves into the ground... say, tranny gears, u-joints, rear end pieces, halfshafts.......

if anyone has some insight it would be very, very helpful. i am lost in the world of SB to BB swaps so any help is good, im just outright confused right now. help me!

AKRAY4PLAY

i may be wrong here, but the LS-7 was an aluminum block crate motor?? the LS-6 was a bad a** iron block offered in the Chevelle rated at 475 hp. an all aluminum big block weighs 20 lbs less than an all iron small block. your 400 build should be 50 lbs lighter than what you have now. going iron big block will require different motor mounts, radiator shroud, acc pullies and brackets, exhaust, possibly radiator, front spring rate, hood and few other things i am sure i forgot. drivetrain life is questionable, better chance of living with an automatic. good size project. brian

Yellow79

heh, unfortunately it isnt the aluminum block one, however the LS-6 was put into the corvette, it was a 454 rated at about 425 horse i think. the LS-7 is the block you are talking about, rated at 465 horse, that was offered in the '70 chevelles. it was supposed to go into the corvettes option book as well but it was cancelled for some reason. it IS a good sized project i know, and Brian you have been following my small block buildup and giving me some very solid information as well, thanks again for the help. could anyone with a converted c3 speak up here? small block to big block, how much did your handling suffer?

VETDRMS

I think you may get a much larger response if you post this in the C3 general discussion section. Lots of people have done the BB swap.

:cheers:

The Green Rocket

Go for it, once you go big block you'll never go back.

Small point: the "LS7" was NEVER factory installed in ANY car - strictly an over the parts counter 12.5:1 c/r version on the LS6, and I think it had the L88 camshaft. G.M. referenced it at 465 hp, vs 450 for the LS6.

Thomas

Yellow79

hm thank you for correcting me. i must have my data mixed up, or the corvette book is wrong. ill tell you once i find it :lol:
either way im assuming this would be a good stout block?

zwede

Use aluminum heads, intake w-pump, radiator. It will weigh just about the same as an iron SB or even slightly less. I have the above on my 454 and it feels perfectly balanced.