1972 C3 Coupe Ls3 Project



Hello and good day to everyone. I am new to this thread and recently acquired a 1972 Corvette stingray coupe. I bought the car with an LS3 from a 2015 Camaro SS, manual shift, Engine -that’s bolted in to the front K-member. It appears to have the correct oil pan on it. I’ll start by saying that I have never completed an LS swap before and all of this is new to me.

Furthermore, the Muncie 4-speed transmission is sitting on my garage floor. I’ve done some limited research and am lucky to have found this resourceful forum of vette enthusiasts. I am greatly appreciative to all the work you have described herein. I am in need of some help, guidance and advice.

Here’s my plan and where I’m at:

My plan

The engine is complete with the factory Camaro harness attached. I’m doing this on a budget, and do not plan to change the transmission to a Tremec TKX or alternate. The plan is to keep the Muncie four-speed and get the vehicle running and driving. After, I would like to consider replacing/modifying the air conditioning condenser/evaporator. Change/upgrade the mechanical brakes by adding a hydraulic/vacuum brake booster. Research options for the steering, Detroit speed or other type of steering drive boxes.

Questions

Regarding the Muncie what bell housing is best for this application? I have researched the OEM housing number 621 will bolt to the LS3? Will the factory Camaro starter bolt in? Alternately if not, which starter?

What clutch, flywheel and pressure plate set up will work for this 425HP LS3? Should I modify the mechanical clutch assembly to an internal hydraulic assembly? If so, what kit should I use and or how should I construct this?

Regarding the accessory drive system on the front of the motor, what have you guys researched and used outside of just buying a kit from Holly or other manufactures? Can I use any of the Camaro accessories and or modify them? Cobble together another GM style system/brackets?

Should I consider modifying the Camaro harness and wiring it into the cars stock existing wiring (tach, gauges etc)? I’ve been told that this can be quite time-consuming and frustrating. Others, have advised me to remove all of that and simply put in a fuel tech FT550.

The car appears to have a new fuel tank (divulged by seller), should I put an external electric fuel pump or an internal pump? What brand/style?

The car has mechanical brakes. What is the budget method to put a hydraulic/vacuum booster- master cylinder set up on this vehicle?

I understand that the steering with these cars aren’t that desirable and steer poorly. What steering gearbox and or set up, on a budget, would be the best choice for this build?

The previous owner of the car told me that he put big block springs in the front, cutting off one ring, henceforth lowering the car. I’d like any input on the suspension modifications that are recommended for my application.

Thank you all VERY MUCH, in advance, for any comments and/or input for my little project. I greatly appreciate it. Thank you, Craig Z.

 

Regarding change to power brakes, not sure budget method but Zip (and others) have kits for about $600. They also have nice write up on the conversion. Many of these cars came with manual and that is what I have on my "72. Bought the conversion kit about 9 years ago and have never installed it as my wife has never wanted to drive the car (it was half the cost then). Yea it takes a lot more force but I have come to like the better control I think it gives me.

 

Holley PN 12-311 is a drop in fuel pump and sender that should work with your tank. Always better to use an in-tank pump since the fuel itself cools it and greatly reduces noise.

I also recommend Holleys mid mount kit because it fits under the hood and between the control arms but doesn’t require water pump modifications. It is quite expensive though. People have been able to piece them together only buying the parts from Holley that you need to. The rest of the parts are generic GM pieces that can be had for much cheaper.



I’d recommend getting the steering box professionally rebuilt by Gary Ramadei @GTR1999 . I’ve heard nothing but good things about his work. As for the rest of the suspension there’s tons of upgrades that can be made, but for the ride height I would see where it ends up after the engine install. An all aluminum LS is significantly lighter than a big block, so you might want to look into a set of semi coilovers to adjust the ride height.