Big Block 502 into my 4th gen

[paxton350]

Gm performance parts has an all forged 502 big block available for about 6k shipped, with 450 hp 550ftlbs torque out the box... http://www.bmrfabrication.com has tubular k members that support a big block into a 4th gen. As far as i know my t56 should bolt right up to it... All hvac and heat is pulled making room for this... only thing obviosuly i cant reuse my edelbrock TES small block headers right? also since this is a carbeurated motor my dash cluster is NOT going to work... any ideas? The only issue i might see happening is i have mac 2" lowering springs in front, this sump should clear the ground right?

thanks

-chris

[Injuneer]

Most of the dash doesn't interface to the PCM - fuel level, oil pressure, coolant temp and system voltage. All those can be made to function with any engine. Tach will probably work from the coil of a conventional igntion. That leaves the speedometer. You can keep the stock PCM in place and the speedo will continue to work, or you can get an interface box from Dakota Digital that allows the VSS to drive the speedo directly.

Are you sure the T56 will bolt up? McLeod make a "universal" bellhousing kit that allows the T56 to bolt to virtually any engine, but you have to start with an LS1 version of the T56, and the conventional "pusher" type clutch, not the "pullback" design used in the LT1's.

[94Z/28]

Another thing to keep in mind is that you will have to cut the windshield wiper cowling for the carb to fit, you will have to cut a lot if you use a tall single plane intake manifold. I have a carbed small block in my 4th gen, ill try and dig up some pictures of how I cut the cowling. I dont know exactly how much more trouble it is to get a carbed big block in a 4th gen over a small block, but if your only getting 450 HP with that 502 why not get a nice small block. You can easily get a 450 horse small block, and think of all the weight you will be saveing.

[Dave Vince]

BB street

I do not think it is a good idea to run a BB in a street 4th gen. I am a BB fan all the way in my race cars. There are tons of parts out there to make lots of horsepower for a reasonable price with them. I just think going thru all that trouble and driving it on the street is not worth it. Especially for only 450 hp. Thats weenie for such a big motor. You will lose all the driveability and your mileage will go from 20mpg to 10. Your distributor will be way under the cowl and it will be a nightmare to adjust. The carb will be way above hood level also. A build up with some good heads, valves, intake, TB, cam, roller rockers, pistons, and upgraded ignition should get you 450 out of your LT1 for about the same price.
Now if you are going race car, by all means go BB. If you have the ability to build it yourself you could easily build a 700 hp BB for under 10K. 6K is not out of the question with some good used parts.

[paxton350]

Thanks guys for all your input guys. But one more thing, as far as the headers go, would a set of say chevelle BB headers be adeqate or would i have to have them custom made?

thanks -chris

[Joe 1320]

I think you'll need to go through the front suspension. That big block is considerably heavier, what' s in there now is not going to be happy. Hal QA-1 shocks/coil overs with higher rate springs would do the trick. You might even consider adjustable upper and lower front control arms with upgraded bushings. Subframe connects will be a must.