fireenginered1500

I just acquired an 79 Sierra Classic out of the backyard of a neighbor of mine. He said the truck ran before he parked it 5 years ago and he said "all it needs is a battery" Got it cheap enough I don't care if it runs or not but I want to rebuild the engine and make it run pretty hot but be able to cruise down the interstate at 80mph without having to fill up at every gas station.


Anybody got any recommendations for how hot to make the motor and what transmission to put behind it?


I would like to be able to put a lockup TC on but from what ive read you cant do that with the TH350 or TH400. Also read that the 700R4 isn't strong enough to hold a lot of power. It has a 350 but not sure on the tranny. I just pulled it to the shop last week and haven't got a chance to tear into it.


Any advice would be much appreciated. Thanks

Slick68

iTrader: (7)

Do you want to keep the sbc, or would you be willing to upgrade to and LS swap?

If keeping the sbc, upgrading the heads to either the Vortec heads, or a set of aluminum heads, and a proper custom ground cam to suit the intended use and rpm levels the engine will see would be the first place to start. Since you're rebuilding, look into stroking to a 383.

A stock 700R4 won't hold over 400 lb/ft torque, but since you're rebuilding it or buying one, they can be built to handle quite a bit. Just don't buy an 82-87 trans. They have a smaller input shaft that is prone to breaking. Be sure it's a post-89 unit with the larger shaft.

If you're willing to LS swap, a stock 5.3/4L60E with some mild upgrades(cam,valvetrain,tune, shift kit, servo) can make approximately the same hp as the built sbc at about half the cost. The sbc may win out in the low-end torque department, but the LS platform still creates a flat torque curve that useable throughout the entire rpm range compared to a sbc dropping torque at about 3500-4500 rpm

Also, the LS will average between 16-20mpg compared to the carbureted sbc possibly getting 14-16 on a good day with a downhill tail wind. LOL

fireenginered1500

I want to keep the sbc, I don't want to hassle with a computer. Plus I like the look of a shiny carb and top hat under the hood.


Im not sure on the cost of a custom cam but are there any cams out there that are good for a mild build. Ive looked them up and they seem to be around $100-200 range. Im going with flat top pistons and vortec heads but don't know if ill bore and stroke to 383, but ill have to see what the internals look like when I tear apart.


Also, for the tranny if running the engine with a lope they say to run a higher stall TC. Ive seen anywhere from 2000 to 3500. Whats the best brand and stall speed?

Slick68

iTrader: (7)

A custom cam won't cost much more than an off the shelf grind, and since it's ground to work specifically for the intended use, it'll make better power/torque. The biggest mistakes people make with engine building is getting parts that don't match and work well together. For example, my LS1 with a mild cam designed to make power quickly, and a set of AFR 210cc heads made 521hp/470tq. The machine shop built a supercharged sbc engine right after mine with parts that the customer bought from Summit Racing. It only made around 400 hp, with the supercharger. He talked the customer into getting a custom ground cam, and it made another 100hp. Yes 100 hp from a cam, because the other cam didn't match the heads, supercharger, and carburetor.

As for the stall speed, it should be based on the cam/heads/rear gear ratio. Even if you consider an off the shelf cam, it'll tell you the recommended compression ratio, rear gear ratio, and stall converter. Again, it's a matter of matching things to work together.

I hear ya about the wiring and computer, that's why I carbureted my LS.