The Stovebolt Site Forums The Shop Area The HiPo Shop '52 GMC engine transplant...again

Well, here we go again.
About 3 years ago, before having heart surgery, I installed a 350 Chevy engine to replace the blown-up 235 in my '52. My first choice was a 292, but I couldn't find any at the time, and had a 350 sitting in my garage, in running condition. I made sure to make my swap reversible, in case I ever wanted to go back to a stovebolt engine.

Well, it ran pretty good, once I finally got the carb and timing tuned. The install wasn't real pretty, because I was hurrying, since I knew I might not be able to do stuff like this for awhile after surgery. The power in secondaries actually felt pretty good. But in order to have enough room, I had to shim the steering box outward and turn some shorty headers upside down; so the exhaust is kind of exotic-looking, sort of like an inboard boat motor. Here's a pic...

http://i664.photobucket.com/albums/vv9/axeimen/GMCEngine.jpg

And here's the truck...

http://i664.photobucket.com/albums/vv9/axeimen/52GMC.jpg

About the past year or so, I've been getting a steadily increasing noise upon start-up, that sounds like a Jamaican steel drum. But it goes away when it warms up. My machinist thinks a piston is cracked, so I've parked it while I look for a new motor. This is a 4-bolt 350 block, but it's already bored 0.030" over. So I'm looking for a new one.

I think I found one, a Vortec 350 from a 1995 Suburban. With Vortec heads, roller cam, and 1-piece rear main seal, it should do pretty good; better than my old 350. I'm going to keep the cam mild, for fuel economy and torque. But the big change is that I'm going to bolt on a Tuned Port Injection EFI from an 80's Corvette. I've got almost the complete setup. Here's the photo of one. It's the best motor Chevy "never" put in a truck.

http://i664.photobucket.com/albums/vv9/axeimen/52GMC.jpg

I'm expecting more torque than hp. Computer estimates give me 402 lb-ft, which I don't doubt. If I could rev high enough, power would be about 370 hp, but TPIs are known to be limited on the top end, which would put me at probably about 100 hp less than that. Still, it should run very very well, and in a truck, torque is more what you want anyway.

I'm still using the stock SM-420 manual transmission, and I have an SM-465 I could use for it, but frankly, I'd rather put a good Muncie M-21 under it for the improved and more usable gear ratios.
The rear end is a Dana 60 posi, with 3.55 gearing. The wheels are year 2000 GMC chrome 16" wheels with 275/65R-16 all season radials. The brakes are upgraded with an under-floor power brake system, which works great. The exhaust is a home-built 2.5" mandrel side-exhaust exiting with slash tips just in front of the rear wheels.

One big change I plan to do with the motor swap this time is to redo the steering. I have a manual rack and pinion I'd like to adapt. But since I still have the solid front axle, I'll have to buy a crossmember to mount the steering on to. Someday I'll do an independent front suspension, but not this year.
And it's time to get the GMC Victory Red re-shot onto the body.

Now...if I can only get it quieter inside...

That is a very exotic exhaust routing ! Do you have another picture so we can see where it goes from there? You should think of stroking the 350 to 383 cu in.I look forward to seeing the new engine and paint.

Does the exhaust come out behind the driver's compartment? In Texas to be street legal, the exhaust has to come out behind the cab.

Yeah it does. The reason it goes down in the back corners of the engine bay was so that I could mainly get around the tight frame rails and still use the stock steering box. It goes straight down from there into an X-crossover right underneath the transmission. Then it splits out into dual exhaust again and into a pair of Thrush Superturbo mufflers (but I wish I used something quieter). Then out of the mufflers with a 45 degree angle out to slash cut tips exiting in front of the rear wheels. But yes, it's behind the cab...

I'm only 7 miles from the Texas border, in Clovis, but still in New Mexico. So there are very few laws saying what I can and can't do. As long as it runs, that's pretty much all they care about.

I'll get out there today and get a pic of the exhaust routing under the truck for ya.

Notice it's wrapped in fiberglass tape? It likes to burn everything around it otherwise. In retrospect, I wish I went out into the wheel wells instead. I might think about redoing it like that with the new engine. If I can find a pair of Try-Y headers, all I'd have to do is weld on extensions on the primary pipes to reach the engine. Then they'd go over the frame rails and into the wheel wells. Hmmm.

...But then again, why mess with something that works. Now that I've got it figured out and it works, it kinda looks neat like that. Maybe I'll leave it.

Well, I thought about that. But the reason why I'm not stroking to a 383 is because I've got a better plan. I've got a 6V53 GMC roots supercharger that's been given to me. It displaces 313 cfm, so it's a good little blower.
And it's harder to get your compression down with a stroked motor. That's the main reason I'm keeping it a 350.

I don't have the money to do all that right now; that motor would cost me 10 grand. So I'm building it with blower dished pistons, thinner steel shim head gaskets, and the small chamber 64 cc Vortec heads for now, which will give me 9.25:1 compression. And I'll use my old Vette TPI fuel injection on it to boost torque.
Later on, in a few years, I'll get a nice set of aluminum heads to drop compression down, and bolt the blower on.

...but really not a bad idea to do a 383...