Repowering a 1990 1/2 ton sub?

arlon · March 9, 2004

I am interested in repowering a 1990 suburban that currently has a tired 350 (153000 miles). My main interest is in legally (in texas) improving the towing ability of the vehicle. Does anyone know if there is a legal or practicle way to use the 383 ci crate motor in the 90 sub? All info I have found on this motor suggests use in pre emission cars only but it sounds like the perfect motor for what I want to do. If I have to use another 350, what to use to get a little performance boost? Torque and mileage are main concerns. I really don't want to have to pay the gas bill for a big block but want more pulling power than I have now. Can I have my cake and eat it too? I'm on about a $2500 budget for the motor... Any thought appreciated. A new diesel PU would be nice but I have a near perfect old sub that could be rebuilt from the ground up for about the down payment and TTL on a new

one. I am also very mechanically capable.. Thanks for any input/ideas..

tmf6902 · March 9, 2004

Talk to Jasper....my sister has a 89 burban, and the engine died on her....she got a rebuilt 350 from them....

intruder217 · March 9, 2004

There is more to towing than just a more powerful engine. Generally when you add a tow package to a vehicle you get additional cooling for engine oil and transmission, bigger brakes, and lower gearing. You might be quite happy if you put a fresh 350 in there and just lower your rear axle ratio. If the truck is 4wd this is probably not a good solution, as you would be messing with two gear sets.

OUMike · March 9, 2004

If I have to use another 350, what to use to get a little performance boost?

GM Crate 350s are built proof. I think you'd be extremely surprised how much stronger your motor would be after a solid rebuild. Maybe replace a few viatal parts such as camshaft, valves, springs and such. Maybe have the crankshaft worked over. I believe that the crank shaft is something that can be reused, but I would emagine a new one would be fairly inexpensive. Maybe have your block bored to 383 and use a similar compression piston. If your concerned about fuel mileage I would highly recommend pulling your TB intake and converting to and a newer EFI system. I would say that for $3500 you could easily rebuild your motor and get power, torque and decent gas mileage. You can't be too picky about mileage, as Subs don't really get good mileage to begin with.

You might be quite happy if you put a fresh 350 in there and just lower your rear axle ratio.

This is also a good solution. If you decide to go with a new crate motor, check with Lingenfelter Performance (www.lingenfelter.com). John built the best crate motors in the world, and knew more about GM motors than anyone I'd ever talk to. It might be a little more than you want to spend, but it will last forever. Was truly a sad day when Mr. Lingenfelter past away. Changing your gear ratio is a decent approach, but many people don't like dealing with problems caused by this. When you do this you change all your gaugues making them inaccurate (less than they already were ), and by going with a higher ratio (3.83, 4.09) you will definatly hurt your vehicles fuel efficiency. Something that you might not wanna do on something heavy already.