Where can you find REAL performance parts for a 86 Jeep Comanche?

Answer 1

Simply put... nowhere.This model year of Comanche only came with a 2.5 litre 4 cylinder motor or the sad GM 2.8 litre V-6 engine. Neither are worth "hopping up". That being said, there may be some GM guys that would tell you that the old 2.8 motor can be improved, but that will have to come from a GM guy... which I admit that I am not.But I suspect that unless you've got deep pockets, this is not a practical pursuit.

AddendumRecently I replaced a defunct 2.8L V6 engine in a 1986 Jeep Comanche (automatic transmission, 2WD with a "GM Performance Parts 'Crate Engine'", which was a 3.4L V6 partial assembly engine which was designed as a bolt-up drop-in replacement for the 2.8L engines which were the main engine for the early Chevy S-10 pickups.

This engine cost me an even U$2000.00 with an installation charge (3rd-party) of a bit over U$1000. The engine is shipped in a crate to the destination. You have to remove most of the exterior fittings from the old engine, including both manifolds, though optional manifold choices to replace the old stock parts are available, including a nice light aluminum Edelbrock manifold designed to accomodate a Holley 390CFM 4-bbl carb. The engine's excellent 100K-mile warranty will be voided if you use throttle-body injection. I stuck with the original manifold but will be replacing the lousy progressive-carb VaraJet 2-bbl with a Weber DGAS 38 synchronized 2-bbl carb. The stock engine is rated at 155 horsepower. After the engine swap, for the first 1200 miles I experienced a lot of rough running, but the power improvement was apparent, especially in terms of low-RPM torque. By the end of the 1200 miles of break-in (I babied it, okay? with oil changes at 300 and 600 miles) the engine runs almost smoothly at idle and is a very very strong puller. But due to the 3-speed transmission (A MOPAR TorqueFlite A-904, I think) and the wide gearing and the load-hauling DANA 80 rear-end, this will never be a race machine. Instead, it is a versatile and adaptable light hauling vehicle. With the old 2.8L (172 c.i.d.) engine I could easily haul a full bed of topsoil, I'm sure it's much more easy now. I should mention that as long as you keep the RPM fairly low, this engine has a _lot_ of power, all you need for a light utility pickup. Winding it out is pretty much a waste of time and engine. Just kick it hard through first gear and let it drop into 2nd, kick it as hard as you can without downshifting, you should be going 45 pretty quickly and if you let off the gas it will drop into converter-locked in 1:1 drive gear, and at that point it has _very_ nice power as long as you don't kick it down into 2nd, which over 50 will simply shake you half to death and not give you much more speed. Between about 45MPH and 65MPH, this thing just runs down the highway with as much as you can load into it and still keep the front wheels on the ground. Hills are not a concern.

What is a concern is that you get the electric fuel pump installed correctly. This replacement Crate Engine doesn't have a mechanical fuel pump and it's not an option. So, get the fuel pump recommended by the Crate Engines site for the engine. Also, find some place to mount it other than inside the engine compartment; on a hot day the temperature will get up around the boiling point for gasoline, and the pump also gets that hot, or hotter. It's not designed to pump vapor. You will get vapor lock, this happens to me all too often. But there aren't too many better places unless you want to re-fit the fuel line into the engine compartment from the fuel tank. (You could possibly rig a cooling fan, not that bad an idea.) The ideal place would be where the fuel line comes out of the gas-tank but you will need to fabricate some sort of protective cover for it if you do that. Also, be sure to use a 4-connector oil-pressure sensor switch to make sure that the pump doesn't operate unless the engine's turning. Otherwise you could find yourself with a stopped engine and perhaps a severed hose, after an accident, with the fuel-pump still working and possibly feeding a fire in the engine compartment. If you install a close-mounted cooling fan to deal with pump heating problems in the engine compartment, this oil-pressure sensor switch control for the fuel pump is probably essential. Also, don't forget to make sure that the carb is fed by a T-fitting so that unused gas will be returned to the tank as in the original design, via the unused-fuel return tube.

If you have one of these and want to fix it up, I recommend replacing the A-904 with a RH-40 (basically the heavy-hauler hydraulic-control modern TorqueFlite with overdrive and locking torque-converter), getting the GM 3.4L Crate Engine, replacing the crappy VaraJet with a Weber DGAS 38 2-bbl, and possibly replacing the rear-end with something geared for better gas mileage.

A shift-kit and perhaps some diddling of the transmission control module might enable you to get torque-converter locking in any gear, and much sharper shifts, and in fact a kickdown-suppress switch might be very useful to help you get the most out of the excellent low-speed torque after the engine swap.

Enjoy!