Good evening all... did a quick search regarding the 318 LA vs 318 Magnum... didnt get quite the answers I needed, but i am going see what everyone elses opinion/options are.... my truck is a 1989 D150 with a stock 318 TBI/Automatic/3.55 gears. The truck is all original except 2.25 inch true dual exhaust and I had a leaking fuel module on the original tank, so I installed a 20 gallon fuel cell in the bed with Airtex 8094 fuel pump. Pump has 3/8 from the cell to the pump, then 5/16 to the stock metal lines. I have the return and EVAP system still in use. Pump is also wired to the oil pressure switch in case of accident, oil pressure drop, etc. A lower psi pump can easily be installed for a carburetor swap on the motor. My truck appears to have 74,000 miles on it currently. Exterior is about an 8 minus some peeling paint and very minor dent, but no rust. Interior is a solid 9. The motor runs good, has great oil pressure, no noises, ticks, rattles, etc. Just dosnt have enough power, which is a common complaint with 150hp under the hood of a pickup. I'm considering either freshening up my current LA 318 or purchasing a 318 Magnum and building it. I do not plan on doing any kind of racing or anything like that. My main goals are possibly a little better fuel mileage and help the truck have an easier time towing a trailer... max load of the trailer with a race car and some vear would be 5000 pounds or less, so I'm not doing severe towing with it. Everyone says get a 360, but 360s have their own little quirks and dont get as good of fuel mileage as the 318s. I was really thinking about staying with my current 318 and do a compression test on it and go from there. If everything checked out, I would use that as the baseline for my build. I would consider taking the 302 heads off, have them magnafluxed, maybe do an undercut on the valves and do a little shroud/port work and call it a day. I want to use a Hughes SER0814ALN-10 Roller cam with 208/214 duration and 110 LSA .491/.500 lift. I will install the recommended 318 aluminum intake manifold with a 600-650 carburetor... Also upgrade the ignition system while I'm# here.I will also install headers to the current 2.25' exhaust. Maybe step it up to 2.5 in the future... I'm thinking this is going to be the most economical way as I already have the engine, accessories, linkage, belt setup, already. If I got the 318 Magnum, I would keep the current accessory setup, get a cam very similar to the one I have planned for the LA 318. Of course headers, aluminum intake, 4bbl, and ignition upgrades. With my LA engine, I dont have to fight with anything being different, one off intake, dont have to cut any wires or anything, etc. I'm looking to make a solid 275-300 horsepower 318 . Thanks for any insight!

 

You will need roller lifters to go with that cam... The LA engines didn't come from the factory with rollers, the magnums did though. You could do a carbed magnum engine, there are intakes out there in the world that will bolt to either, or, carb manifolds with the magnum bolt pattern. I also like the serpentine belt system better...... but, changing over to that may lead to other complications. (where is the a/c compressor on the la motors, and do you even HAVE a/c??)

Difference in fuel mileage between 5.2 and 5.9 really isn't that significant, and the 5.9, with the same mods, will produce more power.

Going to an O/D trans would be a nice boost in fuel mileage as well, (is the truck 2 or 4 wheel drive?) The earlier model RH transmissions would sit behind either engine rather nicely.

I don't like Airtex brand pumps. Too high of a failure rate.... at least yours is easy to get to.

 

My truck does have AC and it works... also my truck is a 1989 and does have a roller cam so the only thing I would need to swap is the camshaft. I have had the intake off to swap gaskets and it does have roller lifters. It is a 2wd and currently has an A500 which is considered a light duty 4 speed overdrive. I do plan on getting it overhauled because it is just starting to slip. Already did a fluid and filter change and added a bottle of lucas, so I am going to run it till it goes and then overhaul it with HD bands and some internal upgrades and a transgo shift kit along with a bump above stock converter and external trans cooler. As far as Airtex, I have heard good and bad about all brands, dosnt really matter what brand you go with, the ethanol will kill it... I have a private fueling station that I use and have been using 90 octane non ethanol since I purchased the truck. Everyone says get a 360 but I am trying to do this the most economical way. If doing the 318 with the cam, head work, headers, intake, ignition, and carb will net me what I'm looking for then thats what I'm going to do. It's not going to be a stoplight truck so I'm not worried about losing a few cubes to save some pennies... it wouldnt have a problem merging into traffic or pulling light car trailers with a built 318. I'm looking for reliability and better mileage empty. Not really worried about mileage loaded cuz that can vary widely.

 

Wow, the 318 got roller lifters way back in 85. Didn't know that.

Yeah, being on a budget, I can understand sticking with the engine you have. You could prolly pick up a rebuildable 360 for a couple hundred bucks, or less.... Up to you there. I don't think the power numbers, given the same mods, will be all that different. Would be interesting to see some dyno tests on that theory.

When you go to buy parts, just make sure they are all designed to work in the same RPM range.

 

If you go carb. Watch what intake you get, I know The Edelbrock won't allow you to keep the A/C. May be different on the LAs but I don't think they are. I did a 360 Magnum swap in my 91. Do yourself a favor and ditch the 42rh trans for a 46rh trans. Casting is thicker, beefier internals, If your pulling and going to upgrade the stock 318. My 360 burned up the 42rh in less than a mile. It's a good cam choice for torque. I built my 360 for torque. You might want a slightly higher stall convertor also. If you go with a Magnum, just keep in mind the rocker arm ratio is a 1.6:1 and the LA is a 1.5:1 all camshafts will interchange from LA to Magnum as long as they are roller. I used my 318LA cam in my 360 Magnum 258/268 duration with a .501/.524 lift with a 112lsa current lift with the Magnum rockers. Rpm range is 1,500-6,000. I got a 2400 stall convertor, it's a tire roaster. The 302 heads are good heads with some port work, and slight tulliping around the valves. Check the cam and make sure it's compatible with the stock oil pump gear. Check your push rod length, you may need shorter/longer push rods. Just keep in mind the tbi is all controlled by computer, so any mods being done may not be supported by the stock ecm such as the cam. And may not yield the full potential of the what your trying to achieve. Only difference in Magnum to LA- Magnums oil threw the push rods, 318/360 use the same heads that flow much better than LA heads (stock for stock) and the Magnums have lighter Pistons with thinner rings. Minus the mpfi. That the Magnums have, and serpintine belt. And 10 bolt valve covers instead of 5 bolt.

 

I think a Magnum will be more work than you expect for what you get. You currently have a modified LA engine. When Chrysler went with fuel injection in '88, the V-8's got roller lifters. That set up was used through 1991. 1992 is when the first Magnums came out. So the 1988-91 engines are unto themselves. I personally would freshen the engine up but with only 75K, it shouldn't really need it. I had an '84 with 3.21 gears and it did okay towing as long as you weren't in a hurry. It sounds like you have a solid truck so go slow.

 

Thanks for the tips guys... the motor only has 75,000 miles and has nothing wrong with it but I figured I would run it u till the TBI starts giving me troubles.... which hopefully isnt for awhile, which will give me time to get the camshaft, headers, ignition parts, intake manifold, etc. I already have a carb, a brand new Street Demon in either 625 or 650 I cant remember. Only reason I was considering pulling the heads was to have them checked for cracks and do some mild port/bowl work to them. I also have a couple exhaust bolts that were broke when I got the truck, so I figured I could probably use a 90 degree air drill and drill them out, but who knows how many more are going to break in the way out. Plus with the heads and exhaust out of the way, I can replace the motor mounts and paint the block and out an oil pump and pan gasket on it for extra insurance. All the parts I have in mind are all within the operating range of the cam. It is a mild cam that uses stock converter, springs, etc but I am going to replace valve springs anyway and add a slightly hotter converter.