84 w150 engine build

Hey everyone, first post. I've got a 84 w150 with a 25 sec 0-60 273 out of a 67 dart....

I will either build a 318 or a 360 for it (obviously). My goals are to be able to pull a trailer and be able to at lease break my tire loose.

Here's it's story. Bought it in 2011 with 99k miles on it and had a 360. It ran pretty good but needed valve seals (smoked some on startup) and had 4 rubber freeze plugs in it. 5 miles after it turned 100k the rear main seal let loose and it poured 4 quarts of oil on my driveway while I was tuning the carb.

Yanked it out and put the 318 out of my 76 d200 pasture truck. It was rebuilt and had 25k miles on it. It ran like a scalded ape for a 318 ( was under 10 seconds 0-60 which I felt was pretty good for an 80s 4x4 with 3.23 gears) after 5k miles or so it started smoking pretty good ( crappy 2 barrel carb that was on it in the 76 wiped the rings out). Pulled it and put a 2000 mile 273 out of a 67 dart just so I could drive it while building one of the others. Runs great and sounds good while it's wound up but it is an absolute pig. Tops out at 75 or so and can't pull a hill without losing 20 mph and me having to pull it down into 2nd.

I want to get 300 or so HP out of the 318 and 350 out of the 360 with as much torque as possible. I want it to not be a pig and pull a trailer if I need it to.

Which do yall think I should build? Both engines still have home marks in them so neither need boring. I am really leaning towards the 360 because they are torquier to begin with and would produce power easier in my mind.

If any of you have done anything like this and would share your build I would appreciate it.

Main thing I need to know is what cam would be ideal. It's a 727 With 3.23 gears. Another are what heads should I use? I have a chance at a set of 3418915 71-72 340-360 j heads.

Thanks everyone.

It all depends on what your willing to spend. If it was me I would build the 360. Put a mild truck cam, clean up the heads slap it back together and throw a EFI on that bad boy. There are a ton of after market fuel injections systems that work awesome, and it'll help with a more even power band. With the 360 you should be able to sneeze and make 300 horse it may not be the 350 your looking for but for the price of heads you can probably get a entry level EFI, you will have tons of benifits including better drive ability, easy cold starts, better fuel economy, and you will make more power over the carb. A 360 with a nice truck cam will have plenty of tq to pull a trailer. If you are completely against the EFI I would still build the 360, still do a nice truck cam, and I would also add bigger heads and spend some money on getting a nice carb and someone to tune it ( it will make a night and day difference) with either setup there will be plenty of engine to pull a decent sized trailer but the biggest help would be to get a lower axle ratio, depending on your tire size I would up to 3.73 if you have up to 33in tires, 4.10 up to 35 and 4.56 if you have 37+ good luck and hope this helps.

Thanks for your reply.

I'm trying to keep the build as low as possible (under 1k) because I can do all of the work (including the heads) myself. EFI would be cool but I'd imagine that it's in the $2000 or so range (I'll research it). I have plenty of carbs lying around but was planning on using a TQ. If not that I have some holleys, afb's and avs, that I could use.

Do you have any suggestions as to what kind of truck cam? I've looked at tons or RV cams but I am clueless on what is the best. What do you think the best RPM range would be?

I have 31x10.50 15's on it. I would like to get some lower gears but I don't know if it will fit in the budget. It has a 9.25 rear end

Would you think the 340 heads would be a worth while upgrade? I could buy some today but I might use my money up on another car to flip and make my budget bigger. Car needs a trans but I just so happen to have one ready to bolt in.

Sorry to ask so many questions but I appreciate your help.

Thanks!

Have you thought about building a carbed Magnum motor instead of the LA? Thats the route I would take.

I haven't, since I don't have one. I know the heads are better, but how's the compression on them? I know I would have to find a roller cam, right?

Thanks.

The 5.2 & the 5.9 Maggy's have a comp of 9.1, yes you would be dealing with a roller cam.

i am with Merc. magnum engines are the way to go. the big thing is whether you are good with wiring or not. if you are good with wiring i think you might be able to keep fuel injection. you can usually find a good used van with a magnum engine/overdrive transmission still in a ram van for fairly cheap and from the looks of it most things should swap over fairly easily. you might have to find some 91-93 truck parts or get creative with what you got but should be able to get it to work. i was looking at my neighbors 99ram van as i was strippin parts off of it and most things look like they would nearly swap straight into my 81. they even use the same bulk head connector and motor mounts still.

Good to know that the compression is higher. If I recall they're 245 HP or so which is a huge improvement by itself over the 84 which I think was 170. I can't find any on craigslist, but if I could I would want a low mileage one that I wouldn't have to do anything to aside from a cam and intake.

I am the worlds worst with wiring. I would rather change an engine than wire something. Haha. If I could find a complete wrecked truck or something then maybe, but wiring it up would take me a few years, if I ever got it done. The overdrive trans would be nice but it's 4x4 so finding a wrecked one of those would be a challenge of it's own.

I came across a low mileage mag 360 a few months ago for $300 but I passed it up because I didn't have the money. I'm kicking myself for it now.

Another challenge would be getting a carbed magnum intake.. Doubt they're very cheap.

You don't even have to change the cam unless you want to. I would stay with carb makes things much easier, use the mag serpentine belt system and the alt from the mag then just a case of wiring up the field wires. Starter would be straightforward and I would use the sending units from the LA motor for the gauges. The mag carb intake is comparable to other aftermarket carb intakes price wise and there are a few opt out there.

Here is the Mopar performance carb intake part number for the mag motor, keep looking I now there are others out there.

P5007380AB 4 bbl carb,aluminum,single plane,rectangle port magnum heads 1992-02 329.00

finding the parts to directly swap in a fuel injected magnum engine and keep it fuel injected would be hard since they only used the magnum 318's for 2 years before they stopped making these body styles and completely changed the design of everything.

as far as intakes go they are not that hard to come by since magnum swaps into older vehicles has become a lot more popular. like Merc said you are best to keep the serpetine belt setup that is already on the magnum engine if you do go with one. would just make thing simpler and would also most likely gain you a higher output alternator since most magnum engines come from the factory with at least a 90, 120 or 136 amp alternator. it would also be a good idea to try getting the starter with the engine if you can. the newer starters are a lot smaller and lighter if you every have to change it.

as far as the sending units go for the stock gauges you could go either way. both new or old sending units would make the gauges work the same. personally i would probably install some aftermarket gauges with more accurate gauges. stock gauges suck.

^^^ Some sending units have different ohm's out so the gauge will work but might not be accurate.

well like i said stock gauges suck anyways. it is always good to upgrade them especially if your hitting the track. i currently got a stock temp sending unit hooked to a aftermarket temp gauge in my 93. seems to work accurately. was easier to pull the temp sensor wire out of the instrument cluster connector and hook it to the gauge than it was to change the temp sensor and wire it up.

Just have to be carefull thats all. I have ran into this issue on marine motors. I do agree aftermarket gauges would be the way to go.

If I bought a complete engine I would use the serpentine. AC compressors aren't the same are they? I can have new hoses made. Would I be able to make 300+ HP with a stock cam? I would like to have at least 350 lbs of torque.

I'm fine with the stock gauges. They work and it's just added expense. What's the difference between the 2 intakes? Different bolt sizes/angles?

I don't think a single plane would be good for low end torque, would it?

What do you think the mileage would be? It gets 4.3 right now if I'm lucky.

as far as i know the compressors should be the same. i think they have use the same compressor design since the late 70's when they stopped using the RV2 compressor. now that i think of it tho i do think you need to get a proper intake run a/c on a carbed engine.

the holes that hold the intake down changed on the magnum engines changed. i am pretty sure you can drill and tap magnum heads to use a LA intake but you got to be careful. dual plane intakes are the best for trucks and torque.

you must idle that things a lot and drive like you stole it all the time because my 81 use to average about 9 mpg with me driving around town.

stock gauges are like idiot lights. i wouldn't trust them.

You'd think most intakes would be made to use with AC. Dodge should have just left the water neck in the same place and moved the ac compressor.

I read you could drill and tap them but that seems kind of sketchy.

I don't idle around any but I have to be heavy on it to get it up to speed. The 318 got 6 and the 360 got about the same. Gets 8 on the highway

My gauges seem to be pretty accurate.. Haven't had any issues with them.

the stock intakes work just fine with a/c lol. this might help
http://www.ramforum.com/f135/my_lowered_84_ramcharger_project_thread-39863/

gas mileage still is still not right. you may want to tune the carb better. my 81 use to see as high as 15mpg on the highway and about 9 around town and had no isses getting to speed. my fuel injected 318 with overdrive can average about 14mpg most of the time and see as high as 18mpg when doing straight highway driving.

the only stock gauge i trust is sometimes the gas gauge and my speedo but i have verified it with gps and road signs that tell you your speed. my truck scoots along pretty good when i am driving.

i like my aftermarket gauges so i know if there is an issue before there is any real issues.

I was talking about the aftermarket ones for the magnum engines. I would imagine most we're made for earlier cars with no ac or the rv2. When they stopped using the rv2 compressor they offset the water neck to the drivers side where as it was centered on the intake before. 80s ac compressor won't fit with one of those intakes. I figured it out when I put my weiand 4 barrel for a 70s compressor on the 318 for my 84 and the compressor sat over the water neck.. Had to pull it off and put an edelbrock on it instead.

It's running rich, I know. Smells terrible. I haven't put different jets in it because I can't find anywhere where people are jetting AFB's for a 273. It ran rich on the 318 too. I've experimented with other carbs and the result is the same. It's a 600cfm carb.

I put my thermoquad on it and it runs good and not as rich, but wen you give it full throttle it likes to stay there even when you pull the throttle back.. No idea why but the secondaries are sticking open.. I'm starting to think vacuum secondaries suck.

The F1 Air Gap made by edelbrock would work but not cheap at all. As I posted keep looking that Mopar number was an example. Found this one so far today, Edelbrock Performer RPM Air-Gap Intake Manifold part #7577 its a dual plane intake made for just this type of swap @ Summit its $300.


I have a set of R/T heads that are drilled for a LA intake I could let them go very cheap if you wanted them.

I have been using the Edelbrock performer series carbs this summer on a few motors and they work great easy to tune and work on. Yeah vac seconders suck alright I have no use for them at all.

Op if you want to drop this magnum idea just post it up and I will start looking for a cam for you.

there is lots of videos on youtube that could help teach you how to adjust the thermo quad. for some reason i think adjusting them is simpler than it seems.