No pictures, no video, just a quick and dirty memory dump about today.
First memorable and important fucking thing – Aaron is not a special boy born in the sun who never ever has to follow the rules. That’s simply not the case. Never, ever is.
I failed in a lot of ways to get this motor swap done in a reasonable amount of time. Between getting discouraged (more writing about that later, because it’s been pretty difficult to fight and enlightening to overcome) and simply trusting that any amount of reading would make up for even a minute of doing has left me without my car for months, and feeling despair a few times along the way.
The short version, for all of you who don’t want to read boring technobabble? ALWAYS DO YOUR FUCKING PRE-START CHECKLIST. ALL OF IT. FROM THE START TO THE FUCKING END. CHECK THE OIL PRESSURE VERIFY YOUR JACK STANDS ARE SQUARE AND KICK YOUR TIRE CHOCKS ALL OF IT AND DONT SKIP SHIT LIKE MAKING SURE YOU TIMED THE ENGINE RIGHT BECAUSE YOU WILL FEEL LIKE A DICKHEAD LATER.
It roared to life, it came to temp, I was just getting ready to diddle with some carb settings on my SWANK ASS new carb (Barry Grant Street Demon, more about this fucking GREAT little guy later) and Nathan heard it burbling, but just as he came out the horrible stamped thermostat neck began to spray hot water all over the engine and I had to shut it down. But it runs, praise Doctor SpaceJesus, thanks to following the fucking instructions and erring on the side of doing more doing instead of more thinking.
So, without further adieu, the full list of caveats for a Mopar LA 318 to Magnum 5.9 Swap are:
Oil Pan – Buy a LA 360 car oil pan if you have a car, and use the Magnum one piece oil pan gasket. This will cause two 3/8″x1/2″ voids in the corners where the LA pan expects the U-channel locators but I just used those holes as injection points for some silicone, left the pan not-quite tightened down until it set, and then torqued the pan gaskets, It’s a low pressure area and the one piece gasket actually has a little skirt that covers most of the void from the inside, so this is one of those “good enough” fixes. If you have a truck you can probably use the cool awesome donor pan with the good gasket and no goop. Or if you are a fancy man you can graft the corners from the magnum pan onto your LA pan.
Motor Mount – The drivers side motor mount for the 318 is different (wider), you can make up the gap with two high grade “thick” washers, give or take a thin one.
Transmission Brace – The drivers side transmission bellhousing brace (which runs from a lug on the block just ahead of the starter to a hole in the bellhousing clocked further down from the lower starter bolt) is not the right length. The 5.9’s mounting point is several inches closer to the front of the vehicle. I haven’t found a fix for this yet. Presumably a 360 car or maybe a brace from a magnum truck, have to hit the J/Y with a ruler.
Induction – Carb or FI? FI is a second-stage type project for me, I wanted something that would get me on the road quickly without having too steep of a learning curve, so I went carb. There’s a few manifolds, I couldn’t get a Crosswind (RPM Air Gap knockoff) so I got an RPM Air Gap. It’s… pretty sweet actually, Edelbrock makes a nice fuckin’ manifold. I need to do some plumbing for PCV and the booster and stuff but there’s plenty of holes there. The big under-hole thing is a terrible crap catch and makes the top of the motor look slobby when you have coolant leaks. Which you will. Because: thermostat housing.
Throttle Cable and Kickdown – Regardless of induction you will be on your own for throttle cable mounting. There’s a lot of options like OEM cables in custom bracket options (Bouchillon again) and modding the LA 4bbl stuff (bring your hammers and torches because it’s pretty crude shit), but after all the hemming and hawing, I went to these Lokar cables. Cheap enough and work good, which I guess is why they’ve been around for a zillion years since the grandpas cars. My new carb has a slightly different mounting bolt to throttle/kickdown linkage measurement than a standard holley type, I may order a new one, since I can see that the cables are about a half inch out of line at max adjustment on the Lokar generic bracket.
Thermostat Housing – The thermostat housing on the RPM Air Gap, at least, is not a standard LA size housing, it’s a “Late” design. You can cut down the donor neck (which is like 90000 miles long) and use it, or you can source one for an 80’s Dodge V8 car. Like a Diplomat with a 5.2LA in it or something. They are shitty, horrible stamped steel, and will require liberal siliconing (or in my situation, re-re-siliconing again again), for the most part. I am still looking for a cast aluminum diplomat water neck. I have seen a picture of one but never found out what the manufacturer was. Still looking, might be another junkyard find, so far all the LPS parts have been stamped steel.
Radiator Hoses – Ho hum. You swapped a motor, now you have to pay the piper by dealing with flex-hose until you can spend an hour in the back of your local parts store to figure out some that will work.
Starter – While the LA starter will fit without any grinding or changes, it’s huge – stupid huge, requires you to drop the suspension and exhaust every time you touch it and is woefully out of date. Ironically the mini starter which is stock to the donor vehicle probably won’t fit. There’s this big lug, just above the oil pan gasket, drivers side, rear, has a plug driven in through the bottom, that needs grinding, maybe a touch more than 1/8″ across it’s radius. Difficult to describe, if you have it in the stand, find the lug (I’ll do a diagram later) and just flatten out it’s radius to a 45 degree bevel instead. If it still don’t fit, it is easy enough to do in the car, as long as you have eye protection and an air grinder/electric die grinder of >dremel tool class. You could do it in place with a dremel but you’ll be there, arms over face, shooting sparks into what you laughingly refer to as your hairline basically forever. With a big die grinder it’s a 5 minute job and 2 minutes is finding your ear plugs. I made a very big deal of this and it set me back many hours of work for my stubborn headed laziness installing, then pulling that ridiculous greasy LA starter after it failed one crank in. This amounted for hours spent on my back in the mud versus five minutes thinking about it rationally while the motor was on the stand. Don’t be like me America, the mini starter whips the motor over effortlessly, well worth the effort.
Timing Cover – This is where you make a big choice. If you keep the magnum timing cover, that lets you keep the magnum serpentine setup. It’s cool, if you want all accessories, that’s awesome. If you got a truck donor motor the power steering pump will be in the middle of your battery box, so be prepared to make some major car mods if you want to keep the serpentine. If you put on an LA timing cover you can’t use any of the magnum accessories at all, except maybe kinda sorta you can mod the alternator and use it but it’s not a great solution (gets close to the block on the output stud). If you’re using an LA timing cover, and using a stock Magnum cam, or a cam ground on a stock magnum core, with no provision for the fuel pump eccentric, Bouchillon makes a cam snout extension. It took mine a silly amount of time to get here for what amounts to a little machined spacer but it works perfectly. If you don’t give a crap and plan to run an electric fuel pump anyways then you can skip this and save yourself a few weeks of waiting on parts and some money. Regardless, do the seal on the cover while you have it out. It’s easy and always worth it.
Harmonic Balancer – If you’re using the stock serpentine setup, you’re fine! Just use the donor one, install the seal saver that came with your timing cover seal kit (you did your timing cover seal right). If you are using any other type of belt system, get ready to throw that guy in the garbage. It’s all cast as one and not worth it. Professional Products makes one that has a replaceable weight that can be set for LA 318, LA360, and Magnum, it’s pretty cheap, SFI approved, and just has a regular LA style bolt pattern, so you can use your 318 pulley, any aftermarket serpentine pulley system, any aftermarket billet pulleys, etc.
Magnum Crank Sensor – There’s a crank position sensor that hangs off the back of the block. You can either clearance your bellhousing for it with a grinder, or unbolt it and plug the bolt holes (or not). Obviously if you are retrofitting the stock EFI you need to clearance it or figure out a different way to get that signal from the engine. I unbolted. If and when I go EFI I’ll use an EDIS type wheel mounted on the front of the engine instead.
Flexplate – If your 5.9 magnum has a weighted flexplate you are good to go, you oval one hole to bolt your LA torque converter to and scoot. I lucked out. There’s a big tone ring for the EFI but it doesn’t interfere with anything when you bolt it all together. If you have a neutral flexplate with weights on the torque converter (afaik neutral flexplates are limited to “early” magnums, 92-94), you either have to source a weighted magnum flexplate and modify as above, find a specialty B&M flexplate weighted for the magnum with a neutral converter, modify a neutral balance converter with mopar performance weld-on weights, buy a custom converter with the right balance, or devise an as to yet unknown method for transmitting power between a motor and a transmission, superior to all before it in every way. Who am I to limit your options.
Air Cleaner – Obviously I’m way off stock here so I can’t reuse anything, and my carb choice makes it even less tested. I think that a stock Mopar dual snorkel would clear the hood on top of this manifold/carb combo but I’m not sure. I bought this and the drop (they claim 1.18″ which sounds right) is just a touch too much, it hits the electric choke on the Street Demon. But I mean just a touch like I think a double gasket under the air cleaner base might do it. The issue is even after this clears I have fears about the 3″ element clearning the under hood, I need to do a clay test.
Valve Covers – The donor valve covers have one totally normal PCV and one weirdball breather thing you’ll have to pry out and replace. They have a nice screw in oil fill hole in em and they have real nice gaskets. There are Mopar Performance and Edelbrock aftermarket parts that fit as well. I believe I’m going to be installing a regular old breather on the passenger side with the cap and the PCV on the drivers side going to a barb on the back of the carb.
Exhaust – Anything that bolted to an LA motor and fit in your LA car will bolt to this motor and fit in your LA car. I am using the stock LA manifolds and they fit great.