360 LA Dakota. Budget!
02-18-2009, 04:14 PM
#1
Guest
Posts: n/a
360 LA Dakota. Budget!
Hello everyone. I'll try and make this as short as possible, but I'm warning, it's going to be a book. 
I have a '92 Dakota, 2wd extended cab with what used to be a 5.2L Magnum. I decided to put in an LA hydraulic flat-tappet cam and lifters, and custom (what I thought was correct) length pushrods. Was running, then I began having lifter problems, and after lots of haggling, I ended up with the passenger bank of valves slapping the piston faces and bending. I was pissed, and never put the head back on. Yeah, not smart. So, no more motor. But, we have an '89 regular cab 2wd Dakota in great shape here with no motor or transmission. And, here's my plan.
I want to use the 46RH out of my Dakota for the trans. Will that bolt up to a 318/360 LA engine? Motor mounts are no problem. Truck had a 42RH I think, and a 3.9 in it. I want to use the 360 LA motor with my 5.2 oil pan, my Magnum heads (with new valves, of course), my cam and lifters, and the Mopar Performance pushrods designed for this application, an M1 intake, and the correct carb. What should I use for a distributor? Anything special, or will a stock 360 distributor be okay? Does it sound like it would all work together? I've been reading a lot into this, and I'm starting to confuse myself with the facts.
-Travis
I have a '92 Dakota, 2wd extended cab with what used to be a 5.2L Magnum. I decided to put in an LA hydraulic flat-tappet cam and lifters, and custom (what I thought was correct) length pushrods. Was running, then I began having lifter problems, and after lots of haggling, I ended up with the passenger bank of valves slapping the piston faces and bending. I was pissed, and never put the head back on. Yeah, not smart. So, no more motor. But, we have an '89 regular cab 2wd Dakota in great shape here with no motor or transmission. And, here's my plan.
I want to use the 46RH out of my Dakota for the trans. Will that bolt up to a 318/360 LA engine? Motor mounts are no problem. Truck had a 42RH I think, and a 3.9 in it. I want to use the 360 LA motor with my 5.2 oil pan, my Magnum heads (with new valves, of course), my cam and lifters, and the Mopar Performance pushrods designed for this application, an M1 intake, and the correct carb. What should I use for a distributor? Anything special, or will a stock 360 distributor be okay? Does it sound like it would all work together? I've been reading a lot into this, and I'm starting to confuse myself with the facts.
-Travis
02-18-2009, 05:59 PM
#2
Admin
First off, welcome to the forum.
Second, LA motors are not the same as Magnum motors. The trannies will bolt up but thats the only thing that is the same. The heads have got different port sizes, different locations, different bolt patterns, and thats just the the intakes and exhaust manifolds. The oil and water passages are different too. That is why you can not swap parts between a LA motor and a Magnum motor.
Now onto your project. You 89 dakota came with a 3.9L non-Magnum V6 that was carb. That 42RH is junk, even for a 3.9. Trust me, I tore through 3 of them in 2 years, and 1 of those 3 was a factory reman from Chrysler.
Your best bet is to find a smashed up dakota R/T and swap in the motor, tranny, wiring, and computer. That will give you about a 14-15 sec truck in that 89 Dakota. Heck, even a normal 5.2L Magnum motor will get you into the low 15s with the right tires and suspension.
What are you planning on doing with this truck? What do you plan on swapping in for a rear axle as that 8.25 rear that is in both of those truck will not hold up.
Second, LA motors are not the same as Magnum motors. The trannies will bolt up but thats the only thing that is the same. The heads have got different port sizes, different locations, different bolt patterns, and thats just the the intakes and exhaust manifolds. The oil and water passages are different too. That is why you can not swap parts between a LA motor and a Magnum motor.
Now onto your project. You 89 dakota came with a 3.9L non-Magnum V6 that was carb. That 42RH is junk, even for a 3.9. Trust me, I tore through 3 of them in 2 years, and 1 of those 3 was a factory reman from Chrysler.
Your best bet is to find a smashed up dakota R/T and swap in the motor, tranny, wiring, and computer. That will give you about a 14-15 sec truck in that 89 Dakota. Heck, even a normal 5.2L Magnum motor will get you into the low 15s with the right tires and suspension.
What are you planning on doing with this truck? What do you plan on swapping in for a rear axle as that 8.25 rear that is in both of those truck will not hold up.
02-19-2009, 06:45 PM
#6
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Posts: n/a
First off, welcome to the forum.
Second, LA motors are not the same as Magnum motors. The trannies will bolt up but thats the only thing that is the same. The heads have got different port sizes, different locations, different bolt patterns, and thats just the the intakes and exhaust manifolds. The oil and water passages are different too. That is why you can not swap parts between a LA motor and a Magnum motor.
Now onto your project. You 89 dakota came with a 3.9L non-Magnum V6 that was carb. That 42RH is junk, even for a 3.9. Trust me, I tore through 3 of them in 2 years, and 1 of those 3 was a factory reman from Chrysler.
Your best bet is to find a smashed up dakota R/T and swap in the motor, tranny, wiring, and computer. That will give you about a 14-15 sec truck in that 89 Dakota. Heck, even a normal 5.2L Magnum motor will get you into the low 15s with the right tires and suspension.
What are you planning on doing with this truck? What do you plan on swapping in for a rear axle as that 8.25 rear that is in both of those truck will not hold up.
Second, LA motors are not the same as Magnum motors. The trannies will bolt up but thats the only thing that is the same. The heads have got different port sizes, different locations, different bolt patterns, and thats just the the intakes and exhaust manifolds. The oil and water passages are different too. That is why you can not swap parts between a LA motor and a Magnum motor.
Now onto your project. You 89 dakota came with a 3.9L non-Magnum V6 that was carb. That 42RH is junk, even for a 3.9. Trust me, I tore through 3 of them in 2 years, and 1 of those 3 was a factory reman from Chrysler.
Your best bet is to find a smashed up dakota R/T and swap in the motor, tranny, wiring, and computer. That will give you about a 14-15 sec truck in that 89 Dakota. Heck, even a normal 5.2L Magnum motor will get you into the low 15s with the right tires and suspension.
What are you planning on doing with this truck? What do you plan on swapping in for a rear axle as that 8.25 rear that is in both of those truck will not hold up.
There's a LOT more differences between LA and Magnum motors, but most are for the better.
This is going to be a street performance motor. I would like to use dish pistons and the closed combustion chambers to get around a 9:1 compression ratio. The Magnum's chambers are closed. They bolt up. The Magnum and LA heads are actually somewhat identical on the exhaust side. But custom full-length headers will be built specifically for this truck by my brother and I if a 360 is to be implemented, so that takes care of any line-up problems. The Magnum intake manifold setup is bolted vertically into the cylinder heads, instead of angled like the LA head design. But the M1 is set up for Magnum cylinder heads, and this won't be a problem. I haven't heard any bad things about the M1. I hung around an R/T Dakota Message board, and most of the boys there that were pushing big numbers didn't have Edelbrock. They had an M1, although they used fuel injection. LA cylinder heads were not designed to be fed oil through the push rods, and as such, the lifters were not made with oil feed holes. But, I have lifters out of a pre-Magnum (LA) Jeep that have those oil feed holes. So oil is not a problem. I don't know where you got information that the coolant passages don't line up, but they do. Look at a Magnum and LA head gasket and see for yourself. You're also wrong with the 8.25 in both trucks. The Gen-2 Dakotas received 8¾" rears. Snoop around a Dakota forum. I'd be using that, and the spindles from the '92 so I don't end up with 5-lug fronts and 6-lug rears. That'd just be weird.
Most of this information has been cited through seeing all of this. The rest was taken straight from How To Build High Performance Chrysler Engines, by Frank Adkins. Good book.
Most of my questions have been answered from some more research. I'm also considering a mild 350 and a TH400 with the 8¾"
Thanks to all who welcomed me. I appreciate it.
Last edited by T.Mihm; 02-19-2009 at 06:48 PM. Reason: Lots of grammar problems.
02-20-2009, 01:44 AM
#7
Admin
You are right about the water passages. It was just the oiling system that was different.
A friend of mine had an 88 dakota, I had a 92, 00 and now an 01 and all four of those had 8.25 in the rear. I never heard of chrylser installing the 8 3/4 in the rear of these trucks.
A friend of mine had an 88 dakota, I had a 92, 00 and now an 01 and all four of those had 8.25 in the rear. I never heard of chrylser installing the 8 3/4 in the rear of these trucks.
Last edited by 78D200; 02-20-2009 at 01:47 AM.
02-20-2009, 01:02 PM
#8
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Posts: n/a
Hmm... I'm pretty sure the tag on the bottom side of my hood says 8¾", but I'm not as sure as I was. You could very well be right.
Couple questions. I think I might actually use the 5.2 block. I figured it would be $250 to bore/hone it, and I could squeeze out the power that I wanted without spending another $200 on a 360 only to have the chance of it needing a bore/hone job, too. Would lose a little torque because of the smaller stroke, but all in good time. I have a couple more questions, they're pretty crazy, but oh well. All in developmental stages before I actually spend the money.
1. How hard would it be to machine the valve guide area to be able to accept a valve guide that would let me run LA valves? Or is that stem size just too big? I can find LA 2.02 valves and guides way cheaper. It would be over $300 for new magnum valves alone, and I could probably get the machining, 2.02/1.60 valves, and guides for less than that.
2. Can I adapt the stock Magnum intake manifold to accept a carb? Adapter plate, or weld the mounting holes/drill new ones?
3. The cam I'm running pulls from 1800-5200. Comp 260H. Will the Magnum long-runner, beer-keg intake be cool with that? Those runners are pretty long, and I don't have enough experience to be able to know if they will hinder performance from 4500-5500 rpm. I'm guessing they will though. That runner design looks to be useful more from idle-3500... Lol. They're long.
4. I have to get new pistons since they were attacked by my valves. What would you suggest? The Mag comes stock with flat tops. Just replace them with flat tops again?
5. What distributor/coil do you guys suggest? Will a stock LA be okay? I don't think the Mag distributor will work, will it? Or could I change that?
-Travis
Couple questions. I think I might actually use the 5.2 block. I figured it would be $250 to bore/hone it, and I could squeeze out the power that I wanted without spending another $200 on a 360 only to have the chance of it needing a bore/hone job, too. Would lose a little torque because of the smaller stroke, but all in good time. I have a couple more questions, they're pretty crazy, but oh well. All in developmental stages before I actually spend the money.
1. How hard would it be to machine the valve guide area to be able to accept a valve guide that would let me run LA valves? Or is that stem size just too big? I can find LA 2.02 valves and guides way cheaper. It would be over $300 for new magnum valves alone, and I could probably get the machining, 2.02/1.60 valves, and guides for less than that.
2. Can I adapt the stock Magnum intake manifold to accept a carb? Adapter plate, or weld the mounting holes/drill new ones?
3. The cam I'm running pulls from 1800-5200. Comp 260H. Will the Magnum long-runner, beer-keg intake be cool with that? Those runners are pretty long, and I don't have enough experience to be able to know if they will hinder performance from 4500-5500 rpm. I'm guessing they will though. That runner design looks to be useful more from idle-3500... Lol. They're long.
4. I have to get new pistons since they were attacked by my valves. What would you suggest? The Mag comes stock with flat tops. Just replace them with flat tops again?
5. What distributor/coil do you guys suggest? Will a stock LA be okay? I don't think the Mag distributor will work, will it? Or could I change that?
-Travis
02-20-2009, 01:44 PM
#9
Admin
1) I'm not sure about that.
2) you would be better off making an adaptor plate than welding and drilling new mounting holes.
3)I would look around for an EFI manifold. The dome shape will not be working with that cam too well.
I remember a guy coming in with a 98 GC Limited with a bored and stroked 5.9 and he was running an aftermarket EFI intake. I never got to talk to him to see where he got it but someone, somewhere makes/made it.
4)I'm no help here
5)I like MSD for ignition. the stoke dizzy should be fine though, just get a good coil and set of wires.
2) you would be better off making an adaptor plate than welding and drilling new mounting holes.
3)I would look around for an EFI manifold. The dome shape will not be working with that cam too well.
I remember a guy coming in with a 98 GC Limited with a bored and stroked 5.9 and he was running an aftermarket EFI intake. I never got to talk to him to see where he got it but someone, somewhere makes/made it.
4)I'm no help here
5)I like MSD for ignition. the stoke dizzy should be fine though, just get a good coil and set of wires.
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