92 Dakota 318 Mods
Record Breaker
Joined: Nov 2015
Posts: 2,232
Likes: 473
From: North Carolina
Yes you can use 1.7 roller rockers with stock springs, that's what I have in my 5.9.
The AX15 is a far better transmission than the NV3500, the Jeep guys figured that out long ago. New Venture has been out of business over a decade, and the majority of parts you find to rebuild the NV3500 are made overseas and subpar. The AX15 on the other had is made by Aisin a Japanese company that is still alive and well, It is very similar and shares many of the same components as the R154 transmission put in the old Toyota Supras, there is a ton of good parts still available for them and they can be built to handle 500hp or more, you can also still buy brand new units from Aisin. People have ran the AX15s on small block and LS swapped Jeeps for years without any issues. I wouldn't trust Chrysler engineers on anything related to transmissions they didn't design the NV3500 or the AX15 but they did design the crappy auto transmissions all the trucks used.
The AX15 is a far better transmission than the NV3500, the Jeep guys figured that out long ago. New Venture has been out of business over a decade, and the majority of parts you find to rebuild the NV3500 are made overseas and subpar. The AX15 on the other had is made by Aisin a Japanese company that is still alive and well, It is very similar and shares many of the same components as the R154 transmission put in the old Toyota Supras, there is a ton of good parts still available for them and they can be built to handle 500hp or more, you can also still buy brand new units from Aisin. People have ran the AX15s on small block and LS swapped Jeeps for years without any issues. I wouldn't trust Chrysler engineers on anything related to transmissions they didn't design the NV3500 or the AX15 but they did design the crappy auto transmissions all the trucks used.
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Joined: Jun 2023
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From: Fairfax, Virginia / Radford, Virginia
Might be reviving my own dead thread but I didn't notice you guys were chatting about on here because DodgeForum stopped sending me emails about this post so I thought it died lol.
Very useful information though, I am glad to have people who are actually familiar with the platform chiming in on this. I have heard that people don't like the 360 as it gulps gas for not too much of a power gain, but I do know that its a more popular platform and a lot of parts are swappable but it can make more power.
After looking at some prices for reman. transmissions, as in the NV3500 for the Dakota, they're almost $2000 and I'm sure after shipping it will be over $2000, but my current AX15 at least I believe it's an AX15 is holding up fine. (Valvoline's info tells me I have an NP2500 when I scan the VIN, I'm sure its wrong but I'm not sure). As it is my second vehicle after reading what you guys have been saying I think I'll just leave the AX in there and if it blows up then I'll look at getting a replacement. Any money I can not spend now would be ideal as I'm in college so knowing this info relieved me a bit.
In terms of cam vs rockers, I know with the 3.9 the Sharps make a wild difference in the power, but for the 318 is there really a difference between getting a mild cam vs getting the rockers? I'd imagine the rockers can get away with having longer duration or lift whatever it ends up doing because the computer doesn't see it happening? (I have no idea how these mods work lol)
I do know after looking more at headers that the long tubes would probably not work on the 4x4 at all because of the torsion bars and the whole front end setup so I would probably go down the route of shorty headers. I bought JBAs for my 3.9 (yes I know, boo) but they actually make quite the difference in the tone of the engine. About the 2.5" duals vs 3" single, how would the tone sound though, I know most trucks have a single exit but most cars have a dual exit with x pipes, does the sound really change at all?
I do plan to do everything at least that I can do by myself, myself, as I would like to have this as a budget project. I'm planning to find a 318 or maybe a 360 if the MPG wouldn't be a lot worse, and pull it apart, buy new heads like you recommended, give it a good rinse down, good cleaning, etc. Then a spray job. I'm basically doing a frame off restoration on this truck unless I can find a new frame that isn't $1000 and in a different time zone. Has some rusted out places that I've put what I call a metal band aid over, but I'm going to cut it all out and properly repair it and reinforce some places of the C channel as well. With the extra money I can save keeping the AX15, I can put that money towards a respray for the body, fixing the blower leak at least what I think is a blower leak, water and air at highway speed coming through the dash on the passenger side. (I checked the AC drain and it does have that extension piece that people have talked about on other forums).
I guess in terms of intake related stuff, if the intake without a tune isn't worth it I can just hold off until I find an aftermarket ECU I can drop in so I can actually tune the motor. In the case I do find one, isn't there only so much I can do with the 1.7 ratio rockers when it comes with a cam? Or can I talk to someone at one of the big companies about what I have and what would work? I know that 1.7 ratio rockers with a bigger cam would cause too much lift.
Feel free to chime in on any more info for me, I'm starting to add up parts for this truck now so I know what I'm getting myself into once I get this project started.
Very useful information though, I am glad to have people who are actually familiar with the platform chiming in on this. I have heard that people don't like the 360 as it gulps gas for not too much of a power gain, but I do know that its a more popular platform and a lot of parts are swappable but it can make more power.
After looking at some prices for reman. transmissions, as in the NV3500 for the Dakota, they're almost $2000 and I'm sure after shipping it will be over $2000, but my current AX15 at least I believe it's an AX15 is holding up fine. (Valvoline's info tells me I have an NP2500 when I scan the VIN, I'm sure its wrong but I'm not sure). As it is my second vehicle after reading what you guys have been saying I think I'll just leave the AX in there and if it blows up then I'll look at getting a replacement. Any money I can not spend now would be ideal as I'm in college so knowing this info relieved me a bit.
In terms of cam vs rockers, I know with the 3.9 the Sharps make a wild difference in the power, but for the 318 is there really a difference between getting a mild cam vs getting the rockers? I'd imagine the rockers can get away with having longer duration or lift whatever it ends up doing because the computer doesn't see it happening? (I have no idea how these mods work lol)
I do know after looking more at headers that the long tubes would probably not work on the 4x4 at all because of the torsion bars and the whole front end setup so I would probably go down the route of shorty headers. I bought JBAs for my 3.9 (yes I know, boo) but they actually make quite the difference in the tone of the engine. About the 2.5" duals vs 3" single, how would the tone sound though, I know most trucks have a single exit but most cars have a dual exit with x pipes, does the sound really change at all?
I do plan to do everything at least that I can do by myself, myself, as I would like to have this as a budget project. I'm planning to find a 318 or maybe a 360 if the MPG wouldn't be a lot worse, and pull it apart, buy new heads like you recommended, give it a good rinse down, good cleaning, etc. Then a spray job. I'm basically doing a frame off restoration on this truck unless I can find a new frame that isn't $1000 and in a different time zone. Has some rusted out places that I've put what I call a metal band aid over, but I'm going to cut it all out and properly repair it and reinforce some places of the C channel as well. With the extra money I can save keeping the AX15, I can put that money towards a respray for the body, fixing the blower leak at least what I think is a blower leak, water and air at highway speed coming through the dash on the passenger side. (I checked the AC drain and it does have that extension piece that people have talked about on other forums).
I guess in terms of intake related stuff, if the intake without a tune isn't worth it I can just hold off until I find an aftermarket ECU I can drop in so I can actually tune the motor. In the case I do find one, isn't there only so much I can do with the 1.7 ratio rockers when it comes with a cam? Or can I talk to someone at one of the big companies about what I have and what would work? I know that 1.7 ratio rockers with a bigger cam would cause too much lift.
Feel free to chime in on any more info for me, I'm starting to add up parts for this truck now so I know what I'm getting myself into once I get this project started.