how many 3.9's here
Legend
Joined: Jun 2009
Posts: 8,025
Likes: 72
From: orangeville ontario
the 3.9 in my 91 was replaced by a 318 a while ago. i know SixGun was running a 3.9 but as of today the 3.9 was removed to make room for the all mighty 5.2.
http://ramcharger.net/index.php/topi...g1406.html#new
http://ramcharger.net/index.php/topi...g1406.html#new
Veteran
Joined: Aug 2010
Posts: 449
Likes: 1
From: San Antonio, Texas
Yessir I really liked that 3.9 but a friend made me a deal I couldn't refuse on a 91 5.2 motor. Pretty easy swap since it's the same year and he gave me all the accessories, TBI, radiator, shroud, wiring harness and computer. 
You looking for some help or just curious if you were the only one. I felt that way sometimes. I had mine rebuilt and I really liked it.
You looking for some help or just curious if you were the only one. I felt that way sometimes. I had mine rebuilt and I really liked it.
Thread Starter
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Veteran
Joined: Mar 2009
Posts: 426
Likes: 0
From: Mt Airy NC
I was just asking. How much different is the 318 compared to the 3.9? Would the 318 work with a manual that is a 4 speed with OD? How hard was it to switch motors?
Last edited by tooltime; Feb 1, 2013 at 06:29 AM.
Legend
Joined: Jun 2009
Posts: 8,025
Likes: 72
From: orangeville ontario
i don't really know. never really drove my 91 with the 3.9 in it. could never get it to run right. i have heard the a 5.2 usually gets better gas mileage than 3.9 because the 3.9 has to work hard to move a full size truck. as far as i know a 318 will bolt the 4 speed but to stick a 318 where a 3.9 was you will need a motor mount extension plate on the drivers side. you should be able to find them on any 88-93 2wd dodge ram trucks with a 318.
this is the bracket you would need. you can thank SixGun for the picture.
this is another picture i found of the same bracket installed.
this is the bracket you would need. you can thank SixGun for the picture.
this is another picture i found of the same bracket installed.
Veteran
Joined: Aug 2010
Posts: 449
Likes: 1
From: San Antonio, Texas
What size tires are you using and do you drive alot on the freeway? With P235/75/15's or even 31's it drives well on the freeway but with the 33's and some hills it has to downshift frequently. My A999 is only a 3 spd so going 70 mph (typical TX freeway) it sees 3100 rpm but with the new radiator it stays cool.
The V6 and 5.2 share the same transmissions so there should be no problems. The motor mount on a 5.2 requires that adapter that CW posted. It basically pushed the mount forward and replaces the triangle mounting plate that is on the crossmember. If you pick one up at the JY, be sure to take the bolts since you need 4 bolts to hold it in place instead of 3 on the triangle one.
I'm sure that there will be more power but like I said previouly, I really liked my 3.9 and had no problems after the rebuild. I put a high flow cat and Thrush muffler and combined with an open element air filter, it's drives better. Typical Dodge truck stuff like relays, sensors, egr and injectors had to be cleaned or replaced but now it starts every time without a hitch. I'll update after the install and some drive time for a comparison.
How does yours drive? Sounds like your concerned.
The V6 and 5.2 share the same transmissions so there should be no problems. The motor mount on a 5.2 requires that adapter that CW posted. It basically pushed the mount forward and replaces the triangle mounting plate that is on the crossmember. If you pick one up at the JY, be sure to take the bolts since you need 4 bolts to hold it in place instead of 3 on the triangle one.
I'm sure that there will be more power but like I said previouly, I really liked my 3.9 and had no problems after the rebuild. I put a high flow cat and Thrush muffler and combined with an open element air filter, it's drives better. Typical Dodge truck stuff like relays, sensors, egr and injectors had to be cleaned or replaced but now it starts every time without a hitch. I'll update after the install and some drive time for a comparison.
How does yours drive? Sounds like your concerned.
Last edited by SixGun; Feb 1, 2013 at 02:37 AM.
Captain
Joined: Sep 2012
Posts: 611
Likes: 0
All I have for camparo is when I went from a 250ci six to a 350 in one of my 1970s chev trucks.
With the six, it got great mileage round town and on the freeway unless I was honking on it. Average was 18. It had great tq, pulled a 23ft flat bed with a full sized Ford on it for 130 miles fine. Problem towing is on long hills it runs outta steam and has to be floored. Empty it is great on the hiway.
After the 350, way more mid range and pulling power in the mid and up but mileage went to 12 average. Around town mileage was horrid. And in town and down the hiway, the six was SMOOTH.
With the six, it got great mileage round town and on the freeway unless I was honking on it. Average was 18. It had great tq, pulled a 23ft flat bed with a full sized Ford on it for 130 miles fine. Problem towing is on long hills it runs outta steam and has to be floored. Empty it is great on the hiway.
After the 350, way more mid range and pulling power in the mid and up but mileage went to 12 average. Around town mileage was horrid. And in town and down the hiway, the six was SMOOTH.