tornado_735 Posted January 11, 2010 Report Share Posted January 11, 2010 Ok, so I have discovered oil in my coolant, which is looking like a leaky LIMG. 3100, 177K miles. In my post about the oil in my coolant, I asked about what I could do while I had the intake manifolds off. RobertISaar suggested a 3400 top swap. Now, this is an idea I have been mulling over in my head for a while, and would like to do it. But I have some questions about it. What are the major differences between the 3100 and 3400 engines? What are the major similarities? What all parts are needed for this job? I thought I read somewhere that it requires only the heads and the intake manifolds (and obviously all the related gaskets). What else would I need? Throttle body maybe? Fuel rail and injectors? Camshaft? Is there a specific year or body style that the donor parts would need to be from? What are the advantages of having a 3400 top end on a 3100 bottom end? Are there any disadvantages? Any other information you guys can provide will do nothing but help me when I go to get the parts and do this this spring. Thanks! Aaron Quote Link to comment Share on other sites More sharing options...
19Cutlass94 Posted January 11, 2010 Report Share Posted January 11, 2010 The cam shafts are the same. The heads have bigger ports and bigger valves. The basic difference between the two is bore sizes and intake/exhaust port sizes, tb sizes, in a nutshell. Everything else, even sensor wise, is pretty much the same. What you will need for the swap, besides all gaskets, are 3400 heads intakes and throttle body. (56mm for the 3400 vs 52mm for the 3100 ) MAP sensor bracket, since it is different. Use your 3100 fuel rail and injectors. Everything else is the same ( unless I forgot something which I probably did ) There really are no disadvantages, unless you forgot you did it and ordered wrong parts. Theres only gains to be made by the better intakes, larger TB and better flowing heads. A 3400 is a 3400, doesnt matter what its out of because your only using a select few parts. Quote Link to comment Share on other sites More sharing options...
tornado_735 Posted January 11, 2010 Author Report Share Posted January 11, 2010 The cam shafts are the same. The heads have bigger ports and bigger valves. The basic difference between the two is bore sizes and intake/exhaust port sizes, tb sizes, in a nutshell. Everything else, even sensor wise, is pretty much the same. What you will need for the swap, besides all gaskets, are 3400 heads intakes and throttle body. (56mm for the 3400 vs 52mm for the 3100 ) MAP sensor bracket, since it is different. Use your 3100 fuel rail and injectors. Everything else is the same ( unless I forgot something which I probably did ) There really are no disadvantages, unless you forgot you did it and ordered wrong parts. Theres only gains to be made by the better intakes, larger TB and better flowing heads. A 3400 is a 3400, doesnt matter what its out of because your only using a select few parts. Awesome, thanks a lot. Will I have to mess with the timing or the computer at all? Quote Link to comment Share on other sites More sharing options...
Crazy K Posted January 11, 2010 Report Share Posted January 11, 2010 ok.... I top swapped the intake manifolds from a 3400 u-van onto a 95 3100. This is basically making the small port 3100 (L82) into a large port 3100 (LG8). The butt dyno says this gives you more high end power, though is not certain... I'd like to see some numbers... since i had a 95 i had to make an adapter plate to mount the EGR, and lucky me, I had roller rocker provisions, so i was able to do that too. You will have to clearance the large port intake if you cannot use roller rockers due to lack of provisions. i would NOT mess with the long block(leave the heads alone!), if you don't need to. Quote Link to comment Share on other sites More sharing options...
19Cutlass94 Posted January 11, 2010 Report Share Posted January 11, 2010 No. Your PCm will adjust to the changes. You cant tune your PCM anyways without swapping to OBDII or OBDI Quote Link to comment Share on other sites More sharing options...
Jonpro03 Posted January 11, 2010 Report Share Posted January 11, 2010 If you use your 3100 accessories you wont be able to use the alternator support bracket that run from the back of the alternator to the UIM. There is a noticeable difference though. My 1/4 time went from 16.7 with a stripped interior and trunk, to 16.44 with a full interior. 40-60mph vids stock 3100 after upgrades: Racing a 4.0 ranger with 75 shot nitrous and 5spd before: after: Quote Link to comment Share on other sites More sharing options...
19Cutlass94 Posted January 11, 2010 Report Share Posted January 11, 2010 ok.... I top swapped the intake manifolds from a 3400 u-van onto a 95 3100. This is basically making the small port 3100 (L82) into a large port 3100 (LG8). The butt dyno says this gives you more high end power, though is not certain... I'd like to see some numbers... since i had a 95 i had to make an adapter plate to mount the EGR, and lucky me, I had roller rocker provisions, so i was able to do that too. You will have to clearance the large port intake if you cannot use roller rockers due to lack of provisions. i would NOT mess with the long block(leave the heads alone!), if you don't need to. If he swaps on 3400 heads and intakes he doesnt have to worry about rocker issues.... Quote Link to comment Share on other sites More sharing options...
19Cutlass94 Posted January 11, 2010 Report Share Posted January 11, 2010 Oh yeah and I forgot about the EGR, youll need an EGR adapter. You can buy those from http://www.wot-tech.com Quote Link to comment Share on other sites More sharing options...
Jonpro03 Posted January 11, 2010 Report Share Posted January 11, 2010 I forgot too... I got the block plate <---- SCREW YOU EGR!!! Quote Link to comment Share on other sites More sharing options...
tornado_735 Posted January 11, 2010 Author Report Share Posted January 11, 2010 Ok, so I can just swap the intake manifolds without swapping the heads? What is the problem with the rockers if I do that? Quote Link to comment Share on other sites More sharing options...
19Cutlass94 Posted January 11, 2010 Report Share Posted January 11, 2010 If you just swap intakes you have to grind down the LIM for clearance for the fulcrum roller rockers. And you wont see nearly the gains as compared to swapping heads as well. Quote Link to comment Share on other sites More sharing options...
tornado_735 Posted January 11, 2010 Author Report Share Posted January 11, 2010 No. Your PCm will adjust to the changes. You cant tune your PCM anyways without swapping to OBDII or OBDI Ok, I didn't know if the PCM would be able to adjust to these types of changes. I know they have preset limits, and figured these types of changes would exceed them. If you just swap intakes you have to grind down the LIM for clearance for the fulcrum roller rockers. And you wont see nearly the gains as compared to swapping heads as well. Would swapping 3400 heads be just as straightforward as just swapping 3100 heads? Quote Link to comment Share on other sites More sharing options...
19Cutlass94 Posted January 11, 2010 Report Share Posted January 11, 2010 PCM does have limits, but it can adjust quite abit. Yes swapping the heads would be like just changing your head gaskets and puttin the 3100 heads back on. Very straight forward. Quote Link to comment Share on other sites More sharing options...
tornado_735 Posted January 11, 2010 Author Report Share Posted January 11, 2010 PCM does have limits, but it can adjust quite abit. Yes swapping the heads would be like just changing your head gaskets and puttin the 3100 heads back on. Very straight forward. Awesome. This is just sounding better and better. Quote Link to comment Share on other sites More sharing options...
Jonpro03 Posted January 11, 2010 Report Share Posted January 11, 2010 Definately swap to 3400 heads. Im not sure if you need the 3400's pushrods though. Quote Link to comment Share on other sites More sharing options...
tornado_735 Posted January 11, 2010 Author Report Share Posted January 11, 2010 Definately swap to 3400 heads. Im not sure if you need the 3400's pushrods though. I was wondering that myself. Quote Link to comment Share on other sites More sharing options...
tornado_735 Posted January 11, 2010 Author Report Share Posted January 11, 2010 It looks like you can buy a top swap kit off that website you gave me Jay! Quote Link to comment Share on other sites More sharing options...
19Cutlass94 Posted January 11, 2010 Report Share Posted January 11, 2010 They should be the same length. But you can verify that when you pull the heads off the 3100 and when you get your 3100 apart. Quote Link to comment Share on other sites More sharing options...
AWeb80 Posted January 11, 2010 Report Share Posted January 11, 2010 I want to U/L/TB swap my GP soon too. I would do the heads, but w/ my new log manifold on there, it's impossible to get to the exhaust studs off because some of the welds around the flanges are in the way. ....sadly, if a HG ever goes out, I gotta pull the motor....LOL Quote Link to comment Share on other sites More sharing options...
19Cutlass94 Posted January 11, 2010 Report Share Posted January 11, 2010 Or you could just unbolt the log manifolds where they meet the x-over Quote Link to comment Share on other sites More sharing options...
tornado_735 Posted January 11, 2010 Author Report Share Posted January 11, 2010 I want to U/L/TB swap my GP soon too. I would do the heads, but w/ my new log manifold on there, it's impossible to get to the exhaust studs off because some of the welds around the flanges are in the way. ....sadly, if a HG ever goes out, I gotta pull the motor....LOL I think that's about the only improvement you could make to an already perfect car. Quote Link to comment Share on other sites More sharing options...
xtremerevolution Posted January 11, 2010 Report Share Posted January 11, 2010 I want to U/L/TB swap my GP soon too. I would do the heads, but w/ my new log manifold on there, it's impossible to get to the exhaust studs off because some of the welds around the flanges are in the way. ....sadly, if a HG ever goes out, I gotta pull the motor....LOL Do what the jaguar guys do and use bolts instead of studs and nuts to put the exhaust back on where its difficult to reach. To get the heads off the V12, you have to disconnect an engine mount and tilt the engine because there isn't enough room. Replacing the studs with bolts solves the problem, and no cases of bolts loosening have been reported. Quote Link to comment Share on other sites More sharing options...
AWeb80 Posted January 11, 2010 Report Share Posted January 11, 2010 Or you could just unbolt the log manifolds where they meet the x-over FK I didn't even think of that Quote Link to comment Share on other sites More sharing options...
tornado_735 Posted January 11, 2010 Author Report Share Posted January 11, 2010 Or you could just unbolt the log manifolds where they meet the x-over FK I didn't even think of that And to think you wanted to do it the hard way Quote Link to comment Share on other sites More sharing options...
AWeb80 Posted January 11, 2010 Report Share Posted January 11, 2010 Or you could just unbolt the log manifolds where they meet the x-over FK I didn't even think of that And to think you wanted to do it the hard way damn you Jay...now I have to do more work. Still need to get all my parts though...then Port/polish and Powdercoat them.. Quote Link to comment Share on other sites More sharing options...
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