PUTTING TOGETHER THE 3400 WITH 3100 PARTS
This is what I had to begin with on the 3400: The long block, heads, valve covers, and the lower intake manifold. I did not have any of the accessories on the side, it was stripped down to the timing chain cover.
There is one difference between the 3400 and the 3100 timing chain covers - this is crutial information. The 3400 has a a protruding stud that just isn't on the 3100 timing chain cover. Here's a picture with the 3400 timing chain cover on the left side.
At first glance you might not even notice the difference. If you wanted you could just cut off the stud on the 3400 though. Another thing to note is that some of the bolts on the 3400 are long since they are meant to bolt on different accesories. For example, look at the smaller peice sitting next to the 3400 timing chain cover in the picture above. It has longer bolts so that it can secure that peice down. In this case you will have to use the bolts from the 3100 there or else the blots will obviously be too long.
The valve covers are identical - accept that mine were plastic and the 3400 one were aluminum. Some 3100s still have aluminum though.
The bolt pattern to the bellhousing on the transmission is identical between the 3400 and the 3100.
The lower intake manifolds on the 3100 and 3400 have the same bolt pattern, but not the same bolt patterns between their upper and lower peices. This means that you can use the entire 3100 intake on the 3400 or vice versa, but you can't swap just the upper parts. Since I did not have the upper 3400 manifold I was forced to use the 3100 for the time being.
The heads have the same bolt pattern, bu t they are different design styles, depending on what year 3100 you had. My 3100 had stamped roller rockers and the 3400 had a partial roller set up. These rockers are not swappable bewteen heads. With the roller style the studs come off with the rocker, but on the stamped rocker style they are very much a part of the head. Both heads have "D" shaped ports. This design style is something that branched off of the performance scene. The guy, Vince, that did the work on my heads said he personally new the designer who had this engineered into the 3100 heads. They have found that this design in the "D" shape with a short radius turn flows less but faster than the bigger round port. So over a time interval it will get out more exhaust more efficiently.
The heads on the 3100 have a spot for the the temp sensor that goes to your instrument cluster. The 3400 heads don't. I'm kinda stumped right now because I haven't found a solution to this yet (11/2/01). But I'm looking into a few things and I'll get it fixed soon hopefully.
The exhaust manifolds from the 3100 bolt right up to the 3400.
If you use the 3100 intake the 3100 fuel system bolts right up, obviously.
The oil pump is the same between the two.
The 3400 suposedly requires platinum plugs and a gap of .060". Thats all true. I don't see why you wouldn't just use normal plugs though.
Swapping all the parts is really cut and dry for the most part, and its the easiest part of the job too. Let me know if I missed anything.
