3400 Top End Swap onto 3100 Block - COMPLETE w/ Pix

[GP1138]

I just got done driving my new 3400/3100 hybrid Grand Prix.

Anyway, the whole thing went alright, but the biggest news is we discovered something that (I think) nobody else really knew yet. My car is a 1995.5 model year, made in May of '95. It had the provisions for roller rockers, and we just swapped the roller rocker arms onto the new heads. This apparently has worked perfectly, as I don't hear rockers hitting intake runners. The heads with the rollers that I picked up from the junkyard ended up being fairly nasty, so we just decided to try the roller swap, and it ended up working perfectly. A shame we found that out AFTER we pulled the 3100 heads. We ended up doing that like 3 times, and the exhaust manifolds are a BITCH on this car.

For being the first engine job I've ever done, I'd say it went smoothly. I'm already noticing high end (read: +5500RPM) gains, not a huge amount, but the car pulls to the yellow line on the tach now. The ass dyno is definitely accurate here. The only problem I have right now is that the engine runs hotter than it used to. Maybe there's some air still in the system, but it just worries me. It doesn't peg itself like it was doing when we were bleeding the system, though. That was annoying as hell.

We worked from about 1 in the afternoon Saturday until about 5 in the morning Sunday, so Chris and I are fried. Matt didn't seem to get tired at all, we got back to my house and he just drove the hour home right then while Chris and I just crashed.

Definitely a bitch of a job, but a lot of fun, too! And I can say I've modded my car beyond adding Beavis and Butt-head stickers now!!


Pictures!


Before the carnage started...


Plenum Removal


This is why the swap is worthwhile... and why before my car fell flat on it's face after 5500RPM... look how much bigger those intake runners are!


Chris monkeying around with something...


Me getting ready to yank off the LIM of the 3100....


Lower intake manifolds! Left: 3400 Right: 3100...


Yes, it's an engine!!


What a mess!


No!!!!! Stop!!! Don't remove those head bolts!! (Funny: we actually broke 2 3/8" Craftsman 15mm sockets before we switched over to 1/2" and a cheater bar...)


Chris with a light and oil dipstick tube between his legs trying to remove rear manifold nuts...


Me trying to do the same thing...


.....


Engine!!

Not many more pics because my Grandpa's very expensive camera need not have been damaged by our greasy hands, and we got too into what we were doing. Finished shot soon...

[ikessky]

RE: 3400 Top End Swap onto 3100 Block

I broke 1 Craftsman socket and 1 extension when I was removing my heads. Hopefully my next car will have more room to manuver in the engine bay than my N-Body does!

[korbendallas68]

Nice. I used the black impact-wrench sockets on those. They are a PITA!!! I was trying to removing them from my old 3.1, Goddamn. I had a huge freaking bar on that bastard to even budge them. Of course the block was pretty rusted too.

[JamesonGT282]

I tried removing the heads on my original 135k 3.1 and the studs and exhaust mani bolts were so baked that a breaker bar was of no use.

It was too bad because I had gorgeous flow benched heads with a 3 angle valve job and custom springs and retainers read to install

[94CuttySL]

That's a job that hopefully I'll be doing this summer. Those pics really show how much of a difference those 3400 plenums make. I'm stock now (besides a cone intake) and I pull above 5500rpms. I LOVE how this engine revs! Can't wait to see my results after this mod.

[AaronGTR]

Nice. I woulda removed the exhaust manifolds before the other stuff though... just so you don't have to sit on your engine and risk contaminating it with dirt and stuff while the lower intake is off. Anyway, you should definitely notice a big improvement with that gear. The 3400 stuff was designed to flow much better. Did you switch cylinder heads too, or just intake manifolds and rockers? I would think if you used the 3400 mani's with 3100 heads that would reduce their effectiveness since the ports wouldn't match in size.

[GP1138]

Nice. I woulda removed the exhaust manifolds before the other stuff though... just so you don't have to sit on your engine and risk contaminating it with dirt and stuff while the lower intake is off. Anyway, you should definitely notice a big improvement with that gear. The 3400 stuff was designed to flow much better. Did you switch cylinder heads too, or just intake manifolds and rockers? I would think if you used the 3400 mani's with 3100 heads that would reduce their effectiveness since the ports wouldn't match in size.

We just switched the roller rockers from the newer 3100 heads onto my car's old heads and used them. All the stuff on my car was clean as hell, the 3100 roller rocker heads were dirty as hell, so we didn't want to use them.

We made sure the engine stayed clean as much as possible.

I did detect a little low end loss, but it makes up in spades in the upper end.

If I don't like the way this project turns out, I may end up buying a whole 3100 and dropping that in....

[fierofanatic88]

Yeah when I took my heads off I cracked two 15' and broke a 3/8 drive. (couldnt find the breaker bar)

I am doing the same swap to a 3100 only I have a 3400 set of heads as well. PLUS my regrind from Comp just arrived!!!!! Which should compliment this Topend even more.
So its time to get the engine built back up and drop it in.

[v6h.o.]

I always pull both heads with the manifolds and Xover still attached, then again I have air tools to break the exh manifold nuts loose with after they're out so I guess it would be easiest to crack the nuts loose Leave attached, Pull as one bit unit (its not that bad) and hten on the bench remove all nuts with easy access.


Looks good. Have fun with the new setup!

[RODAN]

Does it matter if you use the original exh.mani. or the 3400's?

[dbtk2]

IIRC the 3400 manifolds and 00+ 3100 manifolds flow better...but i could be wrong.

My heads were not easy to get off (you can't expect them to be, otherwise how is the gasket gonna seal?). I just took a 15mm impact socket, and my breaker bar with a 6ft. pipe on the end of it and they all came off with no problem.

I'm thinking about pulling my intakes off my STE and going with the 3400 intakes since I have the small port 3100 stuff, but I don't want to change my heads so I don't know if it will make much difference. I know that going from the Gen II to the Gen III topend made a HUGE difference above 5k. My STE used to drop off at about 5k and really drop off at like 5500, with the topend (and cam of course), it just keeps pulling all the way to the limiter, and I'm running 3psi less boost than I did before!

Shawn

[Rhedalert]

With the exception of the bigger intake port on the '00+ 3400 heads, all 3x00 heads should flow the same. Just the older ones ('93.5- early '95) have the stamped rockers w/ no provisions for the rollers.

Fierofanatic: Let us know how it responds to the cam! I want to get a cam grind which improves low-mid range on my engine. Did you get custom length pushrods too?

[fierofanatic88]

With the exception of the bigger intake port on the '00+ 3400 heads, all 3x00 heads should flow the same. Just the older ones ('93.5- early '95) have the stamped rockers w/ no provisions for the rollers.

Fierofanatic: Let us know how it responds to the cam! I want to get a cam grind which improves low-mid range on my engine. Did you get custom length pushrods too?

They only took .02 of the base circle so ther really shouldnt be a need to change pushrods, but I am going to check the preload just incase. Also I talked with Matt at Comp Cams in their Tech dept. He was the one who helped me spec the cam He said this particular setup should start making power at 2200. I'll let ya know.