3500 plenum swap check list.

[IsaacHayes]

Ben, that sounds great. I'll take it! I'll need to swap out my original shaft anyways to keep my cruise control, so no biggie there! PM incoming.

I'm not sure how much shipping will be on the 25 u/l manifolds... But still cheap! I still do want the 3500 as it really is designed better IMO.

If I were to do 3400 heads, I would need:
3 wire ECT sensor
Head gaskets
Exhaust gaskets
Bolts
Pushrods that come with the 3400 heads..

... and that's it right? And I just remove and replace right? No worries about keeping something alingned etc correct? How hard is taking off the exhaust manifold?

I'd essientially have a large port 3100 w/3500 plenum then without pulling out a motor! Only with 180k on the bottom end still!

[bszopi]

To answer the question about the rockers and interference with the manifold... I would still check it. It appears that the newer manifolds are ground down, but I think I remember hearing that someone had one that still needed ground down slightly more in an area.

As far as checking by turning the engine over, I just put a breaker bar on the pulley nut and turned it over. Then I visually watched each rocker as it passed by the manifold. Could use a feeler gauge as well to check clearances.

[IsaacHayes]

Ok, that will work. Might have to have another person on the back side looking while another turns it. How much clearance is recommended? at least 1mm? Oh and what's a good angle to get a breaker bar in there, from under neath with the wheel off? Not much room to work, you know what I mean...

ADDED: BTW Brad, I happened to notice your 1/4 times, not much different from my stock time, is that with the 3400? How come not many people with berettas and 3400 swaps are very fast? My track conditions were -far- from ideal and it was my first time to a strip. Do I have a freak stock 3100 and I should just leave it alone!!! Hate to do all this work and only get .1 sec shaved off!! lol.


For gaskets/bolts for the heads looks like 100. Felpro regular headgaskets and bolts work ok? Are the exhaust manifold gaskets re-useable?

I would just unbolt the heads, and bolt on the replacements? Going to cost a couple hundred more for that, but I wouldn't have to worry about rocker clearance and I'd get more power of course...

[bszopi]

With the exception of the 62mm TB and FPR, that was a completely stock 3400. It was actually an improvement over my 3100 times in various states of modification. As I think Ben stated, the 94 & 95s are pretty much restricted by the lack of tunability.

[onefastV6]

To answer your question about the KR, yes my car had 10* of KR stock, however when I dynoed for the first time I managed to put down 143.2 HP which is identical to 2 other Grand Am's that have dynoed stock.

[IsaacHayes]

Brad, so why do I have such a good stock time? If I mess with the heads, is there a chance I might not gain much at all over my stock power? What about intakes? I would think the intakes would only improve me, and perhaps my heads are magic and keep KR low, LOL.

onefast: Hmm. What octane do you normally run? Is it ethanol, or have any other additives?

I always thought my 3100 ran a bit rich, O2 sensor has 180k on it. Perhaps that just happens to help me out! hahaha.

[SappySE107]

he is running 89 now, not sure on additives but I don't believe we have them in indiana.

That O2 sensor is beyond done.

[IsaacHayes]

sappy, yeah I figured the O2 is toast, but car runs so excellent & responsive, that I never bothered replacing it. Would a Denso brand work good? And any idea why my stock motor runs so freaking good apparently? Would putting different heads on there perhaps ruin that? I kind of think of my motor as "seasoned" and "experienced", is why it runs nice lol.

[rx191]

? why is there a tunablity problem wit hthe 94 95 engines, so what they are obd1.5 engines, the sofware is just a mix of obd2 logic with obd 1 simplicity. i have seen the files for these computers and there really isn't anything to compicate about them, i think the obd2 computers are harder to program.
some one enlighlten me.

[SappySE107]

I think you should enlighten me on the OBD1.5 code then since its not a removable chip and the only programmer for it is a tech 1 and probably tech 2. What software did you use to read the computer and decode the hex to real data?

OBD2 has programmers with software already setup to give the data information so you can edit it. I haven't seen anything near that simple for the flash OBD1.

Isaac, i really dont know what to tell you as far as the swap and what it will do if you change the heads. I only know what I have seen and flowed. No way to know for sure unless you do it.

[IsaacHayes]

Well the ODBII cars there are stuff like DHP I believe that you can just edit the computer's parameters. With 93 you can custom burn a chip with the program and drop it in. With 94-95, it doesn't have a chip, and it's not ODBII so nothing like DHP offers anything for them. They don't have a ODBI diagnostics port, yet they run ODBI. If you know of someway to get access to tune it, I'm all ears....

[IsaacHayes]

Getting back on topic here, I've been continuing to edit the first post to update it with information and corrections. I've just added a new section on gaskets. Hopefully this thread will help anyone wanting to do a 3500 plenum, regardless of what gen3 motor they have. They can print it out, and have every issue covered. If they've removed their lower manifold before to replace a leaky gasket, then with this thread they should know what they need to get it done in one day/afternoon.

Many, many, thanks to sappy and everyone else who has helped with (and continues to) this info and my PM's!!

If any part of the first post is inaccurate let me know and I'll edit it.

Soon I'll have another tough thing to figure out, what color(s) to paint the 3500 plenum! What do you think about black, with filling the grooves with red? Or yellow? Or black with a large bowtie in the grooves? Or "SS". Or CHEVROLET, or BERETTA?

EDIT: I'm going to replace the O2 sensor also. Just thinking about it with 180k on it, and knowing my car has smelled rich before, I was out last night and in the drive through of Wendys, while I was gagging on rich exhaust. I know my cat is old, but it shouldn't smell like raw gas with no cat. No gas smell under the hood so it's not the EVAP cansister, and it got worse with blipping the throttle and the exhaust rolling by my window.

I'm running pig rich because of the bad O2. ECT is new, so it must be o2. However, the car doesn't run bad because of this, throttle response is great and so is power. But my gas gauge dropped 1/8th of a tank just driving to wendys, to two bars, then back home.... Hopefully replacing it won't take away my motors magic power... hopefully I'll gain some!

[IsaacHayes]

I need a little more help. Which paint scheme do you like for the 3500 manifold? I will be painting the valve covers and lower intake black as well. It will be in my bright aqua metallic Beretta.

I hope MidnightriderZ24 doesn't mind me using his photos to make A&B. Colin, I used your pic for C. If you guys mind, let me know.

A)
B)
C)

Do you like A or B more (painted lines)? Also, I think I should cut off the 2 tabs on the front of the plenum that has the holes in there. I can't think of anything to mount or attach to them, so it would be cleaner without them. C shows a manifold where they've been cut off.

[PCGUY112887]

I like A.

Now say for someone with a 96 3100 from a GP Sedan, would this be as striping down to the LIM to replace the gasket, then insted of putting the stock pieces back on put a 3400 LIM and a 3500 UIM on? I notice you guys talking about the MAP... well I have a MAF so i'm not sure what to do there.

[IsaacHayes]

Update on the paint scheme: I'm going with C (no red stripes, and the tabs removed). I'm also going to remove the side tab. In addition, I think I'm going to try to polish the valve cover when I take it off. If that takes too much time, then I'll say forget it and paint it orange. Yes orange. Might look bad in my aqua color engine bay. If it does, it's easy to take it back off paint it black and be done with it. Below is a photoshop of the valve cover orange:

I've got a Denso O2 sensor coming in wednesday, so hopefully my mpg will go up. Got to get on the ball on getting the lower manifold ordered. Then it's just getting the little things and painting/porting the stuff. As mentioned above I'll be doing a fenderwell intake setup. Probably a 7" K&N. I will wait until after the manifold is on as the neck comes off further than a 3100.

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PCGUY112887: Pretty much. You have roller fulcrum rockers I believe, so no worries about clearance with the 3400 lower. You will have to tap the coolant passage where the heater core metal pipe goes in with a 3/4" (i think) NPT or get a 96-99 3400 van LIM. Or you could get a different pipe that is the newer no-screw on type that uses an O-ring. I think I'll do that if the cost is ~8 as that's as much as that screw on adapter thing that always falls apart when you take it off. (I hate that thing).

You'll of course have to do all the same mods to get the 3500 upper on though. You have a MAP and a MAF, so that's not rellevant. The MAF is just a peice on your air filter ductwork that goes to your TB. Mine doesn't have one but that doesn't change anything in regards to this swap. We both have MAP's. It's by the coilpacks up on the intake manifold, little rectangle thing.

Summary: do all what I have to do but you don't have issues with rockers.
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I got the 56mm TB body and blade, allong with the TB adapter in the mail. Nice adapter, even has top screws to hold the TB linkage bracket in place. It's pretty much plug and play, other than modding the stock TB for the IAC to work. I might keep the o-ring on the adapter and plug the IAC passage facing the adapter, then drill a hole on the inside to let the passage open up on the other side of the blade. A little more work but you get to use the o-ring the adapter has. Then again I might just take off the o-ring and keep it as a spare and do the method listed on the adapter page on the store....

-Isaac