1994 3100 rebuild

[achievasc92]

I have a 1994 3100 with 105,000 miles, its burning oil at about 1.5 quarts every 3,000 miles. So I've decided I'm going to rebuild it over the summer. My question is, where do I find pistons for my engine? And what material rings do you guys recommend I should use? any help and experience would be appreciated. Thanks.

[achievasc92]

This will be a street driven car, I'm not going all out performance-wise but small gains would be welcome.
BTW this will be my first teardown and my daf's first teardown on a "modern" engine.

[Corpse]

Well, I'm sorry to hear that your engine quit out early for you. As for pistons, are you just looking for a stock replacement or performance part?

I'm assuming performance, since you're in here.

These are performance pistons that are stock dimensions I beleive,

Sealed Power H692CP - Hypereutectic with Coated Skirts
(I have a set of H562CP's and they are nice)

I don't know what other companies really have to offer, I couldn't find anything easily. Most companies can offer custom pistons but, as you listed, you are only looking for a little bit extra.

The piston I listed won't really improve power at all. But, it will be a great performance replacement for a GM part that is not always up to par with what it should be, the pistons.

But, you really don't need to alter the pistons whatsoever to add a little oomph and also, this would be a bad starting point unless you wanted to go crazy eventually. The only benefit is that it would make a better scenario for if you wanted to use something like a "50" shot of nitrous. But, it doesn't seem like that is what you would want.

Realistically, a better method may be to get the intake manifold, intake plenum and throttle body off of a 2000+ 3x00 setup. You may be able to find them for less than a $200 or so, set of pistons. (you don't want the injectors though)

Even a cone type or other high flow air filter, high flow cat & muffler ( or hollow cat) would probably ring you up a bit less than the pistons and give you a better overall gain than even adding a little compression.

Also, using Platinum or Iridium based spark plugs will improve performance of the coils due to the fact that they use less power to be fired. That means your ignition will seem a little better when going toward the upper RPMs. Also, there are other performance benefits of the "precious metal" that is used.

Also, about the build, make sure to use newer style intake gaskets, to avoid leaks. And also, if your engine didn't come with roller rockers it might be worthwhile to pick up a cheap used set. I got a used set on eBay for $18 + shipping so, for the increased longevity design and also, slight performance increase, it may be worthwhile for you.

-Dave

[achievasc92]

Its funny, the engine doesn't seem to have "quit" on me, it still performs very well and regularly gets 28-29 MPG (mixed driving) It just burns 1.5 quarts or so every oil change. I don't see any leaks when I park the car and the exhaust isn't "blueish" so I'm comfused. I just thought I'd use it as a reason to learn how to teardown the motor

I've heard that I need the 2000 + heads for the manifold swap (?)

When did they start using roller rockers in the 3100?

If it helps at all, my goal is a mid (maybe low ?) 15 1/4 mile,
I will be getting a magnaflow cat, and some sort of cat back (probably a crossflow muffler to match the stock setup) And a CAI from Tranzgenic or maybe make my own if I get the initiative.

Thanks a lot for the help.

[bszopi]

I've heard that I need the 2000 + heads for the manifold swap (?)

Not neccessarily... the newer style 3x00 lower will mount up and work, but the ports may not line up 100%. BUT, the ports don't match up perfectly with what you have stock anyway....

When did they start using roller rockers in the 3100?

Some platforms started using them late in the 95 model year, but pretty much all of them went to it in 96.

If it helps at all, my goal is a mid (maybe low ?) 15 1/4 mile,

If that is your goal, you'd be better off starting with a 3400 from a junkyard. You can usually pick one up for $500 or less with low mileage. That way, you could start the rebuild while still being able to drive your car.

[xxrollin]

As mentioned above. You can usually find a good 3100 or 3400 for a modest amount and build it to suit. The pistons mentioned above also are very good for the price, you cant beat'em. As for rings, I've always used Total seal's ring set's. I havent herd anyone seeing big gains but total seal claims gains in the 5-10hp is common. I believe the 2000 and up 3100 and 3400 both have the same heads with the 1.76" intake valve. I got a 2000 model engine and the O/D of the valve head measured 1.762". A 3 or 5 angle valve job should be a good starting point. You should look at having someone do some bowl work to smooth out the throat behind the valve. These few mods should get you up to 180-190hp (3100) to 190-200 (3400) for a low price rebuild.

[achievasc92]

So if I'm burning oil, I'm guessing that I have a ring or 2 shot or near shot. I'm only guessing though. So if its only a ring problem, I can just replace the rings right? The stock pistons should be ok for mild performance? These rings should work right? http://www.partsamerica.com/PartDeta...e=1267&PTSet=A

I was thinking about doing the full 3400 swap, but I have yet to find a decent 3400 at any of the yards around here. But the only major differnece between the 3100 and the 3400 is the topend (?) so a topend swap should bring me to the same power (?)

If I so the roller rocker swap I just buy them from a 96+ 3x00 and thats all I need?

Sorry if I sound like an idiot, I know how everything works but I am at a total loss with all the hybrid swap stuff.

Thanks again for the help.

BTW I have another car that I can drive while I do the rebuild and whatever else I decide to do, so thats not a problem.

[xxrollin]

You can be burning oil by the rings or even the valve seals. Those are the 2 most common areas that oil can get into the engine.
I didnt see the rings to the site you listed but from the begining, it looks like near factory replacement parts. Total seal rings are unique cause they have no gap which is better for performance and economy. They run from 100 to 200 on average. As for the differences between the 3100 and 3400, its the bore size. As of 2000, I believe the top end is the same, just the upper intake manifold says 3100 or 3400. The gains between the 2 are because the difference in the bore size. And if you want to use the factory roller rocker arms from a 96 and newer model, they wont fit your 94 heads. The rockers are on a pedistal that has a slot that centers the rocker into a groove in the head. You'll either need to find 96 and newer heads (cheaper route), or have your 94 heads modified to accept them (might be costly). Either way, it might be best to look at your options you have infront of you. You can do one of the following as either is a good direction toward a better engine:
1) Start ordering parts such as gaskets, pistons, rings, maybe even fuel pump and or fuel filter before you start to tear down the engine so you'll have these ready and waiting.
2) Find a newer 3100 or 3400 from a yard in your area to do a once over on the heads to clean them up, (the build up is pretty bad so it'd be a freashening toward a new engine).
3) Get a set of 2000+ heads and intake manifold along with some pistons and rings and have the heads ported n polished with a valve job and have the intake manifold ported n polished also. Get some newer style injecters up to a 22lbs/hr, should be good, and a 190lt/hr fuel pump and send your cam out for a regrind and look for about .02 more lift and a few degrees more duration should get you up there in power.
And all these should be done with new rings and valve seals.
Thats all I can think that should get you going in the right direction. If your looking for a little more power and economy, option #1 might be best. If you have patience and want a newer engine like the 2000+ 3100 or 3400, go for option #2. If you want more power but dont want to go for an all new engine, option #3 should work. Hope this clears some things up and helps you out.

[achievasc92]

Thanks a lot,
I still have a few months before I have time to do the build, so I still have time to look for a 3400, (if I find one, Then I'm doing the complete swap) If I don't find one , then I'm doing the rebuild.

Thanks for all the help and bearing with me.

[Corpse]

Edited for correction..

The rings you mentioned above will work, I was going to provide them as a possiblity but, I didn't want to get into rings too much.

The 2000+ manifold will work but, not line up, the port on the 2000+ and 3400 heads are 1MM taller. It would be beneficial to use 3400 or 2000+ heads but, is not completely necessary.

Swapping in the whole engine as noted above would be your easiest bet. But, you have OBD I right? You'll have to swap some stuff around a bit.

-Dave

[achievasc92]

ITs the )BD 1.5 like many 95's. It has an OBD 2 diagnostic port but a OBD 1 (as I'm told) computer.

[Sorin]

I was thinking about doing the full 3400 swap, but I have yet to find a decent 3400 at any of the yards around here. But the only major differnece between the 3100 and the 3400 is the topend (?) so a topend swap should bring me to the same power (?)

If I remember right, the blocks are ever so slightly different, in that, I think, the 3400 block is slightly meatier because of the increased bore over the 3100. 3100 is 89mm, 3400 is 92mm. People are saying there is no way in hell you want to bore a 3100 out to 92mm. I guess GM saw it this way too, so the block is a little meatier in some areas.

Or something to that effect. Depending on what you are eventually going to do to the engine, that may or may not be a "major difference" for you.

[bszopi]

As far as the notches go, I have had 3 sets of 94 heads and none of them had the notches. All of the people I have talked to about this (mainly GM service techs on this site) have said they didn't start seeing notches until mid-year 95.

If you want to read up more on a complete 3400 swap, goto www.3400swap.com

[Corpse]

That is weird because one set of heads I have were off a 94 made in Canada. It was an Olds Ciera a friend of mine junked. Whole car was a canadian made model. Could be possible the heads were swapped though.

Also, these heads had pushrod guideplates and non-roller rockers but, they have the notches. Sorry about the mishap.

Edit: Well, they are not the 10154743 casting and they are missing the coolant temp sensor tapped hole in one side of each head. So, it appears someone repalced the heads on the 94 car with 96+ heads and bolted the guideplates and non-roller rockers on.

That agitates me, I actually wanted a set of 94 heads for comparison. But no, some mechanic had to do a half-azzed job and mix parts.

-Dave

[Corpse]

Also, I was wondering if someone had a spare 3.1+ connecting rod laying around? I need the width measured on the small end. I have just read some info that tries to state that the 2.8/3.1 connecting rods have a differently sized small end. It is more than likely myth considering some of the facts we already know but, I like to take stuff to the numbers.

Width should either be .850" or 1.0"



-Dave