Which engine is better? stronger? faster? i know the 3.1 is bored? out more than the 2.8 and has i think 15 more horse power but is the 2.8 a better engine? if i do keep the 2.8 im going to take the 700R4 off the 3.1 and put it on the 2.8.

 

3.1 is actually a longer stroke than the 2.8.

Both are equally reliable.

3.1 has slightly more power due to the increase in displacement.

Your car should already have a 700R4.

 

oh ok, so both are about the same engine pretty much?, and it does but i heard that the tranny on my 3.1 is better/ stronger than the one on my 2.8, also does anyone know where i can get some intake manifold bolts for my 2.8? im missing two bolts

 

I'm pretty sure it's just 5 more horsepower. probably not something you would ever notice. The transmissions are identical, if the car you are taking about is your 1990

you can go to any junk yard for those intake bolts.... you mean the bolts holding down the plenum? Tons of GM cars have 2.8's, not just camaros...

 

so the only way to get them is a junkyard? cause the cloest one is like an hour and a half from me

 

are you talking about the bolts that hold down the plenum or the bolts that hold down the intake manifold?

 

You can get bolts from Lowes, Home Depot, Napa, Car Quest, Canadian Tire, etc, that will work for what you want. They aren't anything special.

 

Just swap the missing bolts over from the 3.1. However, if your 2 missing bolts are the ones I'm thinking of, they're actually studs, and they go at the front on the driver's side, for the upper bracket for the A/C compressor. ANY bolts can be swapped over from the other engine and swapped back again when you want/need to put in the other engine.

2.8 and 3.1 are essentially the same engine. 3.1 has a bigger crank throw, and dished pistons compared to the 2.8, giving it 8.5:1 compression (compared to 8.9/9:1 compression on the 2.8), 140 HP vs 135, and 180# torque vs 160. They have the same heads, engine block, cam, and connecting rods. 3.1 is internally balanced whereas the 2.8 has a balancing flexplate. They have almost the same fuel injectors. 3.1 has an improved fueling table for cold starts, improved plenum and TB design, and the digital EGR valve.

And yes, you can swap over the 700R4 from the 3.1, which I would actually recommend, as those 5 years between cars had changes to the design and building of the trans.

 

Arent they hardend bolts?

 

, no i have one stud, but the bolts on the 3.1 are shorter than the ones on the 2.8 i cant get them to thread in tight, they just keep spinning, also i got the tranny swap idea from you dan remember? lol, anyways the bolts are hardend bolts arent they? if thats the case i dont think ill be able to get them at a hardware store.

 

The bolts may or may not be hardened. I have 2 identical sets of bolts, having received the second set with my 3.1 plenum when I had to ditch the 2.8 plenum and throttle body (plenum fatigued and broke one of the TB mounting ears off). The bolts are the same between the 2 engines, as they have the same lower plenum. It's possible that the lower plenum needs to be rethreaded in those holes as the torque spec for those bolts is only 12-15 ft lbs, and they are easily overtightened, especially with a decent air ratchet.

 

Wanna sell two? lmao kidding, anyways i compaired the two and the 3.1 is smaller compaired to the 2.8s, so im thinking that the PO jsut slapped this thing together because that would also tell me why i was losing compression in the 3.1...

 

Wait, which bolts are we talking about here? If you're talking about the lower intake manifold, between the cylinder heads, those shorter bolts go in the front and rear, and the long ones in the middle. Same for the lower plenum, the part between the fuel rail and the lower manifold. Every bolt in the upper plenum is the same length from the part the socket goes on to to the bottom of the threads that go into the lower plenum. It's the part above the bolts on the studs that are different.

 

I'm talking about the bolts on the upper plenum, the bolts on the 3.1 are shorter than the bolts on the 2.8 so i cant use them, iv already tried i havent take the lower plenum off so those are all still there, i just need those two upper plenum bolts

 

Which ones? Just plain bolts or the studs? I can take a look in my spare bolts bin and see what I can dig up.

 

i need one stud and one plain bolt, hold on ill go get a pic of both bolts side by side

 

87+ 2.8L are internally balanced.

All bolts are hardened....

I've been using hardware store bolts for years for things like intakes, plenums, even pulleys. There's a select few fasteners I wouldn't source from a hardware store, but they are specialty fasteners anyway.

 

Got the picture but its taking forever to send to my email, also just about ALL the bolts on the 3.1 are studded and when i try putting them in on the 2.8 they just sink in unlike the bolts on the 2.8 they dont.

 

if you really want to go first class, look up fiero plenum bolts on ebay

 

first class?

 

mark i dont need chrome bolts

 

i need 10 mm bolts, the bolts on the 3.1 are 12 mm

 

I think the bolts on the 3.1 are the same as the 2.8. are you sure you don't mean the studs?

 

ALL the bolts on the 3.1 are studs, except 1 and its too short aswell

 

what? what kind of funkafied engine do you have? there should be one short bolt, several long bolts, and one or two studs...

post a pic, this is odd

 

That don't make sense at all. I doubt even the PO of your car replaced all 8 of the regular 10mm bolts with 13mm studs. There should be 8 bolts and 2 studs, the 2 studs, like I said before, in the front of the driver's side of the engine, for the A/C compressor bracket. The bolts are identical between the 2 engines (as I have swapped plenums before). Worse comes to worse, you'll need to use more gaskets out of the intake set and swap over the entire plenum set from one engine to the other. And the short bolt holds the throttle/TV/cruise control cable bracket to the upper plenum.

 

I'll get a picture when my phone starts working again for some reason i cant get it to send pictures to my email, the PO of my parts car wasnt the brightest.

 

idk like i said all the bolts are studs, except one, ill see if i cant zoom in on my old engine pic to the
plenum

 

Take the upper plenum back off and look in the bolt holes where the 2 bolts are having problems. If the holes don't look like the others that do have threads (in other words, a lot smoother than the others), then you'll need to rethread them.

Or, you could just get rid of the headaches altogether by swapping over the lower plenum from your 3.1, or the whole plenum and TB together. The hardest part is redoing the vacuum lines (probably needs to be done anyways) and rewiring the TPS and IAC. Everything bolts up.

If I can find them all, I might be able to send you a set of plenum bolts. There will, however, be 4 studs instead of 2, because I nabbed 2 of the bolts for my A/C delete .

 

all the bolts go into all the bolt holes amazingly on the 2.8 because i thought maybe it was the wrong hole but its not, so idk i just got the pictures so hopefully ill get them in a few, you could always send the bolts with the spoiler lmao

 

, the stud is off the 3.1 and the long bolt is off the 2.8

 

 

 

that's just not right.... if somebody jacked it up, you're better off using your lower plenum off your 2.8. is that an option?

my plenum

 

how...did....you get a chrome plenum?!?!?!

 

it's called... a file, followed by sandpaper.....60, 220, 400, 800, 1200

followed by a buffing wheel


here's a thread

https://www.thirdgen.org/forums/v6/5...ppearance.html

 

i like it... i like it alot lol, anyways, so those bolts on the 3.1 arent the right bolts are they? i cant get them to go very tight on that engine either

 

no they dont look right... what happens with the bolts? (not the studs) do they not tighten up either? somebody could have cranked them down and stripped them... it's just aluminum

you should have an extra lower plenum, right?

 

you mean the one bolt? its not tight, none of them are tight i can break them apart with ease... and i guess i have the 3.1s lower plenum but i might have that car sold...

 

if you need an extra lower plenum, I have one. I'll sell it cheap. $20 plus shipping..

I should be able to come up with a bunch of those plenum bolts for you too I'll throw in for free

 

I didn't think there was anything wrong with the entire 2.8 plenum?, also im going to see what dan (maverick) decides to do before ill let you know mark

 

yeah, I'm a litlte confused at what your needs are, and what parts you have available for this project. If you find yourself in need, let me know

 

What i need are those two bolts to get this plenum down tight like it should be. thanks mark

 

if your lower plenum is stripped then no stock bolt is going to do that. will no bolt you have tighten up in those holes?

 

the bolts tighten up on my 2.8, its when i take bolts off the 3.1 and try to use them on my 2.8 is when they dont tighten up

 

Looks to me like the PO of that engine, whichever lower plenum you are using, ROYALLY screwed up the plenum bolt holes. Every single one of those bolts is HORRIBLY oversized, and if the other 2 holes are the same, even the oversized holes have been stripped. I could just about tell you where each one of the bolts on that one side of the plenum you showed in the pic is supposed to be, and none of them are in the vicinity of the upper plenum. You'll NEED to swap over the other lower plenum to this engine if you want it to bolt up, or you'll need to fork out about $80 for a Heli-coil kit and some extra inserts (I think they only come with 6 inserts per kit).

 

well i found one bolt, it was on the 3.1 holding up the alturnator...., i hate the PO of the 90