Hey there. I'm trying to make contact with anyone who either is versed with the different versions &/or variations of the 1982 2.5 TBI or... someone who physically owns one & could potentially take some pictures for me. I am very close to having mine road ready but have stumbled on some vacuum issues. I have the original build sheets, the original shop manual & the original parts catalog. While they've helped immensely, there's still some very puzzling & unanswered questions. Any help would be greatly appreciated! Thanks!!!

 

What do you need to know that isn't in the Genuine GM service manual set for your vehicle?

I never saw a stock Iron Duke that had adequate power. Saw lots of 'em that had crappy cylinder leakdown test results, and broken head-bolts.

There are, over the course of many years of production, more than 200 "updates" and changes to the Iron Duke. Gotta be REALLY careful to get the correct replacement parts. Keep in mind that parts--cylinder heads, for example--may have the same casting number, but be machined differently leading to different part numbers.

 

Isn't there a vacuum routing/schematic sticker under the hood?

 

Hello and thank you for responding. In regards to the factory vacuum routing decal, no. If there was one, there isn't now. I have the factory books for an 82 but, they (as you probably know) cover many variations. Heck, I never knew they made a carbureted version of the 2.5! My problems began when I didn't know where the one hose that goes to the air cleaner housing went. After finding the diagram of the TBI that showed what connected to the different piping on the front of it, I was able to figure out where that hose went. However, I also found out that someone else had several of the other lines connected to the wrong ports. So I got everything switched to where it was supposed to go & ended up with two new issues. First, there is a fine metal tube that runs along the base and 80% of the length of the valve cover. On the front end (towards the front of the engine) a rubber hose attached to that metal line, was attached to the TBI... which according the the diagram, was incorrect. So, I have that line hanging out in space & have no idea where it goes. Second... and this is where it really gets interesting, in the diagrams that clearly show a drawing of the TBI unit, it also shows a simulated cut away of two modules underneath the intake manifold. One is a Vacuum Pump, the second is a Servo Assembly. I'll upload a pic & move on from there.

 

 

My vehicle has neither of those. No pump & no servo. And it's not just missing. Everything I can tell says it never had one. If you look closely in the diagram, you can see the distributor & to the far right, the canister oil filter. In addition, if you go to the diagram page specifically for the Vacuum Pump, it clearly shows a tail that extends past the mounting surface (just like a mechanical fuel pump would mount to the side of the engine). Common sense dictates that's how this pump works & would also indicate that there should be some opening or one that's been covered up, to accommodate the pump, but there's nothing there. I'll upload another from my vehicle.

 

 

While my picture is from the opposite angle, you can see the distributor, the oil filter, a motor mount & probably the oil pressure sensor. But clearly there's no place for anything like a pump to mount to. So I'm assuming that I have a different variant, that never had either the Vacuum Pump & Servo. However, if you look to the left of the TBI & where those two are located in the diagram, you will see a little plastic canister with 3 ports. In the picture, the angled port goes to the Vacuum Pump, while the end closest in the picture goes to a hose with a #3 in a box next to it. I'll upload the portion that shows where (#3) goes.

 

 

If you look below Pontiac, you can see that (#3) snakes up and over the brake booster and down around to a Transducer Assembly that presumably controls Cruise Control among other things (maybe). Anyway, my vehicle has none of this. Bringing me back to the little plastic canister. The outgoing (#3) hose is capped off with what appears to be a factory plug & the one on the side, it "had" the remains of a rotted hose that was ripped off. I've since removed the rotted piece of hose but, I can't find anything that would give me any indication of where that hose once went. I'll upload one more for reference.

 

 

If you look in the center of the previous photo, you'll see the little grey plastic canister. I'm going through all of this because while many gear heads will simply dismiss the Iron Duke, I'm 52 years old & have owned several, not the least of which was a Mercruiser I/O variant in a salmon fishing boat. They're not the smoothest running, they're not the most high performance but damn it, they are positively durable & can return some really excellent MPGs. I had an 84 Cutlass that returned 35/36 MPG all day long. Even better if I really babied it.

I'm out of options at this point. I've spoken with a GM technician I personally know, I've spoken to several independent mechanics, I've even tried the "ask a Camaro specialist" channels and get the same song and dance... "Well, it's pretty difficult when you're talking about a vehicle that old." What the hell would GM do if someone bought it to them? It's their damn product. Am I supposed to believe that they wouldn't have the answers? Somebody has to know. So any assistance ANYONE can offer will be GREATLY APPRECIATED.

 

1. No idea what the vacuum pump is for--although there's numerous vacuum-powered accessories, and the Iron Turd is not known for developing lots of vacuum. So I guess "some" variations get the vacuum pump and some don't. Are you certain that the engine that's in your car is the original? As I said, there were over 200 variations of the Iron Duke over it's production lifetime. As fast as they wore-out, it wouldn't be surprising to find your car has been re-engined--and the replacement engine isn't a perfect match to the original.

2. If you don't have cruise control, of course you don't have the cruise transducer and cruise servo, and the vacuum hoses and wire harness associated with all that. MAYBE only cars with cruise control got the vacuum pump. This seems likely since both vacuum hoses on the vacuum pump connect to cruise control items. I don't know what the metal tube along the valve cover is supposed to connect to, maybe originally it was for vacuum advance on an older, non-computer-controlled vehicle or some-such. You don't seem to need it--or the three-nipple "canister" any more.

3. Interesting that your fuel supply and fuel return tubes have thread-tape on the flare nuts, since those threads are not intended to be fuel-tight. The sealing is done with O-rings on the tubes, not with the flare nuts.

 

Well, I had considered that very same thing. I've been told there is a way to research & verify if the numbers on the block match the car. This is an avenue I haven't tried yet. However, (while I can't remember the exact mileage), it's relatively low. My son said he remembered it being about 85,000. In addition, this car was titled & purchased in Iowa. Midwestern winters turn vehicles into rust buckets (especially one that old). And while I have found one spot in the passenger side wheel well that's perforated & needs to be repaired, the rest of the vehicle is remarkably solid. So while it's not necessarily the case, I just can't imagine (especially with all the flack the Camaro received from the press over the 2.5)... why the engine would have been replaced (in the first place) with that mileage & second, that it would have been replaced with another 4-banger. Again, that's not to say that it couldn't have happened, but in my mind none of it adds up. So I need to research if the engine is original & will do so. Having said that, any ideas on figuring out the vacuum hoses? 😂

 

My source says (provided it's accurate), of 193,747 Camaro's sold (of all variants in 1982), 90,371 were equipped with cruise control. So, it's entirely possible it doesn't have it. Again, I'll have to look. But this really begs the question, why would they use a different engine variant (one that has an entirely different block), rather than simply cover the hole with a plate, a gasket & two 10mm bolts?

 

How'd you make out on your vac. Issues? I've got a 84 firebird with the dukie motor. U can't kill this thing. Second owner. Don't drive it much but pull 28 to 32 mpg. Mine has cruise control so probably not much help. Since there's not a lot of duke motors anymore. Everyone switched. I was glad to see that you kept the Duke. Putting mine on the road this year. Need to source an exhaust. Near impossible to find these days. Good luck with the dukie