307 Olds/Blackjack Headers/Emission equipment

[kustomkyle]

I have a 1986 Regal with a 307 Olds, 88,000 miles. The engine, overall, runs decent for a 23 year old car. It does not have any carb. related problems, that much seems fine (for now). Driving it around town below 50 MPH would make someone feel like there is nothing wrong with it at all; it just purrs without any issues. However, on actual daily commutes, it starts to have trouble. I drive about 10-15 miles on a 4-lane highway at about 55-70 MPH, depending on traffic conditions. The car loves to cruise as fast as I can get it to go safely (70-75 MPH). But if I get caught up in traffic and have to let off the accelerator, then get back into it to stay at a constant speed, things go awry. Detonation occurs, as well as smoking (anything from black, to blue, to a light brownish color). The "chattering" (which sounds a lot louder than a car I used to drive with a 350 SBC TBI) goes away when I stab the gas a little, but the brownish-yellow smoke puffs out. Seems like it's running lean, but who knows.

On the way home it's even worse. After the car sits for 2-6 hours (depending on which day it is) I let the oil get circulated for 1-2 minutes when I start it up. When I leave college and first accelerate out onto the road, a huge cloud of blue smoke usually comes out of the exhaust for about 1/4 mile, or until I'm up to speed (normal acceleration from a stop). Once I'm back on the main highway, a vibration occurs after about a mile or so. It feels like the front tires are out of round or out of balance, but I think it is the engine.

Basically, I have no idea what is wrong with the engine. It doesn't have that much mileage, and I don't think it was ever abused. I've been told it has a bad valve guide somewhere or a ring is stuck. I have two anti-fowlers on it; a front cylinder and one on the opposite side in the back cylinder. Those two spark plugs were oil fowled, but the rest stay fairly clean.

I've played with the exhaust many times, usually when inspection comes around. It's a single exhaust with a glasspack. The original cat converter got clogged about a year ago, and I hallowed it out. The car had a huge increase in power, and quit having most of its problems for a while. The only thing that went wrong since then was that some white corrosion built up around the anti-fowlers. A few weeks ago I had to get it inspected, so a barely used cat from my dad's Roadmaster went on it temporarily. It was a high-flow aftermarket unit. On the second try the car passed. There was a slight loss of power, but the week after that, it never put out any blue smoke or had any real problems, except the detonation came back, and its getting real bad.

I was thinking that if I get the exhaust "uncorked" some of this stuff will go away. The car runs better without a cat, but not the way it should be. I've been told before that dual exhaust won't help anything, but it just seems like it would. The way the factory crossover pipe is designed makes me wonder if it is the reason for many of the problems (it is amazing how the car can run at all with the way it looks).

So, my temporary solution would be to get the "Blackjack" headers by Dynomax, run true duals with glasspacks. It is A LOT cheaper than an engine rebuild or valve job, which I'm not sure the car even needs. I'm wondering about if anyone has used a similar setup before. Do these headers fit alright in the engine compartment of a 307 equiped g-body? What also worries me is the head design on the 85' and up 307 (swirl port/roller engines). Is the gasket/flange design compatible or require some sort of modification? I'm also concerned about how this will all effect the emissions equipment. I don't think that headers for 307's have places to put knock sensors, so I'm confused about that too.

Any help or suggestions on my hair-brained theory would be greatly appreciated. Please keep in mind that I know this won't "fix" the engine if there is something wrong. I just want it to run a little better without spending a lot of money. Thanks.

 

[megaladon6]

you really need to do a full compression check. preferably a leak-down test. i think you have a serious ring seal problem, probably also a bad valve guide. trying to patch things will only lead to a blown motor.

 

[kustomkyle]

Yeah, I had a compression test done not long after I bought it. I think the two cylinders that have anti-fowlers were down in compression, and the rest were alright. I think that would indicate that the rings were the problem, but if they were the problem, wouldn't there be more drivability problems? Sorry about asking the same question twice (I think I posted the same question with less detail a few months ago). It's just that the engine has gotten better over the two years I've had it.

Then again, the car was parked for a year before I bought it, so I guess that's where the rings could have gotten stuck from moisture or something.

 

[megaladon6]

when i do a compression test i do each plug twice. the second time i squirt oil into the cyl first. if the reading goes up, that's rings. if it stays the same, that's usually valves.

wouldn't there be more drivability problems

you want more?!?!?! i think you've got enough already. what i think is happening is that cruising there's enough positive pressure to force the rings out and get some sealing. when you back off the throttle the rings "relax" and you get a lack of compression and a bunch of blow by causing a misfire. this dumps raw fuel out along with black smoke. when you hit the throttle i think it's causing the cylinder to go lean for a second, resulting in the brown smoke, then the rings get some pressure and re-seal. i think, this expansion/contraction is causing some of the chattering. mostly it's probably the rings trying to seal, but "skipping" on the walls instead of scraping. this can happen from the blow by and raw fuel washing the oil from the walls.

After the car sits for 2-6 hours (depending on which day it is) I let the oil get circulated for 1-2 minutes when I start it up. When I leave college and first accelerate out onto the road, a huge cloud of blue smoke usually comes out of the exhaust for about 1/4 mile, or until I'm up to speed (normal acceleration from a stop).

this sounds like a bad valve seal to me. they usually leak worse at startup. and burning oil gives you blue smoke. the vibration is probably a misfire, quite possibly on multiple cylinders.
what color(s) are you plugs? all 8. if possible post pics of them, i'm not the greatest at reading plugs, but i'm not bad.
oh, you're not anywhere near danbury CT are you? i hate diagnosing cars by e-mail or phone, i like being able to hear and play with the engine myself. if you're close i could take a look at it.

 

[kustomkyle]

The "good" plugs have slight white-ness to them. The two that have anti-fowlers would be oily with carbon if they weren't spaced. Earlier before the anti-fowlers were on, the car could go for a short trip but would soon vibrate pretty bad because the plugs got covered in oil.

This past oil change (a few weeks ago) there was a lot of carbon chunks in the oil as well. The oil was changed a little early (2500 miles) because of this. In the pan that the oil was drained into, there was big chunks as well. It may have been because prior to the oil change I flogged the car a bit, the only time I've really push it very hard. I was just trying to clear the carbon before inspection.

Also not long after I bought the car, I had a valve cover (driver's side) off to see if the drain holes in the heads were clogged. They weren't, but there was some black sludge in there that had to be "spooned out", like the previous owners didn't change the oil very often. It wasn't too bad though. The passenger side valve cover was never taken off because it's such a pain to disconnect all the wires and vacuum lines/tie them back. I figured if one wasn't clogged the other wouldn't be either.

I figure the engine has to be rebuilt, but would the possible condition of the engine make it cost more? Would the bad cylinders that aren't functioning properly likely have bad scoring? Thanks for all the help.

By the way, I'm in Southern Delaware. I might be able to post pictures of some things if it helps. My dad does all the mechanical work because I don't have any experience with that stuff. We aren't capable of rebuilds though (no tools, experience, etc.). Just the basics.

 

[megaladon6]

white like the top right in this pic? http://www.aa1car.com/library/reading_spark_plugs.jpg
or brownish with some white like the top center?
since the bad plugs are oily and they get fouled so quickly without the anti-foulers i'd definately say you have bad valve guides at the least. pull all the plugs and clean them off, then reinstall them and see if the car runs at least a little better--even if for only a few dozen miles.
oil sludge on the heads is somewhat normal due to age and lack of oil changes, but CARBON chunks?!? :shock: i've seen soft lumps of sludgy oil but not hard chunks. except when it was metal from the engine tearing itself apart. i'm not really sure what that is.
i think that you should be fine on a rebuild, but it would have to be a complete one. i'm pretty sure that you're going to have to bore the cylinders, but the question is how much? a rebuild isn't too hard, except for the machine work. you need basic tools, a good torque wrench, plastigage, a ring compressor, and a good how-to manual. you do need to find a good machine shop and have them do things like the cylinder bore/hone, ring gap, and cam bearings but the cost isn't too bad. i built my 383 (first time build) in my living room. yep, i'm a redneck :lol:
actually i'd use this as an excuse to drop a 350, olds or chevy, in there. you might have to do a rebuild on the new engine, but the cost is the same and you'd have a lot more power. plus you wouldn't have to take the car off the road until you're ready for the swap.

 

[kustomkyle]

The white plugs look like the "TOO HOT" picture.

I want to keep the car original, I'm not really into power all that much. I think temporarily a small block Chevrolet would be good because they seem to be the best of the GM V8's. I actually found a "350 LM1 4-bolt main" crate engine on GMPartsDirect for $1341 on sale. I don't know how much it would be to ship though, and it doesn't have an intake manifold, etc. Can't really afford that either, and there would be too much for me to handle. I've never seen a 350 Oldsmobile for sale around here, and there isn't much in junkyards that would have a 350 or a 403. Tons of 307 cars though (Delta 88's), I can probably see why. A lot of people seem to hate 307's but mine seems like it's the only one that has issues, especially for the mileage/condition of the car. The car was very cheap, and clean, and the engine didn't seem that bad when I looked at it. The oil was a little low and carboned/black though, and it was most likely the same stuff that was in there when it was parked. The oil was changed before I took it home and then again not long after that. The oil does get black pretty fast after changes too.

As for the valve guides, I've seen a lot of 80's GM cars with small block Chevys put out blue smoke at start-up, but they seem to be perfectly fine otherwise. My car doesn't do that. The only time it really puts out blue smoke is when I start driving it, on initial acceleration. I think I made the other stuff seem a little worse than it really is with a confusing description. I don't know. I've heard the valve guides are plastic or something in these engines too, but I have no idea. That doesn't sound too good of an idea to me if it is true.

I'd like to rebuild the engine myself, but there is a lot of fine tuning and everything has to be perfectly tightened. I work in a body shop, so I do have some decent tools, but not torque wrenches or any real engine tools (not even a decent compressor). No garage either, or an engine hoist/stand. I guess getting someone to rebuild it would be best, but there aren't too many repair places around that are very reputable either. It's crazy. Most places take your car (for smaller jobs) and let it sit and they don't touch it for a week. Then it isn't right, and so on. I can't deal with that because I like the car too much and it's the only one I've got.

By the way, do you have an idea of what a full rebuild might cost? I'm thinking $2000 or so? Hopefully less (probably not). I have to call around still but the people around here probably over-charge.

 

[megaladon6]

the most common causes of excessive combustion chamber temps are over advanced ignition, lean air-fuel ratio, stick/bad valves, and an overheating engine.
how the car acts also depends on how bad the guides are. if they're just worn that's one thing, cracked and missing pieces--a LOT worse.
i'm used to listening to people without the slightest clue about cars trying to describe a problem, trust me, your description is fine.
i know nothing about these guys (google search) but, http://www.performance-auto-parts.c...s/engine-rebuild-kits-buick-cadillac-pontiac. http://www.rpmmachine.com/engine-rebuild-kits-buick.shtml

 

[kustomkyle]

Maybe the chunks in the oil were pieces of the valve guides? They didn't look like metal and they didn't stick to a magnet. I just assumed it was carbon. They might have been aluminum, but they weren't silver pieces, they were dark (black, brown, bronze? too hard to see). I don't think 307's have internal components made of aluminum either. Thanks for the links.

 

[dan2286]

They do use plastic valve seals that will get dark over time. That could be it.