Seff

My '72 Supreme is my only car at the moment, so it'll be getting some miles the next few months, if not exactly many. Since this has moved beyond being a pleasure cruiser, I need to get some of those small doubt issues straightened out - never driven an American car before, especially not of this vintage, so some of the do's and don't's aren't clear to me. Standard '71 350 4bbl, TH350, 2.56 rear posi, HEI ignition, 0.060" plug gap. 71 Q-jet. Timing is set correctly, no chugging or pinging or anything all along the RPM band.

What I'm looking for is mileage tips and proper maintenance so I don't break anything on my ol' beauty here.

Right now I'm running the '71 carb, a 7041250. I have two 17057253 carbs lying about that need cleaning, assembling and new gaskets, that I could use. Would they be better for emissions and/or mileage? Drove to base and back, along with some small shopping trips (3 trips of 5 mins, max), netting me 313 km om 50 liters of gas. That's 14.69 MPG, with a cruising speed of 50 on normal roads, and 80 MPH on the freeway, 65-35 ratio between those two. With a rear like mine and HEI, I was expecting closer to 20 MPG.

I stomp the accelerator two or three times before cranking on a cold morning, and I can clearly hear that it takes 3-5 seconds for the vacuum to kick in and disengage the choke.

When driving to the base last Sunday, I experienced that my #7 spark plug wire came clean off the plug while driving. Never heard of anything like it, but all it did was to make her chug and shake a good deal more. Fixed it, of course.

I get vibrations at 80 MPH, felt clearly in the steering wheel, but quite pronounced throughout the car. Accelerating or not doesn't seem to affect it much. Barely feel the vibrations at 80 MPH.

That's all I could think of at the moment, but I'm sure there'll be more later. Thanks.

MDchanic

DON'T punch the gas in a curve on a wet road.

- Eric

Seff

But that's when the posi really shines by neatly eliminating ALL rear end grip. You're taking away my source of fun, Eric.

Not that I ever really gun it, though. That'd explain the mileage, but I don't.

lshlsh2

MPG sounds about right to me I get 14-15 in my conv. on pleasure crusies. That is a 350 2bl single exhaust and 2.56 rear. From everything I have seen and heard the only way to get near 20mpg is with an overdrive trans. Vibrations, check tires for balance and check steering for any worn parts.

Larry

Seff

I have an extra set of tires, will try switching over to those and take a cruise.

A five speed manual is the long-term plan.

White_Knuckles

Sorry, but are you in Denmark or is that a city here? I'm wondering about parts availability and insuring the car's value in Europe may be a concern for a daily driver.

Back to your list. Is .060 the right plug gap for HEI? I was thinking .035-.045 but not sure. The vibes showing up at 80 mph is unusual and could be many things. Usually speed sensitive shimmy shakes hit sooner, let's say, 60 mph or so. Rotating mass, when out of round, can rear its head at any speed but 80 is up there. I'd look into a proper tire balancing all around at a shop that uses a balancing machine that "loads" the wheel to simulate road pressure. Your symptoms point to an out of balance issue. A worn U-joint or out of balance drive-line would normally not be felt in the steering wheel but certainly create a vibe.

I chased a 60-70 mph subtle vibe for months where switching to winter wheels would clear it. The summer wheels and tires (expensive new stuff) seemed to balance fine. I was told "BMW's have this issue 'cause they're so sensitive". Didn't buy into that. Finally, on the THIRD re-balance they cured it. Point - find a good tire shop with an experienced tech!

Seff

Denmark the tiny Scandinavian country. I charmed the insurance lady and managed to get a good price for insurance. Having driven in the army helped with propagating the idea that I was an experienced driver. As for parts, I'm gonna stock up on small **** like flashers and such. Most other stuff is readily available, if not necessarily super cheap like in the US.

I based my choice of plugs with this passage from the Olds FAQ (since I'm a newbie):
My father suggested getting it balanced as well, so I'll do the tire swap to see if that's the issue, and then go on from there. None of the joints were worn when I assembled the car. I assume that an out of balance tire will be evident at any speed, and that 80 MPH- Ah, wait wait wait, I mixed up KPH and MPH. The vibrations show up at 50 MPH (80 KPH) and are gone again at 80 MPH (130 MPH). That just means it sounds even more like an out of balance issue. :P

White_Knuckles

Cool on your clarification. I've been to Copenhagen and it's not exactly a "tiny country" LOL. AC plugs are preferred for these babies if you can get 'em. Maybe others will chime in on proper gap setting? .080 sounds crazy but I'm no expert.

I spotted your other post quoting 80 mph with your window issue. We're thinking you're tearing around in that thing trying to go airborne! The conversion now makes better sense with the tire balance issue. Also, this makes you look less like an F1 driver.

Cheers

Seff

A country of 5.6 million is not a lot compared to most. :P

Windows work now, BTW. 80 MPH is the speed limit on the freeways, 50 on the normal roads. It's less dangerous to follow traffic than to go 65 or something like that and become a bottleneck for distracted people to ram into.

I CAN get AC plugs, am currently running the BOSCH equivalent of an AC R46SZ.

Lady72nRob71

15 MPG seems reasonable. If you get 20 on the highway on a long trip, rejoice!
Let the spark plugs tell you if you are running rich.
My car has a similar powertrain as yours. It will be a nice daily driver!

Seff

I think I saw someone say that you rev the engine to cruising RPM and then shut it off to correctly 'coat' the plugs to show if it's running rich or lean, yes? Burning oil, etc.

White_Knuckles

Wow, you guys can haul **** nearly Autobahn style over there! (Jealous)

I'm spooked going 80+ in a 45 year old car but have tested her to 95. Keep looking at the lap belts, no head rests, and my body being the "crumple zone" for a high-speed crash. But then again, in '67 these weren't concerns.

Drive 'em like a stolen bicycle before we're all stuck in electric golf-carts!

Seff

With modern cars being what they are, and less than 10% of the daily drivers being from before 1990, brakes and steering are very up to date across the board over here. All those old cars rust away or get too expensive to drive. Except for me, of course. >.> Good mileage over here is anything above 40 MPG.

Going 80 MPH was okay - steering slop keeps you awake!

White_Knuckles

So, I gotta ask Seff, how many of your type of car (American iron) made it over there?

Were they sold as new or specialty cars imported? The Swedish seem to have interest finding old Cadillac's over here and shipping 'em back. Kind of like us finding a decent MG or Alpha as a project. I guessed yours would be a rare bird compared to tons of Euro stuff in your area?

Edit: Care to share what a liter of petrol runs you? I just want to feel better.

Seff

The common Dane has never heard of Oldsmobile. They were never sold in Denmark, and the closest is the one with some kind of import plaque for import to Holland or such.
I don't think very many cars made it over here in the 45-75 period, given that we weren't rich like Americans in that period. Marshall Plan was still in effect into the 50s, so we were busy buying cheap cars like beetles and stuff like that. With smaller roads and less money, nobody was interested in big cars, muscle or not. A Capri or Manta was about as sporty as you got before the Golf hit the streets, and they're still going strong.

Nowadays Mustangs and Corvettes are by far the most popular, from the 65 to 70 era, though a LOT of different cars are represented. There are few barn finds, but they DO exist. I've seen something like ten different Oldsmobiles, half of them Cutlii, the rest a mix of full-sizes and wagons. I could find you a few that are for sale, and let you choke on the price. :P

As for rarity, about a third of the veteran car community is American cars, so it's a common thing for car enthusiasts to indulge in. Virtually none are daily drivers, though.

Octania

when bringing my newly purchased used truck home a few yrs ago, it developed a vibration. I noticed it was less bad or gone at 80 mph so stayed there mostly. 5 miles from home I found the source of the problem when the last lug nut fell off the Left Rear wheel [why is it ALWAYS the left rear?] and the rear axle dropped down to brake drum on ID of wheel. Wheel stayed with truck though.

Ck your wheels, TIRES [TYRES for ye Euroaeans], and wheel bearings first.

Seff

...I think I'll torque down my lug nuts once more, yeah. o.O

EDIT: The import tag mentioned, White Knuckles:

White_Knuckles

Wow, that's really interesting information Seff. Kind of thought she was a rare one in your neighborhood. Must be a serious head turner!

Yeah, I think I'd erect a small, barbed fence around it every time I parked. Rock-On with that baby 'cause you are stylin' in Dane-Land.

Seff

Barbed fence? I certainly took the ***** off my inside locks, and am entertaining the thought of a hidden kill switch.

The one positive thing is that she's so rare and weird that the only people that would steal her are joyriders, and they're not normally the kind of people that have intricate knowledge about archaic outlandish car technology (no offence). :P

White_Knuckles

Kidding about the fence. Meaning, reasonable care to prevent door dings and freaks messin' with your toy. I have a nice 3-series and discovered someone demonstrated the properties of Diamond vs. Glass by adding artwork to my side glass with their ring."Keying" is also a favorite where people walk by your car with a key or sharp object cutting a deep line into your paint.

This is not uncommon to us. Seems the have-not's like to put the hurt on those who have. I hope your people still have respect for others property. Vikings are nice guys right?

Seff

I got the intent of the fence joke, and added what I thought to be the real-world equivalent. :P

Doing things like parking in two spots is the only kind of thing that makes people key your ride over here.

White_Knuckles

That's known as a "plug chop" often used to dial-in main jet sizing for your carburetor when new or unknown. The first step is, install new plugs or seriously clean a couple plugs on both banks (sides) with a wire brush. Then after a higher RPM run, shut her down quickly without idling much. Pull your two test plugs for a look. Maybe let it cool down a little or they can fly!

The plugs should not be wet with oil (bad rings or tired motor). The plug electrode tips should not be covered with fluffy black carbon (too rich). The tips should not have heavy white deposits (too lean). The ceramic insulators after normal usage (500 miles) should appear a tan color.

That all was good when fuel was fuel. Today, with Ethanol and other additives, reading plugs can be tricky where white or tan deposits may be normal. Also, most of us don't perform plug chops if your carb is happy. Just inspect the condition after normal driving and look for obvious trouble signs.

Seff

I thought the car was running great until I noticed the mileage, so I'd say my carb is happy. Will look for wet oil, though, since I feel it's burning a fair deal of it.

Nice to know what the different kinds of deposits mean. The more you know. :P

White_Knuckles

Glad to help.

Hope this "chit-chat" is interesting to others as you may be our only Euro guy active on this forum? I better bug out before the Moderators lock the thread as too much "Pen-Pal" activity. I'm pretty new here as well, wouldn't want to make the veteran contributors mad!

Feel free to PM me anytime for extended conversations! Oh, your mileage is normal from what I know from many similar carbed V-8's. Just make sure your KM/Mile and Liter/Gal conversions are correct.

~Gregg

Seff

No need to press your luck, eh? Most of it is Olds-relevant on some level, and all it's doing is derailing my own topic. No harm, no foul.

Lady72nRob71

Don't, worry, that is not against the rules here, as long as it is friendly. Seff is okay with it, so keep it up - it's his thread...
I also enjoy hearing tales from across the pond. I visited Europe and Scandinavia and they are very different in the world of cars and driving. Fun to hear from the guys who have unique cars there. I myself would be driving a big ol' American car, too. Of course, parking in Paris could be challenging!

Seff

I'm glad I can see out the back windows so well, because otherwise I would be afraid of parking ANYWHERE.

jerseymike

one thing I'd thrown in is to be sure you hoses and belts are all in good shape. make sure your hose clamps are tight and your battery and alt are in good shape.

not sure what season you are currently preparing for over there but be sure your coolant and therm are in good shape...maybe a new therm and gasket if it's going to be winter, a nice warm therm to make some good heat and good wipers too never hurt.

forgot about the fuel filter, you might want to have one handy or change it out after a few weeks of driving. if your car has sat for a while now using it as a daily driver and the constant up/down fuel level and useage may cause some debris to find its way through the fuel system so changing to a fresh one and having one on the side couldnt hurt.

Seff

Hoses look good and fresh, I have new belts on her. I fought with the alt for a week and it now works wonderfully, supplying 14.5-15 V.

We're in the northern hemisphere, north of Germany, so wipers are on the list. Heater works like a charm. I'm looking into extensive undercoating to fend off the salt that'll come when snow hits. The current tires are M+S, so I hope that'll be adequate.

I changed the fuel filter during assembly, it has collected a little bit of gunk, but not quite enough to be suspect yet.

Speaking of small parts for "just in case", I have fuses, bulbs, wires, tools, jump cables, fuel and fluids, just in case. Carrying several hundred kilos, most likely.


Checked a spark plug as mentioned - the threads were oily, but the electrode was dry and tan. Plugs have about 300 miles on them. Oil smells very faintly of gas.

White_Knuckles

Small amounts of gas makes its way to the crankcase various ways and is not unusual to detect a slight odor. It separates and doesn't mix with the oil. I've caught it on several carburetor cars, not to worry.

Traction tires are a must to greet winter driving in snow country. Chains can be used for serious situations but normally are for back-up not continuous use. Rear wheel drive adds an element of technique but with proper throttle control you're fine. We drove these cars for years in severe winter conditions. I think you have a limited slip (LSD) not open differential? That's a huge plus for slick conditions.

Seff

I do indeed have a positraction diff. The main thing is to get off the gas way ahead of time instead of relying on brakes to stop when it's slippery, yes?

Glad the gas odor isn't a big problem.

jerseymike

good to hear you're carrying extras which = some added weight,getting weight to the rear wheels in wintery conditions is a big plus. Growing up I remember many of the old timers actually putting some flat pancake (cement) blocks in the trunk (along w/ some kitty litter in case they did get stuck) just to get some added traction in the rearend.

Speaking of the trunk be sure your spare is ready and jack is working. Maybe throw in a 16" piece of a 2x8 to use as a base in case you're off on a soft shoulder.

good luck and enjoy the winter driving,these cars are fun to drive in the winter especially in a snow covered empty parking lot. Just in case though,remember to turn into the direction of the skid if the backend does kick out on you.

jerseymike

wash her down when possible after a salting...if there is a car wash that has undercarriage washing/rinsing use that too. be sure and get a coat of wax on her too.

Seff

All things that will be added to the list.

Miles71

I have a vibration in my 71 supreme. I have narrowed down the problem to most likely the Old tires. Due to limited funds I have not replace the tires yet, may be next month. At 63-65 MPH the AM radio begins to rattle and the whole car vibrates in predicable ossiciliation. If I hold a constant speed, it’s easy to feel the repeating oscillation pattern. I am 99% sure it’s the tires. When I drive faster, the vibration goes away. So far, I have replaced front bearings, U-joints and rebalanced the SS-III rims and it still vibrates. Since my tires are 15 years old, it’s time to toss them.
Next month ill update the results when I have new tires.

Seff

You've just corroborated my theory about needing a balance job or new tires. Come weekend I'll test with my spare set and see if it changes.

StarGeneral

My DD is an unrestored 1965 Delta 88. Although I don't have a lot of experience with cars in general, I take extra precaution with my car because its old. I always let it warm up to operating temp before driving it anywhere, especially in cold weather. I check all fluid levels and do a walk-around of the entire vehicle and engine bay before leaving with a flashlight, looking for leaks, cracks or anything unusual. I change my oil about every 4,000 miles or so, don't buy gas from stations where the tanks are being filled. ALWAYS have my toolbox in the car, with spare fuses, spools of wire, crimp connectors, wire cutters, the usual. It's saved my butt so many times. Also carry a jug of premixed coolant and a bottle of oil. That's a sweet ride man, hope you have as much fun as I'm having

Seff

I carry tools and fluids as well. Right now I'm getting some leaks from the cowl area into my carpets and behind my dash, which I'm working to fix. Apart from that, my headers seem to want to shake loose ever so often. One of my reverse lamps keeps corroding, need to get it properly waterproofed.

All in all, small stuff.

MDchanic

For whatever it's worth, somewhere in the early to mid-'60s car companies stopped recommending warming up the car, and started recommending starting and driving off as soon as the oil pressure comes up (about ten seconds, usually), but to avoid pushing it too hard until it's fully warm.

The rationale was that the engine warms up much faster when in use than when idling, and thus has less run time in a cold state, and less time with a rich mixture, which washes more oil off of the cylinder walls, accelerating wear.

You should check your owner's manual.

- Eric

Seff

I've been told and have read the same thing multiple times, and I act accordingly. Plus, no need to stink up the front of the house before I leave in the morning.

Oh, and for those who thought 80 MPH was bad, I pushed her to somewhere between 121 MPH and 124 MPH the last time I had the freeway to myself. Had to see what she was capable of.