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finally solved my idle vibration Pages: 12Last

mhamilton on Sun January 28, 2007 2:53 PM User is offlineView users profile

I had a couple threads over a year ago about my 229 V6 idle vibration... nothing seemed to affect it. Nick had suggested I had a misfire, not a vibration, and that was a more accurate description of the problem. While it was not actually misfiring (at least not completely), it was more of a shaking than a vibration.

Last month I bought an original 1980 Malibu V6 DualJet carb with only 20k miles on it, and all the factory settings (steel plugs and all). Even with the low mileage, I sent the throttle plate out to have new shaft bushings installed.

Got that all assembled and installed yesterday, and finally the idle shaking is gone! Still has a slight vibration, just a light "hum" through the steering wheel (no doubt just the 90* V6), but that is something I can live with!

Looking at my old carb, I have so much throttle shaft slop it's a wonder it worked at all. In addition, the old mixture screws were back out so much just to get it semi-smooth, they could have not been in there at all. I'm sure that with the correct idle mixture I can change my plugs and see an even smoother idle. With the old carb I would see slightly fouled plugs if I only made a short trip.

So, now it's just the ticking and trans shifting I have to fix...

NickD on Mon January 29, 2007 12:16 AM User is offline

I went a bit crazy trying to tune up my 82 454 CID, recalled the timing marks on this engine were around the 2 o'clock position this one was more in the 5 o'clock position, using #1, the timing light flashed no where near the timing marks.

I checked the timing mark accuracy by putting a brass rod in the spark plug hole and carefully rotating the engine both ways by hand until the piston stopped putting precise marks on the timing pulley, turned out that 0* was exactly in the center, but for the #8 rather than the #1 cylinder, so used that for the reference after checking out the theory. Engine was timed at 32*BTDC that explained why the engine speed increased rather than decreased when I plugged the vacuum advance hose, reset that to ten.

Carburetor was also a mess, mixture plugs were missing and idle mixture screws just about ready to fall out, I set those at a turn out, and had to play with the idle adjustment to keep the engine running. Adjusted alternately, both mixture adjustments and idle speed at 700 rpm peaking out the idle speed with the mixture adjustments, then turned in each 1/16th a turn, manual doesn't call for that, but only dropped about 10 rpm and rather have it a tad lean than rich. At this point the engine was converted from a rock shaker to a ripple free wine glass test sitting on the air cleaner. Did do a compression test first, all eight were exactly at 150 psi, that was good news.

When I warms up a bit, will put on my air/fuel ratio meter and adjust the power jets.

mhamilton on Mon January 29, 2007 3:50 PM User is offlineView users profile

It always amazes me how some people can drive around with an engine so out of tune. Had pretty much the same experience when I bought my Malibu years ago. Purchased it from a neighbor after her husband past away, they were the original owners, but always brought it somewhere to have it serviced. I found the radiator nearly empty, what was left looked like mud. The timing was way off, with a stuck mechanical advance. Also had oil shooting out the pressure sender, missing engine mount bolt, broken trans mount, half the vacuum hoses missing or just going the wrong place, spark wires chaffed and cut open... not to mention the heap of plain broken items--heater blend door linkage, door panel falling off, trim pieces hanging off the car. . .

How did your starter even turn the engine over with 32* initial timing? I remember you having issued with that timing light, you'd think there would be mention of it on the EPA sticker.

The mixture adjustment you did is exactly how it's supposed to be done. The GM manual for my car has those instructions, along with the propane enrichment setup for checking that the mixture is correct. Dropping down from max rpm should be the perfect mixture. I had tried that procedure, but could never get a max rpm reading (never dropped from being over-rich).

But, I'm very happy with the factory idle settings on this new carb. The plugs look perfect after a few miles of driving, and no exhaust odor at all. Also have a working choke heater... finally! Now when I start the car, it will not let the idle kick down to curb idle until the engine is sufficiently warm. After about a minute of fast idle, I can kick it to ~1000 rpm, and run back inside while the engine warms without fear of it stalling. I suspect my old choke heater was stuck on fast-warm mode, along with a misadjusted choke pulloff, it would try to idle at 700 rpm on a 20 degree morning.

NickD on Tue January 30, 2007 7:49 AM User is offline

It was like that engine was locked in a cage and was fighting itself to get out, it took quite a bit of grinding to start the engine, but did get me home, surprised I was not getting preignition, but what a difference a proper tune up made. The previous owner tried, did put on a new rebuilt carb, but his mechanic sure messed it up.

I was only getting 10" of vacuum when first started, both the cruise and heater vacuum lines were disconnected, the first things these guys do with screw around with the mixtures, know several shops in town that would do this plus way jack up the idle to keep an engine running without even looking for the problem. Probably why the government took over and gave us engines that won't even run if one spark plug is misfiring plus lighting up the dash with heart attack lamps. Every OBD I car I looked at, even my DeVille and my son's 90 T-bird that were supposingly meticulously maintained by dealers had the initial timing way off, something that simple to adjust. So we get engines a guy can't time anymore. That T-Bird was only getting 17 mpg, new plugs and timing shot it up to over 30 mpg.

These older cars were so simple to tune up with a the minimum of equipment, spark advance timing light, Air/Fuel ratio meter, and a vacuum gauge and could really get great performance and fuel economy, always got better than 20 mpg with my 78 Fleetwood. Can't see much improvement in the DeVille better aerodynamic and a thousand pounds less with an OD AT added computes to about the same ratio improvement in fuel economy, but a heck of a lot more stuff to go wrong.

Even back in the 60's would set up a carb for a 12:1 power ratio and a 14.7 cruise ratio, easy and quick.

If it ain't there, won't go bad and some of this electronic stuff can drive a guy nuts trying to find the problem plus emptying your pocketbook if and when you do find the problem. I don't see any improvements here.

2005Equinox on Thu April 05, 2007 2:15 AM User is offline



-------------------------
2008 Chevrolet Impala LS
1981 Pontiac Bonneville


2007 Sears Craftsman Lawn Tractor


1985 Chevrolet Caprice


1986 John Deere 165 lawn tractor

2005Equinox on Thu April 05, 2007 2:21 AM User is offline

I had some issues with the 1981 Bonneville as for the carburetor and ignition timing. I had my carburetor rebuilt in hopes of the engine running better. It does as it warms up. At least now it doesnt stall every time you drive it while it is warming up. But it shakes when it idles like there is a vacuum leak but I cant find it. When they rebuilt the carburetor they said that it like some here had very worn throtle shafts. Funny that it was like this with only around 100,000 miles. When I got it the ignition was retarded to a large degree. Now keep in mind that in the time my grandparents had it they never had the ignition adjusted. So I am wondering how it got that way? It was 4 years old when they got it. I has an Olds 307 V8. I did have a 1981 Caprice with the 229 V6. It ran pretty well. I never could get it to stop leaking oil though.

-------------------------
2008 Chevrolet Impala LS
1981 Pontiac Bonneville


2007 Sears Craftsman Lawn Tractor


1985 Chevrolet Caprice


1986 John Deere 165 lawn tractor

mhamilton on Fri April 06, 2007 10:51 AM User is offlineView users profile

The emissions warranty only had to hold for 5 years/50k miles back then, no need to make a carb last 100k+ miles. GM did know about that problem, they had tools and repair kit for the throttle shafts. Probably just because of the soft aluminum they used, along with the dual return springs, TV cable spring, just wore out that shaft.

I can't keep up with the oil leaks on my 229 either. 10k miles after rebuilding it, the rear main seal started seeping. Must be the crank vibrations causing that. Doesn't loose any noticable amount on the dipstick, just makes a mess of the oil pan and trans.





Edited: Fri April 06, 2007 at 11:09 AM by mhamilton

mhamilton on Fri April 06, 2007 3:56 PM User is offlineView users profile

Nick, you were right about part of my idle vibration being ignition related.

I just got a newer HEI, since my old one had worn out bushings and was beyond repair. My old coil primary was just over 1 ohm, so given error in low scale of the meter, probably still within GM specs. The service manual says the primary should be
Now that my advance curve is back where GM designed it, my trans is feeling a lot better when shifting. Lot more low end torque and efforless cruising with the correct mechancial advance.

NickD on Sat April 07, 2007 7:49 AM User is offline

In 1972, Delco had to provide the V-8 HEI distributor including the vacuum advance, spark plug wires, ready to drop into the engine with one vehicle connector and snap in the eight plug wires for six bucks. Didn't leave much money for fine tuning the centrifugal advance, just about everyone was off, talking about brand new units here. But a couple of minutes of extra time could tune these perfectly for drastic improvements in performance. Another weak area was the unplated brass connectors that would turn green shortly after the warranty period, plating was legal then, but every 1/10th of a penny had to be saved to meet the budget, also cold soldering joints on the trigger coil was a major problem, but those girls had to really push it.

I like the HEI and still do, but use a high voltage scope probe for testing and use a fine reamer for the bushings, least you can do something with it. Also need an improved ground for the breaker plate and wire brushing on the clamp for a good ground, all simple stuff to get a nice hot spark.

mhamilton on Sat April 07, 2007 11:30 AM User is offlineView users profile

Sometimes I wonder if it's worth keeping this antique technology running down the road every day. Had I bought a 1981 model I would have gotten the new HEI with all spark control managed electronically. Not to mention 1981 saw the introduction of 4 speed AOD transmissions that would have given more performance with the same cruising economy. Plus, CCC increased highway mileage estimates 2 mpg, up to 28 mpg with the 6 cylinder. Some cars today are hardly pushing that number. Hmmm... perhaps it's best just to stop driving all together!

FrankD. on Sat April 07, 2007 5:29 PM User is offline

Nick what carburetor is on that 454?

“When I warms up a bit, will put on my air/fuel ratio meter and adjust the power jets.”



-------------------------
FrankD.

NickD on Sat April 07, 2007 7:48 PM User is offline

Frank, it's a four barrel Rochester M4MC series with the none-electric bi-metallic choke, looks like the previous owner just put on a rebuilt, I didn't pull it yet, but plan to. Has both the exhaust damper and thermionic air cleaner, choke seems to be set right, but still a cold weather beast, have to let it run for about 2 minutes before putting it in gear or the engine will die. I did get 15.2 mpg at 55 mph on country gas, but only 12 with city gas, so it's not too far off. Runs great when warm and even leaving parked for several hours after that morning warm up start, pops right over and moves without the engine killing.

Just learned the other day when I pulled a dual with a bead leak, new tire, just didn't clean off all the rust, that I have a 4:11 rear end ratio so should be turning about 2,673 RPM at 60 mph. Been looking for the torque curves of this engine, but haven't found them yet.

Did spend the day working on my kid's car and freezing my can off, we woke up to near zero weather this morning and only got up to about 20*F. Least we could put his cars in the garage and turn on some heaters, but way too cold to work on the motorhome, that won't fit in my garage. Windchill is way down there and cuts through you like a knife.

I am heading a committee to fight global warming, anyone want to send me a couple of bucks? LOL.

FrankD. on Sat April 07, 2007 9:23 PM User is offline

You will have to copy the part # off the side of the Q-Jet and see if it is the correct part.

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FrankD.

NickD on Sun April 08, 2007 7:06 AM User is offline

Did check that much out, Frank,

Engine GM T12, 140154445, K10 81
Carburetor 64849T

Engine block was cast in December of 1981, correct carburetor model number. Was told that motorhome manufacturers would buy a bunch of chassis's and let them sit around for awhile, manufacture date of mine is Feb 1982, so it didn't sit around very long. Was confused about emissions, does have an emissions label yet, no EGR was shown, has a plate where the EGR would go, but has the original engine paint and the bolts were never disturbed. Verified this with my GM truck dealer.

Did show an electronic tach that kicks up the idle about 100 rpm when the vehicle is decelerating between 1,900 to 1,800 rpm, with that kind of load, doesn't stay in that rpm range very long. While the module was there, no signs that the kickup solenoid was ever installed, can't even find that solenoid listed anywhere, so said the heck with it. The rest of it is there according to the emissions label. GM truck manuals really suck, had to buy several of them to get all the data I needed. The 79 manual tells me how to remove the AT, how to change the filter and proper fill and AT type, but nothing about how to overhaul it. The 82 manual only has the overhaul procedure, nothing about AT maintenance.

Emissions sections state to refer to the emissions labels, those are pasted to the air cleaner cover, don't want to lose that cover. I carefully masked off the labels to paint the cover, then sprayed a clear varnish to protect the labels.

2005Equinox on Sun April 15, 2007 10:58 PM User is offline

The 1981 Caprice I had with the 229 V6 leaked from the rear main seal all the while I had it. I managed to get it to stop leaking from the valve covers for a little while though it didnt last long. But it didnt burn any oil and it ran pretty well.

-------------------------
2008 Chevrolet Impala LS
1981 Pontiac Bonneville


2007 Sears Craftsman Lawn Tractor


1985 Chevrolet Caprice


1986 John Deere 165 lawn tractor

Edited: Thu April 19, 2007 at 4:31 AM by 2005Equinox

mhamilton on Mon April 16, 2007 10:03 AM User is offlineView users profile

Quote
The 981 Caprice I had with the 229 V6 leaked from the rear main seal all the while I had it. I managed to get it to stop leaking from the valve covers for a little while though it didnt last long. But it didnt burn any oil and it ran pretty well.

Sounds identical to mine. I don't loose a drop of oil between changes, but makes a mess under the car. I changed the front seal, and the rear started leaking. Fix the valve covers, the front of the intake starts seeping. Just can't win.

My 229 has its issues, but it does run fine. I use it in a daily driver (70 miles round trip), and now I'm getting 21 mpg with mixed city/highway driving. Original EPA ratings were 19/26 mpg, and I have seen 24 mpg on a long trip. Many new cars are not exceeding those numbers even today (saw that new Chrysler compact was only rated at 26 mpg highway). Your '81 would have been higher, 28 mpg highway with the CCC. I do like the low end torque of these stock GM engines, although it really dies in the top end.

NickD on Mon April 16, 2007 10:31 AM User is offline

It was a pleasure getting my first Honda with a die cast aluminum valve cover with a neoprene gasket insert after all the tin GM crap, well, Ford too. I had good results using GE silicone glue on the GM's coating both the top and bottom of the valve cover gasket and a drop of loctite on the screws that were always coming loose. A ball peen hammer had to be used on the bolt holes in the valve cover because they were always smashed down. Fel-Pro actually came out with metal spacers in their gaskets so you could tighten the screws without smashing the gasket.

Valve cover leaks were only a small part of the problem, it's where that oil dripped that caused major problem, like on the drive belts or on rack and pinion boots. Had one where nothing was left of the boot, tried to buy a new one after repairing the valve cover leak, they wanted to sell me the entire front end of the car.

Rear rope seal was only good for 5-10K miles, then was leaking again, would always put cardboard on the garage floor, and only fill the oil to the add mark, filling to the full mark only increase the drip to the point of overnight, you would have a quart of oil on the floor. I got one of those chinese rope pullers, but that was always a dirty chore having to remove a lot of stuff to drop the pan on engines where you could drop the pan, those days are gone.

Ha, Leak is a great name for these cars, windshield, windshield washer fluid, PS fluid, AT fluid, brake fluid, and of course, fuel, oil, and coolant. Worse and most expensive, and can't forget that, is refrigerant leaks.

mhamilton on Mon April 16, 2007 8:21 PM User is offlineView users profile

Yeah, it took Chevy until 1987 to figure out valve cover seals. That's when they machined the perimeter of the head, and used center bolts. My Impala is going on 170,000 miles with OEM valve covers gaskets and no leaks.

It's crazy, because Buick (and others) V8s back in the '50s had the center bolt valve covers. Guess Chevy owners had to fend for themselves as far as oil leaks

I changed over to the FelPro rubber gaskets, no metal core, but have been leak free for a long time now. I straighten the cover's sealing edge with the ball peen, then RTV the gasket to the cover. Hold it with clothes pins for a few minutes, then they don't fall off. I like to put a dot of RTV in the bolt holes, keeps oil from seeping out.

2005Equinox on Thu April 19, 2007 4:38 AM User is offline

Glad to hear you got most of the leaks fixed. And you are right. For such an underpowered engine(The 229 V6) even in the caprice you really didnt notice the deficiency until you got it on the highway. Though this car was on its 3rd engine by the time I got it with 116,000 miles. The V8s last longer in a car like this. My 307 Olds in the '81 Bonneville is like new with only slight valve cover leaks. Even the 1979 Impal with the 305 V8 had 146,000 miles when I got rid of it and it was still fine. Remember, at one time each GM division designed its own engines. No surprise than that some were better than others in terms of leakage.

-------------------------
2008 Chevrolet Impala LS
1981 Pontiac Bonneville


2007 Sears Craftsman Lawn Tractor


1985 Chevrolet Caprice


1986 John Deere 165 lawn tractor

NickD on Thu April 19, 2007 8:38 AM User is offline

I never been hot on the 90* V-6 more commonly known as the sawed off V-8 with that added counterbalance shaft to keep the engine from being a paint can shaker. We had a Nissan 60* V-6 that would idle nice and smooth and somehow they manage to put all that top crap on the side of the engine to keep the profile down. Did have the Continental 90* V-6 with that huge intake manifold on the top plus the air cleaner, never could get a smooth idle with that engine, inherently impossible.

I thought it was insane to put anything larger than a 4 cylinder in a FWD vehicle, that Continental V-6 was near impossible to work on, so like an idiot I buy a V-8 in a FWD car, that is in my 92 DeVille, but they used intelligence in the layout, just remove four nuts for the strut tower bar, a couple of wing nuts to swing out the relay box and have a clear shot at the four rear spark plugs, was rather easy. Can't say the same about our 98 Escort ZX2, worse water pump I have ever changed was in the Continental, second worse was in that 4 cylinder Escort. I spend an hour last night with my left hand all torn up just trying to change the right burnt out headlamp bulb in that Escort. Did you hear me cuss?

Later Caddies have become an nightmare to work on, I won't even look at one, so not really dependent on the number of cylinders, but on the consideration of the designers for serviceability. My Caddy idles like a dream with a 90* V-8, and no slacker either with 200 HP in a 3,600 pound car, love the self diagnostics that is completely interactive by playing with the climate control buttons. Wife says I should sell it, too many cars around here, said, I can't part with my Caddy, also gets 30 mpg when driven sanely, GM can do somethings right. Also the first Caddy that wasn't rusted out before the 36th payment, still looks great on it's 15th birthday. All the switches have tungsten contacts, no problems there either. And no engine oil leaks, did have problems with coolant leaks, with those stupid pills that don't work, dumped in a can of aluminized power coolant sealant, and hasn't used a drop since.

mhamilton on Thu April 19, 2007 9:46 AM User is offlineView users profile

Equinox, I've heard that those Olds 307s were pretty good little engines, with a nice bore/stroke ratio. Never owned one myself. I've always ended up with engines made by Chevy. I've found that with the stock gearing, my Malibu ends up right at the 229 torque peak at 70-75 mph. Cruises effortlessly on the interstate, but passing on 2 lane roads is another matter. Since this knocking 229 has to come back out, I'm considering cleaning up the heads, see if light porting and polishing adds a bit to economy and performance (not expecting miracles, though). The 305 is capable of some impressive numbers when done right, and of course the 229 is 3/4 the 305.

Nick, I was reading that GM managed to make the 4.3L V6 an even fire engine... plus the added balance shaft. The 200/229 V6 were semi-even fire. They had 3 "groups" of pistons, with 2 firings close together, then a large gap, 2 more, etc. The sequence was something like 60-60-120-60-60-120... can't recall the exact numbers. Better than an odd fire, I guess.

I don't remember how the '92 FWD Cads looked, but once I opened the hood of a '97 Eldorado. I just about stumbled backward gasping at the compaction of mechanicals under that hood. At least they leave a small hole in the plastic cover to allow you to add oil!

Remember when car brochures in the '70s touted "ease of serviceability" on the new models? Evap and heater core were in the engine bay, radios could be pulled without removing the dash, spark plugs could even be seen... Seems that went out the window in 1984, then FWD forced everything back under the dash.

My '96 Impala had the same DexCool issues as your Cad. Those clay pellets GM added clog the heaters on these cars. General consensus from the SS group is to flush thoroughly and add fresh Dex, no clay pellets.

HECAT on Thu April 19, 2007 11:06 AM User is offline

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Another related problem that is occurring in virtually all models is the improper mixing of coolants. The chemical reaction that can occur when mixing OAT, HOAT, and Regular Antifreeze can cause a gelling of the material that will also clog the heater core.

This tool is already available through 2 major auto parts chains and being evaluated by 2 OEM's. Look for a tool review coming soon in Professional Tool & Equipment News. A video of this tool in action is on our web site home page. Lowest Pricing available on any HECAT products is always at AMA.

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-------------------------



HECAT: www.hecatinc.com You support the Forum when you consider www.ackits.com for your a/c parts.

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NickD on Thu April 19, 2007 2:34 PM User is offline

My 2nd car was a 41 Chevy, ironically for awhile the only GM vehicle with an OHV engine besides the Buick straight 8, but after working on them in the 30's to 70's, no where near the quality of the Buicks or Cadillacs that did such things as machine the combustion chamber. Odd I feel that way, as no Chevy's for years, now I have two of them. One GM car I have never owned is their Pontiac, something about that car justs turns me off. Looked at the 04 Sunfire and it's grille looked like it was going to take a big bite out of my butt, so got the Cavalier instead. Pontiac was the last GM car to get rid of the flathead, buddy of mine had a straight 9 flathead 54, believe it was in 55 they finally got an OHV V-8. My father-in-law at the time got a brand new 76 Pontiac, nothing but problem after problem with that car.

Even with only 26K on his Pontiac the rear axle wheel bearings went bad, was plenty of grease in the differential, swear the balls were made out of lead in that thing.

Buick was my favorite for the longest time, had a 33, 41, 51, 65, and a 70, feel the best car GM ever made was the 1941. Switched to Caddies in 1973, did look over the 92 Park Ave very carefully, and said no way, an electronic and mechanical nightmare Buick was GM's first car and the one for years they took the most pride in, but that is history.

mhamilton on Thu April 19, 2007 6:01 PM User is offlineView users profile

Quote
One GM car I have never owned is their Pontiac, something about that car justs turns me off.

That's funny... I feel exactly the same way. Never liked Pontiacs, that exagerated BMW grille has never appealed to me. The only Pontiacs that are halfway decent are the early '50s models, the old Star Chief and such, the models that were made before GM tried to make the brand "youthful."

My Grandmother had a '60 Buick, that was a nice solid car. My father had an '86 LeSabre, remember the FWD AOD trans failed 3 seperate times... all under 100k miles. Engine required a major overhaul at some point, too. I remeber that car was going back to the dealer countless times under warranty.

Chevy had great cars up to 1980, but the '46-'48 models have always been my favorite. Don't care for the Aerosedan that much, but the Sport Master with the notchback and "Aerolines" on the front fender is my all-time favorite.

Nick, I remember you commenting on the quality finish of Cad cylinder heads. Do you (or anyone else) think a bit of light machine work will be of any benefit for my little V6? I know a good porting and polishing job on a performance engine is significant, had that done on the Corvette 350... but this V6 never sees over 3,000 rpm with the stock gears. A few extra hp and more torque would be nice with today's traffic.

Edited: Thu April 19, 2007 at 7:30 PM by mhamilton

CorvairGeek on Thu April 19, 2007 10:36 PM User is offline

The 4.3s are still odd/even fire engines. Too much bottom end strength loss to make a truck engine in an even fire 90 degree. Some 4.3s do have the counter balance shafts, but I have no idea on applications.



-------------------------
Jerry

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