I have this problem with my 69 Coupe deville: The engine starts easily, but runs rough until it warms up to normal operating temperature. It acts as if it were not runninng in all 8 cylinders and when I press the gas there's a lot of vibration going on and it struggles to gain speed.
However, once it's warm, it runs fine.
The only change that I made this year is the oil type (I used 15W50 instead of 10W40) because I noticed that with the 10W40 I had to add 1 Quart every 600 miles so I went with a thicker one.
Any ideas ?
Sticking choke would be my first guess.
Sounds like the choke isn't working properly.
Closes to start it , but then doesn't open correctly , while warming up.
Roy
Had the same thing happen on one of my cars. I chased the problem around the vacuum circuit, the ignition circuit, and the carburetor circuit. As a "last resort" I pulled the plugs.All four on one side looked perfect. I started pulling plugs on the other side and the first two again looked perfect, but I went on and I found the #6 plug was discolored (fouled). Replaced that plug and the problem went away. Apparently (on mine anyways) once the engine is warmed up it can "drag" a cylinder or two along with little problem, but until the motor warms up it is quite noticeable.
I suggest you try the plugs. If your motor has a few miles on it or if the valve seals have not been replaced, chances are that the oil consumption is the "clue".
Greg Surfas
Agree with all advice so far - very likely, check choke as that is real easy and check plugs. My 1970 Cadillac needed a valve job because it consumed oil and every time you stepped on the gas from the red light a puff of black smoke emitted from exhaust. It never got to the point of rough running.
The heads are the weak point on these engines. However, save removing the exhaust manifolds it is not too difficult to remove the heads and have them rebuilt at a quality local engine re-builder (then you can also specify the valves for unleaded gas too). Also Maximum Torque sells rebuilt heads already to bolt onto your car. The heads do have the engine number in the casting, so if originality is critical get yours rebuilt.
Check the choke pull-off diaphragm. It's a little diaphragm mounted on the carb with two lines coming off of it.
When the car is cold the chokeplate completely closes when you pump the pedal. The pull-off opens the plate slightly as soon as the engine starts and has vacuum to allow some air in the carb.
I have the same issue with my 70 and I bought an NOS pull-off at a car show but have not installed it yet. I'll let you know if that solves my problem, but these were commonly replaced when these cars were a few year old used cars.
Brian
Brian, are you referring to the vacuum break diaphragm, aka dashpot?
On a cold engine it's easy to check, It should set (close completely)with a full press of the accelerator pedal. After that, you should be able to push down gently on the lower edge of the choke plate and it should open up for you. You can also visually check while running after a cold start for the choke plate to be slightly open. The car should also be on fast idle (highest setting if a completely cold engine)
Yes those can be a problem. A bad cylinder could also be the culprit. My # 7 was bad, turned out to be that a loosened up pushrod fell right out from under the rocker arm!
Thanks everybody for the replies.
I don't think it's the choke, because I've already checked it and it seems to be working OK. When I pump the pedal it closes and when the engine is warm, it's open.
I'll check the plugs. I had a problem with the plugs last year. After I switched to electronic ignition, I installed Denso iridium (IW16) plugs and they were destroyed after about three months. I thought that they are not the best match and went back to regular plugs (Bosch WR9DC) which worked ok until november of last year. Come to think of it, that's another 3 months.
The plugs are most probably the problem. I'll check them next week when I get the car out.
Thanks again !
Also, there are two vacuum units on the carburator (Quadrajet), both on the passenger side, one towards the front of the engine (vacuum brake I think) and another towards the firewall. The one towards the firewall has a vacuum line on it on one side and a little rod on the other side. I noticed that there is a metal ball stuck in the vacuum line, like bearing ball.
I bought the car like this and I have no clue as to why the previous owner would have wanted to obstruct that vacuum line.
What does that unit do ? Should I remove the ball or not?
Mihai,
IF IT WERE ME, and the problem just started, I would find the problem before I started making changes. Many of the QJ's did not in fact have the rear vacuum actuator. Find the problem first.
Greg
Just because the choke closes , ands then its open when hot, doesn't mean it is set up right.
If you do have the rear choke pull off on the car, and I say if you do, that unit opens the choke a set distance once it starts. That's all it does. The choke must then open slow enough to stay in tune with the motor warming up.
If you have ball bearings or old jeeps stuck in the vacuum line ,you have your first problem.
If it doesn't open or opens to quick, you will get a rough running engine, until its warm.
You have to check this from a cold start , with air cleaner off, and watch it while the engine warms up. You also may have to give it a quick shot on the gas once in a while .Pull back on throttle while its warming up, just a bit.
Picture of carb would help a lot. Sounds like a newer carb, if it has a rear choke pull off.
Mike , a dash pot is on the drivers side. It just slows the return action of the throttle when coming back to idle.
This was from Clay Tynan a.k.a. blue 68deville.
We were talking about the rear vacuum pull off on carbs, and he corrected me on this carb for his 67.
I wonder if yours is the same way.
Roy
His posting;
------------------------------------------------------------------------------------------------------------
The diaphragm on the rear of the 67 carb is for the idle-up function. It increases the idle speed when the a/c compressor is engaged and the car is in park/neutral.
The vacuum break/choke pull-off is low on the front pass side, should tee in to the vac port on that side of the carb. It is a full mainfold vac source. It will slightly open the choke when the eng starts, keeps it from bogging down due to a rich condition.
The vacuum advance should come off the vac port on the front driver's side, just above the idle mixture screw. It should correspond to a port in the throttle area, right above where the butterfly edge rests when at idle position. That makes it ported vacuum, it won't provide a vac signal untill the throttle is slightly opened.
Isn't this one of the years that has the exhaust cross over is open under the carb? Seems like I remember reading about this symptom not that long ago and it turned out that the wrong gasket was installed and it was slowly burning through and allowing exhaust to leak into the intake.
Quote from: Roy Schroeder on April 11, 2013, 04:30:18 AM
This was from Clay Tynan a.k.a. blue 68deville.
We were talking about the rear vacuum pull off on carbs, and he corrected me on this carb for his 68.
I wonder if yours is the same way.
Roy
His posting;
------------------------------------------------------------------------------------------------------------
The diaphragm on the rear of the 67 carb is for the idle-up function. It increases the idle speed when the a/c compressor is engaged and the car is in park/neutral.
The vacuum break/choke pull-off is low on the front pass side, should tee in to the vac port on that side of the carb. It is a full mainfold vac source. It will slightly open the choke when the eng starts, keeps it from bogging down due to a rich condition.
The vacuum advance should come off the vac port on the front driver's side, just above the idle mixture screw. It should correspond to a port in the throttle area, right above where the butterfly edge rests when at idle position. That makes it ported vacuum, it won't provide a vac signal untill the throttle is slightly opened.
Roy, thanks for the clarification.
You really can't go by a 1967 diagram. The engine was completely different.
My 1968, which is essentially the same as the 1969, had two vacuum break diaphragms on the passenger side, one by the primaries and one by the secondaries. I had the rear one (secondaries) taken off and the line plugged, but I can put it back if i want. The Idle speed up solenoid is on the drivers side, and it does not really come into play on a cold engine because the fast idle cam will cause a much higher RPM than the idle speed up would cause. There no way a 68-74 will have the idle speed up at the rear on the passenger side. It needs the electrical connection and that's over on the driver's side. The breaks on the passenger side were vacuum operated only.
Roy, is correct, you have to start with a
cold engine, one where the exhaust manifold is cold to the touch. Have someone start it while you are looking at the choke plate. It should close then set by depressing the accelerator all the way and slowly releasing it. As soon as the engine starts, the plate should open about 1/8 inch. If it doesn't then something is stuck with the linkage or bushings, etc.
Only after this is is confirmed as not the problem should you go hunting for other issues, but you may want to close off any loose vacuum lines as well.
And yes these years did have the exhaust crossover. I'm still thinking I should have had those ports welded off and the riser on the passenger side brazed permanently in the open position. If I ever have the intake manifold removed again, that will get done.
Here is a link on vacuum choke pull-offs, AKA vacuum break diaphragms:
http://autos.yahoo.com/maintain/repairqa/engine/ques072_0.html
Maybe I'll put my secondary one back on now!
Mike,
Once again you didn't read all of my postings. Reply 10 is talking about the vacuum choke pull off on the rear of the carb. I am fully aware of what this does.
One of the posters posted that he didn't believe there was a vacuum pull off on the rear of the carb, for this year. I wrote about it, IF he had that type of carb. Some Quads did NOT have one.
I don't know when the carbs changed over to the rear pull off.
That's why I posted one about the rear vacuum pull , ON CERTAIN YEARS , being used as a fast idle for when the air conditioning is on. Post #11
This is a TRUE set up. When you turn your air on vacuum is supplied to that rear vacuum device.
It moves a mechanical linkage to step the idle up.
Drivers side ELECTRICAL idle solenoid is on my car. It pops out when the air conditioning is on.
I never said it had anything to do with a cold start up.
On that same side , on some of the carbs , there was a unit called a dash pot.
This slowed the return of the throttle linkage , on SOME models.
So to recap;
Some Quads don't have rear vacuum brake.
Some Quads do have a rear vacuum brake.
Some Quads use the rear vacuum device as a idle control for air conditioning.
Some Quads use an electrical device to step up idle , located on the drivers side .
Some Quads use a dash pot on the drivers side to slow throttle linkage down.
And we are talking about carbs here, not so much the year of the car. There have been plenty of posters at this site that have orphan carbs on there cars. So, it was more important to find out what he was using on the car.
Guess its all moot anyway, as he has not returned to answer any questions.
Roy
Hi !
I'll go to finish up my tach project on Sunday, and I'll take some pictures of the carb and post them here.
Thanks, and sorry for the delay.
Quote from: Roy Schroeder on April 10, 2013, 05:24:35 PM
Just because the choke closes , ands then its open when hot, doesn't mean it is set up right.
If you do have the rear choke pull off on the car, and I say if you do, that unit opens the choke a set distance once it starts. That's all it does. The choke must then open slow enough to stay in tune with the motor warming up.
I'll try to take a video of the choke plate from the moment I start the engine until it warms up, with a thermometer measuring the temperature as the choke opens up. Then we'll know what's what, right?
This is how the passenger's side of the carburetor looks like. It's a crop from the service manual and my carburetor looks exactly like that. The vacuum line that is obstructed by the metal ball goes on the unit that's on the left side of the photo.
OK. That rear vacuum device is the idle unit , for the idle when air is on. There is a vacuum line coming out of the fire wall with a white stripe on it, according to what Clay posted for me.
Vacuum comes on when air conditioning is turned on.
On newer carbs like mine , in my 78, it is a choke pull off mounted there.
Roy
Ok. So we know that it has nothing to do with the symptoms.
I'll try to take that video on Sunday, as I think that it's the best way to determine whether the choke works properly or not. If it does, at least we can rule that out as the source of the problem.
Mihai, please check the operation of the
primary vacuum break. That's the one at the front of the carb. You can clear the obstruction on the rear one, if the break is not damaged. The line may have been plugged with the ball because a damaged break will cause a vacuum leak, and these went bad quite regularly. Because of this, removing the rear break was common and as long as the line is sealed / plugged, it does not hurt operation of the engine, because the secondaries almost never come into play on a completely cold engine. It's better to have the line plugged than have an open line with a leaking break.
But your primary break must be working or you'll get rough idle when cold.
And now for something completely different:
Quote from: Roy Schroeder on April 12, 2013, 06:27:40 AM
OK. That rear vacuum device is the idle unit , for the idle when air is on. There is a vacuum line coming out of the fire wall with a white stripe on it, according to what Clay posted for me.
Vacuum comes on when air conditioning is turned on.
On newer carbs like mine , in my 78, it is a choke pull off mounted there.
Roy
Roy, that is the secondary venturi choke pull-off. It is not the idle speed up for when the A/C is on.
There is no electrical connection, which is needed for the A/C idle speed up. From 1968-onwards, that was on the driver's side of the carb, just like yours.
And, i did read all the old posts. We can't go by 67 or earlier on these cars for just about anything in the engine compartment, they are just too different. The poster who stated that many of the QJs did not have the rear break has a 66 and a 72. the statement that 67 has the idle speed up on the passenger side is correct, but it
does not apply to 68 and later cars.
Remember, in 1967 and earlier the AC compressor was
waaaay over on the passenger side of the engine on a long extended bracket. It was logical to have the A/C idle speed up on the passenger side of the carb. That's why 67 and earlier basically does not apply in the engine compartment.
1968-70 were almost identical in the carb, but are very different in many respects from everything that came before or after. I have had all three years, for over 24 years total, and all with the original carbs. They all had dual vacuum breaks. They might have not been on some later years, but the manuals for all three years all have both breaks on the carbs. (68 and 69 used the same model QJ)
A lot of changes came in 1971 as well mostly WRT emissions, which invariable changed the carbs, making these 3 years unique. Some years might not have had dual vacuum breaks, but we are discussing a 69 here which originally did, and it has a vacuum line that must be dealt with with or without the break.
Mike, if he has a 69, why is he posting a picture of a 67 carb with the idle step up on it.
All I said is , that is , the 67 carb. HE said that was what he had on his car. If he does then we have a problem .
That is why I asked him to post a picture of the carb on the car.
To many people have carbs on there cars that didn't come with the car originally. One of the other guys with a 77 had a Chevy carb on his. Went around for days with him on that one.
A simple picture of the carb, taken from both sides would help. Pictures are better . Or a carb number.
Right ?
Roy
I pulled both of these off Ebay.
The cleaner carb is suppose to be from a 67. That is the tag he has on it anyway.
The dull one is off a 69.
Not a whole lot of difference.
BOTH have the front vacuum pull on them. This keeps the secondary upper plate from opening up until the vacuum drops under acceleration. It also moves out of the way to let weighted shaft help take it off of the fast idle cam as engine warms up. If it didn't pull in it might have a problem coming off of the fast idle cam.
It really doesn't pull the choke open though.
Roy
Mike/Roy,
We are way off topic here, but 1967 was the first year for the Quadrajet, and the engine was still a 429. The motor itself did need the AC idle speed up and it was mounted on the passanger side of the carb in the rear. In 1968 the 472 motor had enough torque at idle to run the AC compressor at "normal" idle speed so the AC idle speed up was deleted.
Mihai,
have you had a chance to check the plugs yet?
Greg
That does happen Greg.....ha
But the carb could be part of his problem.
Roy
Now I'm thoroughly confused, partly because i don't have any of my books out here, to check anything. :(
That pic that Mihai posted of the manual looks like the 68 and 69 carbs, but we don't know, and the contours of the fast idle cam look different than mine and Roy's 69 carb photo. It looks suspiciously like the 67 photo that Roy posted. Of course you can't trust ebay any further than you can throw it.
Mihai, it would help if you mentioned what year your service manual is. And again, that primary vacuum break is the most important one, it has to work correctly or you'll get rough idle, and worn bushings, etc can also be a contributor to the problem.
I'll post pictures of the carb on Sunday.
For the plugs, I'll have to take the car into the shop next week because I don't have a plug socket.
I'll get back with details as soon as I can.
Thanks!
Mihai
Mihai, what's the year of that service manual?
P.s: the manual is a pdf version called "Detroit Iron"
That's all I know about it , but it's been very accurate so far
The year of the manual is 1968
This is running in all directions.
Hi guys
So this is a very interesting discussion. Sooner or later we will figure it out, I am sure.
So I will post two pages out of my original 1968 Cadillac Shop Manual regarding the Dash Pot and Air Conditioning Idle Speed-Up System.
Quote from: "Cadillac Kid" Greg Surfas 15364 on April 12, 2013, 11:01:13 AM
... In 1968 the 472 motor had enough torque at idle to run the AC compressor at "normal" idle speed so the AC idle speed up was deleted.
I don't think this statement is true, because my Shop Manual tells me a different story. All vehicles with air-conditioning system do need a idle speed up system. And only
some vehicles have a Throttle Dash Pot.
But, read for yourself below. (two pdfs attached)
If you like, I can scan the complete chapter of my book.
Kind regards,
Nicolas
Hi
I forgot to mention: You can search for your Carb Number on the Website: http://www.carbguy.com/ and it will show you the specs. I do not know if one can trust that source, but it seems accurate.
So for my 68 DeVille with Air Conditioning a Carb with the Number: 7028237 would be correct (according to shop manual). And indeed the description given by the mentioned website is: Rochester Quadrajet, A/C, late production, Standard body.
However, my Carb currently on the car is from a Eldorardo without Air-Conditioning. And thus I do not have a Idle Speed up system associated with that carb. This fact is confirmed by the website: Carb Number: 7029232 Description: Rochester, Quadrajet, Eldorado, w/o A/C
So I guess there where very distinctive versions of these Carbs used, such that they mounted the correct carb to the correct cars when assembling the engines. So you might want to check your carb number with the help of that website.
Kind regards,
Nicolas
Thanks!
I'll do that, but as far as comparison with the shop manual goes, it seems to be the right carburator.
The car is matching numbers and I bought it in original condition as far as I can tell. Aside from the horn contact I have yet to discover any mods.
Given these facts it would be surprising to find that the carb is not the right one. As far as I can tell, the carb is as described in the shop manual. There's nothing to suggest otherwise.
Well there you go.
Thank you Nicolas. That clears up some of the mystery.
Roy
Mihai,
I worked on these cars all the time because i always drove used Caddy's from age 19 on up.
As I said before, your car has the classic faulty pull-off symptom.
Take off the air cleaner with the engine cold. Move the throttle slightly. The chokeplate should snap closed. Shut tight.
Now look at the small vacuum diaphragm on the front part of the carb and move the linkage by hand. You will see that it pulls the chokeplate back open a little bit. That's because the car needs air to mix with the fuel as soon as it starts. As the thermostatic control of the choke gets warm, then hot, it allows the choke to open all the way.
So you are getting black smoke and a rough idle because the car is fighting to get air, but when the choke gets warm enough it starts opening and the symptoms go away, if i am reading your post correctly.
By the way, you can buy a set of sockets, wrenches, a spark plug socket and a gapper for far less than your mechanic will charge you to replace one set of plugs. Just a suggestion.
Brian
I found this picture of an older Quad. I see in this picture what Brian is talking about. I didn't realize that the front vacuum break, did two things. Hold secondary door shut, and pull choke open.
My carb on my 78 only does the first thing. Holds the secondary door shut.
Although I cant see that set up in the picture of the 69 carb I posted, I can see how it works now. To many changes in these carbs........ha
Roy
I'm going through the same issue with my 70.
When I fix it, I'll take photos.
Brian
Problem solved.
I took the car to the shop, they replaced the spark plugs and it runs like a dream.
I also ordered a choke pull-off just to have it around as a spare part, even though the choke seems to be operating normally.
I'm glad that worked out Mihai.
I do recommend that you get the real 1969 shop manual, either hardcopy or searchable PDF. They are all over ebay. 1968 and 69 were very similar but not 100% identical in all aspects, especially WRT Climate Control, engine cooling and front suspension, not to mention the bodies were vastly different...
The shop manual is for 1969, but it's probably printed in '68.
This is the cover:
That's the one you want.
The manuals, etc are always printed in the previous calendar year. Remember, the cars usually come out in September, and production starts mid-end July for the new model year...
That's the one I have. It's pdf, but unfortunately non-searchable.
It was one of the first things I bought for this car.
Well, you have the correct manual then.
But you confused the hell out of us with these two earlier posts:
"P.s: the manual is a pdf version called "Detroit Iron"
That's all I know about it , but it's been very accurate so far"
and this:
"The year of the manual is 1968"
And just for the record, your car's carburetor originally had TWO vacuum breaks on the passenger side and the A/C idle speed up (if you have climate control) is on the driver side where the accelerator linkage connects to the carburetor. And it did originally have a dashpot in that same driver side area. These are probably all still there.
If your secondary vacuum break is defective or removed, you must be sure to plug that vacuum line, otherwise everything goes to pot.
These cars ran on vacuum. Gasoline was converted to vacuum in a secret area, and any vacuum leak played havoc with the car's operation. :P ;)
:)) sorry for the confusion, but I wasn't sure what you mean by "year of the manual" as I didn't think you'd assume that I' m trying to repair a '69 car based on a '68 manual.
Mihai,
Sounds like the plugs (or at least one of them) was the culprit. Like I suggested earlier, with an engine that burns (not leaks) oil, you have the distinct possibility of fouled spark plugs. If the car just gets occasional and not highway use this condition will reoccur more frequently. Next time it happens I would suggest you ask your mechanic (if you don't change the plugs yourself) to number the plugs as he pulls them out (by the cylinder they came from) and give them to you. If there is only one (and it sounds just like mine where there was one) you can change that plug (again the NEXT time) instead of the whole set.
Thanks for tolerating all the "static" and seeing the project through.
Greg
The mechanic gave me the old plugs, but unfortunately I don't know which is which. I'll take a look at them, maybe take some pics and I'll get back to you.
The car doesn't leak oil, but I'm very curious how much oil it consumes, since the initial consumption of 1quart per 600 miles was determined when the car used to also leak oil due to a bad oil pan gasket. That is fixed now and I'm positive that the car no longer leaks oil.
The car doesn't see highways as we (Romania) have a total of about 300 miles, most of them in the south-east (I'm in the north-west) :)). I'm mostly driving around town.
Thanks for all the suggestions !
So you are tooling around with chaushesku's old car eh?? :P
:)) As far as I know he had a Mercedes-Benz 600 Pullman, which was sold in the early 90's at a ridiculously low price... but good one! :))
Mihai,
These cars were intended to be "road burners" and see a lot of highway usage. If they set for extended periods or don't get driven at highway speeds often they tend to get "cranky". 30 minutes at 60 MPH every few weeks will do wonders for you car's temperament. I would just see how long it takes before the rough running returns if it does. Plug changes, especially if you isolate any particular easily fouling ones are easy on your car.
Greg Surfas
Quote from: "Cadillac Kid" Greg Surfas 15364 on April 19, 2013, 10:08:08 AM
Mihai,
These cars were intended to be "road burners" and see a lot of highway usage. If they set for extended periods or don't get driven at highway speeds often they tend to get "cranky". 30 minutes at 60 MPH every few weeks will do wonders for you car's temperament. I would just see how long it takes before the rough running returns if it does. Plug changes, especially if you isolate any particular easily fouling ones are easy on your car.
Greg Surfas
Except for # 7!
Quote from: cadillacmike68 on April 19, 2013, 11:22:24 AM
Except for # 7!
That is why you need an Eldorado. Engine sits higher and forward (and off center) so all 8 are easy to get to.
Here are some pictures of the plugs. Unfortunately I don't know which is which.
And the other four:
How many miles on those plugs? How often do you drive the car and for what sort of distances?
1500-2000 miles. I usually drive it on short distances every 2-3 days from March until October. Over the winter I store it in the garage and I start it once a month and let it run until it warms up.
I installed an electronic ignition conversion kit bought from rockauto.com (Standard motor products)
I'd say you are not getting the engine up to full operating temperature. Plugs have to get to operating temperature to burn clean, Those plugs look fouled from cool running. If you can't get the car out for a 50 mile non stop highway speed drive on occasion, I'd suggest putting the next step hotter plug in the engine. A hotter plug will get closer to operating temperature at lower speed short trip durations. They may be too hot for a sustained trip at highway speed, but would help in your described style of driving. Another alternative would be to resign yourself to put new plugs in it every spring.
HTH,
David
Plugs look carbon fouled (rich mixture) except for the first one in the second group pictured, it looks like oil fouling. Its hard to tell from the pictures, but the gap looks too small on some plugs. With the Electronic ignition conversion, did you open up the plug gap? I'd suggest at least .045 to see how it does.
Besides the short trips, other causes of carbon fouling like that are wrong/stuck/missing T-stat, late ignition timing, choke not fully opening, carb adjustment. I'm sure others can add to the list.
T Lewis
Thanks for the replies. I'll look into all those things to make sure everything is OK.
Not to hi-jack the thread, but its time for me to check out my spark plugs too.
I had the points replaced with Pertronix, but they didn't change the plugs. In fact, the plugs are the same ones that were in my car when I bought it 4 years ago! Since the original spark plugs are no longer made for this car, what do you guys recommend...brand and # and why...and what gap with the Pertronix?
And anyone have any tips or tricks for getting at that #7 plug on the 472 in the 68 Coupe deVille?
Quote from: Steve W on April 24, 2013, 01:42:17 AMNot to hi-jack the thread, but its time for me to check out my spark plugs too.
I had the points replaced with Pertronix, but they didn't change the plugs. In fact, the plugs are the same ones that were in my car when I bought it 4 years ago! Since the original spark plugs are no longer made for this car, what do you guys recommend...brand and # and why...and what gap with the Pertronix?
And anyone have any tips or tricks for getting at that #7 plug on the 472 in the 68 Coupe deVille?
A competent parts store can get you the proper AC plugs for the engine.
I use a dual hinge swivel to get # 7 out.
On 1994-96 Fleetwoods the # 8 (same position, down by the suction throttling valve assembly) you have to remove the passenger side front wheel to get that plug out! :o
I agree with the others that trips are a little short. IF that is what they looked like with long trips I would say you are either going to have to live with it or rebuild it but with short trips you just may need to get it out for a nice long run. I think I would throw a new set of plugs in it, an oil and filter change, and then take it out for a couple nice long cruises maybe 100+ miles if possible. Ideally not a lot of stop and go stuff. See what it runs like after that. Have a look at the plugs then too and see what they look like. Be sure to note which ones came from where.
I have had a lot of older engines that just did not quite seem to run right but as soon as I got enough stuff fixed on them to make them safe / reliable enough for a mini road trip I got them out and after the trip things seemed a lot happier.
Many years ago I had the spark plug thing all figured out but of course I did not write it down so I seem to have forgot it all now. I think you can still get the correct plug they just changed the numbering system around a little. I think it had to do with the fancier plugs that you can't field gap. The new number system includes the gap and they just applied the same system to the 'old' copper plugs too. I'm pretty sure the points vintage 472-500 use the R44 XLS. I don't think they changed the plug when they dropped the compression for 71. When they changed the head slightly in 74 they went to the R45 but I suspect that is just one temp range different otherwise the same plug. When they went to the HEI around that same time there is now an extra number at the end so a plug R45XLS is likely the standard 0.35 gap. An R45XLS6 is the same plug but factory gaped to 0.60.
0.045 should be safe for any sort of electronic ignition system. More starts to get a little more complicated.
TJ, I think mine are R44XLS as well (but I'm not home to verify).
All this talk about the plugs, but I don't believe I read anything about the points.
If they are not set right, the coil could be producing a weak spark.
The dwell is needed for the coil to have enough time to build up its correct charge. If the dwell is wrong , your going to have a weak spark. Then you will get fouled plugs.
If points are to close , you will burn them. Timing also will be off.
Set dwell then timing. 30 degree dwell on this car.
Plugs are gaped at .035 . One site I looked at called for R44N plugs.
To me it looks like you either have a weak burn on the spark, or you are using some oil in that car.
But there can be other problems too.
Roy
Roy,
FROM THE SYMPTOMS of running rough when cold and ok when warmed up I would deduct that the spark being "hot" enough is not the issue. When the engine warms up and the cylinder pressures get higher (due to increased compression) is when a weak spark would show up. What is apparent (to me at least) in the fouled plugs is probably a combination of oil fouling due to worn rings and/or valve seals, and an "under driven" vehicle that needs more exercise.
Greg Surfas
Greg, I would agree with you that this car is probably TIRED IRON , and has oil problems.
Just tossing out other ideas. It probably isn't the cause of the problem in this engine.
Probably would be nice if owner would give mileage ,and the type of driving they do in the beginning of these types of postings.
Roy
I did not go back and read every reply in this thread but fairly early there was mention of electronic ignition and plug problems so I think that is how we ended up coming back to spark plugs and why there was no talk about points. Just recently I asked about the type of driving and we got a reply that most of us think is a a little on the short trip side so we were thinking before condemning the engine condition that it would be worth seeing what the plugs look like after a longer trip.
He did mention electronic ignition on page 1 and how it devoured his plugs!
I would Rip it out and put in a proper Delco P&C ignition. 8)