Can't do burnouts with 1968 Eldorado

[mikanystrom]

I wonder if there is a "Cadillac Owners Anonymous" group anywhere?  I just bought another Cadillac.  It's a 1968 Eldorado, just like the basket case (rusted bottom, everything broken) I bought last year, but much prettier, and has very low miles, about 48K DMV-verified in .. 48 years!

Anyhow, coming off the trailer it ran like c***, a few vacuum hoses later, it ran OK, and after a Pertronix, tune-up, and a rebuilt carb, it runs like new!  A relatively faint clicking from one of the even-side lifters, and that's about it.

But but but.... the basket case I have, when I got it, it also ran pretty poorly, and after the same treatment that the shiny one got, it burns rubber in both first and second gear.  OK, it also has really lousy tires.

The pretty 48K one, though, it feels like a dog off the line.  Once on the freeway, it accelerates well, there's nothing wrong there.  The timing on the engine is if anything a bit too aggressive (I get full-throttle pinging up in the revs, too much centrifugal advance maybe). 

Pulling out of a parking lot on a slope, you have to give it a LOT of gas to make it move.  Once moving, it's like any old Cadillac with a 472... a soft rumble and it keeps up with any normal traffic. 

As I was working on the car today a gentleman came up to me to talk about it, he said he had worked on a lot of Turbo 425s while working for Buick, and when I mentioned the issue to him, he suggested it was the stator clutch...  I am thinking either something like that, or I have missed something about the timing curve on the engine. 

Hmm I should drive the two Eldorados back-to-back for better diagnosis.

Any ideas out there?

[bcroe]

That is a very powerful engine.  First thing I always do is make sure the
original timing chain has been replaced.  There may be a lot of slack, and
anyway if the plastic falls off the original cam sprocket, it could very
seriously damage the engine. 

After that, check out ignition advance and the carb.  With 2 cars you
can swap parts to see what happens. 

There could be a problem with the trans; if its original, it needs a set
of soft parts (seals, etc) no matter how low the mileage.  And if the
torque converter stator clutch has failed, you won't get much low end
torque.  Bruce Roe

[Dave Shepherd]

Correct Bruce, a properly tuned engine should  have about 1800 rpm stall speed, if not the engine power is down or the torque converter is bad.

["Cadillac Kid" Greg Surfas 15364]

Mika,
A "burn out" is what r4ace cars do to warm up their slicks (racing tires). Sprinning the tires and burning rubber is just that.   And yes, ANY good running FWD Eldo has a hard time not overpowering their tires.

[Jeff Rosansky CLC #28373]

Ok, stupid question. I admit I dont know much about transmissions.  What is the stall speed?
Jeff....... Uh, I mean Bill

["Cadillac Kid" Greg Surfas 15364]

In simple terms the stall speed of a (torque) converter is the speed up to which you can get the engine with the transmission in drive and the brakes held on with the car stopped of course.  It is the speed at which the coupling becomes positive.  It ranges from somewhere around 1200-1600 for a stock car and up to 6000 rpm in some (1/4 mile) race cars
Greg Surfas

[Bobby B]

Jeff,
Have fun…..
             Bobby
http://www.converter.com/faqs.htm

[Jeff Rosansky CLC #28373]

Ok, so brake (pun intended) this down to kindergarden level for me............ Thinking of it like a clutch. The transmission will "slip" a bit until it gets to the stall speed. At that point if the wheels are not turning, the engine won't either?
I read the link above (thank you) but still don't understand why it should be high for a non racing car. 1600 seems hi, but would it allow the engine to speed up to a better rpm in the torque curve when say pulling from a stop going uphill? Seems like it would allow an underpowered car to 'cheat' a bit. Not really necessary with our bigger engines.
When sitting at a stoplight, is it just fluid in the torque converter trying to advance the car? If so, and the idle is high such as a cold start, then it really doesn't put much wear on the transmission??
Bill

[Jeff Rosansky CLC #28373]

Sorry by the way, I realized I think I just hijacked this thread.

[savemy67]

Hello Mika,

When the tires spin on the basket case, most likely the engine RPMs increase before the tires grab.  When the tires do not spin on the shiny car, the effect on car movement feels much different, as you observed.  If the tire's traction between the two cars is significantly different, you might consider swapping the tires between the two cars to see if the shiny car will break traction with the worn tires from the basket case.  The idea is to determine if the observed symptoms are tire related, or engine/trans related.

From your post, it sounds possible that you could have an engine or transmission problem.  You mentioned that the carburetor was rebuilt, and that you have altered the timing.  Either or both of these actions could affect the shiny car's performance.  Additionally, you could have a problem with the stator in the transmission, but if this is the case, this would be the most costly and time consuming to repair.  You may want to do the tire swap first, then proceed to reset your timing and verify that the rebuilt carburetor is adjusted correctly before tackling the stator in your transmission.

Respectfully submitted,
Christopher Winter

[TJ Hopland]

Mika, when you were in the distributor the weights and vacuum advance all seemed to be working?   If that is good then I think I am with Bruce thinking timing chain or old age in the trans.   Christopher has good thoughts too if you can get both cars together.

[mikanystrom]

Thanks for the input everyone!  It will likely be a few days before I get a chance to debug further, but I'll post updates.

Today... well indeed, I'm stupid, I forgot to hook the vacuum advance back up after I messed with it before.  Now it's hooked up again, and it sure makes the car feel a lot more peppy off the line when driving like a normal person, but it shouldn't affect the behavior too much with the pedal all the way down.  It's set up stock, as far as I can see.. ported vacuum, manifold vacuum, wax plug, and it seems to work as it should (at least I get ported vacuum out of it normally).

What did have an effect though, for sure, was that the throttle linkage wasn't really adjusted quite right.  Is it common for these cars to have very little margin in the throttle linkage?  By "little margin" I mean that I have to pull the cable so far back that if I can get full throttle by pressing the pedal all the way down, it's a hair from not being able to go back to idle... is that normal?  I had to grease the cable to get it to go back to idle and it's close that it just wouldn't be able to mechanically reach both ends of the carb throw.  I do have cruise control (but it's not hooked up, I don't have the link between the cruise control unit and the throttle cable?)

As far as advance, yes, when you install a Pertronix properly (as I do nowadays), you take out the distributor and shim the end play on it, so I had it on the bench, and the advance weights seemed fine.  Indeed I get a slight bit of pinging at full throttle as the revs rise, so that must be good.  I've backed it off to about 1-2 degs BTDC now, running on California premium gas of course.  And yes it runs on all eight.  New springs, and a new (adjustable) vacuum advance.  I have it limited to about 12-14 degrees of vacuum advance (close to factory specs).  It pings ever so slightly (not all the time and you really have to know what to listen for--as it should be I think) accelerating at half-or-so throttle.

Short summary: the throttle adjustment helped.  I will have to try swapping the tires.  They might just be a lot stickier on this car.  Now I get a bit of a chirp at least :-)  But the transmission is definitely not working at 100% no matter what, sometimes it has a bit of a delay in going into drive.  Nothing that feels like "slip" though, and the fluid seems clean.  Oh well... 48 years.

I'd be surprised if the cam chain had been replaced.  How serious is it, do they snap, or do they "just" slip a link or two?  I suspect factory instructions for replacing the cam chain involves taking the engine and trans out of the car, and then we're in the "while we're at it, might as well overhaul A, B, C, D, ... , Z" territory.

Oh and if we're in overhauling transmission territory.. I want to ask, has anyone reading this put a variable pitch transmission in a 68-70 Eldorado?  I've always wanted to try one of those, sounds like magic to me.

[66 Eldo]

If you have a timing light you can see if the distributor advance including the centrifugal portion is working. Aim the light while it is flashing and rev the engine to about 3000 rpm. The timing mark on the pulley should move/advance out of view. This test is most accurate with an advance timing light but if you just have a basic one it will tell you if its working enough.

BTW, if you just want to do a burnout, pour some anti-freeze in front of the front tires and do a power brake burnout.

[Scot Minesinger]

Don't put a switch pitch trans in your Eldorado unless a perfect operating 67 trans is delivered to you and switching them is the cure for the faulty one in your car.  There are some mounting issues and then the angle of the pitch has to be controlled.  I would keep it stock, it will work best that way.  The switch pitch to me is a better transmission.  However it is more work/resources to get it working as it should, and it may not be worthwhile.

It is difficult to diagnose this type of problem over the internet, for example we would not have figured out that the vacuum advance hose was not reconnected for example.  You will need to continue working away until you find the problem, that is what ends up happening to most of us, I think.

On the timing chain, that should be replaced because the cam sprocket is nylon coated and the nylon breaks off and goes into oil pan clogging pick-up.  Also as the nylon comes off of course your timing will be compromised because the nylon leave s the sprocket unevenly.  I have seen pictures of this.  I have replaced 4 timing chains on Cadillacs ranging from 36k to 104k miles and they were all relatively intact, getting ready to go on the higher mileage ones.

To remove the timing chain, you have to drop the oil pan to get front cover off, which requires removing engine from car according to shop manual.  You can change it without removing pan though.

If you decide to re-build your transmission it of course will have to be removed, and then you might as well remove both engine and transmission.  The advantage of removing engine is you can drop the pan and replace the rear main seal, which undoubtedly is going bad.  Further you can clean out oil pan and replace that block to pan gasket too.

What we do for our Cadillacs...

[bcroe]

Don't wait till the trans fails; the damage will be far more serious.  The TH400/425
had some upgrades in the early years; perhaps the best ones are just past 1969. 
Any TH425 trans (except 67 Eldo) will directly bolt into your 68 Eldo. 

If you decide to get a SWitch Pitch trans, a 67 Eldo won't bolt up.  It is possible to
rework a couple holes so it does; I have album pictures on my PHOTOBUCKET
showing how someone did this: SWP 67 ELDO TRANS CASE CONVERTED TO BOP.
Use a 66/67 Toronado trans, or put SWP parts into a later trans.  Manny makes a
super duty TH425 suitable for GMC motorhomes, SWP an option. 

SWP cars were originally equipped with the (very crude) mechanical switch.  The
mechanical switch only uses the SWP function at idle and near full throttle. 
If converting to SWP you can instead use an electronic SWP controller, which
uses timers and torque sensing to enhance the mid range where most driving
occurs, adding some zip, smoothing and sometimes eliminating the need for shifts. 
When I converted my first Olds 88 (350, 2.41:1 axle), it took a whole second off
0-60, and passengers would comment on how smooth the trans was.  Sometimes
they still do.  I think gas mileage improved a bit too. 

     http://s93.photobucket.com/albums/L71/bcroe/

  click on an Album
  click on a picture to enlarge + description
BRUCE ROE

[Glen]

What did have an effect though, for sure, was that the throttle linkage wasn't really adjusted quite right.  Is it common for these cars to have very little margin in the throttle linkage?  By "little margin" I mean that I have to pull the cable so far back that if I can get full throttle by pressing the pedal all the way down, it's a hair from not being able to go back to idle... is that normal?  I had to grease the cable to get it to go back to idle and it's close that it just wouldn't be able to mechanically reach both ends of the carb throw.  I do have cruise control (but it's not hooked up, I don't have the link between the cruise control unit and the throttle cable?)

I noticed a lack of full throttle performance on my 68 ELDO a few years ago.  I found that pushing the petal all the way to the floor did not open the secondarys in the carb.  Checking the linkage, I found the lever under the pedal was bent.  I had to bend it back to the correct shape to get the performance back.    It was not hard to do, apparently the lever is soft.