1950s What does my exhaust tell you? 1954

[Laspaz]

Hello,

I have recently done some work to my series 75 and am trying to get things back together and running well.

Here is a video of the car running at 400rpm after about 5 minutes. Is this enough white smoke / steam to be concerned about a head gasket? Does it sound like its running ok otherwise?

https://youtube.com/shorts/LsTi4cyHCH4?si=GGxJKM1n6QuhvJYy

I went to change the RHS exhaust manifold, which led to snapped bolts in the head, which led to the head being removed. I cleaned everything up and lapped the valves and installed a new gasket. I also did the rear main seal which is leaking already (best gasket neoprene  ). I also rebuilt the carb, new points, new distributor cap, new plug wires, new fuel/vacuum pump. Timed to mark "C" at 400rpm.

Cheers!

Bevan

[James Landi]

It sounds ''ok'' I suggest that you hook up a vacuum gauge to the manifold and check for a smooth 18 vacuum reading -- a partial cylinder combustion failure will show up with a vibrating needle reading on the gauge.  I'd also check your vacuum advance.... that's nearly always overlooked and does create an uneven idle --- I'd be interested in hearing it after you've driven it on the highway for 50 miles at 60 mph. Getting these engines up to temperature, entirely drying out the block of all condensation, and then visually checking the exhaust pipe exits for uniform brown color are tell tales.  After an extended drive, you will actually feel improvement at all ranges of rpm. ALso, an infrared thermometer will help you detect hot spots in the upper regions of the block and cylinder heads. Rust and gunk usually plug water jacket passages in the heads, and cracks in the head often occur as a consequence.  Hope this helps, James 

[Laspaz]

Thanks James, I'll address your comments, I did bring the idle up to 600rom and re-time and here is the video of the results (definatly steam coming from the exhaust as it fogs up the camera lense at the end):

https://youtube.com/shorts/fAZHF-KS0eA?si=kP8qmt4ZNHWZqq5L

And with some revving:
https://www.youtube.com/watch?v=QU9i0Et1_1E


- Vacuum reading is 16 and very stable.
- Vacuum advance is hooked up and working.
- Infared thermometer readings are stable across the heads and valve covers

I do have one cylinder with lower compression. I believe it to be the rings. As you say, I think some miles on the car will help with that and the whole engine to get back into it's groove.

Unfortunately I have a transmission issue, and the first step to sorting that out is to get the engine running well. Hopefully i am finally getting there as much smoother now.

Thanks again,

Bevan

[James Landi]

That sounds so much improved! About as good as it's going to get. You've nailed it. A couple of cautionary notes, as follows:  Starting it in the garage and not getting it on the road and bringing it up to temperature is NOT GOOD.  Without a PCV set up, all of the moisture is trapped in the engine and can create stuck valve stems,bent push rods and a world of pain.  Another cautionary note, the fuel pump that is located on the oil fill neck does not supply sufficient lubricant for the mechanical parts in the  pump casing, so that mechanical lash occurs and your engine will begin to starve for gas when it's under load.  Old timers, like me, used to pack the internal casing with axle grease  in order to extend the life of the mechanism.   Hope this helps, James 

[Jeff Rosansky CLC #28373]

I don't know how long the car was down, but drive it a bit.
Our 55 had been sitting for years. When we woke it up, it had stuck rings and some odd shifting issues.
After getting it nice and warm several times, and driving it a few hundred miles, things seemed to have straightened themselves out.
So, before you get overly concerned, drive it.
Good luck
Jeff R

[Laspaz]

Thanks fellas, the car has done less than 1000 miles since 1996. But has been driven once or twice a year over that time.

I would love to put some miles on the car but until its road legal here I am a bit limited. Would be obvious with no license plate etc. Once I have the transmission sorted I will get it out for a few sneaky back road drives to work the niggles out before it's inspection to have it legal.

Thanks again for the feedback.

Bevan

[Caddy Wizard]

That smoke just looks like vapor (water steam) to me.  If so, that is pretty normal until the engine and exhaust gets fully warmed up.


It sounds to be running a bit rough and slow.  Move the timing to the "A" make on the pulley (5 degrees advanced -- 5 degrees before top dead center). It will run better after that.

[Laspaz]

That smoke just looks like vapor (water steam) to me.  If so, that is pretty normal until the engine and exhaust gets fully warmed up.


It sounds to be running a bit rough and slow.  Move the timing to the "A" make on the pulley (5 degrees advanced -- 5 degrees before top dead center). It will run better after that.

Thanks Art, are you saying this in response to the first video or the second one?

[Laspaz]

It sounds to be running a bit rough and slow.  Move the timing to the "A" make on the pulley (5 degrees advanced -- 5 degrees before top dead center). It will run better after that.

I might be confused, but I though "A" was TDC and "C" was 5 degrees advanced? I am on the "C" mark now.

[Roger Zimmermann]

TDC is the mark "C" and 5 degrees advance is the line "A".

[PHIL WHYTE CLC 14192]

From memory you time it midway between the 2 marks. You may need to adjust for today's fuel though.

[Laspaz]

From memory you time it midway between the 2 marks. You may need to adjust for today's fuel though.

That's what it says, to go further to the "C" mark for lower quality fuel. I'll try and go back towards "A" after I get the transmission back together.

[64\/54Cadillacking]

Hey Bevan,

The engines idle definitely sounds a bit too low in the first video,  but the second one where you have it at 600 RPM's sounds perfect! I never understood how anyone can get these engines to idle at only 400-450 rpm's in Drive without the engine sounding like it's about to croke. My '54 and '64 engines run smoother and sound better when the idle is around 550 rpm's in Drive. Make sure you also have the carburetor adjusted correctly too.

Also remember that fuel today isn't the same as it was in the 50's when lead really boosted octane levels into the 100's. So you really can't go by the shop manual anymore when it comes to timing marks set up, or even carburetor tuning at least that's been my experience especially if the timing chain has stretched a little as well. You might even have to enrich the original carburetors mixture screws if the jets haven't been increased in size after a rebuild, to compensate for the thin alcohol based fuel we have today.

I notice my 70's Classics however run fine on modern fuel because of the very low compression of the engines, but it's the older ones from the 60's on down that engines need a bit of tweaking with the carburetor and timing adjustments to really dial in the best performance as possible.

A vacuum gauge is more telling and helpful when it comes to adjusting your timing and getting the best outcome. I'd say advancing the engine by a couple of degrees will wake up these motors and make the engine run smoother including enriching the carburetors idle/mixture screws to also give a smoother idle, and not necessarily a "faster idle". 

Most modern fuel injected cars run at higher rpm's anyway at idle. I know my '07 Lexus LS460 runs at 650 rpm's in Drive and that V8 engine is as smooth as butter, I can't even tell it's running most of the time.

[James Landi]

''So, before you get overly concerned, drive it.''

I entirely agree with Jeff.  In your second video after you've adjusted it, it's running perfectly. With that steady vacuum reading, you've a good running 70 year old engine.  Leave it alone, and avoid the temptation of long periods of running it at idle and not under load. Once you get it out and running at steady speeds under load, you'll actually feel the engine becoming more responsive, so that after that first long run, you should check the vacuum, hot spots, dwell, and timing...and finally, a piece of old geezer advice that my grandfather gave me when I was in my late teens back in the 1960's, ''If you take care of your car, your car will take care of you.'' James

[Lexi]

Good comments. My '56 also idles best at 600 rpm or a touch less. Never have been able to get it to idle properly at 400 or at the revised speed of 420 as is an AC car and all engine systems rebuilt. Once at a GN a few years ago, I chatted with an owner of a 56 Cad which was a true survivor. Fantastic reference car. I asked the owner about idle speed and he said his runs best at 600 and that he could never get it to run at 400. Perhaps this is a reflection on the new gasoline as some have speculated? Clay/Lexi

[PHIL WHYTE CLC 14192]

Good comments. My '56 also idles best at 600 rpm or a touch less. Never have been able to get it to idle properly at 400 or at the revised speed of 420 as is an AC car and all engine systems rebuilt. Once at a GN a few years ago, I chatted with an owner of a 56 Cad which was a true survivor. Fantastic reference car. I asked the owner about idle speed and he said his runs best at 600 and that he could never get it to run at 400. Perhaps this is a reflection on the new gasoline as some have speculated? Clay/Lexi

I could be looking through rose tinted glasses but I'm sure I got both my wife's 51 and my 58 to happily idle at 400rpm with lead 4 star petrol back in the 1980s. We used to have 5 star leaded petrol but that was gone by the 80s, that was for cars like E type Jaguars etc, very high octane and loads of lead!

[Lexi]

I could be looking through rose tinted glasses but I'm sure I got both my wife's 51 and my 58 to happily idle at 400rpm with lead 4 star petrol back in the 1980s. We used to have 5 star leaded petrol but that was gone by the 80s, that was for cars like E type Jaguars etc, very high octane and loads of lead!

Perhaps the old leaded fuel did result in a more stable idle at lower rpms? I remember that you could dial in octane right at the pump with some choices being over 100. Seem to recall at least a 102 as being available. Clay/Lexi

[Laspaz]

Thanks for all the feedback guys, I really appreciate it.

I managed to get the transmission back together today after going through the valve body and unfortunately my problems remain.
- Runs great in neutral and reverse. D1 stalls the engine, D2 drops the revs by at least 200. it's not practical to drive like this.

I tried to mess with the timing and my vacuum gauge stays at about 16 for a few degrees either side of A and C. This is with the vacuum advance plugged.


I have sprayed carb cleaner around looking for vacuum leaks but didn't find any.

[64\/54Cadillacking]

Perhaps the old leaded fuel did result in a more stable idle at lower rpms? I remember that you could dial in octane right at the pump with some choices being over 100. Seem to recall at least a 102 as being available. Clay/Lexi

I believe so Clay. Our engines were designed for 100+ octane when new. Although the compression was lower compared to Cadillac engines of the 60's, they still required premium fuel and in those days, they had octane ratings of 105-106 as being the norm. So definitely, modern fuel has caused a disruption in how we are supposed to tune our engines.

I know some parts here in the U.S. depending on the state they have octane ratings of 93, but most place especially in commie California, it's only 91 which is way too low for our classics IMO.

[64\/54Cadillacking]

Thanks for all the feedback guys, I really appreciate it.

I managed to get the transmission back together today after going through the valve body and unfortunately my problems remain.
- Runs great in neutral and reverse. D1 stalls the engine, D2 drops the revs by at least 200. it's not practical to drive like this.

I tried to mess with the timing and my vacuum gauge stays at about 16 for a few degrees either side of A and C. This is with the vacuum advance plugged.


I have sprayed carb cleaner around looking for vacuum leaks but didn't find any.

Bevan, have you tried adjusting the idle speed screw on the drivers side of the carburetor near the TV rod?

I had the exact same problem with my '54. After getting the idle in P/N smoothed out, once I dropped the transmission into Drive, the idle bogged down heavily and the engine almost cut off.

I didn't realize at the time that these old Carters WCFB's have a tiny air/idle screw which is hard to see located behind the linkage where I believe the TV rod is at, screwing in the screw increases the engine speed slightly, just enough to where when you drop the engine into D, the engine won't stall.

You might have to readjust the timing and idle/mixture screws again. I totally forgot about the other air/idle screw, but it does make a big difference when adjusted properly. Hopefully that'll help. 👍