‘69 280sl - Rough Idle/Rough Running

[lagolag]

As I have some issue below 2000 rpm I found these two video clip that might be helpfull to do a proper set up.
https://youtu.be/F6sxlOFmoYw?si=GX4cXG7SbsUhA0f_
https://youtu.be/cOLeyZtfoqk?si=YbIGTuI07qzucv0t

[sens]

Hi again!

If you don't have one yet, buy yourself a (used) stroboscopic lamp to set the timing correctly.
That is a must before doing anything else.

Is your WRD getting hot when the engine heats up?


All the best!

Halvor

[cjpoulos]

Thanks guys! Very proud of this car!

The WRD is pretty cold, and the car stays rich even at temp. Maybe the thermo pod is plugged up?

There’s a bit of a “burble” in the exhaust note, a bit of soot, idle bounces between 700-900 revs, and when the linkages are split, the intake can travel down a bit less than an inch (maybe 3/4in) before the car stalls (it will stall with any added gas during the test). The coolant hoses going to and from the heater core are hot, but pipes to the radiator are seemingly only getting hot from the blocks heat.

I’ll check the thermostat and see if I can find any blockage in the other areas. I replaced the water pump about 2.3 miles ago (or about 9 months ago haha).

Thanks guys!

[Jonny B]

Will you be making the trek to PagodaFest in Knoxville in September?? I am sure everyone would like to meet you and see the car!

[sens]

Hello!

You make good progress, but you are not there yet.

I would start by adjusting your timing with a stroboscopic lamp.
Make sure it is set correctly.

Obviously there is an obstruction in your cooling circuit.
The radiator and the WRD should be too hot to touch when the engine is warm. That is not the case…
You could flush the cooling system with water and see if dirt comes out.

Good luck!

[cjpoulos]

Will do, I'm having my mechanical buddy come out to help me with it - I'll keep you updated.

Halvor you seem to have the right thinking! Water isn't flowing, and the WRD can't adjust the mixture to compensate for the engine temp. I'm curious how that effects high range running - will a WRD that stays in the "rich position" cause the car to run imperfectly through the entire rev range, or does it only effect a lower range/idle?

[sens]

I know a little on the Pagode, but you ask the right questions!!!

The WRD adjusts the mixture when cold (more fuel and more air) to get a higher RPM.
But indeed only at idle to approx 1500 RPM.
At higher RPM's it has no effect.
The shims under the Barometric Compensator will influence the mixture for all RPM's.

I would really solve your coolant flowing issue, because running the engine with an unknown obstruction somewhere is not a very good idea.
Once you solve that, the WRD will start to work correctly.

All the best! You will get there!!

Halvor

[cjpoulos]

Little update.

The WRD hoses leak coolant when I remove them, but it isn’t getting hot. I’m going to pull the thermo pod bit and clean it out to see if that’s causing the lack of flow.

The idle has smoothed out quite a bit. I realized that the three leftover washers I had after pulling the head were not oversights, but they were the three round shims for the WRD. Luckily, they were the only spare parts I had, and they made the ole girl idle 70% better.

I used a timing light on the balancer and it looks like the ignition timing is working properly. I set the timing at 6 degrees ATDC, and the advance looks to be working properly.

I think it’s narrowed down to a fuel issue now (plus the water flow bit).

[sens]

Hello,

Timing should be 38 dgr. BTDC at 3000 RPM.

Try that, but be careful.
3000 RPM is a lot!

Are the round shims you mentioned the small ones in the WRD?
Not the oval shims under the WRD?

All the best!

Halvor

[cjpoulos]

Yes, they were the smaller round shims for the WRD. I have two oval shims in place at the moment. I'm going to do a valve adjustment and check the new valve seals tonight because plugs 4 and 5 are a bit oily.

I'm going to put a lower temp thermostat in as well because the one I have currently opens at 192F, and knowing the situation with this car I think a lower temp will be beneficial. Water IS flowing through the thermo pod, and water is also either flowing through or "sitting" in the upper hose to the WRD. What directions does the water flow through the WRD? Maybe a higher pressure back flush will help clear the channels out?

Once things are put back together I'll verify the advance at 3000 RPM. Is 6 degrees ATDC the correct setting at 800 RPM?

Thanks!

[sens]

I would advise not to change too many things at the same time.

First try to solve your coolant flow issue. There should be a good flow through the WRD to make it too hot to touch. If not do a flush or back flush and look for the plugged tube.

Around 8 dgr ATDC is about OK at 800 RPM, but I prefer to set it at 3000 RPM.

[cjpoulos]

I've definitely learned by (limited) experience to go one step at a time! I'll finish checking on things under the valve cover and verify timing from there.

Also, I figured I'd show you the car in question. Purists may be a bit stunned... The original owner did the work in 1970.

[sens]

Nice!!!


Halvor

[Bonnyboy]

Diidn't the car have lake pipes on it when you got it?  Have you switched over to a stock exhaust system? The reason I ask is that my car had a straight pipe / blue bottle on it when I got it and it didn't like to idle.  I put a stockish setup on it and made just a few adjustments, got the cold start valve working and replaced the springs on the distributor and it settled down to an idle. 

 

[Jonny B]

Post a few more shots of the car - this group just loves to see photos of Pagodas!

Great job, keep it going.

[bracurrie]

Ignition timing is an old subject for me.  I took a shortcut because my retarding system failed and I haven't been able to fix it. I simply set the timing as if the retard system wasn't there after completely disabling it.  The distributor timing at the higher RPMs are valid either way because the retard system would have been switched off at those engine speeds. Once the distributor timing was set the trick was to get the idle speed back down to 700-900 RPM range since there was no retard to bring it down at idle. This I did by adjusting the idle mixture and idle air.
For you and your 051 distributor you may already be there but I thought you might find the attached data from the BBB factory manual interesting.
Good Luck.
Brad

[cjpoulos]

Gentlemen, I think she's ready!

I'm not too proud of this bit, but I realized that I set the intake valve clearances at .030, NOT .003. I am very dyslexic, but that's a massive difference! I have never seen one of these cars sound and run as smooth as this one does now, I could not believe how smooth it was. No rattles, taps, shakes, pops, bangs, and you can't even hear the valves at all. I'm sure this is jinxing things, but it runs perfectly now. I also fixed the flow issue with the WRD. Must have been an air bubble, because it politely disappeared when I drained and refilled the cooling system again. It may also have had something to do with the 160 degree thermostat I installed, who knows.

I did a thorough inspection of the friction surfaces, rocker arms, springs, keepers, etc. Everything looked great, this thing barley has break-in miles so it's nice and pretty under the valve cover.

Thanks for all the help guys, I'm sure I'll find more issues to bug you all about in the (near) future!

[sens]

Waaauw!
That is fantastic news.
Enjoy your beautiful Pagode!!!