Quote:
Originally Posted by Laird Scooby
Timing is the first place to start Alan - you can't check/adjust the mixture if the timing is wrong.  There's also a chance that might sort it all out with no further intervention.
Which screw are you referring to as the slow running screw? A photo would be helpful as i'm not wildly familiar with the Pierburg carbs, i know they can give problems but given the mileage on yours, the problems are going to be age rather than mileage related and finger trouble from people playing with things they shouldn't.
The mixture screw is the CO adjuster, usually on the bottom of the jet and many Strombergs had a castellated nut for adjustment - chances are this was carried over onto the Pierburg but i can't be sure.
If it's reached 40 years old without ever having been touched, even to correct a rich mixture due to jet/needle wear at MoT time, i'd be surprised.
Might pay to invest in something like this Gunson Gastester for checking/adjusting the mixture.
This mixture adjusting tool might also be useful depending what sort of end your mixture adjuster has on it, the Stromberg style castellated nut or the later sort.
*** EDIT *** Forgot to say, if you get the back of the car facing the sun and have the bonnet up to do the timing, it should give you enough shade to see the flashes from the neon bulb. You can also lower the bonnet a bit to reduce any ambient light getting in but it gets a bit cramped doing that! |
Good morn Dave,
As always, many thanks.
It is a bit overcast here this morn, so I'll check the timing when I get back from Bob's first walk (but late enough not to offend my neighbours). You are right, that may solve the issue (and I should do it anyway after moving the auxiliary shaft).
Here is a photo of the slow running adjustment screw:
That is more or less the only regular adjustment on the Pierburg - the low throttle stop is changed by bending the tab a bit (yes, really) plus the 3 cables.
The CO adjuster is right at the bottom of the carburettor and difficult to photograph, but easier to see in the drawing from the Autodata book:
When the head was off I had a look at it and saw the anti-tamper seal was not fitted (nothing nefarious, as you say the CO has probably been adjusted for the MoT some time over the past 40 years). I noticed a long 8mm socket fits perfectly.
The Gunson gastester is an interesting idea, I had not come across that previously, but I'm tempted (I like gadgets). It would only be of use with an older car (but the the RB is an older car)... so I've saved it on eBay and will think about that one.
As often with my relationship with the Royal Barge - there is not much wrong and I'm looking around for issues. The engine vibrates a bit on tick-over and the slow running jet is screwed right in at 1000RPM (probably 900RPM as per my previous measurement). The timing check may well resolve the issues.
What did you think about changing the two engine mounts? They seem okay, but I'm mindful the rubber is probably 40 years old. It looks like quite an easy job and the parts are cheap. New rubber may well change the harmonic frequency away from tick-over speed?
Stay alert,
Alan