I checked the ignition timing this morn... and found it to be just over 10 degrees BTDC (should be 15). Perhaps that is one tooth different from the previous arrangement (I used the belt marks)? So well done Dave, you hit the nail on the head, the ignition is retarded by about 3-4 degrees.

Try as I might I can't get the distributor to rotate - even with the clamp bolt removed completely it refuses to budge:

https://i.imgur.com/pcACo13h.jpg

I've given the base of the distributor a spray with some penetrating oil and come in for a break. It feels really firmly fixed, and I don't want to apply too much force to aluminum parts.

The RB has the breakerless distributor (from a later 240 I think), but as far as I know it should adjust the same way as the CB type, shouldn't it?

https://i.imgur.com/Puv3Wkxh.jpg

... I put the blob of Tipex at the bottom so I could see if I'd managed to move it.

I'm always mindful that this is a 40 year old car, so it is best to look and think 3 or 4 times before using too much force :-)

Alan

Ignition timing...
 

... well that was much more difficult than it should have been, which was down to 40 year old pieces of cast iron and aluminium having grown a bit too fond of each other.

I managed to get the distributor to move anti clockwise (the way I wanted) in tiny increments using a long drift (actually a piece on M10 threaded bar about 18" long) and some taps of a hammer - brute force and ignorance won through at the end of the day. This is the first time I've done this on a Volvo and I've never come across a distributor that could not be turned by hand or with some plumber's grips. Is what happened normal or has the Royal Barge just seized up a little with old age?

No matter, as I said, I got the distributor to move in small increments to what I thought was 4 degrees away from some scratch marks I'd made on the base (yes, I know, measuring 4 degrees by eye - but then I am a surveyor by profession!).

I wasn't going to be able to rotate the distributor with the engine running, but when I tested it again with the strobe my 4 degrees was pretty well spot on 15 degrees BTDC. To confirm I've just taken the RB out for a spin and got it up to 90C, the tickover is much steadier (I no longer think I need to change the engine mounts) - so that has been a good result.

I don't think there is much wrong with the carburettor settings. I've adjusted the 3 cables by the book and am confident they are correct. The slow running adjustment is only screwed out about half a turn, but it does what it is supposed to (and as Loki says, it may make up its own mind). It is possible, or even likely, that the CO adjuster has been tampered with a bit. I suspect this may have been the case because (as you may remember from about 800 posts above) the PO thought the car was overheating (but it was the gauge misreporting) and had turned up the tick-over speed because it hardly ever warmed up properly. I could just try tuning it by ear, but perhaps I'll try to acquire a gas analyser as Dave suggested.

I hope everyone has enjoyed their Saturday morn; mine has been quite productive (walked Bob, done the laundry, fixed the Royal Barge... and Dan still isn't up - 15 year olds aren't good in the morns).

Many thanks again chaps,

Alan

What an incredibly daft idea on that slow running/idle air screw! I can understand why (emissions regs) they've done it, just not why they did it the way they have!

I'd hazard a guess there's an "O" ring around that slow running screw, there appears to be an anti-diesel valve immediately after it all of which suggests the throttle butterfly should be firmly shut or only open a prescribed amount at idle and all other adjustments are done with the slow running and mixture screws.
It might be an idea to check the setting for the throttle butterfly and also to see if there is (or should be) an "O" ring on that slow running screw. While it's out and you're checking it, spray some carb cleaner into its orifice, i'd also be tempted to remove the anti-diesel valve, spray the plunger on the valve and also the manifold orifice where it lives with carb cleaner - check the plunger is free to move in and out (in under spring pressure so should return easily to the closed position) and isn't worn on its edges/contact points where it meets the manifold.
Also clean the cone on the end of the slow running screw.

I can see this being one of those niggly faults where you can either chose to live with it as it is or take some time to get it right. Getting it right will pay dividends but you'd have to weigh up the gains Vs the efforts. Alternatively you could go mad and buy a new inlet manifold for a Weber 32/36DGV twin choke down draught carb, economy benfits from running on the primary barrel (32mm) and when/if you want the extra power, floor it and the second barrel opens up.

https://www.dellorto.co.uk/shop/car-...av-dgas-dgms/#

They also produce a complete kit (carb, manifold, linkage adaptors, gaskets etc) to convert the B18/20 to a 32/36DGV but obviously that has the wrong manifold for yours.

https://www.dellorto.co.uk/shop/webe...manual-choke/#

That's a "sledgehammer to crack a walnut" solution but if you were getting horrendous economy, flat spots and poor starting, probably the ideal solution.

As for the engine mounts, apologies for missing those last night but Clifford has said pretty much what i was going to suggest. Your idea of a pice of wood between the wings has a commercially available version :

https://www.machinemart.co.uk/p/clar...gearbox-suppo/

If nothing else, will give you ideas. :thumbs_up:

............ and you've done all that while i was typing my first response above! :tounge_smile:

On my first 740, the only 740 to have the block mounted dizzy, i had exactly the same trouble, lack of movement over 18 years due to the timing not normally needing adjustment caused the seizure of the dizzy in the block. I've also experienced the same with Opel CIH engines and Ford Pinto engines, both of which use a similar dizzy to yours (even the points, condensor and rotor arm/dizzy caps were the same) where lack of adjustment caused the aluminium castings to seize in the cast iron blocks.

On my 740 i used a brass drift about 30mm diameter and about 10" long with a lump hammer to shock it free after first marking it. Once i was able to turn it by hand (and had added some penetrating oil) i put it back to where it was when i marked it, left the adjuster locknut slightly loose, restarted and checked the timing again. It was closer (i'd advanced it slightly) so i used the ring end of the spanner i had for the lock nut to tap the base round a little at a time to where it should be then locked the adjuster nut.
If you ever feel adventurous, you could remove the dizzy, renew the "O" ring on the base of the body where it sits in the engine block and smear some silicone grease on the "O" ring and the body (after it's all clean) so when you refit it, there will be much less chance of it seizing again.

Thanks Dave,

Yes, the Pietburg is a really simple instrument! I'll keep fiddling around with it as you suggest to see if I can improve the set up a bit, but it isn't too bad. The idea of a twin choke Weber is tempting - but I have to keep the RB in perspective - the Pietburg will be fine (if a challenge).

Stay alert,

Alan

Thank you for that vote of confidence Dave, whilst I was hammering away at the base of the dizzy this morn some self-doubt crept in, I kept looking for a second (non-existent) clamp bolt. I'm sort of pleased to know the issue was not unique and just down to the RB's age.

I gave the base of the dizzy a good spray with penetrating oil, and I think that will do for now. I would not expect to have to do that job again at least until the next cam belt change in 2025 (and maybe it won't need it then). If I fixed it now it might well have seized again by the next time it has to be adjusted.

You were dead right about the ignition timing being over retarded, I suspect that is all that was causing the lumpiness (although the very simple Pietburg carburettor doesn't help much).

Once Dan is up I may take Bob out on a needless errand somewhere, the lock-down rules having been relaxed sufficiently to allow such.

Stay alert,

Alan

The distributor was stuck in a similar way on a 245 I used to own- I used a piece of wood as a drift and tapped it up and out from below with a hammer, then cleaned up and greased it before refitting.

Cheers

The Weber is even more simple than the Pierburg and almost certainly more reliable as well Alan. It depends which perspective you look at, it was standard fit on many Fords of a similar era, a recognised conversion for Vauxhalls (in fact i believe many Opels came from the factory with the Weber instead of the Solex or Varajet carbs fitted to UK built Vauxhalls) and many others. It's a period correct upgrade for the car, as already mentioned, when you drive normally, economy should be better but give it the beans and it should improve power as well, possibly with an extra few degrees of advance (to about 16-18 deg BTDC), a slight richening of idle mix to compensate then enjoy the improvements!

Maybe a long term thing, like the 4-speed auto conversion, just to bring the RB into a slightly more modern state without detracting from the originality too much. :thumbs_up:

A Needless Errand...
 

Having not really gone anywhere (apart from to the local grocery stores) since March, I was looking for an excuse to try out all the minor improvements. I couldn't think of one, but it is a nice day, the lock-down has been lifted a bit and I'd finished my current list of jobs on the Royal Barge - so I just went out for a drive.

I've just got back from a really pleasant 35 mile drive around Leicestershire, Rutland and Northamptonshire - single A roads and B roads through pretty villages and some of the nicest countryside in England (roughly Harborough > Upingham > Caldicot > Corby). The Royal Barge was lovely: sunroof open, Smooth FM on the radio, auto box and comfy seats:

https://i.imgur.com/pgbFMpqh.jpg

The new cylinder head and corrected ignition timing have together been a revelation. The thermal management is very good now, it is much smoother, more powerful and responsive - I suspect it is also a bit more economical.

:-)

Now that might be an interesting longer term package Dave: a twin choke Weber, 4 speed auto box and one of those stainless tubular exhaust manifolds I saw someone was advertising on this forum a few days ago. I suppose the whole thing might be done for something around £1500 - less if I could find some of the bits second hand.

Perhaps I'll start acquiring the bits next winter.

:-)