P6B S Project Car

Elsewhere noted some speedo issues due to the LT77 install - showing close to 40kph when GPS says 60. With some difficulty changed the cable driven gear from 22 to 20 teeth - barely any change in speedo reading, certainly not the calculated +4 kph. Bugger. Just have to keep using the tacho and GPS I guess. Idle still a bit variable - with it showing ~750RPM, fully hot through I squirted some WD40 on both ends of the throttle shafts - no detectable change in rpm, so I dont think the issue is worn spindles. At those revs the ign light was flickering, but a rev brought the volts up to 14v, so the alternator would seem to be OK.
Run today was ~20kms, mostly light traffic, some twisty ups and downs, but once in 4th she was very nice to drive, smooth, quiet, no problems. The engine shows its age on some hills, but never missed a beat, very pleasant run. Temp gauge never varies from centre.
 
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You could try running speedo with a drill, that will tell you if its reading low, which it seems to be. Maybe just needs a clean...
alternatively if youcan run the car at a steady speed for long enough you can compare the odomenter reading to the the needle reading. The odometer works on fixed gearing whereas the needle is driven by magnetic drag on a plate against a spring.
 
Speedo has been overhauled recently (at some expense!) so I doubt its an issue in there - very steady readings. Most likely due to fact that I have changed the gearbox, and where the P6 4 speed box seems to have a 2:1 speedo cable drive gear, the LT77 is (now) 5:2 with the orange 20 tooth driven gear -20:8 . The km speedo is marked as 780 revs/km, mph as 1284/mile. 780 x 2 = 1560 propshaft rpm, 505 wheel rpm. With my 195-75R14 tyres being ~5% bigger, this goes down to 480 wheel rpm, which gives 1482 propshaft, and 592 speedo cable rpm, which will indicate 45.6 kph at a true 60. Something to lift cable revs by 31% would get readings very close. Anybody know what the thread on the speedo head is - its 25tpi, OD is 0.462" ? Or is the pitch 1mm? Size is close to M12x1. I assume the angle drive is 1:1 ?
 
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Do you not have anyone over there who can recalibrate the speedo? Mine was done when the LT77 went it and was super accurate until I changed the diff ration. I will get round to recalibrating it again soon though.
 
When i replaced the differential for a V8 one, i spliced in the speedometer cable a small gearbox that restored the accuracy of the speedometer readings. Over here there used to be shops that deal with tachographs of heavy vehicles, that could produce these custom gearboxes according to your needs. Now probably everything should be electronic.

Speedo gearbox close 1.JPG
 
Quattro, I havent asked a detailed question of any of the recalibration shops yet - when I had the speedo overhauled the wallet shock was considerable and some harsh words were exchanged. Cant go back there! Especially galling was the CLOCK cost more than the speedo to overhaul, then found the club had new ones for A$40. Question will be - can they change speedo from 780 turns/km to around 600? Also looking into spliced gearbox approach. For electronic speedos there are many recalibrating units.
 
Next question. Have tried to reset hot idle a couple of times, but after its fully hot after maybe 10kms it becomes unstable - sometimes coming to stop at lights rpm drops as though its about to stall, then recovers by itself to 7-800rpm. There is some lost motion in the linkage on the offside carb, which I have tried to remove by adjusting the link between the carbs.
Cold starts - 20C/68F ambient. Full choke, crank, catches , rpm goes to 1500. I start to reduce choke immediately, but as soon as it gets down near 1000rpm its starts to die, and needs more choke to keep running (or help with the throttle). As it warms the rpm rise, and I gradually reduce choke by very small amounts, but its not very stable. This continues until the temp gauge is into the centre range.
Is this behaviour to be expected, or does it indicate a problem I should tackle? Reset fast idle? Both carbs have new jets, needle and seats and cold start Orings recently. Engine is well worn, but revs cleanly to 3500rpm, cruises very nicely. Timing 8-9 BTDC on 95RON fuel, 9.25:1 CR model. No sign of pinging. Exhaust not sooty, Wide band O2 sensor says mix is in the 13.5 area, slightly rich.
thanks
 
Was looking for mudflaps for the rear, so when they appeared on Wadhams....
They come with metal braces along the fixing bolt holes, attached with rivets, on the FRONT face of the rubber - the braces should go on the back when installed – while my original flaps were long gone I still had the original brace. JRW supplied nice new bolts with washers and nyloc nuts – M6. These bolts will just go through the rubber, but will not go through the metal brace holes, or the original bolt holes in the body - I used 3/16 bolts. I had to drill out the rivets. On my car (1974, D suffix chassis) the centre hole in the brace did not match the holes on the car, so I had to drill a new hole ~3/16 away in the brace bar, and in the rubber. The angle designed to screw to the boot floor lines up nicely.....but will need a 1/8 spacer under it. Thats my experience with the RHS, now to tackle the LHS. Looks good but!
I passed the above comments on to Wadhams, and they have responded that they are looking at the issues raised. They said they copied an original Rover set .....

Thinking back to my 4cyl cars I seem to recall the mudflaps being small, and made of light rubberized fabric - can anybody confirm that?
 
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my 1970 P6B had a couple of "squares"with tabs of soft rubber attached by screws to the wheel arch. Still have the driver's side, the passenger side is long gone. It would impede getting a karcher in!!
I do marvel at some of the incredible Heath Robinson devices that the aftermarket seems to have produced to replace what was really bog simple.
 
Near side flap in place. Bit easier than offside - no battery box to impede access to the rear of the bolts. Fit of the boot floor fixing slightly different from offside. This time after drilling out the rivets I pop-rivetted the brace on the back of the rubber to make it easier to install in one piece. Then drilled the new centre bolt hole beside the original hole. Where the original brace was quite thin (< 1/16) the new one is probably 3/32 flat steel.
 

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Was looking for mudflaps for the rear, so when they appeared on Wadhams....
They come with metal braces along the fixing bolt holes, attached with rivets, on the FRONT face of the rubber - the braces should go on the back when installed – while my original flaps were long gone I still had the original brace. JRW supplied nice new bolts with washers and nyloc nuts – M6. These bolts will just go through the rubber, but will not go through the metal brace holes, or the original bolt holes in the body - I used 3/16 bolts. I had to drill out the rivets. On my car (1974, D suffix chassis) the centre hole in the brace did not match the holes on the car, so I had to drill a new hole ~3/16 away in the brace bar, and in the rubber. The angle designed to screw to the boot floor lines up nicely.....but will need a 1/8 spacer under it. Thats my experience with the RHS, now to tackle the LHS. Looks good but!
I passed the above comments on to Wadhams, and they have responded that they are looking at the issues raised. They said they copied an original Rover set .....

Thinking back to my 4cyl cars I seem to recall the mudflaps being small, and made of light rubberized fabric - can anybody confirm that?
Yes I have these on my v8.

1680688052954.png
 
Thanks Peter, thats what I remember! How did you get them to last this long?
Mike - these reproductions are based on factory optional extras (in the parts book) , so not wholly an aftermarket invention. Wadhams dont list the original part numbers (363528, 368699).
 
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Thanks Peter, thats what I remember! How did you get them to last this long?
Mike - these reproductions are based on factory optional extras (in the parts book) , so not wholly an aftermarket invention. Wadhams dont list the original part numbers (363528, 368699).

Came with the car. I suspect it wouldn't be difficult to make a set with some hessian and spray rubberized paint. They certainly work as you can see how wet/muddy the car is and the underside of the rear wing is clean. There's also the very fancy thick rubber ones with the Rover logo, these look a little OTT to me, I prefer the simple type because these are what I remember.
 
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er.... going back to your driving issue, I suggest checking you have the correct float height in the carbs and (probably first ) check the fuel pump is providing enough flow and pressure.
What normally causes that problem is the fuel in the bowl/jet moving forward under deceleration which leans out the mixture as the jet is to the rear of the bowl. The reverse happens on acceleration which can lean out the mixture but it's often been compensated for by tuning it rich.
 
I think the mudflaps look quite good....Before fitting them I made copies in 1/16 plastic, so I can make paper patterns if anybody wants to make theior own.
When I rebuilt the carbs last year was careful to get the float heights VERY close to spec, but anything is possible. Not going to pull them off anytime soon. Will try a Colortune on each bank and see if there is a difference in the mix.
 

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Been quiet lately. Did a decent run a weerk ago, ran like a bag of#$%^& - lots of stalling, unsteady idle, hard to get off the mark. Finally looked into it yesterday.......breather hose off nearside rocker cover was displaced! That bank must have been lean as can be. I had the choke out enough to keep it running, but as soon as I put the hose back on the rpm jumped up and all was good again. Phew!
Re the battery and the clock drain, after a month sitting the battery was dead flat, so its not that low a drain. Leaving it on a trickle charger now.
 
Early on I changed all the engine breather hoses (from rocker covers etc) to new ones. Yesterday I was looking for a bit of rubber tubing for something else, and I found one of the old tubes - this might do. Cut off a piece at the end where it went onto the carb connection, to find this sight. Oil crud reduced the hole by at least 2/3rds. Might be worth checking yours?
 

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Getting serious about rebuilding the 3.9 finally. Have found somebody who has experience with the V8s, so thats a good start. When I got the 3.9 the oil pickup tube was a little bent, so I went looking for a replacement. The genuine part seems difficult to source out here, so I ordered a Melling pick up - MELL-20-IS2-BK. Here Melling 20-IS2 Melling Oil Pump Screen Assemblies | Summit Racing
It fits the block, will clear the bottom of an SD1 sump by nearly an inch, and its main tube is a couple of mm bigger than the original part, none of which can be bad.....can they? The pickup screen is quite a bit larger than the original - any problem there? It angles towards the rear, so it clears the baffle in the SD1 sump.
 
Got my rebuilt LT77 back the other day. Tag on it to remind me to put oil in it. On looking for the Castrol type recommended here, (Castrol web site here says Type 'F') found it a bit thin on the ground. Looked up other makers recommendation, found Penrite do a Type 'F' ATF, readily available, so going with that. Its marked as a 25A...C box, so checked for its 5th ratio - 5 turns of primary gives 6 turns of output flange, so its a 0.83 gear (1:1.2).
 
Some time ago when I had the speedo recalibrated, I damaged 2 circuit traces because I left out the white insulator piece when I refitted the speedo. I tried to fix the damage with small wires, but failed, so I bought a used board to get going again. Today I tried again . I got some fine copper foil, ~1/8" wide, and did some experiments getting solder onto it - worked. Had to glue some of the original traces down as they tend to curl up away from the base when damaged. Then I applied a tiny bit of flux, and solder, with the iron on the lowest setting that would melt solder; held one end of the cu foil down , applied the iron.......waited, and it stuck. Eventually got all 4 ends attached, and DVM showed correct continuity. Success! may be able to help somebody as clumsy as me in the future.
 

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