stick the sender in a cup of boiling water and see how accurate it is .or find someone with one of those temp gun things and check how hot it actually is ,pugs
D Special rehabilitation
- Thread starter Greenpeace
- Start date
Hi Pugs, I'm sort of assuming, as the original big stop light and temp light came on (once) when the gauge was reading 110C, that the gauge is fairly accurate. Not sure what temp the original light switch is set to trigger at, but (at atmospheric pressure) boiling point of water + cap pressure (4psi x1.5) gives a system boiling point of 106C. I would imagine the warning light switch would be set to trip very close to this figure (106C). The car clearly seems hotter than "normal" under the bonnet. It may pay to check with a heat gun I guess, just in case both the gauge and warning light are incorrect.
I forgot to mention there are also no symptoms present of a head gasket problem.
Regards Rob.
Hi DS/ID.
It has a timing scale over the cam pulley. From what I can gather the initial timing is 12 (crank) degrees BTDC on this year/model?
The timing is set to 6 degrees BTDC at the cam pulley.
I haven't checked to see if TDC on the cam timing scale matches TDC on the crank/flywheel however.
The car does start easily and seems to perform as expected though??
Thanks Rob.
Yes Hotrodelectric it has the original charging system. The regulator looks like it has never been disturbed but I will have a closer look at the ring termimals. Thanks Rob.Rob-
Does the car still have the original alternator/regulator setup? It almost sounds like the three ring terminals are mis-connected. Difficult to do with 3 different size rings, but I've seen a lot crazier.....
Edit: stupid me. I typed "cat" for "car"
Forget timing scales, do it by ear and feel. It's more accurate. Advance the timing a bit, go for a drive and see if the engine pings when you try to accelerate in a high gear. If not, advance a bit more and go for another drive. And so on. Once it does ping, retard the timing a bit and make sure it no longer pings.
The quickest way to set timing is to find the highest idle speed then retard it a bit. But road testing is more accurate.
Roger
The quickest way to set timing is to find the highest idle speed then retard it a bit. But road testing is more accurate.
Roger
Hi Roger,
I used to "tune by ear" for a long time when I was younger and you are probably correct, with an old "tractor"engine like the Citroen it is a fairly safe way of doing it.
I have been playing with boosted and nitrous injected engines for quite a number of years now and 1 or 2 degrees of ignition timing can be the difference between life and death. Knock, EGT and FA monitoring and dyno time is the safe way to tune. If you hear one of these engines ping it's probably already too late.
I tuned my first nitrous car by ear (1967 Rambler Rebel) ran 12.8 quarters @ 108 mph time after time in full street trim. Blew a head gasket and while fixing this noticed 2 gaps in the top ring. Pulled the other head and checked all the cylinders and they all had 2 or more visible ring gaps. Pulled it down, all of the top rings were shattered into little pieces and all bar one of the second rings were broken as well. Couldn't reuse the pistons as all the top ring lands were hammered down and the new rings wouldn't fit in the gap. This was a full mufflered street car and I never heard it ping once!
I guess I'm in the habit of, if there's a timing scale else there why not use it. I just need to check that TDC on the scale matches TDC on number 1.
Regards Rob.
Hello Rob,
Yes, I was referring to old-technology engines. Where the components are worn, scales might have slipped a bit, and fuel octane levels may be different from when the car was new, I am not convinced the marked scales are all that accurate. Hence my suggestion to time by ear.
Roger
Yes, I was referring to old-technology engines. Where the components are worn, scales might have slipped a bit, and fuel octane levels may be different from when the car was new, I am not convinced the marked scales are all that accurate. Hence my suggestion to time by ear.
Roger
Agreed on that Roger. I'll drop a dial gauge down No 1 cylinder and set up the timing scale for now. Be interesting to see if true piston TDC lines up with the flywheel notch? Given that the scale is registering on the cam pulley the TDC position may well be out next time due to cam chain stretch.
Regards Rob.
Good reason to use a dial gauge by the sounds of it. I have no idea what month in 71 mine is.
Are there any other visible changes made relating to this date?
Thanks Rob.
Thanks alpine, I'll Google it.
My temperature sender for the big red light of doom switched on 84C, pretty useless with a 82C thermostat.
If you do check the sender in a saucepan of water on the cooker, make the sender is not touching the pan bottom, nor the thermometer touching the pan bottom.
Here in the balmy UK, I upgraded from two core to three core, then after I fitted an air-con condenser in front of the radiator, I had an aluminium radiator made, it is 78mm thick and cross flow (copied from an injection rad).
If you do check the sender in a saucepan of water on the cooker, make the sender is not touching the pan bottom, nor the thermometer touching the pan bottom.
Here in the balmy UK, I upgraded from two core to three core, then after I fitted an air-con condenser in front of the radiator, I had an aluminium radiator made, it is 78mm thick and cross flow (copied from an injection rad).
Mmm, I found a NOS sender online and although no specs are quoted it does have the number 105 on one of the brass flats. One would presume that is the trigger temperature for the light?
I might try another gauge first, (I have a capillary one somewhere) if it agrees, the other 2 (gauge and light) can then be assumed accurate.
Thanks Rob.
That's a bloody nice car Rob... and I m loving your approach... preservation and use is a very honest and practical approach to enjoying what we have here and now...
Cheers
Dino
Thanks Dino.
There's something about a car or bike that is showing its age and journey that appeals to me. I appreciate restored machinery too. I was fortunate enough to go to the concours at Amelia Island a few years ago and there was some mighty impressive vehicles on display.
The 1921 Stutz Bearcat that Wayne Carini did the "preservation restoration" on is more my kind of car though. That car takes cool to a new level. Obviously someone else liked it too, I think it went for close to $600K US at auction!
I've had a couple of road registered 1920s cars however (a Rover and a Bean) and sadly I found they were better to look at than they were to drive and maintain.
Regards Rob.
Went for another run today, noticed a couple of things, the charge light went off briefly a couple of times and the temp gauge shows over 100C before the thermostat opens.
Thinking loose/dirty connection for the light so went through all the charging related teminals, didn't find anything loose but certainly dirty, and voila, the light now goes off and stays off.
I haven't had time to check the ignition timing scale's accuracy as yet but I did advance the timing by 4 degrees by the scale before the run (8 crank degrees) and no pinging.
Other than just before the thermostat opened the gauge didn't go past 95C today. Trouble is it is a cooler day today so I am really non the wiser until I verify the accuracy of the gauge.
Rob.
Thinking loose/dirty connection for the light so went through all the charging related teminals, didn't find anything loose but certainly dirty, and voila, the light now goes off and stays off.
I haven't had time to check the ignition timing scale's accuracy as yet but I did advance the timing by 4 degrees by the scale before the run (8 crank degrees) and no pinging.
Other than just before the thermostat opened the gauge didn't go past 95C today. Trouble is it is a cooler day today so I am really non the wiser until I verify the accuracy of the gauge.
Rob.
It feels good to tick these jobs off one-by-one, doesn't it.
For a 1971 D Special (i.e car made between September 70 and August 71), the factory timing settings were for a total of 24 degrees at 2000 rpm - so an extra 6 degrees when measured on the pulley (as opposed to 4). Modern fuels combust more slowly than back in the day, so older cars may even benefit from a little more advance than the manual prescribes. So your timing may not be as advanced as it could/ should be. At the end of the day, home mechanics need to be prepared to use their eyes, ears and noses as well as reference tables. If you've set the timing at 4 degrees advance and you have no pinking, your plugs aren't getting fouled, and your engine pulls and runs happily. Then go with your instincts.
For a 1971 D Special (i.e car made between September 70 and August 71), the factory timing settings were for a total of 24 degrees at 2000 rpm - so an extra 6 degrees when measured on the pulley (as opposed to 4). Modern fuels combust more slowly than back in the day, so older cars may even benefit from a little more advance than the manual prescribes. So your timing may not be as advanced as it could/ should be. At the end of the day, home mechanics need to be prepared to use their eyes, ears and noses as well as reference tables. If you've set the timing at 4 degrees advance and you have no pinking, your plugs aren't getting fouled, and your engine pulls and runs happily. Then go with your instincts.
I'm going for another drive in the country tomorrow, I'm going to add a couple of more degrees of ignition advance before I go. Still unsure if the cooler weather or the timing change brought the car's temp down a bit, maybe both?
Cheers Rob.