AC to ACR conversion

jasper53

Member
Hi all, currently converting our car to run an 18ACR alternator. Mainly because we do night rallies with the car and the old AC just coped with the extra load we need. The old AC is available if anyone needs parts or a casting. On checking the volts output, we could only get it to produce 12.5v., even running without the regulator, so not a replacement item, just for parts or recon. Any cash will go to local animal shelter. If anyone has any interest in how the new ACR fitted I have recorded the fitting in photos. Quite an easy project actually. Probably been done somewhere on the forum before? No problem now with charging with everything switched on!! Cheers, Rob
 
Yes, it's pretty easy, I just did it - good to ditch those external regulators and relays. Why didn't you use the more modern Lucas A127? These fit (in fact look pretty much identical) and give 70amps instead of 45amps and cost £45. That'll help with your auxiliary lighting. I have a huge electric fan and the first difference I notices was the lights didn't dim and the engine slow when it cut in.
 
Did think about the later type. Got the Lucas boxed ACR, uprated to 65amps from a mate of mine, new and unused. To think we used to use the old type 16ACR on our Cooper S rally car in the late seventies and thought that was great. Think they turned out about 30amps? We were comparing to a dynamo though! We were just finding with the 100w spots, 100w headlights, wipers, heater and any other things we had on during the rallies, we were just about on the limit of the old AC. This should be well on top of it's job hopefully. Looking forward to getting back out there.
 
Hi all, currently converting our car to run an 18ACR alternator. Mainly because we do night rallies with the car and the old AC just coped with the extra load we need. The old AC is available if anyone needs parts or a casting. On checking the volts output, we could only get it to produce 12.5v., even running without the regulator, so not a replacement item, just for parts or recon. Any cash will go to local animal shelter. If anyone has any interest in how the new ACR fitted I have recorded the fitting in photos. Quite an easy project actually. Probably been done somewhere on the forum before? No problem now with charging with everything switched on!! Cheers, Rob
Hi all, currently converting our car to run an 18ACR alternator. Mainly because we do night rallies with the car and the old AC just coped with the extra load we need. The old AC is available if anyone needs parts or a casting. On checking the volts output, we could only get it to produce 12.5v., even running without the regulator, so not a replacement item, just for parts or recon. Any cash will go to local animal shelter. If anyone has any interest in how the new ACR fitted I have recorded the fitting in photos. Quite an easy project actually. Probably been done somewhere on the forum before? No problem now with charging with everything switched on!! Cheers, Rob
 
Jasper:
I'm going to undertake the same project, and, would appreciate the pictures, and, any advice you might be able to offer. As a start, did you have to change the mounting bracket? The alternator is mounted on the right side of the car ( the left side as viewed from the front of the car). Many thanks! Drew
 
Last edited:
Hi Drew, mounting bracket is fine as it is. You do need to swap the pulley from the AC to the ACR for size and spacing. Use the ACR fan not the AC one. Everything else fits fine our our car at least. The ACR is the same hand as an MGB as I borrowed one to try it on. Ours in on the right hand side looking from the front of the car. There is a wiring diagram on here somewhere. If you need it just ask me and I'll explain. Easy to do, just need a few terminal ends and a bit of cable. Cheers, Rob
 
Hi Drew, mounting bracket is fine as it is. You do need to swap the pulley from the AC to the ACR for size and spacing. Use the ACR fan not the AC one. Everything else fits fine our our car at least. The ACR is the same hand as an MGB as I borrowed one to try it on. Ours in on the right hand side looking from the front of the car. There is a wiring diagram on here somewhere. If you need it just ask me and I'll explain. Easy to do, just need a few terminal ends and a bit of cable. Cheers, Rob
 
Jasper:
Thank you. If I undertake the project, I will be in touch. A couple of knowledgeable gentleman (Harvey, being one) have made me aware that whether or not the 18 ACR will fit on the mounting brackets current for the 11 AC depends upon the individual car. And, as one of them said, if it doesn't, finding the proper mounting brackets to change over from the AC to the ACR is difficult as best. I've spoken with one of the better known suppliers about how to determine if, indeed, my particular car will accept the ACR without need for modification. Unfortunately, he said that it is not an easy undertaking, and, that the only sure way to know is to have the ACR in hand and see if it fits. Being in the US, my purchasing and returning the ACR, if need be, would require quite a bit of shipping expense. I'm not sure what I'm going to do at this point. If anyone does have an idea as to how to determine if the ACR will fit, I'd appreciate hearing. The car is a 1972 P6 3500, Left Hand Steering. The 11AC is mounted on the passenger side of the car. So, looking at the engine bay from the front, the alternator is mounted on the left side of the engine. Again, thanks for your help. Anyone with any thoughts- your ideas are welcome and appreciated.
Drew
 
Hi Drew, did not know you were V8. However the 11AC is the same size mounting on all versions, so it is only the engine bracket which will differ from the 2000. The ACR will still fit where you take the AC from as the dimension over the mounting flanges remains the same. Attached some photos. First shows standard ACR pulley as it comes in the box. Other two show the AC pulley fitted. You cannot use the standard ACR pulley as it will not line up with the belt. The AC pulley fits straight on to ACR with no problem and gives the extra throw on the front to meet up with the belt. Use the supplied ACR fan behind the AC11 pulley from your old alternator. You will need to make sure you order the right 'hand' of ACR to match the lugs on your original. Other than that should be fine. V8 alternator is on the top of the motor, so a lot easier to work with than the 4 pot cars. I have seen V8 cars with ACR fitted so must be possible. Cheers, Rob
 

Attachments

  • P1010968.JPG
    P1010968.JPG
    262.7 KB · Views: 21
  • P1010969.JPG
    P1010969.JPG
    269.6 KB · Views: 22
  • P1010971.JPG
    P1010971.JPG
    184.3 KB · Views: 20
Jasper:Why did you change from the AC to the ACR? I'm looking to increase amperage. Does the ACR turn out more? Thanks,
Drew
 
I plan to do a step-by-step pictorial write-up. Mine is a 1970 LHD car. The problem if you have a series 2 car might be that you need 1/2" Lucar spade connectors if you need an additional run of wiring to attach to the alternator shunt. The 11AC only has one power connection via a 3/8" Lucar spade with a single cable. The ACR and A127 use the same terminal block with two power cables. It's easy in the s1 as everything attaches to a post of the floor and not the alternator shunt.

You do not need to change any brackets.

I would say unless you have one don't bother with the ACR and go for the more modern design. It looks the same anyway. My charge light comes on now only if I stall the car when the revs drop below 200! I'm really pleased with the results.
 
I plan to do a step-by-step pictorial write-up. Mine is a 1970 LHD car. The problem if you have a series 2 car might be that you need 1/2" Lucar spade connectors if you need an additional run of wiring to attach to the alternator shunt. The 11AC only has one power connection via a 3/8" Lucar spade with a single cable. The ACR and A127 use the same terminal block with two power cables. It's easy in the s1 as everything attaches to a post of the floor and not the alternator shunt.

You do not need to change any brackets.

I would say unless you have one don't bother with the ACR and go for the more modern design. It looks the same anyway. My charge light comes on now only if I stall the car when the revs drop below 200! I'm really pleased with the results.
 
Peter: I'm leaning in the direction of replacing the 11 AC with the 127. If I understand correctly, the only serious issue is increasing the size of the main alternator cable? I've looked online and there are several "127 alternators" on the market. Is there a specific one that you recommend for this application (1972, 3500 auto)? The alternator in this car is mounted on the right hand side of the engine/ the left side if you are facing the car from the front. Is this considered a "right hand" mounted alternator? You had posted directions and a schematic of your car's electrical system earlier. I have this info. Thanks, Drew
 
Hi Drew, we had the alternator available from a mate, unused. Ours is 65amp. We wanted it for our nocturnal rally navigation events where we run around 400w of lighting plus the heater and wipers if raining. The old AC was fine for the standard car. If your car is charging fine with no regulator or relay issues, I would leave it alone.
 
I'm leaning in the direction of replacing the 11 AC with the 127. The alternator in this car is mounted on the right hand side of the engine/ the left side if you are facing the car from the front. Is this considered a "right hand" mounted alternator?

I think you'll find that it's a "left hand" mounted alternator.
 
Hi Drew, we had the alternator available from a mate, unused. Ours is 65amp. We wanted it for our nocturnal rally navigation events where we run around 400w of lighting plus the heater and wipers if raining. The old AC was fine for the standard car. If your car is charging fine with no regulator or relay issues, I would leave it alone.
 
Just an afterthought. If the 127 is a direct replacement for the ACR, the standard pulley on the 127 will not line up the 2000 or the V8 belt. You will either have to change the pulley as we did, or make a new bracket to move the whole thing forward.
 
Jasper: When I am idling, and, I have a load on the system ( high beam lights, heater, radio, etc.) the amperes drop to -30 to -40, the ignition light comes on and the engine stumbles. The alternator (11 AC) has just been rebuilt. I've checked voltages at the battery. The results (in volts) are: Cold battery 14.2, warm idle: 13.99, idle with load: 12.2 (this is when the amperes drop to the minus 30 range). I don't think the voltage regulator is malfunctioning. But, that is another issue. This car was a German export. At some point a Bosch voltage regulator was used to replace the 4 TR. Finding a replacement is proving a bit of a challenge. One of the experts, however, told me that if the voltage regulator was malfunctioning, I would be getting wide changes in the readings (eg 17 or 18 volts), which is not happening. The idle speed is about 600 rpm. I haven't put a tachometer on it yet, but, again, I think that the problem is simply a 48 year old alternator can no longer provide the current that it used to. That's my reason for wanting to switch alternators. Thanks, Drew
 
Jasper: When I am idling, and, I have a load on the system ( high beam lights, heater, radio, etc.) the amperes drop to -30 to -40, the ignition light comes on and the engine stumbles. The alternator (11 AC) has just been rebuilt. I've checked voltages at the battery. The results (in volts) are: Cold battery 14.2, warm idle: 13.99, idle with load: 12.2 (this is when the amperes drop to the minus 30 range). I don't think the voltage regulator is malfunctioning. But, that is another issue. This car was a German export. At some point a Bosch voltage regulator was used to replace the 4 TR. Finding a replacement is proving a bit of a challenge. One of the experts, however, told me that if the voltage regulator was malfunctioning, I would be getting wide changes in the readings (eg 17 or 18 volts), which is not happening. The idle speed is about 600 rpm. I haven't put a tachometer on it yet, but, again, I think that the problem is simply a 48 year old alternator can no longer provide the current that it used to. That's my reason for wanting to switch alternators. Thanks, Drew
 
Back
Top