Topic: Is this voltage regulator correct for a 1970 SCJ?

[ng8264723]

https://www.ebay.com/itm/1970-1971-Mustang-Voltage-Regulator-Autolite-38-42-45-55A-AMK/124367155706?hash=item1cf4dc31fa:g:HCkAAOSwhnNfe1VU

[Bob Gaines]

https://www.ebay.com/itm/1970-1971-Mustang-Voltage-Regulator-Autolite-38-42-45-55A-AMK/124367155706?hash=item1cf4dc31fa:g:HCkAAOSwhnNfe1VU

I don't have any service specifacations manuals for 1970 but on a 69 the 55 amp regulator would bear a C8TF opposed to the C8AF for the lower amp alternator. I am not sure for a 1970 but would guess it would follow suit. Instead of a D0AF it would be a D0TF is why I would say check the 1970 service specifications manual to verify. If you don't have one it is a wise investment along with a shop manual . They are available reproduction by all major Mustang vendors. Assemblyline manuals help if putting a car together or knowing where parts go.

[Mike_B_SVT]

Virginia Mustang has nice repros with electronic internals, made in the US, and cheaper than the AMK on eBay.

https://www.virginiaclassicmustang.com/Search.aspx?s=Name+ASC&ps=48&k=voltage+regulator&c=998

FWIW, my '70 SCJ had a C8AF in it when I bought it.  Not saying it is definitely original, but it had been in there so long the silver print was completely faded and only visible from certain angles and lighting.

[hopey]

FYI, This is what Jack sells and he states C8AF is correct for non-AC cars until 4/1970. C8TF-10316-A Yellow ink stamped heavy duty voltage regulator was only on AC equipped cars and was also sold as a fits everything service replacement. 5/70 is when the changeover to D0AF occurred.

https://www.deadnutson.com/1970-428-cobra-jet-alternators-parts/

[Bob Gaines]

FYI, This is what Jack sells and he states C8AF is correct for non-AC cars until 4/1970. C8TF-10316-A Yellow ink stamped heavy duty voltage regulator was only on AC equipped cars and was also sold as a fits everything service replacement. 5/70 is when the changeover to D0AF occurred.

https://www.deadnutson.com/1970-428-cobra-jet-alternators-parts/

You are misinformed if you think the C8TF was only used on A/C cars. Check the Ford documents please.It just so happens that AC cars typically upgraded to a 55 amp alternator which is why the AC cars got the heavy duty regulator. It is alternator output that typically dictates which regulator and not the A/C accessory status.There are other instances where a 55 amp alternator was used without AC that got the C8TF which is confirmed by the Ford documents. In the instance of the OP ,the D0AF regulator my be the correct one after 1970 which is why I suggested referring to the Ford service specifications manual for confirmation which typically list what regulator goes with which alternator.Yes if you bought a regulator from Ford over the counter back in the day the C8TF was what you got regardless of application.

[J_Speegle]

Unfortunately build sheets don't indicate the voltage regulators installed in certain cars only battery size and alternator or we could used those as reference points. Autoilite manuals of the period will list what the suggested replacement was not what was originally installed in every application. Those manual;s and such all refer to the same replacement for all sized engines and applications (6 cyl - 429)  Just helped reduce the need for multiple ones and reduced inventory/stocking needs. Even in  the 1970 Announcement listing of parts

Looking at the 70 buildsheets I have for CJs, they all show "5C" for the alternator on 428CJ cars with and without AC. Also, all with the same sized battery

[hopey]

You are misinformed if you think the C8TF was only used on A/C cars. Check the Ford documents please.It just so happens that AC cars typically upgraded to a 55 amp alternator which is why the AC cars got the heavy duty regulator. It is alternator output that typically dictates which regulator and not the A/C accessory status.There are other instances where a 55 amp alternator was used without AC that got the C8TF which is confirmed by the Ford documents. In the instance of the OP ,the D0AF regulator my be the correct one after 1970 which is why I suggested referring to the Ford service specifications manual for confirmation which typically list what regulator goes with which alternator.Yes if you bought a regulator from Ford over the counter back in the day the C8TF was what you got regardless of application.

Bob,  I’m just quoting what Jack (dead nuts on) has on his web page “Jacks comments” for voltage regulators. He references his information was confirmed correct by Bob Perkins and Ed Myers......

Personally, I’m just trying to improve my knowledge.

[Bob Gaines]

Bob,  I’m just quoting what Jack (dead nuts on) has on his web page “Jacks comments” for voltage regulators. He references his information was confirmed correct by Bob Perkins and Ed Myers......

Personally, I’m just trying to improve my knowledge.

If trying to improve your knowledge consider this,Jack also posts the C8AF is for 38/42 alternators which contradicts it being used on 55 amp non AC cars . I am aware of the C8AF use on some Boss 9 and BOSS 302 applications which is the context of the BP and Ed M confirmation I believe. That is contradictory but I think the use in those cases  is anomalous to those cars for some reason given the Ford documentation to the contrary which besides being the company that engineered the set up also seems more logical .You may want to ask yourself why Ford would use a heavy duty 55 amp regulator for a 55 amp alternator on a A/C equipped car and a lower capacity 38/42 amp regulator on a 55 amp non A/C car. Not to say that Ford has never made a mistake in there documents but mistakes are typically isolated and and stand out as wrong . The Ford documents are hard to dispute in this case and it wouldn't be prudent to dismissed what is published in all of the Ford technical literature.

[hopey]

I am aware of the C8AF use on some Boss 9 and BOSS 302 applications which is the context of the BP and Ed M confirmation I believe. That is contradictory but I think the use in those cases  is anomalous to those cars for some reason given the Ford documentation to the contrary which besides being the company that engineered the set up also seems more logical .You may want to ask yourself why Ford would use a heavy duty 55 amp regulator for a 55 amp alternator on a A/C equipped car and a lower capacity 38/42 amp regulator on a 55 amp non A/C car.

Bob,
thanks but the context from BP seems very clear in posts where his opinion was sought over on the CJ site as well. That is why I am pursuing. Here is a link to that main discussion(hope that’s ok to do!)

https://www.428cobrajet.org/forum/index.php?topic=8988.msg51566#msg51566

From an electrical perspective, without AC there is significantly lower load on the system, regardless of alternator charging capacity, so I can see how a 42A regulator would suffice.....

As previously stated the build sheet did not include this information, the MPC revision I have at home does not describe what was installed at the factory, only what parts were available to be used for maintenance and even the MCA judging sheets only call out a “blue Autolite” regulator...

[Bob Gaines]

Bob,
thanks but the context from BP seems very clear in posts where his opinion was sought over on the CJ site as well. That is why I am pursuing. Here is a link to that main discussion(hope that’s ok to do!)

https://www.428cobrajet.org/forum/index.php?topic=8988.msg51566#msg51566

From an electrical perspective, without AC there is significantly lower load on the system, regardless of alternator charging capacity, so I can see how a 42A regulator would suffice.....

As previously stated the build sheet did not include this information, the MPC revision I have at home does not describe what was installed at the factory, only what parts were available to be used for maintenance and even the MCA judging sheets only call out a “blue Autolite” regulator...

Maybe you are not aware but the load and the alternator are directly related. In your theory you only talk about regulator and not alternator. You are neglecting to take into account the many non A/C equipped cars also have 38/42 amp alternators and consequently don't need a higher rated regulator.  A non AC car typically gets a 38/42 amp alternator because of less load. The AC car gets upgraded to a 55 amp alternator because of more load. A non ac car can get upgraded to a 55 amp alternator typically if ordered or if it automatically was specified to come with the heavy duty Battery. It doesn't make sense to put a lower capacity 42 amp capacity regulator with a 55 amp capacity alternator. Again the pairing is backed up by the Ford technical documents and is only logical.  If the relationship to amps wasn't important then it wouldn't be used as a measurement for the component.Thank you for posting the link to the other site.The understanding that I have had in the past with BP and ED M on the subject was a Boss context which is the reason for my statement.  I too have owned a lot of CJ cars (GT 500's) and studied many others especially survivor cars .  I can't speak to the Boss cars but can to the many CJ GT500's I have owned and studied which support my point of view that is corroborated by the Ford technical documents. I don't know why some BOSS cars came with the lower capacity regulator yet had a 55 amp alternator which is why they are a anomaly for some reason.

[hopey]

Bob,

Thanks. I understand your logical approach. I am also fully aware of the relationship between all aspects of an electrical load, voltage regulators and alternators. My first (of 3) engineering degrees is in electrical & electronics. EG your assumption that a 1970s vintage 55a alternator was designed to output full rated power on a particular engine/ pulley configuration may not be true. The alternator may be intentionally under driven (limited) on a high rpm engine to protect the machine from damage, so necessitating a higher theoretical output. So in this case a 55A rated alt may actually be operating at a lower max power output on its curve at high rpms and adequate output at idle(under driven) which means a 42A voltage regulator is more than adequate. Today, modern designs of alternators have an output curve that is near flat at all speeds, but older designs had a much more linear output in relation to their speed.

Which Ford documents are you referencing?

[Bob Gaines]

Bob,

Thanks. I understand your logical approach. I am also fully aware of the relationship between all aspects of an electrical load, voltage regulators and alternators. My first (of 3) engineering degrees is in electrical & electronics. EG your assumption that a 1970s vintage 55a alternator was designed to output full rated power on a particular engine/ pulley configuration may not be true. The alternator may be intentionally under driven (limited) on a high rpm engine to protect the machine from damage, so necessitating a higher theoretical output. So in this case a 55A rated alt may actually be operating at a lower max power output on its curve at high rpms and adequate output at idle(under driven) which means a 42A voltage regulator is more than adequate. Today, modern designs of alternators have an output curve that is near flat at all speeds, but older designs had a much more linear output in relation to their speed.

Which Ford documents are you referencing?

Ford typically used a larger pulley to underdrive the alternator on many high revving performance engines. It is commonly referred to as a hipo pulley. If your theory is correct then the Ford technical documents would reflect that which they do not . As mentioned in several of my posts the Service Specifications manual. That manual is part of the 69 Shop manual set . In this case page 14-2 . FYI similar information is in the 65,66,67,68 service specification manuals which makes a oversight by Ford even less of a possibility.

[Bob Gaines]

Bob,

Thanks. I understand your logical approach. I am also fully aware of the relationship between all aspects of an electrical load, voltage regulators and alternators. My first (of 3) engineering degrees is in electrical & electronics. EG your assumption that a 1970s vintage 55a alternator was designed to output full rated power on a particular engine/ pulley configuration may not be true. The alternator may be intentionally under driven (limited) on a high rpm engine to protect the machine from damage, so necessitating a higher theoretical output. So in this case a 55A rated alt may actually be operating at a lower max power output on its curve at high rpms and adequate output at idle(under driven) which means a 42A voltage regulator is more than adequate. Today, modern designs of alternators have an output curve that is near flat at all speeds, but older designs had a much more linear output in relation to their speed.

Which Ford documents are you referencing?

It has been a few days so I posted a copy of the page out of the 69 specification manual that is relevant to the conversation about 69 applications in case it has been hard to find. The C8TF identified with a yellow stamp is for 55 amp alternator .There is no additional designation for A/C only. The C8AF identified with a silver stamp is for 38/42 amp alternator. There is no additional designation for 55 amp without AC . This same information is in other year specification manuals as well so a isolated mistake would be unlikely. The Boss application information although known to be different is not mentioned.

[70cj428]

Just FYI, I've been researching (and hoarding parts) for 70 CJ's for years.....  all 70 CJ's (AC or not) and SCJ's got 55 amp alternators. I've documented a bunch of non AC original cars and they all used the C8TF (yellow stamp ) regulator.  I haven't found any post 4/70 cars that I'm convinced were unrestored originals so I've never seen a D0TF/D0ZF original regulator on a CJ ( a majority of 70 CJ's were built earlier in the model year)

I have some evidence that contradicts the current thinking on what alternator the CJ's with AC got in 70, but that discussion is for another day .....

JMHO, John

[specialed]

All b9s used c8af regulators and had the 4'' alt pulley.  I have never seen or heard of a dotf or a dozf  only the doaf showing up on later 70 and 71 cars with the d2af showing up on the motorcraft regulators.  What i am trying to document is when and why the 15V started showing up stamped in front of the C8  eng # below the autolite stamp.