T-Mack1 Posted January 12 Share Posted January 12 Not sure if this post should go here or under engine. But, the Engine section looks like its a lot of more modern engine questions and I don't think it would get the best response there. The question I have is, what's inside the tube that comes out of the rpm limiter (cable, chain, or some kind of tube)? As you can see from the picture, we received the truck with no air cleaner. So, before we do the compression test, I would like to take the Zenith carb off and make sure there's no critter nest inside. But the tube from the limiter goes into the base of the carb, and makes getting to the bolts hard unless I disconnect it. Quote Link to comment https://www.bigmacktrucks.com/topic/74986-question-on-rpm-limiter-carb/ Share on other sites More sharing options...
Joseph Cummings Posted January 12 Share Posted January 12 As far as I remember on the EN707 it was a rod. But you have an ENF707. Quote Link to comment https://www.bigmacktrucks.com/topic/74986-question-on-rpm-limiter-carb/#findComment-566192 Share on other sites More sharing options...
T-Mack1 Posted February 2 Author Share Posted February 2 Ok, we took carb off to check intake for critters, and only found some dropping under the carb. As if they visited the card and left and couldn't get past the throttle butterfly plates. And we freed up the throttle linkage and most likely the dropping fell straight down. Carb has been cleaned and painted. I also figured out how the RPM limiter works and took pictures. I will post something. 1 Quote Link to comment https://www.bigmacktrucks.com/topic/74986-question-on-rpm-limiter-carb/#findComment-568386 Share on other sites More sharing options...
T-Mack1 Posted February 2 Author Share Posted February 2 Carb before. 1 Quote Link to comment https://www.bigmacktrucks.com/topic/74986-question-on-rpm-limiter-carb/#findComment-568387 Share on other sites More sharing options...
T-Mack1 Posted February 2 Author Share Posted February 2 (edited) Trying to load after picture but having issues. Apparently I've hit my limits. Darn. Edited February 2 by T-Mack1 Quote Link to comment https://www.bigmacktrucks.com/topic/74986-question-on-rpm-limiter-carb/#findComment-568389 Share on other sites More sharing options...
Joseph Cummings Posted February 2 Share Posted February 2 1 hour ago, T-Mack1 said: Carb before. I wouldn't want to drop that cast iron downdraft zenith on my toe lol 1 Quote Link to comment https://www.bigmacktrucks.com/topic/74986-question-on-rpm-limiter-carb/#findComment-568413 Share on other sites More sharing options...
T-Mack1 Posted February 3 Author Share Posted February 3 9 hours ago, Joseph Cummings said: I wouldn't want to drop that cast iron downdraft zenith on my toe lol Getting it out of the left side of the B-model was interesting. Would have made a good viral video, LOL! 1 Quote Link to comment https://www.bigmacktrucks.com/topic/74986-question-on-rpm-limiter-carb/#findComment-568482 Share on other sites More sharing options...
Jack Mack Posted February 12 Share Posted February 12 My brother does do good work, nice air cleaner he made fit, carb was all gone over!…..Jack 2 Quote Link to comment https://www.bigmacktrucks.com/topic/74986-question-on-rpm-limiter-carb/#findComment-569176 Share on other sites More sharing options...
T-Mack1 Posted February 13 Author Share Posted February 13 (edited) First, thanks to the Edelbrock family/team for making an air cleaner that is sort of decent looking on an antique Mack (note the first picture in the thread, we did not get an air cleaner with the truck). I removed the Edelbrock tag and made a plate to mount a front hub emblem on. Had to make a slip sleeve to take up the difference of the air cleaner and the 4 inch cast aluminum intake piece. Hose clamp tightens the slip sleeve on the intake. Next, some may notice, some might not. Jack and I have a diesel exhaust manifold on our Gasoline engine. It came that way. Edited February 13 by T-Mack1 spelling & grammar. Quote Link to comment https://www.bigmacktrucks.com/topic/74986-question-on-rpm-limiter-carb/#findComment-569283 Share on other sites More sharing options...
609albert Posted February 14 Share Posted February 14 Just a suggestion after you get the carb straightened out is change the points to electronics in the distributors and make sure the coils are good . If you have positive ground the Petronic (brand name) have to be for positive ground also Quote Link to comment https://www.bigmacktrucks.com/topic/74986-question-on-rpm-limiter-carb/#findComment-569286 Share on other sites More sharing options...
Joseph Cummings Posted February 14 Share Posted February 14 1 hour ago, T-Mack1 said: Next, some may notice, some might not. Jack and I have a diesel exhaust manifold on our Gasoline engine. It came that way. I held a Maxidyne manifold for a turbo up to my 707 and it looked like a bolt on. I was going to try turbocharging it, but then I bought a R600 Maxdyne truck and never followed through with turbocharging the gas job 1 Quote Link to comment https://www.bigmacktrucks.com/topic/74986-question-on-rpm-limiter-carb/#findComment-569288 Share on other sites More sharing options...
Joseph Cummings Posted February 14 Share Posted February 14 21 minutes ago, 609albert said: Just a suggestion after you get the carb straightened out is change the points to electronics in the distributors and make sure the coils are good . If you have positive ground the Petronic (brand name) have to be for positive ground also I used the Pertronics conversions for a lot of older industrial engines like forklifts years ago and never had any problems. But now I'm reading a lot of stuff online with guys claiming they are junk. I don't know if they are doing something wrong or what's up. Here is another choice, I've seen it done but never did one myself. I was told the pull up resistor is about 1/2 watt. On my 707 a ran a points controlled MSD 5, it worked well, but I think they are expensive now, and you would need 2 of them Quote Link to comment https://www.bigmacktrucks.com/topic/74986-question-on-rpm-limiter-carb/#findComment-569291 Share on other sites More sharing options...
Geoff Weeks Posted February 14 Share Posted February 14 There are a lot of good electronic ign components from which to make a good system. I personally, don't like electronics "under the cap" in a HV environment. So far, my stuff that came with point remain so, they don't get driven enough to justify the change. I like the Ford or Chry pick-up better than GM's. Once the signal is outside the distributor, any ign box is fine. Quote Link to comment https://www.bigmacktrucks.com/topic/74986-question-on-rpm-limiter-carb/#findComment-569292 Share on other sites More sharing options...
T-Mack1 Posted February 14 Author Share Posted February 14 21 hours ago, 609albert said: Just a suggestion after you get the carb straightened out is change the points to electronics in the distributors and make sure the coils are good . If you have positive ground the Petronic (brand name) have to be for positive ground also After getting the truck running, the plan is go Electronic Ignition. Brillman sells the kits. Both Positive ground and Negative ground. I did talk to Doug at the Mack Museum yesterday and starter will work correctly, both POS ground or Neg ground. Also after I got our Federal S6B siren running and found it also didn't care about polarity, asked my friend that use to build race engines and is a electronic guru ( like breaking his Harley CAN bus data stream and making a little display to show the data), the reason is both are NOT permanent magnetic DC motors. So plan is to go negative ground so we can get new accessories. Quote Link to comment https://www.bigmacktrucks.com/topic/74986-question-on-rpm-limiter-carb/#findComment-569367 Share on other sites More sharing options...
Joseph Cummings Posted February 14 Share Posted February 14 1 minute ago, T-Mack1 said: After getting the truck running, the plan is go Electronic Ignition. Brillman sells the kits. Both Positive ground and Negative ground. I did talk to Doug at the Mack Museum yesterday and starter will work correctly, both POS ground or Neg ground. Also after I got our Federal S6B siren running and found it also didn't care about polarity, asked my friend that use to build race engines and is a electronic guru ( like breaking his Harley CAN bus data stream and making a little display to show the data), the reason is both are NOT permanent magnetic DC motors. So plan is to go negative ground so we can get new accessories. Yeah, series wound, and shunt wound dc motors will rotate the same way no matter if you have pos or neg ground. If you have electric gauges, the wires will need swapped on the back. The starter is series wound, and your beacon light is shunt wound. Heater blower motors are also shunt Quote Link to comment https://www.bigmacktrucks.com/topic/74986-question-on-rpm-limiter-carb/#findComment-569368 Share on other sites More sharing options...
T-Mack1 Posted February 14 Author Share Posted February 14 20 hours ago, Joseph Cummings said: I used the Pertronics conversions for a lot of older industrial engines like forklifts years ago and never had any problems. But now I'm reading a lot of stuff online with guys claiming they are junk. I don't know if they are doing something wrong or what's up. Here is another choice, I've seen it done but never did one myself. I was told the pull up resistor is about 1/2 watt. On my 707 a ran a points controlled MSD 5, it worked well, but I think they are expensive now, and you would need 2 of them Hi Joe. I tried this GM HEI conversion on my ONAN house generator. I was tired of the condensers only lasting two years due to the heat from being mounted on top of the engine. In the process of doing it, I found out there are several types of HEI modules, and took buying 3 to get the right one. It worked for a while but failed. The little solid wire leads on the resistor did not like the vibration. So, just changed type of condenser from the standard electrolytic to an "Orange Drop" type of same value, which will out last me and maybe even my grandson. note: the reason the points go bad is because the condenser starts to go bad and the points start to arch. Another note, there is no reason that the condenser needs to be inside the distributor, It can be remotely mounted away from the heat, within reason. (2-3 feet). 1 Quote Link to comment https://www.bigmacktrucks.com/topic/74986-question-on-rpm-limiter-carb/#findComment-569369 Share on other sites More sharing options...
T-Mack1 Posted February 14 Author Share Posted February 14 5 minutes ago, Joseph Cummings said: Yeah, series wound, and shunt wound dc motors will rotate the same way no matter if you have pos or neg ground. If you have electric gauges, the wires will need swapped on the back. The starter is series wound, and your beacon light is shunt wound. Heater blower motors are also shunt When I looked over the generic wiring diagram, I noticed that Mack uses 2 pole gauges. YAY!!!!.... easy to convert. So far, it looks like the biggest hurdle will be the Leece Neville alternator (Orig equip per Mack museum info) and the square finned block thing that I think is a regulator. Need wiring pin-outs for both. As for the heater, No heater in the cab and not sure it had one as it's an open cab truck. Quote Link to comment https://www.bigmacktrucks.com/topic/74986-question-on-rpm-limiter-carb/#findComment-569372 Share on other sites More sharing options...
Joseph Cummings Posted February 14 Share Posted February 14 4 minutes ago, T-Mack1 said: Another note, there is no reason that the condenser needs to be inside the distributor, It can be remotely mounted away from the heat, within reason. (2-3 feet). I'm thinking with the points triggered electronic setups you don't really need a condenser because the current through the points is so low Yeah standard electronic components like for a stereo or something don't hold up well to vibration My 4 cylinder Kohler genset has a magneto on it, it's stone reliable Quote Link to comment https://www.bigmacktrucks.com/topic/74986-question-on-rpm-limiter-carb/#findComment-569373 Share on other sites More sharing options...
Joseph Cummings Posted February 14 Share Posted February 14 4 minutes ago, T-Mack1 said: When I looked over the generic wiring diagram, I noticed that Mack uses 2 pole gauges. YAY!!!!.... easy to convert. So far, it looks like the biggest hurdle will be the Leece Neville alternator (Orig equip per Mack museum info) and the square finned block thing that I think is a regulator. I'd have to see it. I'm sure the bridge rectifier is connected wrong. Some LN could be used for both systems like the JB2500, but that dosen't sound like what you have Quote Link to comment https://www.bigmacktrucks.com/topic/74986-question-on-rpm-limiter-carb/#findComment-569374 Share on other sites More sharing options...
T-Mack1 Posted February 14 Author Share Posted February 14 6 minutes ago, Joseph Cummings said: I'd have to see it. I'm sure the bridge rectifier is connected wrong. Some LN could be used for both systems like the JB2500, but that dosen't sound like what you have Messaged you a picture of the square finned thing. Quote Link to comment https://www.bigmacktrucks.com/topic/74986-question-on-rpm-limiter-carb/#findComment-569376 Share on other sites More sharing options...
Geoff Weeks Posted February 14 Share Posted February 14 (edited) No, the square finned thing is the old selinium (SP?) rectifier. Old L/N alternators of that period had the rectifiers external from the alternator, and they were quite large. I have a similar unit that is 100 amps @ 6 (7) volt. The good news is the rectifier should be isolated from ground and can be used on either ground. Unlike modern alternators, the regulator looks like a generator regulator and, like such, disconnects the rectifier from the battery when not charging. Edited February 14 by Geoff Weeks Quote Link to comment https://www.bigmacktrucks.com/topic/74986-question-on-rpm-limiter-carb/#findComment-569378 Share on other sites More sharing options...
T-Mack1 Posted February 14 Author Share Posted February 14 1 minute ago, Geoff Weeks said: No, the square finned thing is the old selinium (SP?) rectifier. Old L/N alternators of that period had the rectifiers external from the alternator, and they were quite large. I have a similar unit that is 100 amps @ 6 (7) volt. The good news is the rectifier should be isolated from ground and can be used on either ground. Unlike modern alternators, the regulator looks like a generator regulator and, like such, disconnects the rectifier from the battery when not charging. Selenium rectifier like my son's old Honda SL70. Only issue was Honda used the battery to absorb the voltage spikes at high rev's and that would boil the battery water/acid away. Cheap regulator. Only issue was if the water was gone, you would send 18 volts to the 6v light bulbs. Our ALT is 100A per the build info. On the tag on it, it says Rectified, so I was thinking it was internally rectified and externally regulated. Also, when we checked for POS or NEG ground, hooking up the battery as NEG grd, had a big current draw. Swapped leads to POS grd and everything was normal. I was thinking it was a Alt/rectifier/regulator issue. Now I'm going to have to think a bit..... it's only been 40 years since my electronics training..... Mind like a steel trap.... very rusty. Quote Link to comment https://www.bigmacktrucks.com/topic/74986-question-on-rpm-limiter-carb/#findComment-569380 Share on other sites More sharing options...
Geoff Weeks Posted February 14 Share Posted February 14 If you have a rectifier like in the picture, they are the weak point in the system and can be bad for your health if they "pop", and also can be a shorting hazard. The alternator is self is very robust. A lot depends on how "period correct" you want to keep it. On mine you can see the two jumper bands on the bridge and the positive and Negative output wires at either end, as well as the 3 A/C input phases to the rectifier. Because they are external and exposed, there is a full current relay in the regulator that only connects the rest of the truck (and battery voltage) to the rectifier when the ign is on. There are modern replacement external rectifier assemblies to replace these in function (fan cooled external "boxes") or you could rig up an insulated set of diodes from a JB series on the rear of the alternator, but you must have the mount also duct the cooling air for the alternator over the cooling fins on the JB diode packs. unless "period correct" is paramount, I would use modern components for the rectifiers. Quote Link to comment https://www.bigmacktrucks.com/topic/74986-question-on-rpm-limiter-carb/#findComment-569381 Share on other sites More sharing options...
Geoff Weeks Posted February 14 Share Posted February 14 how many heavy wires come off the alternator? does it look like this one? ignore the messy bench. Quote Link to comment https://www.bigmacktrucks.com/topic/74986-question-on-rpm-limiter-carb/#findComment-569382 Share on other sites More sharing options...
Joseph Cummings Posted February 14 Share Posted February 14 Yeah They let out a nasty stink when they burn out lol BTW your son's honda should have had a Zener diode in the circuit. They leak in reverse flow at a certain voltage Just be glad that none of this was designed by Joe Lucas Quote Link to comment https://www.bigmacktrucks.com/topic/74986-question-on-rpm-limiter-carb/#findComment-569383 Share on other sites More sharing options...
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