Ackcruisers
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Not yet. I’ll try that over weekend and report back.
1976 FJ40 2F Semi Transistorized Points Igniter…Dwell measurement?
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Ackcruisers
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I was successful in measuring RPM by connecting the Innova 3340 to the ignition coil and ground. Red to the negative coil terminal and black to ground.
Did you get the dwell back to spec?
And, does having correct dwell reflect a points gap that is more or less withing factory numbers? In other words, can you discern any distributor cam wear?
And, does having correct dwell reflect a points gap that is more or less withing factory numbers? In other words, can you discern any distributor cam wear?
Ackcruisers
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I need to buy a vintage tach/dwell to verify if the Innova is accurate….adjusted the points without the feeler gauge but used it after to verify gap size. Moved from .018 to .020.
I’m posting up an image of my old Non USA small cap distributor 19100-61010 (which is same as 19100-61080) to show where to place flat screwdriver to adjust. The points are 19145-26060. My dwell reading moved slightly. I’m going to leave it there as I‘ve read more about dwell angle on the 2F engines and it apparently matters little for a low rpm motor.
I’m posting up an image of my old Non USA small cap distributor 19100-61010 (which is same as 19100-61080) to show where to place flat screwdriver to adjust. The points are 19145-26060. My dwell reading moved slightly. I’m going to leave it there as I‘ve read more about dwell angle on the 2F engines and it apparently matters little for a low rpm motor.
Using a feeler gauge can be a bit subjective from one operator to another operator, or you one day from another. .002" is a pretty small window. If you get another dwell meter and they read differently from each other, which one is correct? I prefer to set the point gap with a dwell meter. I have someone crank the engine while I look at the meter and adjust the the points.
Curious about this, where are you reading this?
I think that carrying a multimeter in the vehicle is more important than carrying jumper cables. It is best to just get a fresh battery because modern vehicles might not handle the spike in voltage when you disconnect, that is why they say run all electrical accessories while you disconnect when you do a jump-start. With the digital display, and the overall compactness of that, It will fit well in a trail-bag. Confirming a good dwell lets you pretty much focus on valves and carb for engine troubleshooting, so it is good to be able to read voltage, Ohms and dwell with any one portable tool. The only problem is, I use mine in the house and shop all the time, so I carry a "getting-by" multimeter with me.
Ackcruisers
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Distributor RPM? The engine crank rotates twice as fast as the Distributor.
Ackcruisers
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I went back one more time to adjust dwell to bring it closer to spec of 41 degrees (non USA). I decreased the gap to approx. .016 and I’m pleased with the results. My multimeter dwell angle is now showing 39.2 as shown. I then adjusted timing again and am running at 10 degrees BTC (at sea level). My truck likes a bit more advance. Smooth idle at 650 RPM (did another lean drop adjustment).
The road test after the above proved that dwell angle is important for these trucks to find their sweet spot. Yes, they will run well with match book or .018 default gap but to run great, dwell is an important factor.
Also, the final word on the Innova 3340 Multimeter is that it can effectively measure dwell. I will buy an old fashioned dwell meter at some point to compare results.
NOTE: to increase dwell you decrease breaker point gap. To decrease dwell you increase gap. My post #9 included a screen grab from the 8/80 2F manual that may confuse future dwell adjusters running points. The manual was referring to the “rubbing block gap” for electronic ignition systems.
The road test after the above proved that dwell angle is important for these trucks to find their sweet spot. Yes, they will run well with match book or .018 default gap but to run great, dwell is an important factor.
Also, the final word on the Innova 3340 Multimeter is that it can effectively measure dwell. I will buy an old fashioned dwell meter at some point to compare results.
NOTE: to increase dwell you decrease breaker point gap. To decrease dwell you increase gap. My post #9 included a screen grab from the 8/80 2F manual that may confuse future dwell adjusters running points. The manual was referring to the “rubbing block gap” for electronic ignition systems.
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Few questions:
1) are you running ported vacuum or manifold vacuum advance, and is the idle at 650-rpm set with vacuum attached or plugged?
2) does the 2F FSM have any references wrt when the distributor’s mechanical advance starts (rpm) and when its vacuum advance starts (mmHg or inHG)?
Few questions:
1) are you running ported vacuum or manifold vacuum advance, and is the idle at 650-rpm set with vacuum attached or plugged?
2) does the 2F FSM have any references wrt when the distributor’s mechanical advance starts (rpm) and when its vacuum advance starts (mmHg or inHG)?
Ackcruisers
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1) It’s ported on the base of the carb. I set RPM’s with the hose attached.
2) I do not have FSM for my non USA 2F distributor. I did get this info from dizzy faq…
Dizzy FAQ - http://www.globalsoftware-inc.com/coolerman/fj40/dizzyfaq.htm
Mechanical adv starts at 900 RPMs.
Wow, great stuff, I completely forgot about Coolerman’s thread. Full of lots of great stuff. He should get a Nobel for it! 😂
I asked about the 2F manual info, because my 1F Engine Repair Manual (dated 1966) has significantly different info wrt the dizzy (it does specify a vacuum advance dizzy). Here’s it’s info:
You can see why I asked about mechanical advance cuz it says that starts at 500-rpm so timing at 650 would have it already in advance. Vacuum advance specs are similar (not sure about the 16-deg max though). Wonder why the mechanical advance specs are so different, published date of the 1F manual fits in the timeframe window of the 19100-61080 (which I have from city racer). Not sure if the manual lists USA (vs. non-USA) spec’d dizzy 🤷♂️. Timing at 500-rpm (1F manual) vs. 650-rpm (2F ?) is significant in my book for a lot of factors.
I asked about the 2F manual info, because my 1F Engine Repair Manual (dated 1966) has significantly different info wrt the dizzy (it does specify a vacuum advance dizzy). Here’s it’s info:
You can see why I asked about mechanical advance cuz it says that starts at 500-rpm so timing at 650 would have it already in advance. Vacuum advance specs are similar (not sure about the 16-deg max though). Wonder why the mechanical advance specs are so different, published date of the 1F manual fits in the timeframe window of the 19100-61080 (which I have from city racer). Not sure if the manual lists USA (vs. non-USA) spec’d dizzy 🤷♂️. Timing at 500-rpm (1F manual) vs. 650-rpm (2F ?) is significant in my book for a lot of factors.
My understanding is that dwell regulates the duty cycle of the coil. Like, it takes some time (rotation angle) to build up voltage, and so much rotation angle to discharge it for igniting the flame-front. If you get that in spec, then you make the most of every spark, in theory. With it off, it might even overheat a coil?
Wonder if I can get this vintage tester functioning? 😂
(@Grayscale in one of our barns from an 8x10 Kodak Azo contact print from back in my “grayscale” large format days 😂)
(@Grayscale in one of our barns from an 8x10 Kodak Azo contact print from back in my “grayscale” large format days 😂)
Your manual says "distributor rpm" . If your engine idles at 650 rpm, your distributors rpms is 325 rpms.
If you want to see when your mechanical advance kicks in. Hook up your timing light with the strobe and tach working. Disconnect the vac at the dist and plug the vac leak. Now you can read mech advance only. Now slowly rev the engine up and watch when the timing mark starts to move and ref the rpms from the tach. Keep in mind the tach is showing crank rpms, so the dist is running 1/2 the rpms. You can use your strobe advance function to see how the dist correlates to the book. I like using the tdc mark, pointer and the advance function. Don't forget to hook up the vac adv when done.
Well, now I can (and will 😂) go home, I’ve learned something. Thanks @pb4ugo that makes sense, as I see that that whole 1F manual section is with the dizzy on a test stand. With that, it looks like both sets of info are in the ballpark with each other. Thread hammer over!
@Ackcruisers hope your winter is short and spring comes early so you can get your rig out on salt-free roads!
@Ackcruisers hope your winter is short and spring comes early so you can get your rig out on salt-free roads!
Ackcruisers
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It’s amazing how often I rely on Coolerman’s website for technical details on our trucks. His contributions to the community are valuable and appreciated. I’d give him the noble prize for his FJ40 electrical knowledge 🍺….
I’m learning more about the mechanical advance /vacuum advance and the timing/advance curve of the 19100-61010 Very interesting... if anyone has details from a 1975-77 2F FSM and can post the section on mechanical and vacuum advance that would be very helpful.
