cstav86
SILVER Star
I have a similar experience. I hook up a vacuum gauge and set timing that way. I don’t know how advanced it is, but it’s well beyond the 7° and it’s a happy motor there. When I can see the BB in the window it runs rough.
Distributor Position
- Thread starter Jaws87
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If it ain't broke don't fix it, a good running tractor is the goal not one that runs poorly but is in "specs".
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- #23
No worries. Sounds like we have a similar issue. Although even when I advance mine it’s not what I would call smooth. I’ve been playing with the distributor and carb adjustments all day trying to figure it out.@Mace and @Mark W I completely agree, and I would very much appreciate any suggestions. But after pulling and re-stabbing the distributor countless times, I haven't a clue as to what is the issue. I would be much happier if it were a 7 degrees advance. But doing so means I have to turn the idle way up to reach 600-650. The main reason I gave up chasing this issue is that the engine actually sems to perform quite well on the current setting. Starts quickly, idles smoothly with no choke, good vacuum... Sorry for the hijack....
Not trying to be an oral surgeon here, but maybe if you posted the pressures as you move from 7 deg BTDC to higher numbers, that might help the mavens of FJ40 technology here help out with a diagnosis.
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- #25
Good idea. I’m not home this weekend but I’ll try that when I get home. Thanks.
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- #26
I need to get a better gun that will give me that number. I just know I’m another 1 maybe 1.5 times the distance between TDC and the bb.
Green Bean
SILVER Star
Multi-function timing guns are pretty inexpensive these days. I got one off of Amazon That does everything.
I have my advance set at 20 degrees and it runs really well. When it's too low, it doesn't run rough, but I get some hiccups while driving.
I bought a digital timing gun from Harbor Freight that allows me to enter my desired target advance number, and then I line up the flywheel mark to TDC, which actually sets the advance to 20. It's so much easier than my old gun!
I bought a digital timing gun from Harbor Freight that allows me to enter my desired target advance number, and then I line up the flywheel mark to TDC, which actually sets the advance to 20. It's so much easier than my old gun!
I'm in sorta the same boat. The engine is not original and not quite stock. I was not surprised when my BB disappeared, and I just timed by vacuum. First the early vac advance dizzy then a 60 series big cap because all the cool kids had one. And I'd just time to best vacuum and then back it off a tad. And carry a 12mm ratcheting endwrench in the center console.
Then I got a new-fangled digital timing light and found that I was running at 33* BTDC. Even I could figure that something was wrong with my set up. So I replaced the non-functioning double diaphragm advancer unit on the dizzy with a new single diaphragm advancer from @4Cruisers, fiddled with the advance springs for a while and chose a pair that gives full advance (according to the enclosed instructions and my SOP) at around 3K RPM. I was able to retard timing to about 20*, it's happier at 22. I pull about 16" Hg at a 600 RPM idle. I'm just over 3k elevation and this engine is 20 years old. I've been promising it valve job for 10 years. I'll get to that any day now.
I'm thinking that the timing creep is sorta normal. Don't know why, maybe the gas, maybe just age, perhaps the global warming. Maybe they ran better with more advance when brand new and the FSM is a lie.
Green Bean
SILVER Star
Same here. One of the long-time guru's here told me once that it is a 54 year-old motor, with all of the concomitant wear and tear, it would be abnormal if it still tuned to factory spec. Setting timing on the BB requires turning the idle way up to get it to 650. Moreover, when accelerating it hesitates badly. All and all, the motor seems entirely happy at about 28 degrees advance. It does have Petronix ignition, but I'm not sure if that makes any difference. I admit that I'm abit envious of the BB crowd but I've reconciled that our situation it is what it is.
Watch this in detail. It will help I promise. Should be pinned if you ask me.
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- #33
Good information. Thank you !
pb4ugo
SILVER Star
I would make sure the mechanical advance is working properly like in the video. It maybe stuck or the springs are weak or disconnected and the weights are not returning. You can rev the engine up to about 3000rpm and watch if the timing advances and note the rpms once the mechanical advance is all in and that it returns at idle. Be sure to disconnect the vacuum advance and cap the hose. Using a timing light with the advance function is required to see total advance.
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- #36
Thanks for the tip. I will check that out also.
I'm currently chasing a flat spot hesitation on acceleration and come across this thread. Currently l have tried 8 degrees advanced and adjusted the timing back to factory with no change. Vacuum is at 21"HG which is good, will try adjusting to 13 degrees as mentioned above with maximum vacuum and see if this fixes my issue. What is the total mechanical and vacuum advance for these distributors? I have a cheap chinese electronic dissy so would like to confirm that is also correct.Same here. One of the long-time guru's here told me once that it is a 54 year-old motor, with all of the concomitant wear and tear, it would be abnormal if it still tuned to factory spec. Setting timing on the BB requires turning the idle way up to get it to 650. Moreover, when accelerating it hesitates badly. All and all, the motor seems entirely happy at about 28 degrees advance. It does have Petronix ignition, but I'm not sure if that makes any difference. I admit that I'm abit envious of the BB crowd but I've reconciled that our situation it is what it is.
Thanks Matt
