What did I do?

crash-harris

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New owner of one of those new surplus timing meters (Tech-Time) and it works. Yay! But in testing it today, I put the line clamp on the spot I cleaned over a year ago with the offset at 20* and got 16+ degrees of advance at 2K rpm?

History:

Rented timing meter from Gary, timed IP to 9* after installing rebuilt injectors from Russ and had to leave the old IP on. So old IP, new injectors. Also have a #1 injector line from a 7.3L van and a #4 line from a 7.3L F-Series truck, so no factory pulse adapter. Had much less clatter, but EGT's were higher than they should've been. I suspected the pump was turned up, so I turned out down one flat. Mel said that turning the IP down one flat equals about one degree of timing advance, so I should be at 10*, right?

One more thing. I remember also attempting to time it off of the #4 injector line thinking I wasn't getting a strong pulse from the #1 line. Turned out that there was a short or something in the first magnetic probe that was in the kit (of course Gary was very helpful). I didn't have time today to get a reading from the spot I cleaned on the #4 line. Does timing off the #4 line like the van IDI's cause that much of a difference?
 

icanfixall

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Cylinder one or four times exactly the same. Actually if we know the other cylinders degrees we can time off any cylinder.At one time I had the degrees of every cylinder. Sadly that information is now hiding very well from me.
 

laserjock

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Following. I have one too. I'd love to time mine and have someone else check it. I had trouble getting a stable signal off the balancer with 3 business cards. Had to drop to two. I timed no mufflers truck at the rally with it and it showed him pretty advanced. Granted his engine had been apart but he had used the marks from when Corey did it. I don't know. It would be nice to get a cross check.
 

Macrobb

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I'd just use it as a reference and drive it. If you see white/gray/blue smoke under acceleration, advance the timing. Black smoke is correct or advanced timing.

Generally, what feels fastest is going to be a really good timing number. I've ended up basically retarding it to where I hit some blue smoke, then advanced it until it turned black and that felt really good overall.

If your IP is worn, you might find a difference in what 'feels best' off idle/under light load and the higher end; time the pump for best performance/response at the higher end, then you can rotate the light load cam to fix your idle/light load timing.
 

crash-harris

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I'm more interested in correcting timing to deal with EGT's. Btw, I forgot about the 3 business card air gap, I used one.

So how would one figure that I went from 9* to 16* by turning the IP down one flat?
 

Macrobb

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So how would one figure that I went from 9* to 16* by turning the IP down one flat?
I don't understand how turning the IP limit screw down will affect timing, except perhaps at WOT.
Remember how the IP works - fuel from the metering valve ends up pushing the two plungers out inside the rotor; when the IP rotates further, those plungers then squish the fuel out. More fuel through the metering valve means the plungers open more, which means that the injection timing is more advanced comparatively.
The "fuel screw" only changes the maximum amount the plungers open(maximum fueling); without fuel through the metering valve, it doesn't make a bit of difference.
So, it only affects WOT, really.

I've actually proven this with my '92 - with the "fuel screw" maxed out, the truck had 150RWHP. I removed the torque screw, which limits how far open the metering valve can go... 200RWHP proven on the dyno, a couple of hours later.
So even with the fuel screw "maxed out", if you don't have fuel metered in(which is controlled by the throttle pedal/governor assembly), you aren't going to hit that fuel screw limit, and thus changes won't make a difference at all.

BTW, this video explains how the IP works in detail:
xc_hide_links_from_guests_guests_error_hide_media


I'm more interested in correcting timing to deal with EGT's.
Go for optimal timing based on how powerful it is and the smoke. This should be the best you are going to do with regards to EGTs for a couple of reasons:
1. The most powerful = the less the engine is fighting itself.
2. More power at WOT = less pedal/less fuel needed to carry the same load = lower EGTs
So, generally speaking... whatever ends up running the best will give you the best EGTs.

That may not be good enough though, if you are running a cranked-up pump. You can either add a limiter(like the smoke puff limiter), or simply not drive with your foot to the floor. If you see smoke, let off a hair until it stops smoking.

Also, checking for boost and pre-turbo exhaust leaks will help. Beyond that, better turbo.
 

crash-harris

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I'll have to watch that tomorrow when I'm not at work. It was conveyed to me that it affects the internal timing of the IP, or the IP curve? Can't recall or find the PM. 2nd shift work kills a lot of brain functionality.

Either way, I timed a worm IP with new injectors to 9* over a year ago and now I'm reading almost 17*. That's where I'm confused.

@Agnem
 

Macrobb

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Where did the injectors come from?
A worn-out reman, even just the #1 being really low could cause it.

Also, I've heard agnem say this stuff about the fuel screw and timing, but I still don't believe it. Watch the video and understand why or why not for yourself.

Edit: To be fair, at WOT, more fuel = more advance, due to the plungers reaching pop pressure earlier. But only at WOT, something you aren't doing when checking timing, or driving normally. I could definitely see it show up on a flow bench with the throttle maxed out.
 

Dieselcrawler

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if your at 16 degrees, that thing should be very loud and rattle when running, even worse when cold. is it? you say you cleaned the spot on the lines a year ago, did you reclean them? my tech time is very picky on clean lines to get a good reading.
 

Thewespaul

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I don't understand how turning the IP limit screw down will affect timing, except perhaps at WOT.
Remember how the IP works - fuel from the metering valve ends up pushing the two plungers out inside the rotor; when the IP rotates further, those plungers then squish the fuel out. More fuel through the metering valve means the plungers open more, which means that the injection timing is more advanced comparatively.
The "fuel screw" only changes the maximum amount the plungers open(maximum fueling); without fuel through the metering valve, it doesn't make a bit of difference.
So, it only affects WOT, really.

I've actually proven this with my '92 - with the "fuel screw" maxed out, the truck had 150RWHP. I removed the torque screw, which limits how far open the metering valve can go... 200RWHP proven on the dyno, a couple of hours later.
So even with the fuel screw "maxed out", if you don't have fuel metered in(which is controlled by the throttle pedal/governor assembly), you aren't going to hit that fuel screw limit, and thus changes won't make a difference at all.

BTW, this video explains how the IP works in detail:
xc_hide_links_from_guests_guests_error_hide_media



Go for optimal timing based on how powerful it is and the smoke. This should be the best you are going to do with regards to EGTs for a couple of reasons:
1. The most powerful = the less the engine is fighting itself.
2. More power at WOT = less pedal/less fuel needed to carry the same load = lower EGTs
So, generally speaking... whatever ends up running the best will give you the best EGTs.

That may not be good enough though, if you are running a cranked-up pump. You can either add a limiter(like the smoke puff limiter), or simply not drive with your foot to the floor. If you see smoke, let off a hair until it stops smoking.

Also, checking for boost and pre-turbo exhaust leaks will help. Beyond that, better turbo.
Shouldn't the fuel screw also increase case pressure? If so that would be the source of the timing increase, kinda similar to a fuel pump that is pushing 15 psi instead of 7
 

crash-harris

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I did indeed skimp on recleaning the same spots, but one of them was still bare and shiny. Maybe Sunday I'll get to clean them and check it again. Got brake work in the wife's ranger and our Korean roller skate.

It doesn't clatter a lot aside for when the cold advance is on, and still way less than it did when I got it. It was really bad before the new injectors. Not bad enough to swell the Autolite GP's that I pulled out, but bad enough that you couldn't talk in the cab and lots of thick, black smoke from the exhaust. There should still be a video of it running after retiming and installing injectors in the thread linked in my signature. I swear it's gotten a bit quiet since then, or maybe I've talked myself into that through the logic of an aging IP passed its replacement date and new rebuilt injectors.
 

Macrobb

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Shouldn't the fuel screw also increase case pressure? If so that would be the source of the timing increase, kinda similar to a fuel pump that is pushing 15 psi instead of 7
Take a look at the video. The fuel screw is located on the rotor, it holds the spring clip that keeps the two plungers in place. This is locayed after everything else that affects the fuel, after the plungers, it gets injected. So, it cannot affect transfer pressure - except perhaps that at WOT, you are injecting more fuel and the pressure might drop. Note "might" - I'm not sure how much capacity the transfer pump at the ip inlet has compared with the maximum injected amount.
 

Thewespaul

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Take a look at the video. The fuel screw is located on the rotor, it holds the spring clip that keeps the two plungers in place. This is locayed after everything else that affects the fuel, after the plungers, it gets injected. So, it cannot affect transfer pressure - except perhaps that at WOT, you are injecting more fuel and the pressure might drop. Note "might" - I'm not sure how much capacity the transfer pump at the ip inlet has compared with the maximum injected amount.
That is what I'm referring to
 

Macrobb

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That is what I'm referring to
How would it affect case pressure, then? The transfer pump's limiter returns excess fuel to the inlet of the transfer pump, not to the case pressure. What affects case pressure is the "vent wire", along with internal leakage of the various parts.
 
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