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Old 01-21-2023, 04:52 PM   #1
bamashooter
 
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Default Timing Issue or Please Just Shoot Me

Once upon a time

My recently purchased 87 Pathy (V6) ran great short of converted to carb issue (idle).

Terrible slapping / knocking noise.

Sounded like timing belt shredding.

It was actually a small bolt, similar to timing cover bolt, had gotten inside the cover. The bolt would hang up between passenger-side cam pulley and rear cover. It would then get launched for a staccato-series of slaps followed by no noise again (jammed).

Belt appeared fine. Had a nasty oil leak. Hoped it was the front seal. Replaced seal. One good thing out of all this. No more oil leak.

I had planned on replacing belt regardless. I knew enough that if I replaced belt without any of the 3 timing pulleys being moved, all would be well.

In comes my heavy equipment mechanic buddy to help.

Situation goes to hell. Passenger side pulley is moved (I don't know why) a couple of time both directions for perhaps 3-6 teeth. Crank pulley is moved.


New belt installed.

Crank dot is spot on

Cam dots are within 1/2 dot to dot alignment

40 teeth across and 43 down driver side.

I manually rotate crank 4 times.

Faded memory?

Passenger side cam dot is now 2-4 teeth clockwise from alignment.

Believe driver side is off too but not as much. Reasonably confident the belt did not slip.

For whatever reason, it's time to fire it up. It seemed to fire right up and idle ok. Did that twice. Perhaps ran it for about 30 seconds the first time followed by 1200 or so rpm for 45 seconds or so. Done. Happy camper.

The following morning I throw all the other pulleys, covers, everything back on. Gonna take it for a 15 minute or so cruise.

Difficulty starting. Dragged like it had a big cam. Just driving to the stop sign a few hundred feet away, ran fine. Once on the road, I start pressing the accelerator and notice it's under-powered. No doubt. On a fully warmed engine, I had to increase idle speed or it would die.

Background. Truck had been converted to Weber 38/38 carb. I have the carb kit included instructions and such. The paper with the weber fuel pump suggests changing the timing to 7* from the factory 12*. I assume 7 is more advanced than 12.

I noticed yesterday when trying to trouble shoot, the dizzy is maxed on adjustment. Was wanting to advance more to see what happens. We removed adjustment bolt but a damn small electrical connector was hitting the driver side valve cover.

I believe whoever did the conversion may have pulled the distributor and may have missed reinstall by a tooth or two. No idea.

My friend swears were the timing belt off that much, the valvetrain would be rattling, truck running much worse than simply being under-powered, etc.

No idea but I'm bout ready to punt.

I called him this morning to tell him I was gonna redo the belt. He swore up and down there's no issue with the belt and I'd be wasting my time.

I'm too ignorant to know one way or the other.

The carb. I did a conversion on my previous 89 Trooper. Perfect. A lot of work involved due to it dieseling. Always ran nice and lean in a good way. Plugs were a beautiful tan.

I believe whoever did this just slapped it on and called it good. Every adapter plate and gaskets had serious vacuum leaks. I corrected those and it improved some. Always ran great once out of the idle circuit. Both high-speed and fully warmed idles were sporadically up and down. I would adjust air/fuel and even installed leaner idle jets. Still runs rich and now even worse (richer). I feel that's an indication of the timing being too retarded for the carb thus resulting in unburned fuel / rich smell.

That's all I can think of at the moment.

Thanks.

EDIT: My friend had to be shown (manual) that the firing order is 1,2,3,4,5,6. Stated he had never heard of such. He then briefly commented on that being related, cause of, whatever, of the timing marks being off after I had manually rotated the engine. NO idea wtf he was talking about. He suggested I start moving wires around, one at a time, followed by adjusting the distributor each time. No idea what he's suggesting.
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Last edited by bamashooter; 01-21-2023 at 04:58 PM.
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Old 01-23-2023, 02:59 PM   #2
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Thinking out loud here. The possibility exists advancing the timing via the dizzy will fix the issue.

Rotor turns CCW

Advancing the timing is CW

No more room to advance timing

??????

Though considered a band-aide, moving each plug wire over one spot CW? will advance timing and then I might be able to get it timed by rotating dizzy CCW?

Resetting the dizzy 1-2 "teeth" CCW will provide room to adjust/advance CW? This is based on the premise that rotating dizzy CW is the same as rotating the shaft CCW / opposite direction.

Thanks. Fun and games.
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Old 01-23-2023, 03:59 PM   #3
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Are you sure it's the timing?

Could it be a fuel issue from the carb conversion?

Did you make sure everything is plugged back in like it's supposed to be?

Slow down, step back and look at more than just what you've been monkeying with, it could be something else, something simple and you're trying to fix stuff that works fine.
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Old 01-24-2023, 01:24 AM   #4
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Put a timing light on there and see what it shows.

After the VG30 timing belt tension is initially set, the FSM says to rotate the engine around two full turns. Remember that the belt has an odd number of teeth between the gears. Since they are like that, the engine will have to turn over probably 85 times before the belt marks match the cam marks. But as long as the cam marks are pointing at the dot stamped on the rear timing cover with the number one piston at TDC and the distributor pointing to the number one wire, the physical timing is good.

I have two Weber powered VG Nissans. They both run like champs.
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Old 01-28-2023, 02:25 PM   #5
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I manually rotated crank 3 times after install.

I have checked and checked for any wrong connections,, no connections, shorts, all that stuff.

As stated, short of carb idle issues, truck started perfectly and ran great under all conditions. Excellent power.

Current status:

Mostly a slightly dragging starter to near a starter wanting to kick back. The near-kick back has only happened once out of about 10 or so starts.

Runs fine on straight and level. Noticeable loss of power on almost any grade.

Exhaust is nauseatingly-rich smell.

Timing shows 7* BTDC. Don't know if it's coincidence or intentional by previous owner who did the carb conversion. The paper with the Redline fuel pump recommends 7 vs the factory 12.

With the caveat I have little knowledge of engines, my gut feeling and hope is it's in need of the dizzy being advance. Since the slot is maxed out to advance the timing, I assume the dizzy needs to be clocked, re-indexed, whatever the term is.

No idea how many degrees advance or retard when the dizzy is rotated 1 tooth, etc. Hoping it's enough but not too much to allow advancing the timing by rotating the distributor in the simple, conventional manner.

In closing, the vehicle starts and runs fine without a load on it. Hoping that means not having to redo the belt. But if the belt needs redoing, it will take much less time than days ago due to not going through the hell I went through removing the crank timing gear.

Thanks guys.

I have a question for which I find no answer.

The firing order is 1,2,3,4,5,6. The rotor button moves counterclockwise. The cylinder numbers are not in that order. How does it fire in the firing order. Dumb I know but a legit question.
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Old Yesterday, 03:49 AM   #6
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Learning very slowly but learning (I think). Using my multimeter today, I "mapped" the firing order within the distributor cap. Simple (1-6 / counterclockwise).

Decided once and for all to get an understanding of TDC compression stroke on #1 cylinder. Got it, maybe.

I rotated the crank 5-6 times with the last being my (I think I have this) moment. lol

Using a very thin piece of metal, I got as close to TDC as I could. Very slowly on my final run, I let the piston rise to the point between ascent and descent. I hope that's close enough. If not, tell me. As you can see in the pic, the rotor is very close to dead-on. Look closely at the black hose. A silver sharpie line is partially (mostly) blocked by the piece of thin metal. The mark is aligned with #1 as is that raised piece of metal on the dizzy base. But ...

With those 2 pieces of data, I have a problem. My understanding is if all is well and #1 is at tdc compression and the rotor is aligned with #1 electrode inside the dizzy, the 0* mark on the balancer should be aligned with the timing pointer. Mine is way, way off.
Mine needs to travel another 6" to reach 0 when rotating the crank clockwise. It's 4.5" to 30* and another 1.5" to 0. Those distances are approx but close. That's it for now.

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Old Yesterday, 02:05 PM   #7
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If you are 1000% CERTAIN that you have the #1 cylinder at TDC on the compression stroke I can tell you what your problem is.

The crankshaft pulley can be disassembled. There are six bolts that attach the pulley to the balancer. With those bolts removed the timing mark on the pulley can be misaligned with the keyway on the balancer hub. At some point the pulley on your truck has been disassembled and got reinstalled in the wrong position.

To fix this you need to leave the engine set with the #1 cylinder at TDC on the compression stroke. Remove those six bolts from the pulley and rotate the loose portion of the pulley to align the timing mark and reinstall the bolts.

Then check the timing with the light and see what it shows.
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Old Yesterday, 02:10 PM   #8
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Quote:
Originally Posted by bamashooter View Post
I have a question for which I find no answer.

The firing order is 1,2,3,4,5,6. The rotor button moves counterclockwise. The cylinder numbers are not in that order. How does it fire in the firing order. Dumb I know but a legit question.
You should really have a copy of the service manual instead of guessing.

This is from the 1989 Nissan Truck manual:

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Old Yesterday, 02:19 PM   #9
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As for why it isn't running, you should look into how to do the Weber swap.

The Hardbody has a fuel pump that supplies about 45 PSI when running, and I think the Weber only runs at 5 PSI or so. That could be why it is running so rich: Because you are forcing too much fuel into it.

As to why it loses power when you go uphill or accelerate, that sounds like a clogged fuel filter. Those are simple to replace. It's sitting right there in the open between your battery and engine.

In the picture below, mine has an added Fuel Pressure Gauge mounted inline:

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