Vacuum gauge reading, vacuum leak? leaky valve? (1 Viewer)

[Beehanger]

Hey guys,
Curious what make gauge reading mgiht mean. I'm at altitude and my carb mix screw isn't going anything and I'm idling rough.

Here's a video of my gauge. I'm thinking two different things could even be going on.
I've already smoke tested, no leaks except for a few baby ones on the carburetor.

If anyone is good with vacuum gage maybe you can help me narrow down whaat the "vibrating" or "tremor" its doing. That aspect of it I have no idea about.

MY ICS is not hooked up, but is running the same as when it was u(assuming it was fucntioning)

Can a bad ICS make it impossible to tune and idle rough?
P.S. I'm at 5200 feet, this is on a newly rebuilt motor and city racer japaense clone carburetor. Can't get it to idle above 12 HG and can't adjust the carb mix screw.
Link to video:


Thanks,
Dan

 

[BlackCat]

yes, a bad ICS will make it impossible to tune. I can't see the video, but if it's idling "rough" it could also be miss firing which would give low vacuum numbers and be impossible to tune.
Depending on idle speed, it will run with no ICS. It just needs a higher idle to bypass the idle circuit and pull from the main jet. How does it run off idle?

Verify the basics first.
Vacuum leaks
Timing
Valve lash

 

[mdw83fj60]

Hey guys,
Curious what make gauge reading mgiht mean. I'm at altitude and my carb mix screw isn't going anything and I'm idling rough.

Here's a video of my gauge. I'm thinking two different things could even be going on.
I've already smoke tested, no leaks except for a few baby ones on the carburetor.

If anyone is good with vacuum gage maybe you can help me narrow down whaat the "vibrating" or "tremor" its doing. That aspect of it I have no idea about.

MY ICS is not hooked up, but is running the same as when it was u(assuming it was fucntioning)

Can a bad ICS make it impossible to tune and idle rough?
P.S. I'm at 5200 feet, this is on a newly rebuilt motor and city racer japaense clone carburetor. Can't get it to idle above 12 HG and can't adjust the carb mix screw.
Link to video:


Thanks,
Dan

Iam no expert on vacuum readings, but have you seen one of these. Might help give you a direction to look.

 

[CruiserTrash]

“Baby” intake leaks at the carb will cause all sorts of issues, usually starting with the engine not running or dying immediately. That s*** has to be tight. The only exception is maybe the bushing on the throttle blade shafts. Don’t discount intake leaks. Get it tight.

 

[Beehanger]

yes, a bad ICS will make it impossible to tune. I can't see the video, but if it's idling "rough" it could also be miss firing which would give low vacuum numbers and be impossible to tune.
Depending on idle speed, it will run with no ICS. It just needs a higher idle to bypass the idle circuit and pull from the main jet. How does it run off idle?

Verify the basics first.
Vacuum leaks
Timing
Valve lash

It backfires some. What causes misfiring? If i Recall one of my plugs might have been .1-.3mm off the other ones, but I had no way of adjusting it when i heard. Could this cause the issue? The others were at .31 and that one was .33 if I recall correctly.

 

[Beehanger]

It backfires some. What causes misfiring? If i Recall one of my plugs might have been .1-.3mm off the other ones, but I had no way of adjusting it when i heard. Could this cause the issue? The others were at .31 and that one was .33 if I recall correctly.

Definitely runs better off idle. Runs best heavily advanced. Literally 20 degrees BTDC is where I can keep it running . Then again this might be becussr it’s just upping the idle speed

 

[Beehanger]

I CANT GET IT TO IDLE ABOVE LIKE 600 RPM with Timing at BB even with Idle speed screw screwed all the way in. OI'm literalyly maxed out. Insane. wow! Mix screw 4 turns out.

The only way I can get it to about 900-1000 RPM with the timing advanced about 20 degrees....... Wondering if this is a valve or spark gap issue, or a clogged fuel filter/fuel breather tube. I can smell tons of gas fumes in the cab but none in the engine bay.

Dan

 

[BlackCat]

It backfires some. What causes misfiring? If i Recall one of my plugs might have been .1-.3mm off the other ones, but I had no way of adjusting it when i heard. Could this cause the issue? The others were at .31 and that one was .33 if I recall correctly.

backfiring can be numerous things, mostly timing. Misfires can be from a bad plug, wire, cap, rotor, valve, compression, etc. What happens when you adjust the idle speed screw on the carb? IE NOT the idle mix screw.

 

[Beehanger]

backfiring can be numerous things, mostly timing. Misfires can be from a bad plug, wire, cap, rotor, valve, compression, etc. What happens when you adjust the idle speed screw on the carb? IE NOT the idle mix scre it’s already maxed out. It’s worked in the past and when I’m heavily advanced 20 degrees it It’s turned all the way in and d

backfiring can be numerous things, mostly timing. Misfires can be from a bad plug, wire, cap, rotor, valve, compression, etc. What happens when you adjust the idle speed screw on the carb? IE NOT the idle mix screw.

It works but once again is maxed out, but only if I’m advanced 20+ degrees. Once again the rig barely runs when at BTDC, and then the screw must be maxed out to get it even close to idling at 700

 

[Spook50]

Iam no expert on vacuum readings, but have you seen one of these. Might help give you a direction to look.View attachment 3595459

A good vacuum gauge is invaluable with diagnosing mechanical problems on older engines like ours. It blows my mind that vacuum gauges weren't standard in instrument clusters.

Then again, the dealers wouldn't get to charge so much time for diagnosing

 

[Beehanger]

A good vacuum gauge is invaluable with diagnosing mechanical problems on older engines like ours. It blows my mind that vacuum gauges weren't standard in instrument clusters.

Then again, the dealers wouldn't get to charge so much time for diagnosing

I’ve got a gauge, reading it is the hard part for me. I’ve got all sorts of s*** going on Video Mar 30 2024, 1 29 01 AM.mov - https://www.dropbox.com/scl/fi/o8yau7nbrl308ayire83r/Video-Mar-30-2024-1-29-01-AM.mov?rlkey=gjr3pkm8st1vxb5te1kkv03yl&dl=0

 

[Pighead]

My engine likes lots of advance. It's not quite stock but it does have a 2F block and a 60 series dizzy. I'm runing at 22 BTDC on Ca gas at 3300 ft., have had it up to 30 BTDC with good gas at 6000 ft. Your vacuum should improve, up to a point, as you advance it.

 

[Beehanger]

It totally does improve, and the engine shaking goes away. I just thought I was leaning it out way too much doing this... WOW! This might help. I havne't tried tuning heavily advanced yet!!

 

[Beehanger]

Hi guys,
I Can't get the rig started the last 2 nights. Last night it stumbled and died and tonight nothing. It seems to be getting worse and worse so I can't even test out if the mix/idle screws start working when timing is 20-25 degrees advanced... (I have yet to try this). So strange... it's like it's getting choked progressively worse somehow. It was just this gradual decline where it started less and less and every time I would open the throttle it would die. Then towards the end, It would just start for about half a second and then die right after. Tried changing the fuel filter with no effect.

Looked in the sight glass window and couldn't see any fuel, or it was so full I couldn't see the line. One of the two. (or my flashlight was messing up my vision, will check aagain tomorrow). I didn't smell gas in the bay like the other night though. I did smell a major gas smell in the cab last night. Wondering if the rig is trying to tell me something... clogged line? clogged vent lines? (This is what was causing running issues before the rebuild, but I get no WHOOSH from the gas tank. I was also super low on gas, but just put in 2.5 gallons and no difference. (maybe not enough gas still?)

I also recall about 5 weeks ago I had this puppy at 15 mercury at 800-1000ish RPM with a solid needle right when I installed the fuji carb. IF I recall the vacuum was very advanced, like 20+ degrees. I was so excited.
Unforntutaly the next day started it without the air filter on and was driving it, and the carb was sucking in all the hood fabric and dirt. It was chopping and struggling bad and I couldn't figure out why. I messed with tuning without realizing what had happened. Anyway, I'm wondering if a bunch of s*** got in some of the ports somehow and now has finally clogged it to infinity. I've never had it at the beautiful 15 mercury since this happened. I still think it wasn't letting me tune it though even then.

Because the rig is giving me the clue is that startup/running "getting progressively worse" and the sight glass showing no fuel, these are what I can think of:

-the carb got a clog that has gotten to the point it can't fuel itself anymore ( from the no air filter dirt sucking mishap spoken about earlier)
-progressively worse fueling issue from a bad line.
-progressively worse unknown vacuum leak.
-FAULTY vacuum gauge (I slammed it and cracked it in the car door by accident [see video]
-ignition coil wearing out,
-The alternator going out (I had a MAJOR spark session the other day placing a wrench on it....)(I did try jumping it and it didn't help at all),
-Caburtoar overfilling or underfilling per sight class assessment

Here's the VIDEO OF CARB WHEN I HAD IT RUNNING 4 days ago. (approx 15 degrees advanced, 800RPM...) I'm at 5200 ft.... I was told to shoot for 16 HG at this elevation for optimal performance.

Video Mar 30 2024, 1 29 01 AM.mov - https://www.dropbox.com/scl/fi/o8yau7nbrl308ayire83r/Video-Mar-30-2024-1-29-01-AM.mov?rlkey=gjr3pkm8st1vxb5te1kkv03yl&dl=0 ((
~Above is a link to a video of my gauge from when I had it running a few days ago. It seems like one of the cylinders isn't firing as well as it should because you can see the needle shaking rapidly. This is just what I read online.

Trying to give you guys as much data as possible, and so when I finally figure this out people will be able to work back through my symptoms etc.

Thanks in advance, wondering if there's anything I can rule out at the very least.

Still fighting,
Dan

 

[MoaByte]

That hood debris may have gotten pulled in and propped open an intake valve. A cheap Bluetooth endoscope might help
You might be a tooth off on your distributor? I'm having a hard time understanding why a gear driven valve train would require so much advance.

 

[Beehanger]

That hood debris may have gotten pulled in and propped open an intake valve. A cheap Bluetooth endoscope might help
You might be a tooth off on your distributor? I'm having a hard time understanding why a gear driven valve train would require so much advance.

Checked timing already. Not a tooth off as I can see the Bb And Tdc marks around the middle

 

[Skreddy]

Checked timing already. Not a tooth off as I can see the Bb And Tdc marks around the middle

Seeing the marks doesn’t mean you’re not off. I think you need to start back at the beginning with some stuff.
Here’s what I’d do at this point: (in this order)

1. Upload videos to YouTube. No one wants to create a login to Dropbox or google drive or whatever so not many people are probably watching your videos.
2. Check your oil for fuel. If you’re dumping a ton of fuel in the cylinders trying to run it, it’s going to get past the rings and into the oil and trash that new engine.
3. Pull all your plugs, locate TDC on the compression stroke for #1, pull the cap and look where the rotor is pointing (I’d probably pull the distributor and just start fresh)
4. Verify all plug wires for firing order and cross it to the FSM so you know you’re doing the right order.
5. Check valve lash.
6. Get the float level right in the carb. Get mixture screw about 2-3 turns out from LIGHTLY seated closed.
7. Make sure Idle Cutoff Solenoid is working.

Now you should be at a point to try to start it and get it running and tuning.

I’d also try to keep stuff in one thread instead of multiple threads asking essentially the same questions. Then try the suggestions offered and reply with feedback and results after trying. But, I don’t own this site or the internet so my opinion doesn’t matter and these are just suggestions.

 

[Beehanger]

Seeing the marks doesn’t mean you’re not off. I think you need to start back at the beginning with some stuff.
Here’s what I’d do at this point: (in this order)

1. Upload videos to YouTube. No one wants to create a login to Dropbox or google drive or whatever so not many people are probably watching your videos.
2. Check your oil for fuel. If you’re dumping a ton of fuel in the cylinders trying to run it, it’s going to get past the rings and into the oil and trash that new engine.
3. Pull all your plugs, locate TDC on the compression stroke for #1, pull the cap and look where the rotor is pointing (I’d probably pull the distributor and just start fresh)
4. Verify all plug wires for firing order and cross it to the FSM so you know you’re doing the right order.
5. Check valve lash.
6. Get the float level right in the carb. Get mixture screw about 2-3 turns out from LIGHTLY seated closed.
7. Make sure Idle Cutoff Solenoid is working.

Now you should be at a point to try to start it and get it running and tuning.

I’d also try to keep stuff in one thread instead of multiple threads asking essentially the same questions. Then try the suggestions offered and reply with feedback and results after trying. But, I don’t own this site or the internet so my opinion doesn’t matter and these are just suggestions.

Willl do Skreddy, I just got done working on the rig and hadn't seen your post before I worked on it. How would one check for fuel in oil? But......

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