Adjusting fuel mixture screws, and synching questions

[JoBrCo]

First a quote from David Raforth on the Blip (flick) test:

"If you rev the engine and it slowly returns to idle, you are too rich.
If you rev the engine and it drops down then recovers to the correct idle speed, you are too lean."

I have changed my IM's and torqued them roughly to spec, 86.4 in lbs, more like 90 in lbs, and I'm still having problems with a faster idle after taking her out on the road, under load, for a short time, but she does purrr more evenly now.  

So I was thinking, my Morgans Carbtune II Pro is showing me vacuum readings in real time, much like a colortune does (real time) except that it indicates fuel/air mixture, via color of burn, yellow/orange = rich and blue/white = lean, which is in fact consistent with burning fuels, either gas or liquid. From Yellow to just Blue would seem to be optimum, for an ICE.

As I hold the throttle and 'flick' my wrist I notice that sometimes the metal indicators of the carbtune take a dive, each individual cylinder/carb at different rates, down, showing a loss of vacuum, overall, then recover to a higher position, up, than what they were at idle, finally corresponding to the increased RPM's.

So I was thinking that it's possible that their dive corresponds to the part of Davids quote above that I've bolded. He says: "If you rev the engine and it drops down then recovers to the correct idle speed, you are too lean."  So could my manometer be indicating this drop due to the 4 pilot screws settings, indicating the direction in which they must be turned, each carb individually, thus taking some guesswork out of adjusting them?  The ones that lead the way down are definitely lean, while the ones that resist, don't go down as readily, are either less lean, correct, or rich.

To me, this makes perfect sense, that the variance of dive in each individual vacuum tube of the manometer corresponds to Davids dive, indicating lean.  I mean, shouldn't a properly tuned/balanced set of carbs, vacuum, only ever immediately rise from their value at idle, seamlessly?

So does the manometer's individual cylinder/carb indicators direction of movement and rate of travel indicate fuel/air adjustment needs, as well as carb idle speed sync (when they are at the same level)?

Randy?  Anyone?


FJ Forever!  

JoBrCo

[FJ_Hooligan]

What you are seeing when you blip the throttle is a result of the throttle plate opening.  The vacuum you are reading on the Morgan is on the engine side of the throttle plate.  The more closed the plate, the higher the vacuum reading will be.  When you quickly open (blip) the throttle, you're seeing an instantaneous drop in the vacuum as the plate allows more air into the intake.

When the plate snaps shut, you then see the vacuum spike.  The vacuum spike from the plate snapping shut is what sucks the mercury out of regular manometer gauges.

I wouldn't pay much attention to reading the results on the blip test as lean or rich.  There was a good discussion recently of the idle circuit.  Changing the position of the idle mixture screws either adds or decreases the amount of the idle circuit air fuel mixture being allowed in the intake.  The idle and air pilot jet sizes determines whether this mixture is lean or rich.

The important thing to do is experiment with the screws.  Move the mixture screws and continue doing the blip test.  You should be able to find a sweet spot.  Or, you may start out at the sweet spot so adjust both ways and verify it.

[JoBrCo]

What you are seeing when you blip the throttle is a result of the throttle plate opening.  The vacuum you are reading on the Morgan is on the engine side of the throttle plate.  The more closed the plate, the higher the vacuum reading will be.  When you quickly open (blip) the throttle, you're seeing an instantaneous drop in the vacuum as the plate allows more air into the intake.

When the plate snaps shut, you then see the vacuum spike.  The vacuum spike from the plate snapping shut is what sucks the mercury out of regular manometer gauges.

I wouldn't pay much attention to reading the results on the blip test as lean or rich.  There was a good discussion recently of the idle circuit.  Changing the position of the idle mixture screws either adds or decreases the amount of the idle circuit air fuel mixture being allowed in the intake.  The idle and air pilot jet sizes determines whether this mixture is lean or rich.

The important thing to do is experiment with the screws.  Move the mixture screws and continue doing the blip test.  You should be able to find a sweet spot.  Or, you may start out at the sweet spot so adjust both ways and verify it.

I shall put it to the test just the same.  Remember that specifically I'm referring to the differences in movement of each indicator, that happen only for a brief moment, then they all equalize. Obviously they differ for a specific reason, so if not the pilot circuits lack of sync, what?  Even if it's due to varying butterfly position, it still could be an indicator of the pilot circuit imbalance, between carbs, as the butterfly's adjusted position, sync setting, of varying openings, is directly proportional to many things, one being the pilot screw setting.

FJ Forever!   


JoBrCo

[FJ_Hooligan]

The idle fuel mixture has nothing to do with the vacuum you're seeing.  That's determined by the angle of the throttle plate.

The difference in movement of the steel rod in the Morgan is due to slightly different clearance fit of the rod in the bushing.  Have you taken the Morgan apart and cleaned/polished the rods?  I do that periodically, but it's just to help prevent one from sticking and giving a false reading.

The brief transient behavior of the gauge and any difference in movement between the cylinders as you blip the throttle indicates nothing except that the intake vacuum has changed.  With the restrictors, the gauge is designed to give a very overdamped reading of the average vacuum of an individual cylinder.  Any differences in vacuum are far more influenced by potential differences in valve clearances than mixture.  

[JoBrCo]

The idle fuel mixture has nothing to do with the vacuum you're seeing.  That's determined by the angle of the throttle plate.

The difference in movement of the steel rod in the Morgan is due to slightly different clearance fit of the rod in the bushing.  Have you taken the Morgan apart and cleaned/polished the rods?  I do that periodically, but it's just to help prevent one from sticking and giving a false reading.

The brief transient behavior of the gauge and any difference in movement between the cylinders as you blip the throttle indicates nothing except that the intake vacuum has changed.  With the restrictors, the gauge is designed to give a very overdamped reading of the average vacuum of an individual cylinder.  Any differences in vacuum are far more influenced by potential differences in valve clearances than mixture.  

My Morgan Cartune II Pro is brand new, 5 years ago, this is the first time I've ever used it, it's been in it's case since I purchased it. So there is no reason to clean it at this point.

Thanks for the rest, because that's what I like to hear, something I can sink my teeth into.  I guess You've figured by now, that I prefer to understand things, before proceeding, I hardly ever take peoples directions to do something, unless they tell me their rationalization behind it.  I had the same problem in college, I either understood 100% of what the professor was saying or I didn't allow it access to my memory banks.  needless to say my hand was raised more often than not, OK, a slight exaggeration, but I did ask a lot of questions.  You know what they say about computers right? "Garbage in, garbage out."  Thanks for expounding.

Also I really liked the part you said that I bolded above, because it shows you're a thinking person that considers that which may not yet be known.  That makes you a wise man.  Something I try to do, to cover all the bases, though I'm still a work in progress, aren't we all.


FJ Forever!  


JoBrCo


P.S. I'm still going to watch the gauge as I adjust the pilot screws, to check for any correlation whatsoever.     Never take anything I say as personal Hooli, never!!  As it's surely never meant that way.  I just like to stir things up, so people are sitting on the edge of their seat, usually the blood in their brains is circulating faster when they're on the precipice.

Again, thanks for your time!  It's always appreciated!

[Dogsbestfriend]

Remember that it is a four cylinder four stroke engine so that at any given time only one cylinder will be "creating" a vacuum. Suck, squeeze, bang, blow was how it was taught to me back in my yoof! Each cylinder will have to perform that sequence several times in order for an average vacuum to establish itself.

[JoBrCo]

One more thing, I am DEFINITELY buying a colortune as soon as I can, because to be honest, this non reliable method of adjusting the pilot screws is driving me crazy.  I can't stand the thought of not knowing what I'm doing, a shot in the dark, trying to balance not overheating the engine, and then I bought some fuel line that, while it can withstand any fuel up to 100% ethanol it kinks easily, so that using my tank backwards/sideways as a temp tank is precarious at best, I've almost dropped it several times due to vibration of the bike, while ensuring there are no kinks, so I can do the damn sync.  It's just far too much a pain in the ass considering so far I haven't got it right. just to test ride then do it all over again.  I desperately need a vehicle to get my wife to work, or we're royally screwed.  I'm fast approaching loosing my home, we had absolutely no liquidity going into this car-less scenario.  I just wish I could find someones step by step process that ensured results every time, because, RIGHT NOW, I want to be sure that we can get to work to keep our house.

Thanks man, I really appreciate your time, and ears, or is that eyes, my friend!  I'm seriously stressing, under the fucking gun, chopping block, etc.  Gonna have a damn stroke or a myocardial infarction.


FJ Forever!   (I think)

JoBrCo      

[JoBrCo]

Remember that it is a four cylinder four stroke engine so that at any given time only one cylinder will be "creating" a vacuum. Suck, squeeze, bang, blow was how it was taught to me back in my yoof! Each cylinder will have to perform that sequence several times in order for an average vacuum to establish itself.

Yeah, I learned it as Intake, Compression, Power, and Exhaust, for a 4 stroke.  And I'm sure Hooli is right about the valves, this bike has been sitting in moth balls (no, not literally) for 19 years, so I'm sure some compression and expansion of various parts due to atmospheric conditions (winter, spring, summer and fall) have caused things to be a bit different that she was 19 years ago.  So far a guess I can't complain, as most of her still works, all electrical items seem OK for now.

Thanks for your input!


FJ Forever!    (i think)


JoBrCo

[FJ_Hooligan]

None of what you're worrying about is all that critical.  If it was, my FJ (and thousands of others) would be trash.  They're not so whatever non-scientifically exact processes we're following are working.

If you're in as much trouble as you claim, then stop wasting your time and get it close enough for you to use to get you through your current situation.  It may not be perfect but it will be good enough to get you to work and back.  Once your situation improves enough then you can go back to getting that last 0.0001% you're worrying about.

As far as the valves are concerned, as long as you have decent compression and no loud valve tapping, then they are probably good enough to use for many thousands of miles.  They did not somehow spontaneously degrade from 19 years of sitting under a tarp.  If anything some of the valve springs may be a bit fatigued from being compressed for that long so I would keep it away from redline.

Get the thing running and ride it!  Don't let a half turn on an idle mixture screw cost you your house.  Set them at 3 turns out and move on!

Also, you can make a temporary fuel tank.  I use an old lawnmower tank that I hang from my garage door rails with coat hangers.

[Pat Conlon]

Eloquently stated Hooligan. 

[JoBrCo]

None of what you're worrying about is all that critical.  If it was, my FJ (and thousands of others) would be trash.

Finally, someone that is actually helping me, it's about time!!!  This is what I need, understand that it hasn't just been my bike in moth balls for 19 years.  All I've been doing for my Honda Civic was changing the oil and filter.  Though I did change the timing belt, water pump, a few oil seals as well as the rest of the belts in 2009 @ 115,000 miles as required, and in 2005 I changed it's McPherson Struts, (Honda made a boo boo on the 2001 Civic, the struts were not beefy enough, their replacements are still great, well up until the head gasket died anyway.)  A lot of you guys, I'm sure, eat, sleep and breath automotive's, at least for bikes.  I've been counting on someone or a lot of someone's to direct me as to what they'd do in my situation, i.e., resurrecting an 85 FJ1100.  I've been counting on you guys to know what the hell is up, with my quest, assuming that some of you have already "been there and done that." What you think is important, what your priority list would be, what I can get away with, where I should be concerned, etc.  Thing's that someone like me in what is now a very tight spot should consider.  I figured a lot of you guys are old enough, like me, but quite possibly better versed in the proper FJ resurrection considerations/techniques, than I am. Actually that wouldn't take much at all! When it comes to bike maintenance, in the past, I've always paid to have a shop do the work, I was in the US Navy then and had a little spare money.

If you're in as much trouble as you claim, then stop wasting your time and get it close enough for you to use to get you through your current situation.  It may not be perfect but it will be good enough to get you to work and back.  Once your situation improves enough then you can go back to getting that last 0.0001% you're worrying about.

I am, both in that much trouble, and doing something about it, every single day, no time has been wasted here at all.  I've either been working on it, waiting on money to be made, ordering parts online (as cheap as possible), waiting for the parts, installing them, doing research on that which I can think of that I need to consider, then doing it all over again, every since I started this project, even when it wasn't a necessity, when it was just a hobby. I started this back on June 27 2014, you're witnessing the speed at which my limitations allow me to proceed and nothing more.
 

As far as the valves are concerned, as long as you have decent compression and no loud valve tapping, then they are probably good enough to use for many thousands of miles. They did not somehow spontaneously degrade from 19 years of sitting under a tarp.  If anything some of the valve springs may be a bit fatigued from being compressed for that long so I would keep it away from redline.

More great stuff, thanks!  Wouldn't you know it, my compression tester doesn't have a 12mm adapter, it's a sunpro.  I do have a sunpro induction timing light that should work on the bike.  Not a tach though.  I do have a couple older needle type tachs for cars that are probably out of calibration by now.  I need to get a good digital tach.

Get the thing running and ride it!  Don't let a half turn on an idle mixture screw cost you your house.  Set them at 3 turns out and move on!

Today I finally had the balls enough to drive it 25 miles one way, to my wife's work, outside the mass transit loop, and I actually got it up to 85 MPH.  I also downshifted two gears and nailed it once, tached it to about 6-7 grand, then abruptly let off the throttle for some engine braking, to tug on the rings hard in the other direction, as per someones recommendation.  Remember that I'm being cautious because I have no real resources, If the bike had died on the road, I probably would too, as there is absolutely no way I'm leaving it anywhere, so I'd do as I did when I was young and healthy, push it home.  I have no local friends to count on at all, I'm practically a hermit, I have a F-150 that's been down for  about 8 to 9 years, because it's an '89 and the gasohol killed the fuel system.  I wish I could sue the government for the cost of it's resurrection.  It's gonna need at least one new tank, only one is metal, I think the plastic tank is OK.  Three new fuel pumps, and new fuel lines, at the very least. I'm sure the wheel bearings are flattened, the tires are probably shot, and I know it needs a new battery. Oh my plan is to never get stuck with my pants down again, and make damned sure all my vehicles are running, this has been a lesson indeed, that it's not always about not being able to afford to repair my vehicles, rather I can't afford not too.    

Also, you can make a temporary fuel tank.  I use an old lawnmower tank that I hang from my garage door rails with coat hangers.

Yeah I know, someone else mentioned that as well, but I don't have a spare lying around.  I actually looked online for some cheap replacement lawn mower tanks, but they were a bit too expensive for me right now, other priorities.

The good thing is that I have two brand new tires now, no more 19+ year old cracked rubber, new sprockets, the hardest DID chain made, can be used on 1400's, not endless, riveted! The front brakes are really good with the EBC Sintered copper pads, both caliper and master rebuilds, but I am worried about the sight window in both the clutch and front brake masters, because they look like a very old Rembrandt or maybe Michael Angelo painting, with all the cracks in the paint, except we're talking about a little plastic window, that I've been careful not to touch for fear it shall shatter into a million pieces.  Do you think I could take some clear setting two part epoxy and fill up the sight window recess, until it's flush with the outer aluminum lip, the epoxy would be at least 1/8" thick, who really cares if I can see the fluid level from outside, or if there is a bubble or two, it's just two screws to check level, no problem.

My problem is resources, so What I really need from everybody here, that cares to help, is their "sound ideas" that they would consider if they found themselves in my exact same pair of shoes.  Like I mentioned above.  Priorities would have been great from the beginning, up till now you guys seemed to have been tight lipped as to these things that I really need to hear, so I don't kill my wife and I trying to keep the house.  Our lives are more important that the house, of course.

For instance I had no idea that the fuel/air mixture screw was of no real importance, today finally, news to me, thanks again!  I had visions of burning her up if she was too lean.  She's too important to me right now, can you see the dichotomy?  I got to proceed with caution because she's the only hope I have, but I need her, "last month."  Rock and a hard spot indeed!


FJ Forever!  


JoBrCo

[Firehawk068]

"If you rev the engine and it slowly returns to idle, you are too rich.
If you rev the engine and it drops down then recovers to the correct idle speed, you are too lean."

I do believe that you have this backwards.....................

If you blip the throttle, and it hangs up high then slowly returns down to idle speed, you are too LEAN.

If you blip the throttle, and it dips below idle speed, then returns back up to idle speed, you are too RICH.

Just making sure you are heading in the right direction.

[fj1289]

"A good plan violently executed now is better than a perfect plan executed next week."

George S. Patton

You can definately drive yourself crazy and way overthink things trying to make each and every detail of an FJ the pinnacle of perfection. 

Tuning an aircooled dinosaur in the real world is really and truely about "good enough".   What is "good enough" is going to vary depending on how finicky a person is and to what degree they have modified things.    A stock FJ being used for commuter duties and weekend enjoyment has a very wide range of "good enough".  A highly modified FJ used with more serious intent has a much smaller window of "good enough".   

I'd say for anyone that is a new owner of a fairly stock FJ there are a few things to start with to make sure you are working from a good baseline.  Get a manual.  Get a new valve cover gasket, new valve cover bolt grommets, oil filter, oil, and a battery (unless it can be proved to be fairly new and I good condition) and a BUNCH of carb cleaner.  The replacement carb hardware and o-rings would also be wise (and may become a necessity depended on whether there are issues removing the old hardware).  Actually, the o-rings should be mandatory too. 

Clean the carbs.  Adjust the valves.  Clean the carbs.  Charge the battery and change the oil.  And then clean the carbs and you should be ready to get started with getting the new to you FJ running as it should.   

Get it started and warmed up to temp.  Adjust the idle as best you can.  Synch the carbs.  Go back to the idle.  Synch again if desired.  Adjust the idle if desired.  But don't be looking for perfection now -- you just want an engine that idles reliably and responds predictably to YOUR inputs.  Ride it for a few days then try tweaking the idle screws in or a a quarter turn.  Ride it for a few days and see how you do or don't like the change.  Tweak them another quarter turn in be same direction.   See how you like it.  Keep going until it runs as well as you want or it runs poorly.  In that case start going in the other direction until it runs as well as you want or runs poorly.  You will find that range of "good enough" and will know where in that range you are happiest. 

The most important thing is only change one thing at a time.   Write down what you changed.  Evaluate it.  Write down your observations.   Change one thing.  Evaluate it.   Write down your observations.   Repeat until things run to your satisfaction -- or in the case of a highly modified FJ -- until it runs as well as it can in the areas where it wasn't built for, and yanks your arms out in the areas it was built for!

A stock motored FJ is a good solid platform to learn the basics of tuning on - they are solid and dependable and very forgiving.   I'd also suggest to anyone not to start down the road of engine mods faster than your tuning knowledge and experience grows. 

[fj1289]

"If you rev the engine and it slowly returns to idle, you are too rich.
If you rev the engine and it drops down then recovers to the correct idle speed, you are too lean."

I do believe that you have this backwards.....................

If you blip the throttle, and it hangs up high then slowly returns down to idle speed, you are too LEAN.

If you blip the throttle, and it dips below idle speed, then returns back up to idle speed, you are too RICH.

Just making sure you are heading in the right direction.

Agreed!  Lean hangs up, rich dips and recovers (or dies if it's real rich!)

[JoBrCo]

"If you rev the engine and it slowly returns to idle, you are too rich.
If you rev the engine and it drops down then recovers to the correct idle speed, you are too lean."

I do believe that you have this backwards.....................

If you blip the throttle, and it hangs up high then slowly returns down to idle speed, you are too LEAN.

If you blip the throttle, and it dips below idle speed, then returns back up to idle speed, you are too RICH.

Just making sure you are heading in the right direction.

I appreciate anything you take the time to say, right or wrong, because you took the time to say it.  As always when it comes to final analysis, I take "ALL" the ideas/evidence into consideration, assuming the majority is "probably" correct, then watch closely as I implement, looking for further evidence as verification.

But...

That was a direct quote, "cut and pasted" from David Raforth's (carb guru, there is actually a wiki containing his quotes), carb cleaning guide, in the files section on this site, so your beef is with him.  It seems that most people take his words for granted. I do know he's been around for a long while, though I haven't seen him lately, I hope he's doing well, he's helped a lot of people.

FJ Forever!  

JoBrCo

Here it is again a cut and paste from the PDF HERE
It's titled carb cleaning.pdf.  The blip test is almost all the way to the bottom of the doc.  Second to last page, third paragraph from the bottom of the page.


"If you rev the engine and it slowly returns to idle, you are too rich.
If you rev the engine and it drops down then recovers to the correct idle speed, you are too lean."