Running too lean??

I apologize now if I'm the only one who's never heard this, but what does lean smell like? One way to tell if a motor's lean or rich is noticing the difference in how it runs warming up and then at operating temp. On the rich side and it will run crisper as it's still cold and then seem a little flat once it gets up to temp. If it takes 'till fully warmed up to run smooth and is running rough and stumbly till then it could be a little lean.

It takes till fully warmed up to run smooth and is rough and stumbly when cold.  Should i let it warm up and try to adjust the mixture again?

Also will running a little lean damage the engine?  It runs great as it is now and i really dont want to mess with it if I don't have too.

Carburetor adjustments should always be done when the motor is fully warmed up. And even if the jetting is spot on it will run a little rough when cold. If, on the other hand, it doesn't begin to smooth out until it's fully warmed up, a step richer idle jet may be worth trying. If it doesn't do anything you can always put the original back in.

 

Yes, a lean motor will run hotter. If your motor is pushing the limit on compression for the combo, you have to be careful because it won't take much...Al

Thanks for the advice its much appreciated.

Al, could you expound on your last sentence...re:  " it won't take much"...are you thinking detonation, etc. ? If so, could you put a few words down and explain it ? I know about it but not enough to explain it. Is there more than one cure... enrichment, timing, higher octane gas etc. ? Thanks.

Still curious about the "smell of too lean." Too rich smells like gas. Easy. Too leans smells like--what? Air?

leen can crack heads too & is hard on exhaust valve& seat.

It smells like jack sprat, not his wife.  Anyway, I adjusted the carbs and the smell (whatever it was definatley not gas) is gone and the car actually runs even better.  Thanks again!!!

Pulling your spark plugs out and checking condition(ie colour and gap) will tell you if you are too lean or not. To give the most accurate reading car should be turned off @ 3000 RPM rather than @ idle which will usually give you a slightly rich condition. Keeping track of which plug is coming out of which cylinder you should be looking for a brownish deposit with gap slightly wider than factory setting( this is an ideal situation). Black and sooty (too rich) white (lean condition).Oily black condion(internal motor issue). 

3000 isantt a good rpm for a plug check as you are on both circuts of the carbs, a nice highway run 3rd gear&kleen kill as in cutch in ignition off & cost to a stop&pull plugs, it,s best with new plugs.the ground strap(peice of metel that gos from the side of the plug to the center) should change colors about 1/2 way if it changes close to the end its too cold if it changes close to the side or no change&light colored it,s too hot. the thread end portion shopuld be gray to tan. I like all my stuff on the ritch side, it will live longer that way and run cooler.I also use platinum or iridum plugs

Mark, I've been given the same exact advice about determining rich or lean (which I haven't done because pulling plugs is a PITA under the best circumstances, much less on the side of the road!)

 

But you're advising this 'on the road diagnostics' to determine optimum plug temperature... "close to the end: Too cold...close to the side or no change: Too hot

 

How do you determine (what indicates) JUST RIGHT?

I've never, in a LOT of years of checking plugs, heard about running the engine at 3K rpm and then shutting it down to check plug color.  Drive it hard and then check?  Yes.  Drive it easy and then check?  Yes - whatever your "normal" driving characteristics are, do that and then check.

 

But if you want to read what a reputable plug manufacturer says about reading plugs, try this:

 

http://www.ngksparkplugs.com/t...ugs/faqs/faqread.asp

 

This check is done after an hour or so of regular driving, but even 15 minutes will give you a good idea of what's going on if the plugs are brand new!.

BTW:  I've never heard of "smelling" a lean carb condition before.  Rich...yes.  Bad Valve stem seals...yes  Burning oil...yes, but not a lean carb.  Gonna have to try it.  Learn something new every day....

Gordon, you just have to develop a nose for these things...I've been told that Dellortos have a more pleasant aroma than Webbers...kind of like a really expensive hand rolled Cuban cigar!

I've been working on internal combustion engines as a hobby for about 35 years, and I've never been very good at tuning methods that rely on my senses (smell, etc.). I've had almost no luck reading spark-plugs, especially when they are hard to get out, and end up rubbing against the oily mess that is often the lower regions of a Type 1

 

"Rich" and "lean" are relative terms anyhow-- an air-cooled push-rod flat 4 is going to need to run a good deal richer than a small-block Chevy, or any other water cooled car to keep detonation at bay. Trying to tune to the "John Connelly lean-of-peak" method (while great in theory) is a fools errand-- it just doesn't work (you'll get a lean stumble, etc.).

 

The thing is: a carburetor has two circuits and a transition-- there's the idles (which, despite their name, control mixture in about 80% of all circumstances), the mains (which are in play mostly when you are at wide open throttle), and the transition between the two when both circuits are in play.

 

A big engine in a light car will spend the vast majority of its life on the idles. A tiny engine in heavy car will spend a lot of time in the mains, because (greatly simplified) all of this is dependent on throttle position, not RPM. It's possible to be rich in one circuit, lean in another, and OK in transition (or any combination).

 

My point is: if you really want to know where you are, weld a bung in the exhaust and get a wide-band O2 Lamba meter. You're just guessing otherwise.

What causes backfiring when decelerating?

Generaly....Air leaks in the exhaust system, ( most probable ), or the carbs are leaning out for any of a number of reasons.  Leak at manifold to head gasket, or carb base to manifold, and possibly jets too small. ( which would have been a problem from day one. )

 

I would first check the exhaust to head connections.

Wow I pushed down on the left side carb while the engine was idling and it sped up. I'm going to tighten the bolts and see if it stops.

Now you're gettin somewhere!

 

Because those dual carbs are sitting on top of a relatively long intake manifold, they get shaken (not stirred) around a lot and tend to loosen up.  That, plus a lot of folks often mount either the intake manifold or carb to it without lock washers (gasp!) and they tend to loosen up even faster.  When you're checking things, it wouldn't hurt to swap out the nuts (and maybe lockwashers if they're on there) combo for a decent nylok stopnut to prevent it happening again.

 

Oh!  And you might have to replace the gasket where-ever those loose nuts were if it got beat up, too.  It might not seal well enough now, but'cha never know til you try it.

color change about 1/2 way is correct heat range.

 throttell position and load and rpm determan idle transition mains, not just position or rpm.as does size of engine, cam, intake system.and yes carb, and some have extra circuts too.

 I have a wide band,but it's still in the box, I have a narrow band it's on the car.the narow band is good for dio&seeing issues before they become problems. and help in tuning in the genural aera,but wont got it "spot on"

 smelll can be a good indacator when it's a new smell, but with that said these days with all the different additives &corn meal in the fuel your nose might just lead you to the local donut shop. yes there is a leen smell and yes there is a ritch smell, and both are affected by fuel type ,engine type and cam&compression raito.an aluminum head will small different than a iron head.also a leen smell is usualy accompanyed by a hot smell, not to be confuzed with a donut aroma witch can make your car leen after spending tomuch time in the donut shop.

 and yes air entering the system is just like a fart.hole, crack, gasket, joint.and some sound can just like a rod knock.. but depending on how&where the hols is determans what noise it will make if any.

And for the loose carb.check it ALL!!!, intake at head nuts, carb nuts to intake nuts, pull the air cleaners/filters check the screws that hold the top of the carb on too.I had both tops of my carbs loose after about 8 years on the car. i dont mean a little loos I mean the screws backed all the way out. I noticed a rpm varation,slight & also when coming to a stop it would run ritch for a few sec from the fuel sloshing in the front 2  the barrels thats another place where the o2 sensor&gauge come in handy to tell you somethen is up. many things can send a harmonic through the car and loosen many things,for mine I think it was a blown intake gaset or loose air cleaner top, possiably both or none,but after fixing the intake leek&tightening up it all it,s just fine again.( high rpm tens to loosen stuff up too and my car gets the **** ran out of it on a daily basis.(execpt for sunday the day of rest)

How could you take a plug out of a warm/ hot motor, check it and put it back in? Is it not taboo to relace plugs when motor is hot???

Air leaks in the exhaust (pretty damn common)

Get under there and tighten all the flanges and bolts to your pips.

Everywhere from where they exit yours head to the connectors on back.

 

When I picked up my speedster, it popped the whole way home on decel.

Tightened up the pipes and no mas

Is there a torque spec from the exhaust on the head??

"How could you take a plug out of a warm/ hot motor, check it and put it back in? Is it not taboo to relace plugs when motor is hot???"

Heck, no.....put a plug socket on it and spin it out.  I would recommend gloves, though - not those things that Marty wears, but a decent pair of thicker mechanics gloves.  Sometimes the (steel) plug will get caught in the (aluminum) head, but it will catch whether the head is hot or cold and has more to do with electrolysis between dissimilar metals causing a chemical bond than different heat expansion coefficients.  If it doesn't want to come out, then leave it, let the engine cool and then squirt a 50/50 solution of acetone and automatic transmission fluid at the base of the plug so it'll get to the threads, leave it overnight and try again.  You may have to repeat a few times until it breaks loose and then it should spin right out.  There is a whole combative thread on here about whether or not to use anti-seize on plug threads - I do and never had a problem.

Exhaust flange nuts at head:  Those are 8mm so they should be 14 ft pounds. Thicker (or new) exhaust gaskets help, too.

taboo? dont he play foot ball?? wasent he a gator?? add a drop of oil to the threads befor you screw the plug in the head(close to the end&let it run down tward the insulator(wire end) so it gets to all the threads,anti seeze can work but has been proven to inhibit the plug th releace heat to the head.as does other things.dont get burnt, dont drop it in the dirt unless you have some breakleen with you to clean it off.dont mix up your plug wires,dont snatch the end off the plug wire.do use your brain.thin gloves may be handy( but I cant seem to figure out how they work)

Intake air leak can pop on decel too=lean.

Which way do you turn the mixture screw to make it run more rich? counter or clockwise?

Counter clockwise, I believe...

incase you did not know ar any body else did not know, the mixture screws are for IDLE ONLY!! and not for the main circut of the carb, but depending on the engine&car & how it is driven it does work for low speeds(like below 30 mph), but should only be used to adjust the idle mixture.

 for the main or high speed mixture you need to change main jetsand or air bleed/corection jets. easely done on webbers/hpmx/decade,idf style carbs.  the "charts" come close but each engine is different although many are the same. basicly th vent size determans the jet size, but the cr can alter tha amount of fuel needed as does other factors including altatude.(witch changes daily) ever notice the car running a good bit crisper/better on some days? well the jetting is probably closer&probably more air avalible to the motor.

 I was always good at jetting carbs,mostly holly 4 bbls.as I had 2 on my car&did it for a living, but these webbers/hpmx have tought me a lot more than I knew before& didnt realy understand such as air corection/bleed sizes & what they did& what to do to them.I wish I had know all this 30 years ago.but with that said I never had any issues,my 13.8cr tunnell ramed ,roller camed 618 hp ,small block that idles smooth&low& was extreamly responsive.I just wonder how it would of been if I had know what I have learned in the past 10 years running these idf style carbs. if somebody just tells you to throw these jets in and ittell work great you might want to either run or bough down. I like these carbs but wish they had a third circut.but with that said I still havent learned everything there is to know about them..and probably never will.

Jets aren't really "adjustable".

 

Jets can be removed and replaced, but they are just a brass plug with a very calibrated hole (orifice) in the middle. The mixture screws are the only "turn a screw" adjustment in the whole affair, and as Mark said earlier-- they only do anything at idle.

 

The confusion comes because the low speed jets (brass plugs with the calibrated holes) are called "idle jets", even though the are what you drive around on until about 1/2 throttle. You could be going 75 mph on your "idle jets" if you've got a big motor and a light car. Getting the idle jets right is about 90% of making the car run "crisply".

 

At wide open throttle, you are on the "main jets". When a car is dynoed at the hairy-chested engine builder's shop, it's always on the mains-- so getting a car "dyno tuned" tells you something about the engine (and what main jets it likes), but nothing about how it's going to feel on the street (unless your particular street is 1/4 mile long with no speed limit, and has a stop light directly in front of your house). Very few builders who spend any time at all dialing in the idles and transition (where you'll spend 75% of your time). If you're engine cost less than $10K, they didn't.

 

The "air correction" jets alter the transition between the two jets. There's a lot of voodoo happening here. I'm sure Mark understands it better than I do, but there is no easy chats and formulas. Airs effect mains, transition points, and all kinds of other stuff. The "Delloroto Bible" (bookstop) recommends "180s". For everything. It's not bad, but why do they make other sizes you ask? I think that's a great question, for which the book offers... nothing. Suffice it to say, it all gets pretty esoteric.

 

The reason I recommended a wide-band Lamba meter is that I could spend the rest of my existence on earth trying to pull and read plugs to get the amount of streaming, real-time information I can get with an Innovate LM1. There's no way I'd ever attempt air-correction jets without it.

 

There's no "one size fits all" jet recommendations for a 2110 (or 1915, or 2007, or 2332, or 1776)-- if there is, they are set-up pig-rich. Getting it right means buying a LOT of jets you'll end up keeping in a Plano plastic compartment tray, or paying somebody to do it for you. Unless somebody has pretty much all the jet sizes for your particular carburetor (that's where it's REALLY fun. They're all different), they're just syncing them and setting the idle mixture screws.

 

I'm not minimizing that-- if your carbs are out of sync, and have maladjusted mixture screws, getting it right will make it run 10x better. But just getting that part right is about 10% of what is possible if you really tune them.

 

Forewarned is forearmed.

Stan, I agree with everything you say except one. Properly adjusting and synching carbs has to be worth more than 10%. Other than that you nailed it. I wish more people would tinker enough to "get" that part of it.

 

LM1 is definitely the way to jet, pulling plugs is too much a pain in the ass, and questionable info depending on too many factors.

I agree Danny.

 

I did say that syncing them, and setting up the mixture screws correctly will make it run 10x better.

 

10% is probably an exaggeration, but there's so much left on the table in the average engine set-up that it SEEMS like they're 10% of the way there.

 

Everybody talks about engine builders. But nobody talks about tuning these things, because VERY few people know how to do it.

it all has to work togeather, most guys think they need to rejet the carb or do rejet the carb to get rid of a stumble,hesitation,"cam coming on", sort of fealing, when it wasent the cam or carbs at all but the dist addvance curve. A lot of guys run the famous 009 dist, well it is an industrail engine dist.(yes I run it too) it has no vac addvance,all advance is rpm controled, but it has a jump out curve, it addvances then stops addvancing for a few hundrad rpm then starts addvancing again, well the aera where it stops advancing is the flat spot or hesitation, and when you feal the "cam coming on" is realy the advance starting to do it's job again.with a little work down in the dist it can be as smooth as a nice set of babys asses with out the smell.

 as for the jets being non adjustable thats true but they can be changed to adjust them or reamed/driled to a larger size. also the air corection jet,Im not sure it has any thing to do with idle, but it does have a lot to do with the automization of the fuel, biger jets flowing more fuel need more air introduced in the system to automize the fuel so it can be puled through the boosters&burn effectivly.also a duel setup usualy takes a different size air jet that a single carb.

 as for the single barrell carbs I know next to nothing about them execpt for they are a bad induction system for short runner seperated head engines like these vws(IMHO) when you add a cam they dont like tom run all 4 cylinders at idle and the power balance is pretty much always off. think of it like this. what is the firing order on these motors?? 1432. or to put it easyer to see 4321. now split the motor appart in you head, #4 pulls the intake charge then # 3 starts pulling.it,s quite a while before that#4 starts pulling again and it is also pulling charge from #3 cylinder. and the 2&1 cylinders are doing the same thing. it's common for #1&3 cylinders to hit week at idle, and probably all the way through the rpm range. this is where the webber duell IDF style carbs ( 2bbl over each head with isolated runners)realy show how well these little motors can run.(this is why the porsche motors made somuch more power and ran somuch better)  each cylinder is like a single engine, each cylinder has it's own seprate carb, not pulling or pulsing from the other(and yes a lot of intake charge go's back up the intake tract,infact it works just like those steel balls on strings that bounce back&forth, time the back&forth just right and your motor is supercharged by inerta. this is the tuned runner intakes you hear about) the more everything wrks togeather the better.

Stan you are right. Not many people know how to make them run everywhere SMOOTHLY. It can be done, and as Mark says spark is a good part of it too. Another LARGE part is crap linkage that will NEVER, EVER be in sync. I have seen so many cars that are so out, it isn't funny. Last year at Carlisle I did a Weber thing on cleaning the carbs, presetting them, and then tuning and synching them. I even wrote a little diatribe on it and gave out about 20 copies. It really isn't that hard, you just have to keep messing with them until the light comes on in your head.

 

You are coming to Carlisle this year, right? Stanislan can live a few days without you, no?

I would love to meet the High Priest of Power, the Sultan of Speedsters, the President for Life of Stanistan himself, the one and only Stan Galat.

 

C'mon Stan, how can you refuse after a buildup like that?

For those of you who question Stan's existence, I in fact can vouch for it. My last sighting/encounter was in the Home Depot on War Memorial Drive in Peoria, Illinois at about 8:15 am on a Tuesday morning a month ago.

 

As usual, he was the consummate gentleman and offered good advice on a couple of issues with my car. I am pleased to call him friend.

 

 

Oh, we know he exists. Cory says so! Even though Cory is taken to flights of fancy...

 

The West coast comes, maybe the middle can make it also?