Science or Intuition? making a VW go like hell

[Jim Ratto]

Sometimes all the bar graphs, pie charts, calculations and slide rulers mean less than "just knowing when things are right".

It's funny, guys can read volumes of info about Weber carbs, follow all the charts and diagrams and math and in the end, the motor runs like a pile of junk. These guys insist that they've "gone by the book" and squeezed all they can from the motor. A friend of mine up north was trying to get a motor tuned in for a customer, but the customer insisted "the Weber chart says this size motor needs this jet, no bigger!" and the result was a popping, leaned out wimp.

Mark Herbert used to post on the old CLF one of my favorite quotes of his: "Let's go race calculators"

I remember a post on CLF about jetting and some guys insisting "you need an LM1" and Clyde Berg came in and said something about "if a car runs right, then you've got it, without the sensor"

Is it science or good old intuition?

To me I think it is "knowing" when a car is "right" and knowing a baseline. Then getting to the baseline and knowing how to improve on it, no matter what the books say. The charts and all are great for getting a starting point, but sometimes the suggestions published are so far off for a particular application, it's a wonder they'll even run at all.

Anyway, thought I'd start a discussion about going beyond the math, and using your "gut feeling" to make the car go faster.
Any thoughts?

[Zach Gomulka]

About the LM-1.... if you have ever used one, you'd know. My buddies IDA'd 2276 ran like a champ, tuned by traditional methods made 198hp with pump gas on the dyno, and ran 12.6's @ 105- in a true 100% daily driven street car. Got the LM-1 on there and it showed that the AF ratio was waaayy of in some spots. So we tinkered with the jets until the LM-1 was happy. The result was an engine that transitioned from idle circuts to mains much more smoothly, and got 25mpg if you could keep your foot out of it. And it was just as fast at the track. My .02

[Jim Ratto]

About the LM-1.... if you have ever used one, you'd know. My buddies IDA'd 2276 ran like a champ, tuned by traditional methods made 198hp with pump gas on the dyno, and ran 12.6's @ 105- in a true 100% daily driven street car. Got the LM-1 on there and it showed that the AF ratio was waaayy of in some spots. So we tinkered with the jets until the LM-1 was happy. The result was an engine that transitioned from idle circuts to mains much more smoothly, and got 25mpg if you could keep your foot out of it. And it was just as fast at the track. My .02

what was changed after LM-1 was installed?

[Zach Gomulka]

I forgot to mention.... in a word, everything. Different emulsions, idle airs, idle fuels, mains and airs. You would have never thought that it was that far "off". Im sold on the LM-1, Ill be hooking one up to the GTV soon with hopes of improved mileage and performance. Ill let ya'll know how it goes.

It is also the tool my friend used to get his 1915 powered '67 in to the 13's, on pump gas, with radials, through 3 stock gears

[Jim Ratto]

I forgot to mention.... in a word, everything. Different emulsions, idle airs, idle fuels, mains and airs. You would have never thought that it was that far "off". Im sold on the LM-1, Ill be hooking one up to the GTV soon with hopes of improved mileage and performance. Ill let ya'll know how it goes.

It is also the tool my friend used to get his 1915 powered '67 in to the 13's, on pump gas, with radials, through 3 stock gears

hmm. When running a 2276 on Heads Up's dyno, we pulled a 202 @ 7000 and 161 ft lb @ 5500. Roger said "try F11 tubes instead of your F7's and watch what happens", we left jets and timing alone. No air/fuel sensor. Pulled 213 @ 7100 and 175 ft lb @ 5500. That's the kind of "knowing" and "experience" that impresses me.
My old boss Jerry, he was much of the same way. He could listen to my car leave the parking lot at work and next day, he'd say "needs more main". So I'd swap up and bingo.

[louisb]

I forgot to mention.... in a word, everything. Different emulsions, idle airs, idle fuels, mains and airs. You would have never thought that it was that far "off". Im sold on the LM-1, Ill be hooking one up to the GTV soon with hopes of improved mileage and performance. Ill let ya'll know how it goes.

It is also the tool my friend used to get his 1915 powered '67 in to the 13's, on pump gas, with radials, through 3 stock gears

hmm. When running a 2276 on Heads Up's dyno, we pulled a 202 @ 7000 and 161 ft lb @ 5500. Roger said "try F11 tubes instead of your F7's and watch what happens", we left jets and timing alone. No air/fuel sensor. Pulled 213 @ 7100 and 175 ft lb @ 5500. That's the kind of "knowing" and "experience" that impresses me.
My old boss Jerry, he was much of the same way. He could listen to my car leave the parking lot at work and next day, he'd say "needs more main". So I'd swap up and bingo.

I had an uncle that was like that. Could tune an engine by sound and the feel of its vibration. He had also been doing it for fifty years. Me, I am not that good and will be getting an LM1 as soon as I can afford one. I think one of the problems with "By the Book" people is that their information doesn't take into account that each engine is different. I have seen two identically built engines need different jets and timing. (Not a huge difference but still not the same.) I think that is why you have to pay attention to that specific engine on that day.

--louis

[The Ideaman]

About the LM-1.... if you have ever used one, you'd know. My buddies IDA'd 2276 ran like a champ, tuned by traditional methods made 198hp with pump gas on the dyno, and ran 12.6's @ 105- in a true 100% daily driven street car. Got the LM-1 on there and it showed that the AF ratio was waaayy of in some spots. So we tinkered with the jets until the LM-1 was happy. The result was an engine that transitioned from idle circuts to mains much more smoothly, and got 25mpg if you could keep your foot out of it. And it was just as fast at the track. My .02

You forget to mention that Travis is an engineer, and will endlessly tinker.  He digs toys.  A LM-1 is a pretty cool tool.

[Jim Ratto]

I forgot to mention.... in a word, everything. Different emulsions, idle airs, idle fuels, mains and airs. You would have never thought that it was that far "off". Im sold on the LM-1, Ill be hooking one up to the GTV soon with hopes of improved mileage and performance. Ill let ya'll know how it goes.

It is also the tool my friend used to get his 1915 powered '67 in to the 13's, on pump gas, with radials, through 3 stock gears

hmm. When running a 2276 on Heads Up's dyno, we pulled a 202 @ 7000 and 161 ft lb @ 5500. Roger said "try F11 tubes instead of your F7's and watch what happens", we left jets and timing alone. No air/fuel sensor. Pulled 213 @ 7100 and 175 ft lb @ 5500. That's the kind of "knowing" and "experience" that impresses me.
My old boss Jerry, he was much of the same way. He could listen to my car leave the parking lot at work and next day, he'd say "needs more main". So I'd swap up and bingo.

I had an uncle that was like that. Could tune an engine by sound and the feel of its vibration. He had also been doing it for fifty years. Me, I am not that good and will be getting an LM1 as soon as I can afford one. I think one of the problems with "By the Book" people is that their information doesn't take into account that each engine is different. I have seen two identically built engines need different jets and timing. (Not a huge difference but still not the same.) I think that is why you have to pay attention to that specific engine on that day.

--louis

When I first put two dual barrel carbs on my car when I was 17 I was scared to death to get them set. I could get them to pull same amount of air, but jetting and getting mixture set was a Black Art. I got them in as close as possible and took it to Jerry so he could give them a once over. Amazingly, he said I got them really close and just adjusted the air bleed circuits. When I graduated up to 44IDFs in a few years, again I was a little intimidated. But from getting the previous Dellortos set, I knew what was "right" in my book. And again Jerry helped out. I could get the carbs to idle and run steady state, but would hesitate in transition. Jerry heard it run one day and when I got back to shop, in his most typical "Jerry" tone of voice said "I KNOW you didn't leave those goddamn size 50 idle jets in that motherf**ker." With that said, he knew I had. Tried 55's and the difference was night and day. Dicked around more with it, went to 57 idle, opened air bleeds a bit, and it was perfect.
By the time I had a set of 48IDAs in 1991 I was pretty confident in making them run decently. Setting the floats and so on was easy (even with carbs on the car, thanks to help from friend Steve Fuss) and getting them to do what they should was pretty easy. By now it wasn't so much "book says turn the screw 1-1/4 turns with X-size jet..." it was more knowing how the exhaust should sound, smell, the amount of heat coming off the header and what to do to get it all right, and it took a long time and the inhalation of a lot of fumes, but eventually I got it. That was part of the fun of always trying something new (cam/heads/etc) in my car....setting carbs up to make whatever combo happy. After a few years @ Buggy House it was like I had gained respect from Jerry too, he'd get a Weber car in there with a soft idle or a dead spot somewhere, and ask me what I thought.

I guess my point to this post is that while, yes, the sensor and the equations are fantastic tools for a guy to dial his combination in with, there is still something cool about guys like Jerry, and your uncle Louis. These guys cut their teeth on setting stuff up when the only TV's you could buy was black and white. And not only carbs. How a set of heads won't "work" on some motor, or how "no matter which damn motor you drop that cam in, it's gonna rip your head off"....these kind of guys are invaluable and a bit of a rare breed.  I don't know if any of you know Tony Wilkie, but he's around my age, and he definitely belongs to this group. He could quietly stand by, listen to a car and pinpoint what it needed. Amazing guy.

[Bewitched666]

I think that making a vw to go like hell is a bit of science and intuition,i rely mostly on intuition as i'm more old skool like

But i think the Lm can be usefull although i never used it.
Dave Kawell that builds my drag engines relies on intuition too,up till now never seen him use the LM

[louisb]

I am sorta at the start of that with these Kads I have been trying to set up on the 1500. Reading spark plugs is one of those black arts I am just really getting the hang of, sorta. Never tuned an engine with a split, or semi-split manifold like these kads have. I keep going around in circles with the damn things.  And this is only with two one barrels, can't wait to try it with the IDAs. My biggest problem is making too many changes at once or too quickly. I have to remind myself to sit and listen to the engine, the rhythm of the exhaust, the air flow into the carbs, feel the engine vibrate as it turns over, etc.

Here is one for you though not motor related. My dad was in charge of the printing shop for a two year college here in town. One of the guys who worked there was deaf. He could tell if the printing presses were running right by the way they vibrated as they ran. He usually would know if something was wrong before the other operators who could hear.

--louis

[Jim Ratto]

somewhere I read that the infamous Cosworth DFV Formula 1 heads was designed more from "gut feeling" than science by Costin and Duckworth. Look how that turned out.

[tikimadness]

I think more and more people use the LM1 and other tools because there arn't that many people who really know their way with carburators.Most mechanics who learned it during their years of working with carbs are getting older now .The young guys coming out of school as a mechanic nowadays know where to plug in the computer in the car and it will tell them which item should be replaced.

I'm playing with volkswagens for over 12 years now and during the last 3 years it is that I really started to understand what every part of a carb does.

michael

[Jim Ratto]

I am sorta at the start of that with these Kads I have been trying to set up on the 1500. Reading spark plugs is one of those black arts I am just really getting the hang of, sorta. Never tuned an engine with a split, or semi-split manifold like these kads have. I keep going around in circles with the damn things.  And this is only with two one barrels, can't wait to try it with the IDAs. My biggest problem is making too many changes at once or too quickly. I have to remind myself to sit and listen to the engine, the rhythm of the exhaust, the air flow into the carbs, feel the engine vibrate as it turns over, etc.

Here is one for you though not motor related. My dad was in charge of the printing shop for a two year college here in town. One of the guys who worked there was deaf. He could tell if the printing presses were running right by the way they vibrated as they ran. He usually would know if something was wrong before the other operators who could hear.

--louis

louis, that's cool you brought this up. When I mess with carbs, setting mixtures, I probably use 60% sound, 40% vibration to get them set. I leave screwdriver on mixture screw and use it to feel what the motor is doing. Like feeling its pulse.

[Jim Ratto]

I think more and more people use the LM1 and other tools because there arn't that many people who really know their way with carburators.Most mechanics who learned it during their years of working with carbs are getting older now .The young guys coming out of school as a mechanic nowadays know where to plug in the computer in the car and it will tell them which item should be replaced.

I'm playing with volkswagens for over 12 years now and during the last 3 years it is that I really started to understand what every part of a carb does.

michael

very good point Michael!

[louisb]

I think more and more people use the LM1 and other tools because there arn't that many people who really know their way with carburators.Most mechanics who learned it during their years of working with carbs are getting older now .The young guys coming out of school as a mechanic nowadays know where to plug in the computer in the car and it will tell them which item should be replaced.

I'm playing with volkswagens for over 12 years now and during the last 3 years it is that I really started to understand what every part of a carb does.

michael

I can agree with that. Finding a "professional" who knows anything about VWs in my town is a pita. If it is not in their computer they don't know what to do. Found this out the hard way a couple of weeks ago when I went to have the alignment done on my '67. Only person in town who could do it was some ancient little hole in the wall place that still set the suspension manually. And even then they couldn't do the rear. For the life of me I couldn't convince the guy that the rear wheels shold have that much camber when you jack the back end off the ground. He wanted me to take it home and lower the back end a couple of inches so the tires would not have so much camber. 

That also comes into the reason I want an LM1. There is not anyone else around here to ask if it is right or wrong. Until I am more confident I want a second opinion even if it is a little black box. I think I own the only set of IDAs in town and I know I am the only VW in our club with dual carbs.

--louis

[tikimadness]

[/quote] I think I own the only set of IDAs in town and I know I am the only VW in our club with dual carbs.

--louis
[/quote]

well louis it's lonely at the top but never crowdy

[nicolas]

i think the LM-1 and other tools are great and of great benefit to all builders. that is because the persons who actually can hear and feel an engine that good are as rare now as they where then. besides, people have opinions and ideas and blackboxes have one too, but it is all the same opinion. so what works for one engine or person doesn't work for another. if i look at the charts of jets in my 40IDFs it would say a mainjet between 117 and 128 or something along those lines. and if i asked around people told me to put in a 125, that worked OK, but the guy i went to who build the engine said that a 115 would work best. i have switched jets a lot and found that sometimes the smaller worked better and other times the bigger ones. all this to say that indeed there are a lot of things that have to be taken into account. and that is only achieved by knowledge and experience.

[tikimadness]

I think this is also the reason engines get bigger and bigger.How will it be in say 10 or 15 years.How much of the know how will be there for whoever wishes to build or tune an engine?

The computer makes everything easier but in my opinion makes knowhow get lost.

michael

[Tony M]

we use one with our race engine at the track - we know it's close when we leave home - but it sure does work to get the most out of your engine - there is a big gap in the vw game - we have us old schoolers - and then you have the new kids - how grew up with using computers - for them its a no brainer - use to using this stuff - so its both - science and gut feeling

[javabug]

People can learn the mechanics or "theory" of just about anything.  Not everybody can put it to use and get results.  You just can't replace talent.

[Zach Gomulka]

I cant believe how stubborn a lot of you guys are when it comes to new technology. And I thought I was bad! 

The 2276 I mentioned before was tuned very well prior to the LM-1, using the dyno and monitoring the BSFC (brake specific fuel consumption), by my friend Travis Alward and Steve Hollingsworth (knows his way around a VW motor, to say the least). I think Howard Washington was there to give his .02 as well. It was further dialed in after installation into the car. My point is that these were not some ham fisted idiots making guesses as to what the engine wanted, and the LM-1 still made it that much better.

There is no substitute for knowing the exact AF ratio at any given moment, I dont care how long you have been doing this, or how good your ear is.

[louisb]

ham fisted idiots making guesses as to what the engine wanted

Hey now, I resemble that remark.   

I am not so sure it is resistance to new tech, but nostalgia for the way things have been done in the past. We drive old cars that run off of antiquated carburetors. We like the sensation of being intimate with the car. (Not intimate that way.  ) I work in the world of bits and bytes every day. One of the things I love about my VW is that most advanced electrical component on the car is the AM radio. (Well, until I stuck that Pertronix kit in the 010 last weekend.) There is what, seven wires in the whole damn car. It speaks of old world craftsmanship and simpler times. Plus it scores major manly points if you can do it without some magic black box. Having said that, I still plan to save up for one.   

--louis

[lawrence]

The LM-1 is a good tool to utilize, but I would not rely on it soley. Tinkering and tuning ability used in conjuction with the LM-1 is a good combination. I have used an LM-1 on a few occations to tune my 1914 with IDAs.

The sizing of my idle jets is a perfect example of using the traditional and technolgical methods of tuning. I previously had 55 idle jets and I knew the car was running rich because the exhaust smell was very strong and the car idled like crap at operating temp. I could also turn the mixture screws on the passenger side carb all the way in and it would still run. So, I hooked up a borrowed LM-1 and bingo the car was running too rich at idle. I put 50 idle jets in, although many people told me they were too small, and the car idles great now.

My next issue relates back to Jims original point. The car stumbles and goes lean in the transition from idles to mains, but runs good while cruising. I dont really want to fool with it because the a/f ratio is between 15-16, which the dellorto manual says is most fuel efficient. So should I bump the main up one size? Help me out tuners 

[Jon]

I think ALL of you are right! But you are talking about differnt things I think.
Making the IDA run sweet takes time experience and good ears...
Making it run "on the line" of performance rich/lean takes a lot of reading plugs or one hell of a set of ears.
...or a LM1

But remember the LM1 doesn't tune your IDAs... you do.... and it's you that need the skills.

[Bewitched666]

I agree with what Michael posted

[SOB/RFH]

Tuning is science and intuition and it takes a lot of time to do properly. You need to know what works and you need to get the ear/skill to pull the last bits of power out of it. So just looking at flow numbers and calculus results is not the way to go. I think competence is the right word as it is defined as the knowledge and experience. It also takes some guts to really use what you have put together!! A very good topic this!!

[redbluebug]

Your engine tells you what it needs, not the other way around.  It is a skill which is learned, just some learn quicker    I have a LM-1 and I would not
want to give it up.  It amazes me how much the a/f varies with the weather.
Don't be afraid of making changes, just make one at a time and drive it.
Good thread 

[syncro de mayo]

The LM-1 is a good tool to utilize, but I would not rely on it soley. Tinkering and tuning ability used in conjuction with the LM-1 is a good combination. I have used an LM-1 on a few occations to tune my 1914 with IDAs.

The sizing of my idle jets is a perfect example of using the traditional and technolgical methods of tuning. I previously had 55 idle jets and I knew the car was running rich because the exhaust smell was very strong and the car idled like crap at operating temp. I could also turn the mixture screws on the passenger side carb all the way in and it would still run. So, I hooked up a borrowed LM-1 and bingo the car was running too rich at idle. I put 50 idle jets in, although many people told me they were too small, and the car idles great now.

My next issue relates back to Jims original point. The car stumbles and goes lean in the transition from idles to mains, but runs good while cruising. I dont really want to fool with it because the a/f ratio is between 15-16, which the dellorto manual says is most fuel efficient. So should I bump the main up one size? Help me out tuners 

afr of 15-16 is way too lean. What size main is in it now? In fact, what is the entire venturi/jet stack setup?

[Jon]

Your engine tells you what it needs, not the other way around. 

Brilliant answer!

[n2o]

I forgot to mention.... in a word, everything. Different emulsions, idle airs, idle fuels, mains and airs. You would have never thought that it was that far "off". Im sold on the LM-1, Ill be hooking one up to the GTV soon with hopes of improved mileage and performance. Ill let ya'll know how it goes.

It is also the tool my friend used to get his 1915 powered '67 in to the 13's, on pump gas, with radials, through 3 stock gears

hmm. When running a 2276 on Heads Up's dyno, we pulled a 202 @ 7000 and 161 ft lb @ 5500. Roger said "try F11 tubes instead of your F7's and watch what happens", we left jets and timing alone. No air/fuel sensor. Pulled 213 @ 7100 and 175 ft lb @ 5500. That's the kind of "knowing" and "experience" that impresses me.
My old boss Jerry, he was much of the same way. He could listen to my car leave the parking lot at work and next day, he'd say "needs more main". So I'd swap up and bingo.

Imaging what the results would be if Roger had a LM-1. Probably better all over the rpm range.

Personally I like the "seat of the pants" tunning!  And when I need to finetune my engine, I pull my pants down to get "just the right" feeling. LOL