Saturday I took a nice long interstate drive. Not too many big hills, but some WOT...

The readings were as above. About 1/2 way home I turned the CO screw one more full CCW turn (OUT).

The readings at 70 mph and 3200 rpm were closer to 12.8
WOT evened out at the same 12.8
Hills also evened at 12.8

NO more adjustments and no driving 'til Monday AM but the readings changed a bit....

It was a cold morning here... 32*F

My readings during the cold drive in and the warmer drive home.
3200 & 70 mph 13.2
WOT 13.2
HILLS 12.8

It rained today, but Wednesday is clear and I'll get more readings. These are really close to Mark Henry's numbers. I am feeling like I am pretty damn close. And I am curious what this might do to my MPG.

Those numbers are better than the 18+ numbers you were getting earlier with a barely running engine. I think you are in the ballpark, but fine tuning is needed.

I also think it's time to re-introduce the AAV to your setup to assist with cold weather starting.

Yeah, we thought the meter was messed up... nope, it was just super lean.

I have AAV re-install in the plan. I will probably get to it before the weekend. Time to change the oil too. Maybe my Disty O-Ring will show-up and I can add that to the list.

It has been running rich and ruff for about 2 minutes on these cold morning starts.

Any leaks coming from the valve cover, dipstick, or dizzy are not considered 'vacuum' leaks.
Those are crankcase vent leaks

They are supposedly important for cars with FI (not sure why other than emissions).
But a car with carbs does not care at all about crankcase venting, except you want to manage it or you will have an engine covered in oil film.

You tell yourself that while trying to start a Ljet with its oil cap off

Great read, I am in the exact situation with my 1.8 L-Jet. Even built the smoke machine to verify for no leaks. Worked great. Haven't messed with the flapper box yet, but I have a strong feeling mine is lean. My borrowed Wide band gauge is not too easy to get set up for actual driving. I think welding in a bung is next inline for me. The Innovative tail pipe quick O2 mount seems problematic.

I might just have to invest in the Blue tooth solution you shared the link to, pretty cool !

No adjustments or significant changes to the readings:

3200 & 70 mph 12.5 - 13.4
WOT 13.2
HILLS 12.8

I have run 2 tanks of fuel thru the car while using and tinkering with the AFR. I have been getting just over 25.3 MPG. no special gas, just 87 oct, e-10.

Looking back at some notes from 2016 with the OLD, now bent, AFM I averaged a bit over 22 mpg driving to work for a week.

So fixing some vacuum leaks, replacing and adjusting the AFM have gotten me a few extra mpg on daily drives, but it is early. Looking forward to burning a tank on the interstate.

I think your old bent AFM was adjusted abit rich.

I have learned an old Indian trick... "plug reading" Shot from old bent.
Click to view attachment

Mark, I have been studying up on your AFR link from PLX. I am gonna order one this weekend. Going with the gauge model. Looks like you can just buy the blue tooth gizmo later and then use an old I-phone. So that is my plan.

No quick answers,because it's complicated,many factors.
https://www.google.ca/search?q=fuel+mixture...WMeAvEQ_AUIBigB

A lean cruise condition at low loads is at one end of the spectrum,highly loaded under acceleration is at the fat,rich end.(1910s)
Change the fuel and the chemistry changes with it,as with methanol/water additives.(1930s)
A turbo application at high boost pressure benefits greatly,stalling detonation and piston holing.(1930s)
Those holes can be had by a lean loaded condition with air cooled engines,as some of you here know.
All of this has been sussed out for 80 years,the military aircraft application the primary impetus.(1930s)
A direct injection fitment to the Type 4 hasn't been done yet to date,and would yield great results with a fine 'smart' mapping.(2017)
A constraint that aircooled engines have is the physical heat dissipation capacity,the mass and size of the fins and the amount of air that passes over them.
Adiabatic cooling systems are a proven upgrade and an easy fit,tho only practical for above freezing climates.(1970s)
Changing out the pistons and heads for a high quench design with piston squirters,a leaner mix can be had,and the application of ceramic coatings will shield them from the heat of combustion.(1970s)
Carburetor jetting is best done on a dyno these days,less time consuming than road testing and plug reading,as was done in the past.(1920s)
Double plugging your six or four has some advantage in flame-front size and expansion,so a leaner burn can be had.
Ultimately,the engine's ability to dissipate conducted heat is the limiting factor,so,the simplest course is to cool the engine and intake charge.

[url]https://www.google.ca/search?q=direct+injection+flame+front+simulation&espv=2&biw=1229&bih=598&source=lnms&tbm=isch&sa=X&ved=0ahUKEwjPmJ7T2anSAhWG4IMKHW13AsEQ_AUIBigBue

Great advantage.Be the first.
Be cool.
/

I picked up one of the PLX Blue Tooth AFR systems and it works really well. Display is easy to read although I do wish it had a record feature though. I had a bung welded in my Bursh muffler at the main collector as to read all four cylinders.

Did a small drive today for an hour on some hills here and was getting pretty consistent readings in the 15s cruising fairly flat roads, under WOT saw it dip into the high 14s. Climbing with a fairly heavy pedal it would also dip into the 14s.

Coasting down hill throttle closed it goes to full lean condition as expected.

After following this thread, sounds like I am a tad lean? Should I be in the 13s under WOT and 14s for cruising vs 14s and 15s I am seeing now? I do not have a CHT gauge, so not too sure what the heads temps are.

Might have to crack the lid off the flapper box and ritchen it up a few teeth. I have read a lot of adjusting the Bosh AFR over on the SAMBA.

My car is also a 74 1.8 L-Jet

https://youtu.be/owYGugwTguE

Yes 15:1 cruise is too lean for an aircooled 14:1 would be the max and even then I'd want a good headtemp gauge to be sure they're not getting too hot.

That chart might be OK for a watercooled, but not aircooled. WC big advantage is they can control head temps way better than air cooled.

Aircooled has a much narrower burn AFR range.
This would be my aircooled chart;

About 11:1 is the max for rich burn
WOT power between 11.5 and 13
Max performance WOT 12.3 to 13 maximum
Lean burn no higher than 13.5-13.7, nickies can run 14:1-14.3

The exception to the above is decel, AFR on decell is of no concern, of course it's a high reading, you just took away all the fuel, but no load so it's not producing heat.

You can run richer than 11:1 without really hurting the engine, but your power and tune goes to poop.
Anything over stoich you better have a damn good head temp gauge to monitor your temps, you are getting into dangerous territory.
As you head temps go over 350f you will start to lose power as a heat soak condition starts to set in.
Running 17-18:1 and you will have a hole in a piston PDQ.

Basic rule on heat temp and heat soak is you can go over 350f on a long hill, as long as the temps recover on the downside. Once the temps are not recovering on the downside of the hill you have a heat soak issue. Even a cheap VDO gauge you can easily see this heat soak/no recovery condition.
Head temps consistent 325f is about perfect, 350F is OK, but I don't want to see much more for long periods of time.
On my LN nickies I don't see much over 300F unless I'm really hammering it on a hot day.

I agree with and support everything Mark Henry has been saying.

My PLX rig showed up Friday. Looking forward to getting it in the car this week. Turns out they sell on Amazon too. $169 was a little better price.

You got a great price, mine was 180.00 direct from PLX via Ebay...

I have a second AFM flapper box and will be trying it to compare to the rebuilt unit I am currently running. Will start turning the wheel to see if I can get this thing closer to Mark's recommendation numbers..

Be careful. The air flow meter has a wound up clock spring that will take off on you when you loosen the retaining screw and if you don't keep constant pressure on it. There is a air flow meter bible that you should read and re-read 3-4 times before making any adjustments.

http://www.itinerant-air-cooled.com/viewto...f=50&t=7761

Sounds like these early FI cars are set from the factory lean compared to today's fuel.
I have a couple Flapper boxes to try out to compare. I think that they will require to be turned to ritchen the mixture.

Here is my O2 sensor and PLX installation.

Video on how to richen the AFM.

https://www.youtube.com/watch?v=yQukm7lNux4

I do like welding stuff.... but man you can screw things up in a hurry.

Here is the result of my BUNG HOLE welding.

Click to view attachment

It took 3 bungs and some patching of the areas I screwed up, but I am not too proud to show the world.

Point of interest here. I did not really screw up on the welding of the bung to the pipe. I saw a YouTuber that installed the plug that is supplied with the bung. He then welded. His thought was to keep spatter off of the inner threads.... makes sense to me.

Well the bung gets hot and ends up galling up the plug so you can't get it out.

I ended up covering the hole with a small bolt dropped in the bung and a large washer.

Repairs are complete, I'll add some Hi Temp paint to hide my grinding work and start working on where the wiring goes this weekend. Good garage day, it is supposed to snow in Nashville.

Was your wire feed sticking?
You likely need a new whip liner, but you could also try to make you whip as straight as possible.

I had the heat set high (3) to begin with and it ran nicely. But if I did not keep moving consistently... I burned some holes in the thin pipe. Turned down a notch and I got no holes, but did get some spatter and wire sticking on the work piece.

Did not think of keeping the whip straight. I will pay attention to that next time.

PLX is now installed. The guage is temp'd in with a shoe box and a clip.

Reading was 13.8 to 14.5 last night. I closed my CO screw one full turn. Cruising and hills reading is now 12.7 to 13.5.
Heading to NC at lunch. 5 hour drive. I will enjoy monitoring it.

Click to view attachment

I have been playing around a bit with my AFM. I have a couple of them so I figured one would be a good test mule. I read about a mod the VW Bus guys were doing. The later Bosch AFMs had a jumper wire installed to help the conductivity. This is an easy upgrade to do by soldering a jumper wire from the wiper arm to the large connector bar (See blue wire). I also cleaned all the contacts while I had it apart. I did a before and after OHM test and the numbers seemed to smooth out a bit after the mod and tune up. There are You Tube videos on all of this.

Now to try to get some time to get out and test the AFR results.

My AFM has that jumper. Did not know it was an add on.

5 hours of interstate driving. Several big hills.

Cruising at 3400 between 70 and 80 the a/f guage was between 12.2 and 12.7. CHT went to 375 on the hills but was 325 to 350 the rest of the time.

I'll fill up with gas today. It seemed to get good mileage. I think 25 mpg was the last i remember with the now bent AFM. 320 miles and still above 1/4 tank.

5 hours of interstate driving. Several big hills.

Double post

Hey Clark,

PM sent

Joe

Sounds like you are around 26 mpg. I think with this system correctly dialed in, you may get closer to 30 mpg. I'm curious what the spark plugs look like after this trip of yours.

I take back what I said. Maybe you are already getting 30mpg, driving through the Appalachian mountain will skew any MPG readings.

Tested out my AFM mods and seemed to work well. Was a bit lean but a few teeth adjustment on the flapper wheel and I was able to get it to settle around 12.9 - 13.5 cruising and dips to the low 12's under load.

Re adjusted the timing and will try it again tomorrow. So far seems to be much happier.

I made it home.... 800 + mile weekend trip. I don't think I will go that far again until I get some new padding for my seats.

As far as the A/F goes... I filled up with pure gas, 89 oct I believe it was. So the 1st 330 miles started with maybe 25% 87 oct e10 + 75% 89 oct pure.

MPG (best numbers I have ever recorded)
tank 1: all interstate: 337.5 / 11.25= 30 mpg
tank 2: 100 miles of city: 314.2 /9.99 = 31.4 mpg
tank 3: 151 miles of interstate: xxx/xx = still on 1/2

I-40 from Nashville to Asheville has quite a few hills, some 4 to 5 miles long.

The car ran very well. I visually logged @ 12.7 a/f cruising on flat ground at about 3400 rpm. Up the hills still at 3400 rpm, CHT reached 380-ish and the a/f evened out at 12.5. Oil temps were steady at 210.

My total a/f interstate range for the most part was 12.3 to 13. Once thru the mountains with only about 20 miles to go, I noticed there were times it was running richer. I saw some 12.0's even 11.8 for brief times.

City driving on Friday, it would idle at 14.6 then stop-to-stop up to 4th gear and 3000+ rpm I say I saw 12.5 - 13.

I did not see the rich numbers yesterday. the range was about like the City driving 12.3 -12.8 all day on 87 oct e10 fuel. 3400 to 3800 rpm 70 - 80 mph.

Unless someone thinks I am out of whack, I think I may not tweek any further.

I will also edit and add a spark plug photo for Tim....

Ok what do you think? Maybe 1000 miles with this new AFM and it's set up.

Click to view attachment

I got nothing. My work with you is done.

I'd say that plug is a tad hot, what number is it? Brand?
What are you running for total advance?

I'm looking for beige or tan colour on the insulator, your insulator is too white. Or is it just the pic?

Edit: could be my one monitor, on the other one it looks about right. As long as the insulator doesn't have a gloss finish appearance it should be correct.
I run two monitors but one is better than the other.

They are NGK BR5ES. It was cylinder #2. Have not checked the timing in a while. I guess I should.

I thought it was pretty white too. Don't remember seeing one that white. I figured that was a good thing. It was not shiney.

Thanks

Spark plugs are an easy change, you could try NGK 6 in there, its one step colder.

Click to view attachment

This is a great graph for air cooled engines:

https://www.thesamba.com/vw/gallery/pix/1463782.jpg


14.7-15 or so is the 'No go zone' danger. Shoot for ~12.5 - 13.0 WOT/Accelerating and while at cruise (part throttle cond) 16-17 AFR

Use an LM-2 wide band

16-17 AFR at cruise (part throttle cond) is cooler running (EGT's/CHT's) than 13:0-13:5 same scenario.

Well in a 914 one may not see much over 350F or so if everything is dialed in. But temps over 350F are not for much concern. It's when you go over 400+F then start worrying.

As for AFR's once you start pushing beyond 15:1 the EGT's go down. Why? Simple you are closing the burn (fuel off). The below chart shows the relations between EGT, CHT, HP and ICP. Peak EGT is ~14.7-15:1

During 'cruise' get into the 16-17AFR for cooler running. Part throttle cruise is NOT a load condition. Ones foot dictates load. If you're running around during cruise at 13:0 - 13:5 you are wasting fuel and running hotter EGT's and CHT's than you would be if you were running 16-17AFR at cruise (part throttle).

https://www.thesamba.com/vw/gallery/pix/1463782.jpg

350 going up hill at 70 sounds pretty good to me, especially if the CHT is reading cyl 3 and you are in 5th gear.

My car always used to be approaching 400 on long highway hills in 5th. It would be pulling like a champ, but getting hot. I learned to downshift to 4th at the base and keep that air moving. That said I never had valves stretching on me. Now that I'm in EFI and have a wideband I'm looking forward to see if my engine stays on the hot side or if its now going to run a bit cooler. But I'd love to see 350 at 70MPH running up some of the long ass hills here in PA.

Zach

on my daily drive I have a long, low hill that I have been comparing each day.

On my last trip to SC there is a mountain to climb. It seems like it is 5 miles long and very steep. My VDO CHT under #3 needle moves to what I would call 375 in 5th gear on that "hill".

I filled up with 90 octane pure gas yesterday. This morning, on the "hill" maybe 75 mph the A/F was 12.2-ish and cht was dead on 350.

So the A/F seems a bit rich, but still in range. Earlier in the week with 93 oct, E-10 it was reading 12.7 on my daily hill.

I just saw an ad for an AFR from Innovate that monitors 2 sensors. They say left and right banks on a V8 engine may run different numbers. Does anyone have experience/opinions on this? Could this be helpful?

Was it allowed to idle prior to pulling the plug/ It matters even the slightest. Also with today's ethanol blended fuel E10+ it takes a few thousand miles of seasoning the plugs before you can use them as a gauge for AFR.


Load = WOT

Part throttle is NOT load

Cruise = part throttle condition

An AFR of 16-17 at cruise (part throttle cond) is COOLER running than at an AFR of 13:0 - 13:5

With respect to jetting....Get above (14-15AFR range) when on the progression and below (14-15AFR when on the main jets. 90% of ones driving is on the progression circuit (idle jets).

The following chart shows this....

Click to view attachment

Incorrect.

Under load? Yes.

At cruise? No

Cruise = part throttle condition. One is not at WOT/load under that scenario.

Nothing wrong with 16-17 AFR with a cracked throttle. Throttle position dictates load.

There is no "short answer" for this question.

There are some basic references for non forced induction though.

WOT = 12.7-13.2 under heavy load
Cruise = 13.7-14.7 under light load
Idle = Hot-13.0-15.0 / Cold- 11.5-12.5

Now keep in mind all of these are dependent on timing.

You need to know where your base timing is set, what your advance curve looks like and your peak advance.

This is where those old SUN distributor machines come into play.

You need to measure the weights and spring tensions, the diaphragm movement per inch of vacuum in the actuator.

Even off the shelf reman distributors often have the wrong curve as they mix and match weights and springs.

Now that you've got your distributor curved correctly, timing set, and your wideband O2 installed Now you can tune your carbs or check your F.I. to make sure it's operating correctly.

Reading plugs is a good back up to the wideband and will tell you if you're too aggressive or not aggressive enough with timing.

Here's some good reading on that:
https://honda-tech.com/forums/forced-induct...%2A%2A-3063102/

Remeber always make minor adjustments and don't get crazy aggressive and your engine will last a long time.

WOT = 12.7-13.2 under heavy load
Cruise = 15.5-17:0 under light load (better MPG's)

14:0 - 15:0 is where the highest EGT's & CHT's will be. Get above that zone when on the progression circuit and below it when on the mains (WOT).

Idle isn't where we/one drives so it's out of the pic.

Reading plugs takes time. With new plugs you need a couple thousand miles for them to get seasoned.

I have one of these with my 911 engine headers. Info is very helpful tuning carbs. Do not cut the harness to fit your application.