‘74 tii fuel delivery issues: last mile? Or rabbit hole?

[dlacey]

I think its important to understand that all discussion about tunacan adjustments, verboten screws and AFR are made under the assumption that the WUR is out of the picture and the engine at some 'steady state' temperature: meaning that the car is warmed up so that the Top-Hat washer is raised high enough clear of the enrichment lever - so that the verboten screw is up against it's stop ....and.... that fast idle air cone has risen and completely blocked off the air channel. 

 

This 2.6mm you talk about is related to synchronisation of the fuel enrichment with the additional airflow during the warm-up phase. i wouldnt worry about AFR in the warm-up phase, just set it by the book then adjust the TopHat for smoothest running...its quite a dynamic phase, the engine temperature is changing fast...and its all dependent on a properly-functioning WUR.

 

Next step: eliminate WUR from the equation and focus on tuning the fully-warmed-up engine.

Edited September 29, 2021 by dlacey

[0257]

9 hours ago, dlacey said:

I think its important to understand that all discussion about tunacan adjustments, verboten screws and AFR are made under the assumption that the WUR is out of the picture and the engine at some 'steady state' temperature: meaning that the car is warmed up so that the Top-Hat washer is raised high enough clear of the enrichment lever - so that the verboten screw is up against it's stop ....and.... that fast idle air cone has risen and completely blocked off the air channel. 

 

This 2.6mm you talk about is related to synchronisation of the fuel enrichment with the additional airflow during the warm-up phase. i wouldnt worry about AFR in the warm-up phase, just set it by the book then adjust the TopHat for smoothest running...its quite a dynamic phase, the engine temperature is changing fast...and its all dependent on a properly-functioning WUR.

 

Next step: eliminate WUR from the equation and focus on tuning the fully-warmed-up engine.

?Thanks.

[Einspritz]

On 9/25/2021 at 9:40 PM, dlacey said:

Still don't understand your reproducibility issues....air leak? Fuel pressure? Something ignition???

 

the AFR reproducibility issue is due to either wear in the bearings and bushings in the TB (the throttle plate vs. D cam changes with every blip of the throttle in relation to the pump) or a worn /faulty distributor. Wear in the shaft causes the dwell to change with every rev of the engine. I am talking very small increments that have a big effect.

 

You will be chasing your tail every time.

 

As far as the tuning sequence re: idle AFR, first tune at WOT, then adjust the D cam for intermediate running AFR, then adjust idle to 900rpm or so. DO NOT try to set the idle AFR and just leave it. It will be what it will be dependent on your fuel.

 

Please throw the blue Kugelfischer book in your neighbor's pool.

[0257]

Yeah, this…..

 

[0257]

I tried various tricks to get it to stop allowing air through — manually set the cone at different levels, tried different heats, etc.  At 212F it almost gets airtight, but … not.  I am not about to take the WUR apart.  Who is the best bet for saving one these days?

Edited October 1, 2021 by 0257

[ray_]

34 minutes ago, 0257 said:

Yeah, this…..

 

IMG_5442.MOV 23.73 MB · 0 downloads

 

That should go well with some fava beans and a nice Chianti.

 

;-)

[0257]

Almost 13mm extension at 180F.  Who wants to volunteer whether you think I should be able to tune the KF around this size leakage?

[dlacey]

I can't see your attachment, but 13mm extension means the WUR is performing normally.

[0257]

17 hours ago, dlacey said:

I can't see your attachment, but 13mm extension means the WUR is performing normally.

What you’d see in the short video is the WUR in a pan, with champagne bubbles coming out.   At other settings not real close to this one, both at lower and higher extensions, it never gets better and often gets worse. More like a gin & tonic.  So right about 13mm full extension at 180F is as good as it gets.  Now of course the car is never going to run exactly at 180 (especially at idle on hot days), but if I’m going to try to tune around this WUR this seems to be the spot that gives me the best results for a mm or so on either side.  Mind you, the cone now sits at 4mm above flush when at 68F…. So that’s still the question: worthwhile to try to tune around this WUR, or should I just start in on a search for a better one?  Really out of my depth here (no submersion joke intended)

[dlacey]

9 hours ago, 0257 said:

Mind you, the cone now sits at 4mm above flush when at 68F…

Seems like bad hysteresis ..... its simple inside (as we recently found out), if you are getting 10+mm extension at 180F then the wax actuator is working....wax pressure forces it up, spring pressure forces it back down (along with wax contraction).

Could it be a lubrication issue? try some engine oil (something that wont evaporate in the airflow) on the cone and dripped in the side port in the hope to lube the the actuator rod.

Put the WUR thru some heat/cool cycles & see if exercise can get it more reproducible in terms of extension/temp.

[0257]

40 minutes ago, dlacey said:

Seems like bad hysteresis ..... its simple inside (as we recently found out), if you are getting 10+mm extension at 180F then the wax actuator is working....wax pressure forces it up, spring pressure forces it back down (along with wax contraction).

Could it be a lubrication issue? try some engine oil (something that wont evaporate in the airflow) on the cone and dripped in the side port in the hope to lube the the actuator rod.

Put the WUR thru some heat/cool cycles & see if exercise can get it more reproducible in terms of extension/temp.

Have put the WUR through its paces on stove and with wrenches several times over the last day, and it’s now performing predictably, if not perfectly.  Had a chat with Paul Winterton, who reinforced your suggestion to try to find a happy medium between cold and warm extensions.  I have now set the cone so that it’s just high enough to get the retainer tool into the slot at its top when at 68F, a little less than 2mm extension. The extension at 180F is about 9.5, but basically the wax element is too weak to give me more than about 7.5 mm at that temp; thus the high initial setting to allow it to get to 9.5 at full extension.  It’s holding air at light champagne bubbles at 9.5, so I intend to lube it as you suggest and reinstall it.  I think in all but the coldest environments this should provide an adequate warmup.

 

Unless you have seen a lot of these devices operating at different levels of capability it’s hard to make the judgment as to whether yours is acting acceptably.  Consulting this forum is the closest I’m going to get to seeing a lot of them. Grateful for all the inputs; I think we have an acceptable solution for the WUR and now after consulting with Paul I am moving on to ensure the throttle body and d-cam shaft are contributing their share to performance.  Once that’s done I’ll put it all back together and try tuning again. And will report back to the group. Thanks again.

[0257]

An update (you can all stop holding your breath now)!  And a couple of questions at the end for those who hang in there that long.

 

Based on some great advice from some of you, I cleaned the WUR to a fare-thee-well, lubed it and adjusted it to cheat a little on the factory setting — the cone now sits a bit proud of flush.  At 68F I can just insert the retaining plate into the gap. I am now getting close to 10mm extension at running temp, and the hose clamp test confirms that most if not all air is blocked when the cone is at full extension.

 

This was, however, not calming my variation in idle speeds and AFRs to my satisfaction.  Having disconnected/capped/plugged/gasketed and otherwise sealed every other possible point of variability I could find, I pulled the throttle body and inspected the d-cam shaft and bushings.  The shaft had about a .005 flattish spot about where Paul Winterton said it’d be, and the lower bushing was so hollowed out that even the good end of the shaft rattled around in it.  The top bushing was in better shape but you could see how the gap in the bottom bushing was allowing a lot of drift.  Not sure whether it would help, but sure I could not live with it thus, I took the throttle body to Buck Denzer at Verden Tool. Buck relocated to Sarasota a couple of years ago after running Verden in New Jersey, having taken it over from his dad.  Some of you may know Verden as an air-cooled Porsche specialist, but Buck machines everything from telescope adjustment gears to mil-spec navigation devices.

 

The solution we worked out was pretty simple — to press in a bronze bearing the full length of the lower bushing housing and to use Paul’s epoxy fix to build up the flat spot on the shaft.  The original bushing is pretty shallow — only half of the collar is used.  The longer bushing will take up most of the pressure from the shaft along the still-round parts of the shaft on either end, so the epoxy fix is really just gravy.  

 

The resulting fit is very good, and Buck cut some oil channels into the bushing (a la Einspritz’s steering box bushings).  I think the fix will outlast me.

Had to wait on the new cold start injector, and some bolts and clamps from Belmetric, to put it all back together, but when I did my idle and AFR readings calmed down by at least half; ie, the idle changes less than 15 points in either direction, and less frequently.  The AFR reading at idle similarly is more stable.  The d-cam is set at the factory position, on the edge of the 4mm hole (about which more later).

 

Of course, still ran way too rich, richer than before. It also didn’t like starting — I had to really lean out the tuna can screw to get AFR above 10 at idle, which then affected starting.   At this point, with the d-cam at its leanest position, ziss could only mean von ting: time to adjust ze Vieldverdammteverbotenschraube!!

 

Others have pointed out how difficult it is to get at the v-screw.  Some have removed hoses, intake runner, even pressure regulating valve.  I liked the idea of Paul’s special “spring” driver, but didn’t have the right spring or the sophistication to imagine where to get it. So I took an old 3mm Allen wrench, my vise and my torch, a hollow bit of tubing and some Gorilla tape, eyeballed the angles of approach, et voila le tool:

Of course, the v-screw still was a mofo to get to, and mine was rust-welded to the carrier nut. And the edges of the adjustment nut seemed to line up nearly perfectly with fuel injection lines, protrusions on the kf pump, etc., nearly perfectly preventing me from getting the wrench properly seated.  But once the joint was lubed, and the wrench seated, I could turn it just enough that another insertion from some different angle could get it inserted and turned a little further.  Eventually I got it turned 1/4 turn counterclockwise, tightened it, reset the tuna can screws and cranked.  Sure as shit everything gets leaner!  Idle tending into the mid 11s (somewhat rich?).  My ancient borrowed Gastester showed 3.6-8% CO.  Before all my fuel system work the same Gastester showed my idle mixture at 4.7%.  Whether or not it’s very accurate, I trust the trend.

 

So I took Zouave for a drive. WOT very interesting: still dependably 12.3-12.6 in 2d and 3d at 3500-5000 rpm (somewhat rich?) occasionally got up to 12.8-9, but in 4th it sometimes (not always) graduated up to 13.0 on a linear basis between 3500-5500 rpm.  Coasting and light throttle in all gears between 14.7-19, with light throttle tending toward stoich neutral. One run would be lean, another somewhat richer.  A light flutter in the exhaust while cruising in the 2800-3500 range, but no popping or banging or bucking.  The car ripped in high rpm, no hesitation on throttle.  Much healthier vibe than before.

 

After sifting through the runs and thinking about the idle CO, I decided it was still on the rich side.  I know, some will say I should be pulling low to mid 12s at WOT for max power, but I have been watching my gas gauge go down while tuning, and don’t want to get 18 mpg.  Also, I had to really twist the a/f screw to get idle as lean as I did.  Almost cancelled the idle screw.

 

So I leaned the v-screw out almost another 1/4 turn, reset the tuna can screws per the manual.  Cranked.  Car didn’t love starting but did (I think not enough idle screw).  Once the engine was warm, I fiddled with the a/f screw and idle screw till I was getting warm idle in the mid 11s/low 12s (moved around quite a bit compared to previous v-screw setting — average is high 11s — I guess you’d call this lumpy idle, but way leaner than I have seen from this car).  GasTester at warm running showed about 2.5-7% CO.  Car still runs really well, though there’s more AFR variation at idle, and maybe that 2800-3500 rpmm cruising/decel flutter is a bit more pronounced.  WOT AFR is trending a bit higher, mid 12s to 13.1, depending on gear, rpm and speed. On average, mostly mid-12s.   But the partial throttle AFRs have pegging 15-19 — and I mean often 17-19 — at any pedal position that’s not idle or WOT.   Think 1/3 throttle throwing off 17-19.   A little more burble/miss when decelerating/taking foot off gas, and a tiny bit of overrun on shutdown, but no bucking, backfiring or other misbehavior while running.  

 

So the question is: what now?  Is my WOT still too rich?  Is it possible I need to keep turning the v-screw leaner?  At the same time, my cruising and part throttle seem way too lean, even if not bucking….  I worry about over-lean cruising/partial throttle more than over-rich WOT, but are we at the point of that compromise yet?  In other words, do I need to pull the v-screw back closer to 1/4 turn from where I started?  Or is it possible that I can get the partial throttle/cruising AFRs a little richer by adjusting the d-cam further over the hole, and thereby avoid overall richening of the mixture at idle and WOT?  

 

On the whole, I couldn’t be happier with where this is headed.  But this is where KF tuning goes from art to black magic for me. Please weigh in!

 

 

 

[ray_]

Based on that ^ I'd say go back richer almost the 1/4 turn on the V screw and then tweak the idle per tuna can.

 

I think 15 max at light cruise is... max.

 

Good work!

[0257]

On 10/13/2021 at 4:10 PM, 0257 said:

An update (you can all stop holding your breath now)!  And a couple of questions at the end for those who hang in there that long.

 

Based on some great advice from some of you, I cleaned the WUR to a fare-thee-well, lubed it and adjusted it to cheat a little on the factory setting — the cone now sits a bit proud of flush.  At 68F I can just insert the retaining plate into the gap. I am now getting close to 10mm extension at running temp, and the hose clamp test confirms that most if not all air is blocked when the cone is at full extension.

 

This was, however, not calming my variation in idle speeds and AFRs to my satisfaction.  Having disconnected/capped/plugged/gasketed and otherwise sealed every other possible point of variability I could find, I pulled the throttle body and inspected the d-cam shaft and bushings.  The shaft had about a .005 flattish spot about where Paul Winterton said it’d be, and the lower bushing was so hollowed out that even the good end of the shaft rattled around in it.  The top bushing was in better shape but you could see how the gap in the bottom bushing was allowing a lot of drift.  Not sure whether it would help, but sure I could not live with it thus, I took the throttle body to Buck Denzer at Verden Tool. Buck relocated to Sarasota a couple of years ago after running Verden in New Jersey, having taken it over from his dad.  Some of you may know Verden as an air-cooled Porsche specialist, but Buck machines everything from telescope adjustment gears to mil-spec navigation devices.

 

The solution we worked out was pretty simple — to press in a bronze bearing the full length of the lower bushing housing and to use Paul’s epoxy fix to build up the flat spot on the shaft.  The original bushing is pretty shallow — only half of the collar is used.  The longer bushing will take up most of the pressure from the shaft along the still-round parts of the shaft on either end, so the epoxy fix is really just gravy.  

 

The resulting fit is very good, and Buck cut some oil channels into the bushing (a la Einspritz’s steering box bushings).  I think the fix will outlast me.

Had to wait on the new cold start injector, and some bolts and clamps from Belmetric, to put it all back together, but when I did my idle and AFR readings calmed down by at least half; ie, the idle changes less than 15 points in either direction, and less frequently.  The AFR reading at idle similarly is more stable.  The d-cam is set at the factory position, on the edge of the 4mm hole (about which more later).

 

Of course, still ran way too rich, richer than before. It also didn’t like starting — I had to really lean out the tuna can screw to get AFR above 10 at idle, which then affected starting.   At this point, with the d-cam at its leanest position, ziss could only mean von ting: time to adjust ze Vieldverdammteverbotenschraube!!

 

Others have pointed out how difficult it is to get at the v-screw.  Some have removed hoses, intake runner, even pressure regulating valve.  I liked the idea of Paul’s special “spring” driver, but didn’t have the right spring or the sophistication to imagine where to get it. So I took an old 3mm Allen wrench, my vise and my torch, a hollow bit of tubing and some Gorilla tape, eyeballed the angles of approach, et voila le tool:

Of course, the v-screw still was a mofo to get to, and mine was rust-welded to the carrier nut. And the edges of the adjustment nut seemed to line up nearly perfectly with fuel injection lines, protrusions on the kf pump, etc., nearly perfectly preventing me from getting the wrench properly seated.  But once the joint was lubed, and the wrench seated, I could turn it just enough that another insertion from some different angle could get it inserted and turned a little further.  Eventually I got it turned 1/4 turn counterclockwise, tightened it, reset the tuna can screws and cranked.  Sure as shit everything gets leaner!  Idle tending into the mid 11s (somewhat rich?).  My ancient borrowed Gastester showed 3.6-8% CO.  Before all my fuel system work the same Gastester showed my idle mixture at 4.7%.  Whether or not it’s very accurate, I trust the trend.

 

So I took Zouave for a drive. WOT very interesting: still dependably 12.3-12.6 in 2d and 3d at 3500-5000 rpm (somewhat rich?) occasionally got up to 12.8-9, but in 4th it sometimes (not always) graduated up to 13.0 on a linear basis between 3500-5500 rpm.  Coasting and light throttle in all gears between 14.7-19, with light throttle tending toward stoich neutral. One run would be lean, another somewhat richer.  A light flutter in the exhaust while cruising in the 2800-3500 range, but no popping or banging or bucking.  The car ripped in high rpm, no hesitation on throttle.  Much healthier vibe than before.

 

After sifting through the runs and thinking about the idle CO, I decided it was still on the rich side.  I know, some will say I should be pulling low to mid 12s at WOT for max power, but I have been watching my gas gauge go down while tuning, and don’t want to get 18 mpg.  Also, I had to really twist the a/f screw to get idle as lean as I did.  Almost cancelled the idle screw.

 

So I leaned the v-screw out almost another 1/4 turn, reset the tuna can screws per the manual.  Cranked.  Car didn’t love starting but did (I think not enough idle screw).  Once the engine was warm, I fiddled with the a/f screw and idle screw till I was getting warm idle in the mid 11s/low 12s (moved around quite a bit compared to previous v-screw setting — average is high 11s — I guess you’d call this lumpy idle, but way leaner than I have seen from this car).  GasTester at warm running showed about 2.5-7% CO.  Car still runs really well, though there’s more AFR variation at idle, and maybe that 2800-3500 rpmm cruising/decel flutter is a bit more pronounced.  WOT AFR is trending a bit higher, mid 12s to 13.1, depending on gear, rpm and speed. On average, mostly mid-12s.   But the partial throttle AFRs have pegging 15-19 — and I mean often 17-19 — at any pedal position that’s not idle or WOT.   Think 1/3 throttle throwing off 17-19.   A little more burble/miss when decelerating/taking foot off gas, and a tiny bit of overrun on shutdown, but no bucking, backfiring or other misbehavior while running.  

 

So the question is: what now?  Is my WOT still too rich?  Is it possible I need to keep turning the v-screw leaner?  At the same time, my cruising and part throttle seem way too lean, even if not bucking….  I worry about over-lean cruising/partial throttle more than over-rich WOT, but are we at the point of that compromise yet?  In other words, do I need to pull the v-screw back closer to 1/4 turn from where I started?  Or is it possible that I can get the partial throttle/cruising AFRs a little richer by adjusting the d-cam further over the hole, and thereby avoid overall richening of the mixture at idle and WOT?  

 

On the whole, I couldn’t be happier with where this is headed.  But this is where KF tuning goes from art to black magic for me. Please weigh in!

 

 

 

Bumping this thread, now that the pheasants are in the phreezer after a quick round-the-country tour that took us from Austin, TX to Glenham, SD to Dillon, MT, to Provo, UT, to Phoenix, AZ (thence home to Sarasota via SWA), seeing sights along the way in our touring vehicle of choice:

OK, it wasn’t Barney’s trip across Europe…. But driving this baby down twisty mountain passes in 40 mph winds is a kind of excitement of its own.  And I did get to see Old Faithful!

 

So I’m back to the question in my last post (with appreciation to Ray for his early response): turn the v-screw back further in the “richer” direction to get rid of my light-to-mid throttle leanness?  Or first, since my my WOTs are mostly still sub-13s on the AFR gauge, try adjusting the D-cam over the hole (currently sits at the edge per the book) and tuning from there?

 

If I don’t get a definitive view based on responses in the next day I will do the latter first, as messing with the verboten screw is a royal pain.

 

 

[dlacey]

I vote D cam, since your WOT is already 12.x.

 

But if you want to temporarily see what a richer verboten adjustment would be like, try putting a simple shim on the stop for the verboten screw. I use a few folded sheets of aluminium foil. That way you can experiment richer without loosing your original setting.