Comparing fuel injection and carbs

Ron:

 

I've got 40mm dellortos and the last time I had to do something about a clogged jet was around 2004, when I still lived in Rhode Island.  No kidding - they don't give me any troubles at all, other than an occasional intake manifold gasket leak.

 

Just thinking back on my computer days, though, I assume that the injection ECU is in the engine compartment.  Could it be moved someplace cooler by using a longer wiring harness or a jumper cable?  Even if it was temporarily in the rear seat area to isolate it from heat.

 

The other thing that comes to my EFI mind is a weak or defective O2 sensor.  Or at least it seems that the ECU is happy with the O2 sensor when it (the sensor) is cold but then gets a less reliable signal when warm. Have you tried another sensor?

 

Gn

 You really have to put in a wideband gauge to figure out where your issue is,whether you are having a air/fuel or timing problem.

 I have tuned almost 2 dozen cars with stand alone and some 4 & 6 cylinders over 500 bhp,and there is a lot to it,you hace to get it to start/idle/transition/cruise/full power WOT,and not melt pistons,so it is not the easiest thing unless you are experienced with it.

 The things it sounds like you need to work on are your engine temperature enrichment values,accel pump settings via the throttle position,and maybe some timing adjustments.

 If you are close to any tuner shops try to find obne that is knowledgable with stand alone EFI,and if they know their stuff,your car is a easy tune,since you are NA and relatively low power/street car.

 It is all about the combination. Like I mentioned previously in another post,do not try to run it as lean as a modern car,ACVW is a dinosaur and likes a little richer afr IMO.

 One thing to think aboutr is a cold engine requires a richer mixture than a warm engine,so if it runs badly when warm,you may have a excessivekly rich AFR,OR your temp sensor is in a bad spot and giving a VERY HIGH temp reading which the computer will EXCESSIVELY LEAN OUT the afr even though the engine is not "that hot".    Maybe for fun try a different location/sensor for your temp readings,since most VW temp0 sensor sare in the head vs. a water jacket which will not get "as hot" as a VW head.

I feel for your problem, Ron but I just couldn't live with it. Just don't have the patience to even try. I like life simple and I put thousands of miles with a smile on my face with a very simple carb setup. I had a 1915 built up by respected builder on the East Coast and it came with a dirt simple center mounted Weber 32/36. I had to frig with it a bit with the jets to counteract/get amigo with the electronic 009 distributor but I made it work. 10,000 miles on that carb and not one adjustment. Now...I install a 2.2 litre Soob, rip out the entire fuel injection system because I don't want to go thru the learning curve and mount the same Weber 32/36 on a very

slightly modified stock Soob manifold and guess what? Not even one jet change...we just drove the car from Ottawa, Canada to Key West and back. 39.1 MPG US. About 4,300 miles counting all the excursions on the trip. The choice is yours but simple alternatives are out there.  And, yes...that carb has been from 10 feet to 9,200 feet without complaint.

In retropect, JamesBondSilver has stated a very succicint pool of advice which still might cause you a **** load of frustration ( no end to this ?)  ( $$$ ) to figure things out. New Weber 32/36's are under $300. YMMV etc....

Thanks for the comments and advice.  Gordon, my ECU is in a hidden compartment underneath the rear seat.

JBS, you've raised some good point, which I will be discussing with CB in the near future.

David, I miss my old Kadrons that fueled my stock 1970 Beetle for 60,000 miles, with ZERO problems.  I had them adjusted every couple of years-that's it. Having said that, I realize that Kadrons wouldn't work very well on my 2275.

Ron

Ron,

 

JBS is spot on. Your leaning out or going too rich when it is hot. Keep asking questions, between JBS and myself I think we can get you through this. EFI is the best and once tuned, your going to LOVE it.....

 

I'm on holidays in a week, so I'll be able to spend more time on my problem.

Thanks for all the advice.

Ron

Ron--good luck with your problem---it's really a pain when something isn't working as well as it should.

 

I'll echo what Gordon and David said.

 

At 11,500 miles with my 1915 with Kadrons I swapped engines for a Type IV that started out with Empi Weber knockoffs.  Neither the Kadrons nor the Empi's gave me any trouble at all .

14,000 miles ago I swapped the fake Webers for real Dellorto 40s  that had been blueprinted by the master, Art Thaen.  Jake Raby had them and was planning to use them himself.  He wanted to dyno my car with the Dells and said next time I was in his area to let him swap them out, an offer I jumped at.  Jake obtained  his data logging off my engine and for the Empi's I got a great set of Dells installed by someone who knows what he's doing.  Quite a deal for me!  Well I have 14,000 miles on the Dells and haven't touched them. I check my A/F ratio with a meter occasionally and they are still at 13:1 at 70-75 mph on a level road.  Mains are 140s, Idles are 65 and air correctors are 180. The transition from idles to mains is so smooth you can't tell when it happens.  At this point I can't see any advantage for me to go to FI. I just got 26 mpg for the 2,626 mile Carlisle trip doing 75-80 all the way so carbs have been beddy beddy good for me.

 

 

Hey ROblack...

 

Which CB fi system is it?  The old style with the in car adjustable box...or the self learning system?

 

I have a dual dellorto drla 40 setup that Im not using....if u wanna trade??

 

Mike

 

Ron, I have Spanish Weber 44 idfs on my type 1 2165 cc. After 30 seconds of warmup you would never know I have carbs. Idles smooth and pulls great from any speed or throttle opening. Cruises well and WOT is amazing.

When do I mess with them? Only to check them each year after my spring valve adjustment. Plugged jets? With clean air and fuel almost never, like once two years ago. No slop/no wear linkage is as important as clean fuel and air.

Ask anyone who has ridden in or driven mine if I need any changes.......but I do want to try efi someday. It is work, but you can get it if you stick with it. A wideband gauge or a tuning shop with aircooled experience will do it for you. Otherwise you'll be wasting time and getting frustrated.

Danny---screw the fi..  If that car of yours gets any quicker it will be against the law!

Ron:  I thought you were close to that magic number?

Thanks Mike, I'll keep you in mind if I end up swapping out my EFI system.

My EFI is the new kit with an ECU.

Danny, I don't think I'll need a wideband gauge, as my Quick Tune EFI has a wideband display when I hook up my laptop.

 

Here's my dyno run that I did last year.  Any comments?

 

Appears Rich to VERY Rich. Idle should be in the 14's. Full throttle should be 12.7 to 13.2. You should try to get the mid range to 15+.

I plan on emailing CB my dyno run.

It's hard to see on the graph, but the AFR ratio starts dropping at around 3500 rpm and bottoms out at 10.3 around 4000 rpm.  Notice the torque and horsepower take a dip around the same rpm.