weber idf accelerator pump adjustment?

@MotoCarlo

Typically, the accel-pump is adjusted by stroke volume. For tuning my '57 1600 Super Coupe (back in the early '70s) I made a device using a pharmaceutical grade eyedropper (with cc increment markings on it) removed the rubber squeeze and plugged the opening on the delivery end of eyedropper (to retain fluid squirted into it).

I attached a thin gauge wire around the top of the eyedropper to position the eyedropper just below the acc-pump nozzle in the carburetor. Adjusted the acc-pump actuator so that it delivered a specific amount of gas at full stroke. I think a base line stroke volume would be 0.7 - 0.9cc per stroke.

Hope you find this a helpful start.

Yes sir, helpful!

I used the patented and now Industry Standard MUSBJIM method when I last set up my Dells - Easy-Peasy.

I got the syringe (no needle included) from my local CVS pharmacy (no charge if you are pleasant and smile a lot) - I think it's for irrigating a root canal.   

I'll check my Weber book for the spec on the accelerator stroke.  Stay tuned.

Thanks Gordon.

Ok, Thomlinson says that the squirt volume on an IDF should be .2cc - .3cc

Sounds kinda low, but I found it like that in two places in the book.

Gotcha. I will mess with it an d report in my results. Thanks for all the help guys!

OK. Here is how it has gone. Took the carbs off again, checked the acc pumps. I was half expecting to see the wrong diaphragm . They had the correct diaphragms (spring style). But some where during it's life someone had put the diaphragm in backwards !!!. I installed new ones correctly and badabing badaboom, that issue it taken care of.

Also here is an interesting link on how to adjust the  acc pump. (at the Kadron site)

http://www.lowbugget.com/main_page.html

I have been fighting my webers for years. Thinking of trying the Kardrons. Has anyone had any experience with them. I like the idea of having the carbs gone through before installation... ?

I have. I bought a $1000 set of Kadrons set up by “Mr. Kadron” himself (one AJ Sims, owner of the shop at the site you linked). I was disheartened by my first IDF experience as well, and wanted something simpler. The Kad-dogs had every trick Mr. Sims recommended, including the oversized throttle plates, the float vents, and blah, blah, blah. I bought his heads and his custom recurved SVDA distributor because I hadn’t wasted enough of my hard earned cash. I think I gave the man almost $3000 in 2005 money.

The heads and distributor were nice enough (except where he ported all the way through the casting and patched it with some JB Weld), but the carbs were unusable and untunable from day one. After many gyrations and much gnashing of teeth, I took them off and bought a set of Dellortos prepped by Blackline Racing (then ACE) in Salt Lake City. The Dells were love from the first turn of the key. Nothing is foolproof, but those Dells saved me from quitting this hobby before I really got started, and I’m pretty high on them to this day. I have since also learned my way around a set of IDFs as well as the Dells (the carbs aren’t so very different).

I have often thought of selling the “Mr. Kadron Specials”, for pennies on the dollar— but I would never want anyone to go through what I did with those carburetors, so there they sit. They are pure garbage. I think I keep them around to remind myself not to do stupid things just to avoid something that vexes me.

Do as you wish, but don’t say nobody warned you. 

Thank you Stan.
Dellortos are hard to find. Any word on the Empi hpmx?

Just say no to EMPI carbs.

Look for a set of Dellorto DRLA 40s on TheSamba (there aren't any right now, but they often come up). Once you find a set and buy them, order a set of Jet Doctors from CB, then buy a new set of floats from Alfa1750 on eBay (he’s Italian, and the go-to for Dellorto parts).

Install the Jet Doctors yourself, then send the floats and the carbs to Dave at Blackline Racing. $500 and a couple of weeks later, you will receive a set of carburetors that are nearly new. You can reuse all of your Weber linkage and manifolds, so there will be no additional expense, which is good because all of this will have set you back plenty already.

This is the ultimate “buy once, cry once” deal, and will cost up to $1500 in total. You perhaps wouldn’t need to spend this kind of money to make the car run right— but if you do all of this, you can definitely cross “carburetors” off the “things that frustrate me” list.

Forewarned is forearmed. 

Oh jeez, here we go again. Dellorto blah blah blah.........

Moto, don't waste your money on Dellortos. They are good carbs and every bit as tunable as Webers. I don't know if you have actual Webers or the EMPI copies, but if they run well, leave them alone. Guys with Dellortos have just as much probability with idle jet problems as Webers. The only real difference is the lack of easy access of those problem jets in a Speedster with Webers. That's it.

Jet Doctors from CB are available and help for either brand, but good air and fuel filtration are better. The best advice? Leave the darn air filters on, every time you take them off you introduce dirt to the carb tops.

I haven't touched my Webers in over a year and a half. Neither has Kelly Frazer since I synched his Weber copies last May.

I would prefer Italian or Spanish Webers rather than the clones, but like I said, if they run well.....

I do agree that I wouldn't wish Kadrons on my worst enemy.

Glad you found the problem with the backwards pump diaphragms. I "may" have done that once! 

FYI, the accel pump jets available today are zero bypass: ALL the fuel goes to the pump jet. The older ones used on almost all VW IDF carbs were 50s, as in 50 percent bypass. I couldn't get my accel pump volume right with the zero bypass. It would either fall on it's face or bog from too much, no happy medium. Put in my old 50s, and no time at all to dial them back in and drive like fuel injection. After a few minutes of normal burping warmup that is. Once warm, they're perfect.

Danny, looking at the pump jets , how can you tell if they are zero by pass or not? My carbs were new in 2003. But clearly they have been monkeyed with a lot .
So ... who knows?
I appreciate the fiy above. Thanks.

They will have a number on them. Sucks to get to them, you have to take the carb tops off and get them out of the fuel well. Break them loose with a big flat screwdriver.  Then I remove them with a screw-holding screwdriver.

They used to be available in a bunch of sizes according to my Tomlinson book.

2003? Probably 50s.

DannyP posted:

Oh jeez, here we go again. Dellorto blah blah blah.........

FWIW, the only reason I advised the Dells was he was considering Kadrons over continuing with Webers. There's nothing magic about either-- they are basically the same carbs (aside from the idle jet thing). No aggression intended. Give me some credit, dude.

For anyone not well versed in VW performance carburetion basics, trying to follow this conversation and trying to make heads or tails of the Great Kadron/Weber/Dellorto Debate- 

Kadrons come as a reasonably low budget dual single barrel carburetor kit and are a great step up from stock single carburetion. The long intake manifold tubes make the stock set up far from ideal. With their much shorter manifolds the Kadrons can feed a stock or slightly modified/lightly cammed up to 2 liter engine better throughout the rpm range with superior power/throttle response/mileage (as long as you keep your foot out of it) and cooler running as the result. If you can adjust a single carburetor properly you should be able to set up and tune Kadrons. 

Things to watch out for- while kadrons will rev higher and make more power than a stock center mounted carburetor, they do have their limits. With an engine cammed to make power to 5500 or above some people find the uneven idle a little disconcerting and sometimes the immediate off idle performance a little lacking. When they get some mileage on them the throttle shafts begin to wear the carburetor bodies (there are no throttle shaft bushings or bearings) and they get harder to tune, as now they are sucking un-metered air into the carbs. The fix is to get the carb bodies bushed (Kaddy Shack and others do this). The linkage also wears with age, but there are parts for that as well.

I've been told (by someone who's information I trust) that grinding out the inner wall between the 2 ports in the intake manifolds to within about an inch of the head end makes them idle smoothly like Webers/Dellortos with no ill effects. And per Stan's experience, stay away from extensively modified Kadrons- I have heard other people voice the same frustrations.

DCNF and IDF Webers are another step up- with 1 carburetor throat per intake port you can tune the engine just that much better. Even an engine that goes to 6500 or 7,000 rpm with power will be relatively docile in traffic and give good mileage figures if the combo is correct and it's properly tuned (and you keep you foot out of it most of the time). IDF's are way more common than the older DCNF's, have a more modern, superior float design and come in 4 different sizes (36, 40, 44 and 48 mm), but having driven Michael McKelvey's 2100 cc powered car with DCNF's I can tell you that the shortcomings seem to be very slight. Mike- your car goes pretty nice! _{(think big, evil laugh here!)}

I consider Dellortos an ever so slightly improved version of IDF's- the Del's have 1 more idle to main circuit transition hole and don't seem to suffer from plugged idle jets like the IDF's do, but both (when properly sized and tuned) will make the same power on an engine. Although a little more involved, if you've tuned Kadrons you can tune Webers or Dellortos.

Ok, time for bed it is...

I actually did a search on this site about carbs, before mentioning that I am considering a change. This is has been a looong debate.I understand that there are pros and cons to each and everyone's situation and engine are different. I appreciate everyone's input. Thanks. 
I have learned a lot and now am going to focus on my acc pumps' function . But frustration builds, and it is always good to know others have had carb problems too.

"Misery loves company." :-)

Back to the ACC pump. Here is a good video showing how to adjust a Holley Carbs acc pump. The good thing here for us is,  it explains how it works and since the Holley is so adjustable, the symptoms for too much gas vs too little, etc.
Worth watching.

https://www.youtube.com/watch?v=w3F3ssOb8lg

Stan Galat posted:

DannyP posted:

Oh jeez, here we go again. Dellorto blah blah blah.........

FWIW, the only reason I advised the Dells was he was considering Kadrons over continuing with Webers. There's nothing magic about either-- they are basically the same carbs (aside from the idle jet thing). No aggression intended. Give me some credit, dude.

Dude, you get lots of credit. More than most. Glad you talked Moto away from those Kadrons.  

Moto, if you can't get those IDFs to behave then EFI is the answer.

Gordon Nichols posted:

Ok, Thomlinson says that the squirt volume on an IDF should be .2cc - .3cc

Sounds kinda low, but I found it like that in two places in the book.

No, that is about right. I adjust mine up until it bogs(right around .3cc). Then back them off (even turns both sides) until it stumbles(sounds like it's going to stall). Then add just enough until the stumble goes away. You're done.

If you need a big bo-honkin' squirt, something else is wrong.

Here is the bench setup as described by Empi. The measuring method mentioned is, of course, the best. But this could be a good place to start.

Just to run this topic into the ground ... :-)
Here is a good way to dial in the AC pump via the 356 forum.

http://forum.porsche356registr....php?f=1&t=36836