Tuning the weber IDF 40s Options

[malcolm2]

Built a 2.0 from a 1.8. Planning on putting it in my 72 VW Bus. The IDFs finally arrived from Covid ravaged Spain... 5 mth back order, jeez

Anyway, seems to be running great. Starts right up, idles nicely.

I do get some black smoke at idle and just as i let off of the accelerator from 3000rpm. But if I slowly release from the high revs, I get no smoke.

Engine on a stand....
Pertronix 3 module,
just over 3 fuel PSI
Idle RPM is 800
snail reading on all four is just over 10


IDFs are new from Aircooled.net. I got the bench set up from them, so they should have taken them apart, cleaned them up
added
28mm venturis
idle jets are 50
Main jets are 115

What do you think about getting rid of the smoke?


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


https://youtu.be/YvuyDxEeyxI

[bbrock]

Can't help with the tuning. I'm still learning this myself, but is that an SVDA dizzy you are running with the Pertronix 3? And what coil and spark plug wires are you running?

[malcolm2]

Can't help with the tuning. I'm still learning this myself, but is that an SVDA dizzy you are running with the Pertronix 3? And what coil and spark plug wires are you running?

Yes all purchased together...... most from Aircooled.net. The Pertronix 3 SVDA came with the flamethrower 3 module. 3 module is supposed to NOT have the key left on burn-up issue.
Coil is pertronix too: COIL 44011 Flame Thrower III 45000 volt 0.32 ohms

All require NON-Metalic plug wires.

I originally purchased copper wires.... had issues since I missed the NON-Metallic..... requirement, Aircooled has nice customer service and since I did buy the distributor from them and they directed me to....

Petronix 704101 wires, but I had to use the ends from the copper set or I suppose an option might be to use the screw on tips on your plugs. But I suppose any non-metallic wires will work.

[SirAndy]

Can't help you with the tuning either but black smoke usually indicates it running rich.

Does the exhaust smell like fuel? Did you read the spark plugs to see if they have any deposits?
(IMG:style_emoticons/default/idea.gif)

[bbrock]

Petronix 704101 wires, but I had to use the ends from the copper set or I suppose an option might be to use the screw on tips on your plugs. But I suppose any non-metallic wires will work.

Thank you! I suspect the wires are the issue although strange they seem to be working with the 050 but not the SVDA or stock dizzy. I emailed Pertronix about which wires to use but got no response from them. I'll try Aircooled.Net. They have been much more responsive.

Good luck on your tuning. Like SirAndy said, black smoke usually means rich and the four screws at the bottom of the carbs are for idle mixture. The Webber Tech Manual (by Tomlinsons) says after you have the carbs balanced and at desired idle speed, turn those screws in slowly and gently one barrel at a time until you hear the engine start to bog or misfire. Then back it out until the idle comes back up to speed and 1/2 turn further out. Then re-balance and adjust idle speed as needed. That is the extent of what I know from reading that manual so consider the source.

[flyer86d]

Petronix 704101 wires, but I had to use the ends from the copper set or I suppose an option might be to use the screw on tips on your plugs. But I suppose any non-metallic wires will work.

Thank you! I suspect the wires are the issue although strange they seem to be working with the 050 but not the SVDA or stock dizzy. I emailed Pertronix about which wires to use but got no response from them. I'll try Aircooled.Net. They have been much more responsive.

Good luck on your tuning. Like SirAndy said, black smoke usually means rich and the four screws at the bottom of the carbs are for idle mixture. The Webber Tech Manual (by Tomlinsons) says after you have the carbs balanced and at desired idle speed, turn those screws in slowly and gently one barrel at a time until you hear the engine start to bog or misfire. Then back it out until the idle comes back up to speed and 1/2 turn further out. Then re-balance and adjust idle speed as needed. That is the extent of what I know from reading that manual so consider the source.

That is the way I do it. Weber’s like to run a little rich on their idle circuit in order to get a smooth transition to the mains. I think your venturies are small for a 2 liter. 30s or 32s might be better depending on the cam.

Charlie

[malcolm2]

Can't help you with the tuning either but black smoke usually indicates it running rich.

Does the exhaust smell like fuel? Did you read the spark plugs to see if they have any deposits?
(IMG:style_emoticons/default/idea.gif)

Have not sniffed the tail pipe..... With the plug upgrade from 7 to 6, the #7s were JET BLACK and sooty. The soot would just wipe off. Have only run the #6 plugs today, so I have not pulled them yet.

I have 2 set up procedures. I am gonna go thru the LEAN BEST IDLE steps tomorrow.

[930cabman]

Subscribed, we are a week or so behind with our project. Thanks for posting

[IronHillRestorations]

Here's my carb tuning proceedure from a March 03 post:

Assumptions: the carbs have the optimum jet and venturi package (good luck on this one), the float level in the carbs is correct, the cams are correctly timed, the valves are properly adjusted, the ignition timing is dead on, you have the proper spark plugs for your engine, the linkage is good, the fuel is good, the engine is good.

Remember that the mixture and air bypass adjustment screws are precision needle valves, not head gaskets. Use your fingers to tighten them, not your fist.
Start and warm up the engine.
Make sure the two drop links for the throttle linkage are exactly the same length, and disconnected. You can use a 8mm thin igntion wrench to snap them off.
Turn the mixture screws all the way in and then 5 half turns out.
Turn the air bypass screws all the way in.
Turn the idle speed screws out til it just touches, and then in 5 half turns.
Put on your hearing protection and start the car.
Use your STE and find the barrel that pulls the most. We'll call this one baseline.
Balance the barrel in the other carb that pulls the most with the idle speed screw. (if you have a Uni-syn, give it to someone you don't like and purchase a STE airflow meter)
Go back to the other carb, with the baseline barrel. You will have one all the way in, then use the air bypass screws and balance the other two barrels.
Go to the other carb and do the same thing.
Snug the jamb nuts on the air bypass screws.
All six barrels should pull the same amount of air at this point, if not repeat air adjustment proceedure.
Snap the throttle linkage drop links back on the carbs. If the idle changes then you need to barely adjust the linkage mounts so snapping the drop links on, doesn't change the side to side idle balance.
Use the hand throttle or a vice grip and rag to lock the linkage between 1400 and 1800 rpm.
Start back at the baseline barrel and adjust the mixture screw in or out, to get the smoothest running and highest idle, then turn it in 1/4 turn.
Do the same with the five other mixture screws.
If you have to turn the mixture screws more than two turns either way, you've got the wrong jets.
Recheck side to side and individual air balance, adjust as needed.
Road test the car.
If you get snapping and poping out the intake, it's generally a lean condition.
If you get heavy exhaust fumes, or pboofing out the exhaust it's probably too rich.
If you get a flat spot or popping out the intake at between 2800 and 3200 rpm, you probably need larger idle jets.

That's a rough, five minute draft of my carb tuning proceedure, hope it helps!

If it goes good it should take about 45 minutes, if not about three years.

PK

[malcolm2]

Thanks Perry.... You posted that on another carb post I had. I printed it and I have gone thru your method several times.

The engine seems to run very nice, also idles nice. However, I get black smoke at idle and when i let off of a higher rev.

The snails are balanced at a bouncing 10 - 11.

Any ideas?

[rhodyguy]

Rather than linkage locking, just increase the idle with the ds idle speed screw. The ps will come off the stop. The linkage/carbs are now in the position they would be in while driving. Recheck flow. The bypass screws are pretty sensitive. Everytime you make an adj, pause a bit. Carbs need time to respond. Is the cross bar the type with the springs in the outboard ends?

[malcolm2]

Rather than linkage locking, just increase the idle with the ds idle speed screw. The ps will come off the stop. The linkage/carbs are now in the position they would be in while driving. Recheck flow. The bypass screws are pretty sensitive. Everytime you make an adj, pause a bit. Carbs need time to respond. Is the cross bar the type with the springs in the outboard ends?

Yes I have springs inserted in both ends of the hex bar.

Idle speed screw I get.... but what is ds and ps?

Book says to idle at 800 rpm, i am there and very smooth, not much jumping around. Are you saying to increase that with the speed screws?

[Al Meredith]

The smoking issue may go away after the engine is installed and driven and the rings seat.

[IronHillRestorations]

Can't help you with the tuning either but black smoke usually indicates it running rich.

Does the exhaust smell like fuel? Did you read the spark plugs to see if they have any deposits?
(IMG:style_emoticons/default/idea.gif)

Have not sniffed the tail pipe..... With the plug upgrade from 7 to 6, the #7s were JET BLACK and sooty. The soot would just wipe off. Have only run the #6 plugs today, so I have not pulled them yet.

I have 2 set up procedures. I am gonna go thru the LEAN BEST IDLE steps tomorrow.

I'm with Al, I'm thinking your rings aren't seated. Where the heads worked? The other possibility possibility is valve guides.

[malcolm2]

I'm with Al, I'm thinking your rings aren't seated. Where the heads worked? The other possibility possibility is valve guides.

Brand new Camper Specials from TIV store.

I am a couple months (if I lucky) from driving, so I will re-visit the smoke situation after I put a few hundred real miles on it.

Thanks all, we will talk again.

Clark