engine and drivetrain Weber 38/38 Tuning

[jimk]

1 hour ago, wtinker said:

the lean stumble coming off idles.

This is the transition load transitioning from the idle to main jets.  The idle jet is too small.  Increase and readjust idle mixture screw for best idle.

The other points are excellent!

Edited May 22, 2017 by jimk

[wtinker]

Thanks!  I think I have those so I can give that a try tonight!

[wtinker]

On 5/22/2017 at 9:43 AM, wtinker said:

5/17/2017b:           50         170      135        F66                 Cruses at 14-15,   13-14 on medium accel, 12 on max axcel,  still 18+ lean stumble 

                                                                                             light pedal

 

I need to order some smaller Airs so see what that does.   I fell like I aught to stay with the F66 since the majority of you all did good with it.

 

I'll welcome any suggestions to fix the lean stumble......

 

OK....  finally had chance to report back.

             IDLES   AIRS   MAINS   ETUBEs

Now:       55       170       135        F66

 

Best over all running.  Idles happiest at 13:1 with about 1 +/- turn on each screw,   Cruises 14-15:1,  WOT is 12-12.5:1.  Pulls like horse to 7,000 rpm.    Still have a lean stumble when mild accel after steady speed but..... far less than before. 1,500 RPM to 3,500,  lower the RPM the worse it is.  

 

With the 1 turn on the idle screws should try larger idles?   Any thoughts?

Edited August 11, 2017 by wtinker

[Simeon]

9 hours ago, wtinker said:

 

OK....  finally had chance to report back.

             IDLES   AIRS   MAINS   ETUBEs

Now:       55       170       135        F66

 

Best over all running.  Idles happiest at 13:1 with about 1 +/- turn on each screw,   Cruises 14-15:1,  WOT is 12-12.5:1.  Pulls like horse to 7,000 rpm.    Still have a lean stumble when mild accel after steady speed but..... far less than before. 1,500 RPM to 3,500,  lower the RPM the worse it is.  

 

With the 1 turn on the idle screws should try larger idles?   Any thoughts?

 

 

Remember WOT is benefiting from huge gobs of fuel squirted in by the pump jets. What the difference in driving between the 'cruises at 14-15:1' and when this stumble happens? 

 

What's the AFR at the time? Does it react fast enough? I am going to ask you what your ignition is like and how you know it's working properly?

[wtinker]

42 minutes ago, Simeon said:

Remember WOT is benefiting from huge gobs of fuel squirted in by the pump jets. What the difference in driving between the 'cruises at 14-15:1' and when this stumble happens? 

If I'm driving in city, lets say 3rd gear (5 speed) at 2,800 RPM the ATF is good around 14:1.  ease into throttle and ATF go real lean at 16-18:1 and then catches up.  I eliminate this by blipping the throttle.    If I was running my old 4 barrel V8 I'd be looking at the accel pump.

[wtinker]

51 minutes ago, Simeon said:

am going to ask you what your ignition is like and how you know it's working properly?

I've got a 123 and am currently running the attached TI curve found in the Shop Manual and it seems to work pretty good.

Vern1.pdf

[Simeon]

Have you checked your power valve in the carb?

[wtinker]

First off, thanks for the replies.

 

Actually no.   Have not seen bowl draining.  other than that what should I check?

[N2MY2002]

This thread has been very insightful. I have read through it twice and followed several links attached to it. I recently bought a 72 2002 that the owner tried to rebuild a 32/36 and quit and sold me the car. So, now that the carb is in 100 pieces, and I have ZERO experience with carbs, this is completely new to me. 13 years in e30s but carb work on them. So, upon recommendation, I purchased a brand new 38/38.

 

As far as I know, the engine is completely stock. It looks as if there is all sorts of combos for the swappable bits that work...for better or worse. Can this carb work out of the box?

 

I see many people running a AFM meter and seems to be a useful tool, any recommended brands?

Cheers!

[Bibm5]

On 10/5/2017 at 12:38 PM, N2MY2002 said:

 

As far as I know, the engine is completely stock. It looks as if there is all sorts of combos for the swappable bits that work...for better or worse. Can this carb work out of the box?

 

Im in the same boat here. I have a stock 74' with a solex on it now. Im considering buying a K204-38 DGES which comes with a manifold. Its brand new, whats my chances of getting positive results right out of the box? 

Edited October 16, 2017 by Bibm5

['76mintgrün'02]

 

11 minutes ago, Bibm5 said:

comes with a manifold.

is that a heated manifold?

 

 

[Bibm5]

 

is that a heated manifold?

 

 

I'm not sure. I'm still in the newbie phase. Can you tell from the pics? And what's a fair price to pay for this package? Funds are running thin on this project so I don't want to over pay!

 

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['76mintgrün'02]

I believe the large opening in the center is a coolant passage... which is good.

Coolant, as in heatant.

 

Now you just need to buy an adapter and modify a stock air cleaner to fit the Weber, so you can suck cold air in through that heated manifold  

[rstclark]

I’ve had a sage old BMW specialist say he was concerned that the stock air cleaner may restrict air flow for a 38/38 Particularly with the stock hose connector to the snorkel Anyone have any technical knowledge about a This ?

Im about to install a 150 hp build m-10 and would use a stock air cleaner if it would work. Otherwise I’ll go with the little K&N which I’m not a real fan of.the only good side is it makes it easy to adjust the carb 

[Bibm5]

I believe the large opening in the center is a coolant passage... which is good.
Coolant, as in heatant.
 
Now you just need to buy an adapter and modify a stock air cleaner to fit the Weber, so you can suck cold air in through that heated manifold [emoji4] 

Ok, im confused now. I need to do a bit more research on the 38 & what it needs. This kit was advertised as a direct install on a 73' and up 2002. Im not sure i want to have to buy more stuff to make it work. Does the air cleaner that comes in the kit not work for our cars?

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