Weber Set-Up and Tune Discussion - Page 43 - JeepForum.com
Search  
Sign Up   Today's Posts
User: Pass: Remember?
Advertise Here
Jeep Home Jeep Forum Jeep Classifieds Jeep Registry JeepSpace Jeep Reviews Jeep Gallery Jeep Clubs Jeep Groups Jeep Videos Jeep Events Jeep Articles
Go Back JeepForum.com > Models > Jeep CJ Forum > Weber Set-Up and Tune Discussion

ANOTHER Rockridge4wd Creation!! Spare Tire Carrier Delete ROCKRIDGE4WD Introduces a NEW Jeep Wrangler JK *led* tail Engo winches available at www.rockridge4wd.com! Free shipp

Reply
Unread 05-22-2014, 09:01 AM   #631
Matt1981CJ7
Web Wheeler
 
Matt1981CJ7's Avatar
1981 CJ7 
 
Join Date: May 2011
Location: Elbert, CO
Posts: 10,691
rodaton,

Sorry for getting caught up in the carb squabble, and neglecting your question.

Shawn posted this excellent test for the idle circuit way back on post #198. Have you tried it?

Quote:
I recently ran what I believe is a much more relevant test for determining the best idle jet size and I thought I'd share it.

To give you an idea why, and I'm not trying to undermine Redline's tuning methods at all, it didn't make any sense to me to use some arbitrary mixture screw setting with the engine idling to accurately determine the best idle jet size the engine wants when it's actually running down the road.

The test: After driving the Jeep around so it's good and warm, wheel back in and do your best at finding the lean-best idle as described earlier. Using the speed screw, increase the engine speed to 1,400 rpm. This forces the carb into its progression circuit where the engine spends 90% of its time, not at idle. Now, turn the mixture screw(s) in a half turn and note any change in rpm and/or engine sound. Return the screws to where you started and then turn them out a half turn. Again, noting any change in rpm or engine sound. Take the screws back to their starting position and return to idle.

If the engine responded with a cleaner sound and/or more rpm when the mixture screws were opened, you may benefit from a larger idle jet. If the engine responded with a cleaner sound and/or increased rpm when you turned the mixture screws in, a smaller idle jet may be in order.

To quantify that idea with actual findings, I started with 45 idle jets and 1.85mm idle air bleeds. Don't let the air bleeds throw you off too much; it's basically a leaner 50 idle jet that pulls richer towards the top end of the progression circuit than a 45 would. At 1,400 rpm, turning the mixture screws out a half turn really had no impact. However, turning them in less than a quarter turn resulted in a quick drop in rpm and the engine basically choked. Had I not been maxed out on my idle circuit, I'm positive an increase in fuel from the mixture screws would've made a difference in rpm. This particular test shows that the engine wants more fuel. My wide-band air/fuel monitor showed full lean, over 16:1 before touching the mixture screws.

Next test: Installed 50 idle jets and went through the lean-best idle procedure again. Brought the engine back up to 1,400 rpm and took the mixture screws out a quarter turn. No change in rpm or sound. Mixture screws back to the starting position and then in a quarter turn. No change in rpm but a slightly cleaner sound. Took them in another quarter turn and the rpm started to drop and the engine sounded rougher. This tells us that the engine has enough fuel by it not responding to giving it more with the mixture screw and it also tells us what our window is for going leaner by it dropping rpm at a half turn in on the mixture screw. The air/fuel ratio before touching the mixture screws was 14.2:1. Good! Now we know where the lean spot is and where it no-longer responds to more fuel.

Final test: Installed 60 idle jets and went back through the lean-best idle procedure. Again, 1,400 rpm with the speed screw. Take the mixture screws out a quarter turn, no response in either sound or rpm. Turn them in a quarter turn from the starting point and only a vague improvement in sound, being a little cleaner. Another quarter turn in showed another barely detectable improvement in sound. This tells us that the engine is getting more fuel than it wants by not responding to additional fuel from the mixture screws and barely a slightly better sound from reducing the fuel with the mixture screws. Obviously, the volume of fuel being delivered by the 60 idle jets was so much that a smaller, controlled amount being added to or removed from the total by adjusting the mixture screw had very little to no impact. To visualize the scenario, adjust the little flow gate on a river dam that's already overflowing. The engine sounded sluggish and 'heavy' with these jets. Air/fuel ratio before touching the mixture screws was 11.8:1 Really?

The whole point with this test is that not everyone wants to spend $300+ on a wide band air/fuel monitor and the typical "X amount on the mixture screw at idle is perfect while driving" setting leaves a little to be desired. It does take a good ear and "feel" for what the engine is telling you but it's pretty damn accurate. Hopefully this helps bridge the gap by providing a more accurate means of sizing your idle jets.

Any and all thoughts are greatly appreciated, of course!

Matt

Matt1981CJ7 is offline   Reply With Quote Quick reply to this message
Unread 05-22-2014, 11:43 AM   #632
uptillnow
Senior Member
 
uptillnow's Avatar
 
Join Date: Mar 2009
Location: Placentia, California
Posts: 515
Quote:
Originally Posted by Matt1981CJ7 View Post
Not that I'm aware of. Perhaps UTN can confirm.

Comparing a Weber 38 and a BBD is like comparing a Rolex and a Timex. They both tell time, but there's no comparison in design and quality, IMO.

Matt
Thanks Matt,

The only "clone" "Copy" that I know of is from EMPI.

EMPI, does not claim they are qenuine Weber, they claim they make theirs in China.

I like that, they are "empowering" the consumer to make their choice, not the deception that goes on with those guys selling the WK carburetors and conversion kits.

uptillnow is offline   Reply With Quote Quick reply to this message
Unread 07-09-2014, 08:47 AM   #633
bdatkins
Registered User
1978 CJ5 
 
Join Date: Aug 2011
Location: Munster, Indiana
Posts: 328
Gentlemen,
I am getting ready to swap out the single barrel intake and exhaust manifold from my '78 and replace it with a two barrel one from an '83. Right now I have single barrel adapter for my weber 32/36. Below is a photo of the current setup. Ignore the arrows. They were there to point out another problem. My questions are 1) will I need a new/different adapter or spacer plate? 2) Do you think I will see any improvement in performance by going with the two barrel intake?
20131010_092810_zpsd870010a.jpg

bdatkins is offline   Reply With Quote Quick reply to this message
Unread 07-09-2014, 09:52 AM   #634
John Strenk
Moderator
 
John Strenk's Avatar
1976 CJ5 
 
Join Date: Feb 2005
Location: Shalersville Ohio
Posts: 13,164
1. Yes, you will need a weber 2 bbl to small two barrel adapter.

Something like this:

http://www.jeep4x4center.com/weber-c...99004-551.html



2. ???

A new BBD would be better than the 32/36 or get a 36/36 Weber conversion and sell your old 32/36 1bbl conversion.

[Edit] Weber 38/38 [/edit]
John Strenk is online now   Reply With Quote Quick reply to this message
Unread 07-09-2014, 10:27 AM   #635
bdatkins
Registered User
1978 CJ5 
 
Join Date: Aug 2011
Location: Munster, Indiana
Posts: 328
Do you mean 38/38?
bdatkins is offline   Reply With Quote Quick reply to this message
Unread 07-09-2014, 01:00 PM   #636
John Strenk
Moderator
 
John Strenk's Avatar
1976 CJ5 
 
Join Date: Feb 2005
Location: Shalersville Ohio
Posts: 13,164
Quote:
Originally Posted by bdatkins View Post
Do you mean 38/38?
Yeah... Sorry, thinking of something else at that moment...
John Strenk is online now   Reply With Quote Quick reply to this message
Unread 07-09-2014, 01:14 PM   #637
delirious1
Registered User
1982 CJ7 
 
Join Date: Aug 2012
Posts: 291
there's a lot to read hear, so I'll go ahead and ask the question. First, thanks for this post.

I have a weber 32-36. I read on the first page, that in order to find max idle adjustment, you turn the screw clockwise until it makes contact with the linkage and then advance until the "s" port is just uncovered on the bottom of the carb. Then adjust the mixture. I'll have to figure how to do this with the carb on. I would assume just start adjusting idle screw, up to and no more than 1 1/4 turns.

What if you have AC? Problem I've been having is that the AC will decrease idle speed and cause a rough idle and vibration. How would you approach this?

Problem that I've discovered with the weber is that there is no sol-vac unit to kick up idle when you activate the AC. By adjusting the carb with the AC on, wouldn't you be making sure that the engine will pull from the idle circuit rather than the progressive circuit? In other words, better to adjust carb with AC on, instead of setting up the carb with the AC off and then increase the idle speed screw to compensate for the AC?

When I get home, Ill tune the carb according to the first page of this post. The problem I foresee is getting idle screw and mixture set and then turning on the AC and getting a little vibration at idle or rough idle because of RPM decrease. Any suggestions in this case? Should the carb be tuned with the AC on?
delirious1 is offline   Reply With Quote Quick reply to this message
Unread 07-09-2014, 01:45 PM   #638
John Strenk
Moderator
 
John Strenk's Avatar
1976 CJ5 
 
Join Date: Feb 2005
Location: Shalersville Ohio
Posts: 13,164
I think the idea is fine but you will have to see what the RPM is without the AC and Headlights on. It may be higher than you think.

It would be nice if you could find a solvac or something like that off an old Fiat or something.
John Strenk is online now   Reply With Quote Quick reply to this message
Unread 07-09-2014, 01:47 PM   #639
delirious1
Registered User
1982 CJ7 
 
Join Date: Aug 2012
Posts: 291
Quote:
Originally Posted by John Strenk View Post
I think the idea is fine but you will have to see what the RPM is without the AC and Headlights on. It may be higher than you think.

It would be nice if you could find a solvac or something like that off an old Fiat or something.
I'll know more this afternoon when I get home and can tinker. I'm doing a lot or reading this afternoon while at work. I'm the boss, so...
delirious1 is offline   Reply With Quote Quick reply to this message
Unread 07-09-2014, 08:09 PM   #640
delirious1
Registered User
1982 CJ7 
 
Join Date: Aug 2012
Posts: 291
Just a follow up. I set the 32/36 according to specifications. Had to adjust idle up to account for AC. I called redline weber this morning and got a return call this afternoon. Guy recommended a jet pack re calibration kit for 60 bucks to go along with my carb kit I have ordered. He explained that the modern gas is high octane and it's needed. So, I ordered one.

Anyone know what idle jets come stock in the 32/36?

I'm half way through this thread and learning. Thanks to everyone's input.
delirious1 is offline   Reply With Quote Quick reply to this message
Unread 07-10-2014, 11:29 AM   #641
delirious1
Registered User
1982 CJ7 
 
Join Date: Aug 2012
Posts: 291
One other question. Noticed from previous posts the timing was set at BTDC 10 degrees and manifold advance. I have mine set at 5 degrees as specified by the sticker on the hood. I am assuming this of for stock. Should it be at 10 degrees and why different from 5 degrees? I've had the emissions system gutted. I assumed this was done when the weber 32/36 was installed.

second question, Where are you guys porting the manifold on the 258? Any pictures?
delirious1 is offline   Reply With Quote Quick reply to this message
Unread 07-10-2014, 12:02 PM   #642
John Strenk
Moderator
 
John Strenk's Avatar
1976 CJ5 
 
Join Date: Feb 2005
Location: Shalersville Ohio
Posts: 13,164
should be 10* before you hook up the manifold vacuum...
John Strenk is online now   Reply With Quote Quick reply to this message
Unread 07-10-2014, 12:11 PM   #643
Mike Romain
Registered User
1986 CJ7 
 
Join Date: Nov 2007
Location: Off the Grid in Chester Grant, Nova Scotia, Canada
Posts: 13,741
Quote:
Originally Posted by delirious1 View Post
One other question. Noticed from previous posts the timing was set at BTDC 10 degrees and manifold advance. I have mine set at 5 degrees as specified by the sticker on the hood. I am assuming this of for stock. Should it be at 10 degrees and why different from 5 degrees? I've had the emissions system gutted. I assumed this was done when the weber 32/36 was installed.

second question, Where are you guys porting the manifold on the 258? Any pictures?
Well.... Lots of folks here are sure that manifold vacuum is best for running. It advances the timing at idle for a smooth idle so when you tromp on the gas the timing dives and the takeoff is real nice and smoothly slow.

All the Jeeps I helped remove the computer from all had to pass emissions and I put them all to ported vacuum with the base advance at 9. That way when you tromp on the gas, the timing jumps up and it will peel tires taking off. When tuning I put a beverage glass on the air filter looking for no ripples, so it is nice and smooth too.

Same deal for emissions, I tried manifold vacuum for a while and when I took it in for emissions it failed miserably. While the tech was writing up the fail, I quickly set it back to ported and reset the carb speed, then had him test it again. He laughed saying I needed more than that to pass. Nope. Bingo! Passed with flying colours.

All of us that I helped nutter (computer bypass) also report over 20 mpg with the folks running stock tires getting 25+. I currently have two 4.0 HO engines running the stock BBD carb and stock 258 distributors on ported vacuum giving 25 mpg and passing emissions.

Even wiki says that manifold vacuum is best for a cold engine, but once it warms up, ported is better. When I got mine in 98, it was set up that way using the CTO valve. It would switch from manifold to ported when warm.

I would highly recommend you try both ways to see the difference for yourself.
__________________
Mike
86/00 CJ7 Laredo, 33x9.5 BFG AT's, 'glass nose to tail in '00, 'New' frame,wires and plumbing in '09. Carter BBD Carbed 4.0 HO in '10.
89 YJ Renegade. BBD Carbed 4.0 HO. Locked front and rear with 33x9.5 BFG AT's
Some Canadian Bush Jeep Runs and Build Photos: http://mikeromainjeeptrips.shutterfly.com (10 new albums added Sept 16/10)
Mike Romain is online now   Reply With Quote Quick reply to this message
Unread 07-10-2014, 12:19 PM   #644
delirious1
Registered User
1982 CJ7 
 
Join Date: Aug 2012
Posts: 291
Quote:
Originally Posted by Mike Romain View Post
Well.... Lots of folks here are sure that manifold vacuum is best for running. It advances the timing at idle for a smooth idle so when you tromp on the gas the timing dives and the takeoff is real nice and smoothly slow.

All the Jeeps I helped remove the computer from all had to pass emissions and I put them all to ported vacuum with the base advance at 9. That way when you tromp on the gas, the timing jumps up and it will peel tires taking off. When tuning I put a beverage glass on the air filter looking for no ripples, so it is nice and smooth too.

Same deal for emissions, I tried manifold vacuum for a while and when I took it in for emissions it failed miserably. While the tech was writing up the fail, I quickly set it back to ported and reset the carb speed, then had him test it again. He laughed saying I needed more than that to pass. Nope. Bingo! Passed with flying colours.

All of us that I helped nutter (computer bypass) also report over 20 mpg with the folks running stock tires getting 25+. I currently have two 4.0 HO engines running the stock BBD carb and stock 258 distributors on ported vacuum giving 25 mpg and passing emissions.

Even wiki says that manifold vacuum is best for a cold engine, but once it warms up, ported is better. When I got mine in 98, it was set up that way using the CTO valve. It would switch from manifold to ported when warm.

I would highly recommend you try both ways to see the difference for yourself.
will do mike. and you are probably going to laugh after helping me out, but I decided to get a weber 38 instead. After considering the cost of the jet kit and rebuild kit for the weber 32-36, I can get a Weber 38 DGAV for 299. I also decided to get a jet pack kit for that instead. I know I originally didn't want to put much into it but after reading about the 32/36 and the 38, I decided to go with the 38 based on the 33 inch tires I have. I have 4:11 gears. It's peppy but struggles some on hills. Figured, why not. I'll compare those vacuum spots.

Thanks John for the info as well
delirious1 is offline   Reply With Quote Quick reply to this message
Unread 07-10-2014, 12:33 PM   #645
Mike Romain
Registered User
1986 CJ7 
 
Join Date: Nov 2007
Location: Off the Grid in Chester Grant, Nova Scotia, Canada
Posts: 13,741
Quote:
Originally Posted by delirious1 View Post

will do mike. and you are probably going to laugh after helping me out, but I decided to get a weber 38 instead. After considering the cost of the jet kit and rebuild kit for the weber 32-36, I can get a Weber 38 DGAV for 299. I also decided to get a jet pack kit for that instead. I know I originally didn't want to put much into it but after reading about the 32/36 and the 38, I decided to go with the 38 based on the 33 inch tires I have. I have 4:11 gears. It's peppy but struggles some on hills. Figured, why not. I'll compare those vacuum spots.

Thanks John for the info as well
Someone mentioned a source for a sol-vac unit that will work on Weber carbs. That might be your ticket for a smooth idle. Or you could just go old school and use a choke cable as a manual fast idle for when you have the AC on. Just have a stop on the cable so it only pulls so far and stops or a bicycle gear changer lever and cable, they have a positive click stop in them.
__________________
Mike
86/00 CJ7 Laredo, 33x9.5 BFG AT's, 'glass nose to tail in '00, 'New' frame,wires and plumbing in '09. Carter BBD Carbed 4.0 HO in '10.
89 YJ Renegade. BBD Carbed 4.0 HO. Locked front and rear with 33x9.5 BFG AT's
Some Canadian Bush Jeep Runs and Build Photos: http://mikeromainjeeptrips.shutterfly.com (10 new albums added Sept 16/10)
Mike Romain is online now   Reply With Quote Quick reply to this message
Reply

Quick Reply
Message:
Options

Register Now

In order to be able to post messages on the JeepForum.com forums, you must first register.
Please enter your desired user name, your email address and other required details in the form below.
User Name:
Password
Please enter a password for your user account. Note that passwords are case-sensitive.
Password:
Confirm Password:
Email Address
Please enter a valid e-mail address for yourself.
Note: All free e-mails have been banned due to mis-use. (Yahoo, Gmail, Hotmail, etc.)
Don't have a non-free e-mail address? Click here for a solution: Manual Account Creation
Email Address:

Log-in

Human Verification

In order to verify that you are a human and not a spam bot, please enter the answer into the following box below based on the instructions contained in the graphic.


Thread Tools


Suggested Threads





Jeep, Wrangler, Cherokee, Grand Cherokee, and other models are copyrighted and trademarked to Jeep/Chrysler Corporation. JeepForum.com is not in any way associated with Jeep or the Chrysler Corp.