What do I need to make a Holley carb work on stock 258 manifold - Page 4 - JeepForum.com
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post #46 of 60 Old 06-11-2019, 04:18 PM
whollsee
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Hey Agear, have you abandoned your original weber thread?


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post #47 of 60 Old 06-11-2019, 04:36 PM
Shawn Watson
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We've got a Nissan Altima with a four cylinder, only a couple of years old, and the idle dips and recovers when you come to a stop with the a/c on. Are you sure you're not getting overly picky? I'm overly picky and I have to check myself once in awhile.


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post #48 of 60 Old 06-11-2019, 07:43 PM Thread Starter
agear
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Thank you for the follow up .

I think you do. My needle comes off its resting spot but does not make it to the 1 mark.

This is kinda a new issue and 1 reason I'm looking into another carb so I just posted it here rather than my last Weber thread.

I'm not sure if I'm being picky but with my needle dropping well below 500 when I let off the gas when the a/c is on and even stalled out before and it doesn't always do it and sometimes stays low for a little while so it makes me think there's a problem with my carb but on the other hand my idle is set at 650 when the a/c is off
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1984 jeep cj7, 258 I6, rebuilt T176,rebuilt Dana 300, amc 20 , dana 30, 4.10's Trac-lok in rear , 4.10's detroit soft locker in dana 30, 2.5 inch bds suspension lift, 1 inch polyurethan body mount lift. Line ex. weber carburetor. factory tach. factory clock ,oem replacement speedomter cluster, and oil pressure gauge, factory volt gauge.
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post #49 of 60 Old 06-11-2019, 07:47 PM
John Strenk
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Originally, the CJ had a sol-vac valve to kick the idle up a little when the AC was on.
just saying...


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post #50 of 60 Old 06-12-2019, 01:43 AM Thread Starter
agear
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Quote:
Originally Posted by John Strenk View Post
Originally, the CJ had a sol-vac valve to kick the idle up a little when the AC was on.
just saying...
It doesn't do it everytime but that's true

1984 jeep cj7, 258 I6, rebuilt T176,rebuilt Dana 300, amc 20 , dana 30, 4.10's Trac-lok in rear , 4.10's detroit soft locker in dana 30, 2.5 inch bds suspension lift, 1 inch polyurethan body mount lift. Line ex. weber carburetor. factory tach. factory clock ,oem replacement speedomter cluster, and oil pressure gauge, factory volt gauge.
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post #51 of 60 Old 06-12-2019, 02:02 AM Thread Starter
agear
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Looking at th Weber install instructions and they say the idle speed screw should be no more than 1/2 turn in for tuning but that you can go a little afterward to set the idle higher. Just want to make sure I'm understanding it right. Its definately in there . It may not stall if I bump up the idle rpms to 720. Here is a copy paste from the instructions. Looks like its saying 1/2 turn for tuning but you can go just under 3/4 for final setting

"**Now that the mixture screw is at its best running location, you can adjust the Idle speed the screw. The idle speed screw will be sensitive and should only take turn to achieve the idle speed you like."

"Also check the speed screw and note how many total turns from initial contact. You may have opened (turned in) the speed screw. Your final setting should be under 3/4 turn in."

1984 jeep cj7, 258 I6, rebuilt T176,rebuilt Dana 300, amc 20 , dana 30, 4.10's Trac-lok in rear , 4.10's detroit soft locker in dana 30, 2.5 inch bds suspension lift, 1 inch polyurethan body mount lift. Line ex. weber carburetor. factory tach. factory clock ,oem replacement speedomter cluster, and oil pressure gauge, factory volt gauge.
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post #52 of 60 Old 06-12-2019, 05:50 AM
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Where do you have your initial timing set? One thing that can happen when using manifold vacuum is if the engine gets dragged down, manifold vacuum will drop and pull some timing out until the engine recovers and the vacuum comes back up.

A vacuum canister that lets you adjust how many degrees of timing are added could be helpful here as you could add several degrees of initial timing and pull a similar amount out of your vacuum canister.

You may just have to bump the throttle to reset the vacuum canister and not worry about it. Just a thought...


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post #53 of 60 Old 06-12-2019, 06:26 AM
Matt1981CJ7
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Agear,

IIRC, the maximum 3/4 turn on the speed screw is for the Weber 32/36. The Weber 38 max setting is 1/2 turn in.

As Uptillnow stated earlier, you may have to drill small holes in your throttle plates to allow enough air for a stronger idle. This is especially true with AC equipped CJs.

IMO, you should be striving for a 700-725-ish idle without turning the speed screw beyond the 1/2 turn in max setting (0 vacuum at the s-port).

A little more timing wouldn't hurt either. I ran my 258 at around 11 BTDC initial timing.

Matt
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post #54 of 60 Old 06-12-2019, 01:06 PM Thread Starter
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Quote:
Originally Posted by Shawn Watson View Post
Where do you have your initial timing set? One thing that can happen when using manifold vacuum is if the engine gets dragged down, manifold vacuum will drop and pull some timing out until the engine recovers and the vacuum comes back up.

A vacuum canister that lets you adjust how many degrees of timing are added could be helpful here as you could add several degrees of initial timing and pull a similar amount out of your vacuum canister.

You may just have to bump the throttle to reset the vacuum canister and not worry about it. Just a thought...


Shawn
Quote:
Originally Posted by Matt1981CJ7 View Post
Agear,

IIRC, the maximum 3/4 turn on the speed screw is for the Weber 32/36. The Weber 38 max setting is 1/2 turn in.

As Uptillnow stated earlier, you may have to drill small holes in your throttle plates to allow enough air for a stronger idle. This is especially true with AC equipped CJs.

IMO, you should be striving for a 700-725-ish idle without turning the speed screw beyond the 1/2 turn in max setting (0 vacuum at the s-port).

A little more timing wouldn't hurt either. I ran my 258 at around 11 BTDC initial timing.

Matt
I have it set at 8 degrees. I dont have a vacuum canister unless there's one in the carb I dont know about. Thanks for the suggestion if you mean I could add a canister. I would only want the timing boost when I let off the gas I guess. I get a ping any more than 8. Here is the page I was going by if you want to check it out.

http://www.redlineweber.com/html/Tec...as_tunning.htm

Its true I am particular . I'll bump the idle up to 720 when a/c is off . For some reason I seem to have lost some driveability a while back when it's not up to temp yet im noticing as well but the rpm drop im talking about happens when the jeep is up cold or warm. Another thing that's got me wondering about this carb my sparkplugs colored good st 10 minutes idle and interstate run but around town they turn black

Sorry I'm brainstorming here but what's the connection to vacuum at the s port and idle speed. Too much turning on the speed screw exposes the enrichening hole but....
Still trying to figure out if the needle bump on the vacuum gauge matters. I know I have my speed screw turned in right so the enrichening hole shouldn't be exposed like you dont want

I may look at float level if its related to the rpm drop

1984 jeep cj7, 258 I6, rebuilt T176,rebuilt Dana 300, amc 20 , dana 30, 4.10's Trac-lok in rear , 4.10's detroit soft locker in dana 30, 2.5 inch bds suspension lift, 1 inch polyurethan body mount lift. Line ex. weber carburetor. factory tach. factory clock ,oem replacement speedomter cluster, and oil pressure gauge, factory volt gauge.
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post #55 of 60 Old 06-12-2019, 02:53 PM
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Take a small piece of tissue and place it against the s-port at idle. If the tissue sticks in place, there is vacuum, and the speed screw is turned too far in. Or, as I stated earlier, just stick your finger in front f the s-port at idle. You should be able to feel even the smallest amount of vacuum.

Black plugs after driving around town is usually a rich idle circuit. Remember, your engine is usually at idle before you turn it off, so the plug color will almost always indicate the idle circuit mixture. The only way to check the carb's primary circuit by looking at the plugs is to shut the engine off while cruising at speed, then coast to a stop and pull the plugs.

I believe the "vacuum canister" Shawn is talking about is an adjustable vacuum advance canister usually located on the distributer, not the vapor canister.

Matt


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post #56 of 60 Old 06-12-2019, 03:31 PM Thread Starter
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Quote:
Originally Posted by Matt1981CJ7 View Post
Take a small piece of tissue and place it against the s-port at idle. If the tissue sticks in place, there is vacuum, and the speed screw is turned too far in. Or, as I stated earlier, just stick your finger in front f the s-port at idle. You should be able to feel even the smallest amount of vacuum.

Black plugs after driving around town is usually a rich idle circuit. Remember, your engine is usually at idle before you turn it off, so the plug color will almost always indicate the idle circuit mixture. The only way to check the carb's primary circuit by looking at the plugs is to shut the engine off while cruising at speed, then coast to a stop and pull the plugs.

I believe the "vacuum canister" Shawn is talking about is an adjustable vacuum advance canister usually located on the distributer, not the vapor canister.

Matt
Oh okay cool. So idle speed screw setting and vacuum at the s port are related. Good vacuum check trick- will do

1984 jeep cj7, 258 I6, rebuilt T176,rebuilt Dana 300, amc 20 , dana 30, 4.10's Trac-lok in rear , 4.10's detroit soft locker in dana 30, 2.5 inch bds suspension lift, 1 inch polyurethan body mount lift. Line ex. weber carburetor. factory tach. factory clock ,oem replacement speedomter cluster, and oil pressure gauge, factory volt gauge.
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post #57 of 60 Old 06-12-2019, 06:10 PM
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This vacuum advance canister is what I was talking about although I don't remember if you have an HEI already. The idea would be to raise the initial advance from 8* to 12*, add a heavier spring to one side of the centrifugal advance and set the adjustable canister to limit vacuum advance to ~12 degrees (full manifold vacuum to the distributor so it'll show 24* on the balancer at idle when it's hooked up) and have it "all in" about an inch below whatever vacuum your engine pulls with the a/c on.

As a test, just set the initial timing at 12*, take it around the block and see if it still wants to dip and stall when you come to a stop with the a/c on. Don't lay into the throttle and make it ping; just see how it does when you come to a stop.


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Last edited by Shawn Watson; 06-13-2019 at 06:59 AM.
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post #58 of 60 Old 06-13-2019, 07:04 AM
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Quote:
Originally Posted by Shawn Watson View Post
This vacuum advance canister is what I was talking about although I don't remember if you have an HEI already. The idea would be to raise the initial advance from 8* to 12*, add a heavier spring to one side of the centrifugal advance and set the adjustable canister to limit vacuum advance to ~12 degrees (full manifold vacuum to the distributor) and have it "all in" about an inch below whatever vacuum your engine pulls with the a/c on.

As a test, just set the initial timing at 12*, take it around the block and see if it still wants to dip and stall when you come to a stop with the a/c on. Don't lay into the throttle an make it ping; just see how it does when you come to a stop.


Shawn
There are online sources that spec the advance curves for OTC/OE advance cans, if you want a simple vacuum upgrade. I run a CRANE adjustable unit, but adjustables usually require limiting the total advance available at idle/low speed. 258's seem to like 12* BTDC once you start modding them a little.

You can make (or buy) a timing tape and use a timing light to 'see' what's going on with advance. About 60* is all you need to mark off BTDC to find out what the vacuum can and mechanical advance are doing from idle to roughly 3000 rpm. My initial is 14* (with HEI). Running at idle the actual advance is closer to around 34* with the vacuum added in and no load. My mechanical advance starts around 900 and is pretty much all in by 2400 (one silver/one blue spring). 35-36* cruising
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post #59 of 60 Old 06-13-2019, 07:53 AM
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I can hear Agear's head exploding.


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post #60 of 60 Old 06-13-2019, 12:36 PM Thread Starter
agear
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Lol. Yeah you guys are way ahead of me. But I'll set the timing to 12 and see what it does

1984 jeep cj7, 258 I6, rebuilt T176,rebuilt Dana 300, amc 20 , dana 30, 4.10's Trac-lok in rear , 4.10's detroit soft locker in dana 30, 2.5 inch bds suspension lift, 1 inch polyurethan body mount lift. Line ex. weber carburetor. factory tach. factory clock ,oem replacement speedomter cluster, and oil pressure gauge, factory volt gauge.
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