need help setting a 1406 carb - The 1947 - Present Chevrolet & GMC Truck Message Board Network

junkyardpartseeker · 04-03-2003, 03:27 PM

I am trying to set my 1406 edelbrock, but I am not understanding all of it. Can someone put it into words I can understand. One of my steps state "Adjust the IMS on one side to get the maximum possible RPM. Do not go rich beyond the maximum speed point." Can someone tell me what this means. I am setting my normal idle at 550 RPM.

low 84 · 04-03-2003, 03:49 PM

it is saying idle mixture screws (IMS) these are the two screws on the lower part of the front of the carb.

junkyardpartseeker · 04-03-2003, 03:53 PM

I know what the IMS is, this is the part I don't understand what it means "to get the maximum possible RPM. Do not go rich beyond the maximum speed point" I am trying to set it at 550 RPM on idle and 1500 on fast idle.

*1FaastC10* · 04-03-2003, 05:01 PM

dont worry about idle speed when you're adjusting the IMS. adjust your IMS for maximum idle speed, and then adjust your idle speed screw. they are independent of each other.

MSL · 04-03-2003, 05:15 PM

I have that same carb and mine runs to rich. So my question is if i scrwed the two screws all the way in how many turns out should i start with from each screw.

79BIG10 · 04-03-2003, 07:31 PM

Start with 2 turns out. DO NOT TURN ALL THE WAY OUT!! What you want to do is turn in one side to where the engine starts to stumble then back out about 1/2 turn. This will get you very close. Then to the other side. Once you have this set readjust idle screw.

low 84 · 04-03-2003, 09:48 PM

Quote:

Originally posted by 79BIG10
Start with 2 turns out. DO NOT TURN ALL THE WAY OUT!! What you want to do is turn in one side to where the engine starts to stumble then back out about 1/2 turn. This will get you very close. Then to the other side. Once you have this set readjust idle screw.

i do this too and it works good. i usualy start 1 1/2 turns out from full lean. then in with one till it stubles, then back out 1/2 turn. then do it agian to the other screw and they should both be set the same number of turns out. repeat the procedure a few times and it will be good. you are trying to get it to idle the highest possible by adjusting these screws which gives you the most amount a vacuum.

msl - is you carb running rich at idle or all the time? the idle mix screws are only gonna effect the mixture at idle.

MSL · 04-03-2003, 10:12 PM

It runs rich at a idle.

bigd65 · 04-03-2003, 10:20 PM

MSL, so does mine and has sence it was new. i dont care how i adjust it, it always runs rich on idle. i just get the highest possible idle with both sides equally adjusted out. the only thing i do is set the idle about 800-850, i think 550 is to low but thats my opinion.

MSL · 04-03-2003, 10:39 PM

Mine seems to only run with the screws pretty far out. and it runs rich it seems even when i adjusted them in it ran rich.

84Stepper · 04-03-2003, 11:52 PM

I've got the same carb. I even took my truck to a tune up shop to adjust the thing because I thought it was running rich. They told me they did the best they could but it still runs too rich and could not adjust it properly. I checked my plugs and they're REAL black. I don't know what to do. I may try your suggestions this weekend.

twistedmetal · 04-04-2003, 12:05 AM

Step by step tuning for edelbrock 1406 follow this link

http://www.carbs.net/Weber/adjust.htm

Rainbird · 04-04-2003, 01:00 AM

I took mine down to my local mechanic and they put it on the dyno to get it just right. I had the same frustrations as you did with running rich. Now it runs smooth all the way up to 8k rpm.

Just kidding

MSL · 04-04-2003, 04:06 AM

Just kidding what about 8krpm. or both. so did you take it in what did they do if you did.roughly how much did youy pay.

MSL · 04-04-2003, 04:54 AM

Also im not sure if this happens to you guys but when i start my truck first time when engine is cold the choke comes on like it should revs up. but it will stay on until i kick it down. is this supposed to happen and sometimes like if i just go into the store and it isnt more than maybe 15 minutes the choke kicks on again and i have to kick it down.

79BIG10 · 04-04-2003, 02:56 PM

The choke sounds like it's working. The choke gets cold and kicks in. Did you set your choke correctly? If not this can cause a lean rich condition.

MSL · 04-04-2003, 05:41 PM

I havent touched it yet. maybe i should adjust it and see what happens.

Rainbird · 04-05-2003, 12:03 AM

I was kidding about the 8k rpm. I believe it was around 75.00 for them to adjust it, may have been less. I messed with it for a while but could not get it exactly how I wanted it, so I let them do it. Probably the only time I let someone else work on my vehicle except for smog testing.

junkyardpartseeker · 04-05-2003, 12:09 PM

I just wanted to thank everyone who helped me with my carb problem. I have it now running a lot better. Just need to get a tach so I can set the rpm's right. Everyone here took the time to walk me thru this. I have asked questions on other boards and made to feel like the stupidest person in the world. I am not a mechanic and do not know much. I have been a cross country driver for almost 9 years now and never really had time to work on our vehicles. I am now staying at honme and have more time to fix these things up. Now, if I can only fix my brake problem, I think I will be done until it's trans repair time. Thanks again to all who helped guide me on this. Tommy Davis Little Rock,AR

04-03-2003, 03:27 PM	#1
junkyardpartseeker Registered User Join Date: Mar 2003 Location: Mabelvale, AR Posts: 695	need help setting a 1406 carb I am trying to set my 1406 edelbrock, but I am not understanding all of it. Can someone put it into words I can understand. One of my steps state "Adjust the IMS on one side to get the maximum possible RPM. Do not go rich beyond the maximum speed point." Can someone tell me what this means. I am setting my normal idle at 550 RPM.

04-03-2003, 03:49 PM	#2
low 84 Registered User Join Date: Jan 2002 Location: Houston, TX Posts: 2,144	it is saying idle mixture screws (IMS) these are the two screws on the lower part of the front of the carb. __________________ '51 F100, backhalf with a narrowed 9 and coil overs, 18.5" mickeys, monte front clip, +400" sbc in the works '05 1500 Crew Cab RIP '84 swb 5/7 drop, solid cammed 408 w/ fully ported dart heads, th350 w/ 10 inch hughes, 12 bolt w/ 3.73 richmonds and a locker '80 swb 4x4 in progress: 7" lift, 350 th350/np205, d44 and 1.5" ORD tie rod, 14BFF w/discs , armored diff covers, 40" MTR's

04-03-2003, 07:31 PM	#6
79BIG10 I'm back with 2nd truck! Join Date: Feb 2002 Location: Texas Posts: 3,775	Start with 2 turns out. DO NOT TURN ALL THE WAY OUT!! What you want to do is turn in one side to where the engine starts to stumble then back out about 1/2 turn. This will get you very close. Then to the other side. Once you have this set readjust idle screw. __________________ 1979 Chevrolet Bonanza Big10 "Tootsie Roll" 1985 Chevrolet Silverado (wife's) Member of the Southern Bowties Club "Don't underestimate how sexy a fat man who drinks to excess can be." Homer Simpson

04-03-2003, 10:20 PM	#9
bigd65 Registered User Join Date: Mar 2000 Location: Lake Jackson, TX. Posts: 1,930	MSL, so does mine and has sence it was new. i dont care how i adjust it, it always runs rich on idle. i just get the highest possible idle with both sides equally adjusted out. the only thing i do is set the idle about 800-850, i think 550 is to low but thats my opinion. __________________ 2004 Silverado Crewcab (Dark Spiral Gray)

04-03-2003, 11:52 PM	#11
84Stepper Registered User Join Date: Feb 2003 Location: Edmond, Oklahoma Posts: 425	I've got the same carb. I even took my truck to a tune up shop to adjust the thing because I thought it was running rich. They told me they did the best they could but it still runs too rich and could not adjust it properly. I checked my plugs and they're REAL black. I don't know what to do. I may try your suggestions this weekend. __________________ 84 Chevy Stepside, 350, TH350, 268h Comp cam, Hooker headers, MSD Pro Billet, Edelbrock Performer manifold and 1604 carb, 40 Series Flowmasters dumped, and Western Chassis 3/5 drop w/ c notch. New 3:73 Eaton Posi

04-03-2003, 03:53 PM	#3
junkyardpartseeker Registered User Join Date: Mar 2003 Location: Mabelvale, AR Posts: 695	I know what the IMS is, this is the part I don't understand what it means "to get the maximum possible RPM. Do not go rich beyond the maximum speed point" I am trying to set it at 550 RPM on idle and 1500 on fast idle.

04-03-2003, 05:01 PM	#4
1FaastC10 Account Suspended Join Date: Oct 2002 Location: Elkhart, IN Posts: 6,400	dont worry about idle speed when you're adjusting the IMS. adjust your IMS for maximum idle speed, and then adjust your idle speed screw. they are independent of each other.

04-03-2003, 05:15 PM	#5
MSL Registered User Join Date: Mar 2003 Location: So.Oregon Posts: 765	I have that same carb and mine runs to rich. So my question is if i scrwed the two screws all the way in how many turns out should i start with from each screw.

04-03-2003, 10:12 PM	#8
MSL Registered User Join Date: Mar 2003 Location: So.Oregon Posts: 765	It runs rich at a idle.

04-03-2003, 10:39 PM	#10
MSL Registered User Join Date: Mar 2003 Location: So.Oregon Posts: 765	Mine seems to only run with the screws pretty far out. and it runs rich it seems even when i adjusted them in it ran rich.

04-04-2003, 12:05 AM	#12
twistedmetal Take it to the limit Join Date: Mar 2003 Location: Manitoba, Canada Posts: 145	Step by step tuning for edelbrock 1406 follow this link http://www.carbs.net/Weber/adjust.htm __________________ 1995 GMC SLE Ext cab 4X4 Z-71 loaded daily driver 87 k25 Fully Loaded inc captain buckets and console,12" susp lift,3" body lift 42"swampers 66 Cutlass 2dr hardtop currently undergoing frame off 55 chev 2dr hardtop awaiting attention 85 Chev silverado 1/2 ton loaded,daily driver(stolen) 80 chev silverado 1/2 ton farm truck 87 S-jimmy V-8,lowered ,Parting out 49 Chev 1/2 parting out parting numerous 73-80 chev trucks 01 Polaris edge X (highly modified) 58 NSU Prima scooter awaiting total restoration

04-04-2003, 01:00 AM	#13
Rainbird Registered User Join Date: Mar 2003 Location: Sacramento, CA Posts: 9	I took mine down to my local mechanic and they put it on the dyno to get it just right. I had the same frustrations as you did with running rich. Now it runs smooth all the way up to 8k rpm. Just kidding __________________ 1980 1 ton utility 350 4bbl, manual, 4:56 rear work in progress, just ask my neighbors about the screaming coming from under it!

04-04-2003, 04:06 AM	#14
MSL Registered User Join Date: Mar 2003 Location: So.Oregon Posts: 765	Just kidding what about 8krpm. or both. so did you take it in what did they do if you did.roughly how much did youy pay.

04-04-2003, 04:54 AM	#15
MSL Registered User Join Date: Mar 2003 Location: So.Oregon Posts: 765	Also im not sure if this happens to you guys but when i start my truck first time when engine is cold the choke comes on like it should revs up. but it will stay on until i kick it down. is this supposed to happen and sometimes like if i just go into the store and it isnt more than maybe 15 minutes the choke kicks on again and i have to kick it down.

04-04-2003, 02:56 PM	#16
79BIG10 I'm back with 2nd truck! Join Date: Feb 2002 Location: Texas Posts: 3,775	The choke sounds like it's working. The choke gets cold and kicks in. Did you set your choke correctly? If not this can cause a lean rich condition. __________________ 1979 Chevrolet Bonanza Big10 "Tootsie Roll" 1985 Chevrolet Silverado (wife's) Member of the Southern Bowties Club "Don't underestimate how sexy a fat man who drinks to excess can be." Homer Simpson



Register or Log In To remove these advertisements.

04-04-2003, 05:41 PM	#17
MSL Registered User Join Date: Mar 2003 Location: So.Oregon Posts: 765	I havent touched it yet. maybe i should adjust it and see what happens.

04-05-2003, 12:03 AM	#18
Rainbird Registered User Join Date: Mar 2003 Location: Sacramento, CA Posts: 9	I was kidding about the 8k rpm. I believe it was around 75.00 for them to adjust it, may have been less. I messed with it for a while but could not get it exactly how I wanted it, so I let them do it. Probably the only time I let someone else work on my vehicle except for smog testing. __________________ 1980 1 ton utility 350 4bbl, manual, 4:56 rear work in progress, just ask my neighbors about the screaming coming from under it!

04-05-2003, 12:09 PM	#19
junkyardpartseeker Registered User Join Date: Mar 2003 Location: Mabelvale, AR Posts: 695	I just wanted to thank everyone who helped me with my carb problem. I have it now running a lot better. Just need to get a tach so I can set the rpm's right. Everyone here took the time to walk me thru this. I have asked questions on other boards and made to feel like the stupidest person in the world. I am not a mechanic and do not know much. I have been a cross country driver for almost 9 years now and never really had time to work on our vehicles. I am now staying at honme and have more time to fix these things up. Now, if I can only fix my brake problem, I think I will be done until it's trans repair time. Thanks again to all who helped guide me on this. Tommy Davis Little Rock,AR

Register or Log In To remove these advertisements.