Choke pull-off operation - E4ME carb
Thread Starter
Melting Slicks
Joined: Nov 2005
Posts: 3,323
Likes: 142
From: Green Valley Arizona
Choke pull-off operation - E4ME carb
On my '81 with the stock E4ME carb, which has the electric choke - I just re-installed the electric choke and the choke pull-off and made all the adjustments according to Lars' procedure.
And now I no longer have the eye stinging rich exhaust at start-up....yeah. But after letting the engine warm-up and kicking off the fast idle cam....I saw that the choke pull-off was still pulled in all the way. Even with revving the engine, the rod never moved to allow the secondary air valves to open. Is this normal operation? Would I really need to be driving to get the secondaries to kick-in?
It has been over 2 years since I have had the choke pull-off on the carb.
Thanks,
LannyL81
And now I no longer have the eye stinging rich exhaust at start-up....yeah. But after letting the engine warm-up and kicking off the fast idle cam....I saw that the choke pull-off was still pulled in all the way. Even with revving the engine, the rod never moved to allow the secondary air valves to open. Is this normal operation? Would I really need to be driving to get the secondaries to kick-in?
It has been over 2 years since I have had the choke pull-off on the carb.
Thanks,
LannyL81
Instructor
Joined: Jun 2005
Posts: 135
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I told Lars that I removed the choke pull-off on my '81 back in 1983 and the car is much more responsive. Most 4BB carburators do not have these silly air valves e.g. Carter, Motorcraft, Holley and once I removed the rod, the car functioned as my Carter AFB-equiped cars. i had the same problem where the air valves remained closed unless you really pop the accelerator. Lars claims the air valves control the secondary air/fuel ratio - I claim the car gained 20 HP and is much moreresponsive with the rod removed. Punching it in neutral, the air valves open wide and stay open until you let the throttle close.
Melting Slicks
Joined: Mar 2006
Posts: 2,465
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From: Orange Park Fl
The people who designed these things knew what they were doing! If it is not working right, something is broken/ adjusted wrong. If you start doing off the wall stuff like this, it will never be right, you create three problems trying to fix one. FIX IT THE RIGHT WAY!
God bless, Sensei
Instructor
Joined: Jun 2005
Posts: 135
Likes: 0
The people who designed these things knew what they were doing! If it is not working right, something is broken/ adjusted wrong. If you start doing off the wall stuff like this, it will never be right, you create three problems trying to fix one. FIX IT THE RIGHT WAY!
God bless, Sensei
Racer
Joined: Nov 2004
Posts: 485
Likes: 1
From: Oakville ON
On my '81 with the stock E4ME carb, which has the electric choke - I just re-installed the electric choke and the choke pull-off and made all the adjustments according to Lars' procedure.
I saw that the choke pull-off was still pulled in all the way. Even with revving the engine, the rod never moved to allow the secondary air valves to open. Is this normal operation? LannyL81
I saw that the choke pull-off was still pulled in all the way. Even with revving the engine, the rod never moved to allow the secondary air valves to open. Is this normal operation? LannyL81
. If the hole is much bigger, the air valve will open before there is enough air flow to pull fuel on the secondary side and you will lean out / bog. You can enlarge it a bit, but then the air valve spring adjustment gets very sensitive. There are adjustable pull-0ffs available afermarket that allow easy access to the control hole - just be sure to enlarge VERY small amounts at a time!
Drifting
Joined: Aug 2008
Posts: 1,381
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Taking the rod off only helps if the air valve spring is adjusted too tight or if you have a problem in some other area. If you choose to run the motor this way you're leaving some performance on the table. Rich is correct.
Thread Starter
Melting Slicks
Joined: Nov 2005
Posts: 3,323
Likes: 142
From: Green Valley Arizona
I agree that taking the rod off and then having the air valve spring tension to light would result in a performance decrease, as do not want the air valve to flop open. It just seems that the rod adds too much resistance and delay in the air valve opening.
I do not think I have anything broken or out of adjustment now...thanks once again Sensei.....I am going to just see what happens with the rod in place and the rod removed. This is a slightly modified engine and this may help performance or not....easy thing to try, although I will not be putting this on a dyno or anything, just the ole "seat gauge"....
Thanks to all for the replies.
I do not think I have anything broken or out of adjustment now...thanks once again Sensei.....I am going to just see what happens with the rod in place and the rod removed. This is a slightly modified engine and this may help performance or not....easy thing to try, although I will not be putting this on a dyno or anything, just the ole "seat gauge"....
Thanks to all for the replies.
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3rd Gear
Joined: Nov 2008
Posts: 3
Likes: 0
choke pull off
ive been reading your posts on the e4me choke pull off this being my first vette beige/ dark bronze metallic st louis vin one of those test to tone paint jobs my problem is when the engine is cold the primarys are closed i push the acelorator to the floor and start the engine it fires up but stalls right away i re fired the engine and opened the primarys by hand about a 1/4 inch this workedthe engine idelled at about 1200rpm i let go of the primary right away and the engine started to die i opened the primary again 1/4 inch waited the engine warmed up i let the primary go and it remained open waited 1 minute and the throtle kicked down to aprox 800 to 850 rpm how do i check to see if is the choke pull off or the high idle cam setting remember just a novice not to hip on carb lingo
Instructor
Joined: Jun 2005
Posts: 135
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HHMMMM - Ever look inside a Carter or Holley 4BB carburetor? They DO NOT have these silly power-robbing air valves. GM put them there for emissions control, NOT performance!
3rd Gear
Joined: Nov 2008
Posts: 3
Likes: 0
choke pull off
ive been reading your posts on the e4me choke pull off this being my first vette beige/ dark bronze metallic st louis vin one of those test to tone paint jobs my problem is when the engine is cold the primarys are closed i push the acelorator to the floor and start the engine it fires up but stalls right away i re fired the engine and opened the primarys by hand about a 1/4 inch this workedthe engine idelled at about 1200rpm i let go of the primary right away and the engine started to die i opened the primary again 1/4 inch waited the engine warmed up i let the primary go and it remained open waited 1 minute and the throtle kicked down to aprox 800 to 850 rpm how do i check to see if is the choke pull off or the high idle cam setting remember just a novice not to hip on carb lingo
Instructor
Joined: Jun 2005
Posts: 135
Likes: 0
ive been reading your posts on the e4me choke pull off this being my first vette beige/ dark bronze metallic st louis vin one of those test to tone paint jobs my problem is when the engine is cold the primarys are closed i push the acelorator to the floor and start the engine it fires up but stalls right away i re fired the engine and opened the primarys by hand about a 1/4 inch this workedthe engine idelled at about 1200rpm i let go of the primary right away and the engine started to die i opened the primary again 1/4 inch waited the engine warmed up i let the primary go and it remained open waited 1 minute and the throtle kicked down to aprox 800 to 850 rpm how do i check to see if is the choke pull off or the high idle cam setting remember just a novice not to hip on carb lingo
Drifting
Joined: Aug 2008
Posts: 1,381
Likes: 11
I stand by my previous statement.
There are many things you can do to the q-jet to increase performance, disabling the secondary pull off isn't one of them.
The Quadrajet can be a superb performance carb, but it is somewhat complicated, often misunderstood and subseqently misdiagnoised and then adjusted or modifyed incorrectly. This is why it's reputation is what is. There are a lot of cars running 12s and even a few running deep into the 11s with q-jets that still have the pull off rod attached.
There are many things you can do to the q-jet to increase performance, disabling the secondary pull off isn't one of them.
The Quadrajet can be a superb performance carb, but it is somewhat complicated, often misunderstood and subseqently misdiagnoised and then adjusted or modifyed incorrectly. This is why it's reputation is what is. There are a lot of cars running 12s and even a few running deep into the 11s with q-jets that still have the pull off rod attached.
Instructor
Joined: Jun 2005
Posts: 135
Likes: 0
I stand by my previous statement.
There are many things you can do to the q-jet to increase performance, disabling the secondary pull off isn't one of them.
The Quadrajet can be a superb performance carb, but it is somewhat complicated, often misunderstood and subseqently misdiagnoised and then adjusted or modifyed incorrectly. This is why it's reputation is what is. There are a lot of cars running 12s and even a few running deep into the 11s with q-jets that still have the pull off rod attached.
There are many things you can do to the q-jet to increase performance, disabling the secondary pull off isn't one of them.
The Quadrajet can be a superb performance carb, but it is somewhat complicated, often misunderstood and subseqently misdiagnoised and then adjusted or modifyed incorrectly. This is why it's reputation is what is. There are a lot of cars running 12s and even a few running deep into the 11s with q-jets that still have the pull off rod attached.
Drifting
Joined: Aug 2008
Posts: 1,381
Likes: 11
Rebuilding a carb and modifying / tuning it for increased performance are completely different things. The secondary dashpot controls the rate of opening, not how much. If it is correct for the carb and the rod hasn't been bent or "modifyed", the secondary air valve will open as designed. It will not open by winging the throttle on a stationary engine. It needs to be under load. Unless you run the car at the track or have dyno numbers you can't determine what you're gaining or losing!
3rd Gear
Joined: Nov 2008
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thanks jon s if the climatic control is factory set can the setting still change due to age this would not have anyrhing to do with the choke pull off btw the primarys are closed all the way when the engine is cold the weather here is cold and raining will check to see if the climate control is riveted is there any adjustment for the choke pull off
Instructor
Joined: Jun 2005
Posts: 135
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thanks jon s if the climatic control is factory set can the setting still change due to age this would not have anyrhing to do with the choke pull off btw the primarys are closed all the way when the engine is cold the weather here is cold and raining will check to see if the climate control is riveted is there any adjustment for the choke pull off
Melting Slicks
Joined: Mar 2006
Posts: 2,465
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From: Orange Park Fl
The pull off is needed to control the secondary transition. The rate can be adjusteded with a wire guage drill set to match the demands of your engine. It is not "just a poor design from GM to keep emissions down as well as performance!" I'm sorry but telling someone to take that rod off is just bad tech advice.
God bless, Sensei
Instructor
Joined: Jun 2005
Posts: 135
Likes: 0
The pull off is needed to control the secondary transition. The rate can be adjusteded with a wire guage drill set to match the demands of your engine. It is not "just a poor design from GM to keep emissions down as well as performance!" I'm sorry but telling someone to take that rod off is just bad tech advice.
God bless, Sensei
Drifting
Joined: Aug 2008
Posts: 1,381
Likes: 11
The blast of power is actually a bog. It is caused by too much air too quickly and then the motor catches up all at once. A motor that is tuned right will just pull hard - no big blast - like shifting into passing gear.
The purpose of the secondary choke pull-off is to keep the air flaps closed during high vacuum conditions AND to prevent them from flopping open too quickly under hard acceleration. Basically, it allows the secondary air valves to open gradually as vacuum bleeds off when going to full throttle. If you feel yours is to slow you can purchase a different one with a lager orifice for faster action. If you have yours removed and the car does not bog / hesitate, then your spring has to be set too tight to get full opening.
This is just simply how the quadrajet works. If you would rather not beleive me, just read Doug Roe's book or get a copy Cliff Ruggles' new book (it covers everything q-jet). It is not my intent to be obtuse, back in 1976 my thoughts were the same as yours until I ran my car down the track. I just want to put accurate info out there.
The purpose of the secondary choke pull-off is to keep the air flaps closed during high vacuum conditions AND to prevent them from flopping open too quickly under hard acceleration. Basically, it allows the secondary air valves to open gradually as vacuum bleeds off when going to full throttle. If you feel yours is to slow you can purchase a different one with a lager orifice for faster action. If you have yours removed and the car does not bog / hesitate, then your spring has to be set too tight to get full opening.
This is just simply how the quadrajet works. If you would rather not beleive me, just read Doug Roe's book or get a copy Cliff Ruggles' new book (it covers everything q-jet). It is not my intent to be obtuse, back in 1976 my thoughts were the same as yours until I ran my car down the track. I just want to put accurate info out there.