Olscarb Or Carb Experts
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Joined: May 2004
Posts: 59
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From: JONESBOROUGH TN
Olscarb Or Carb Experts
Need advice on slow off idle acceleration with 1406 Edelbrock.Tried 1455 & 1458 rods which both stopped popping in exhaust when letting off throttle,but not much in acceleration.Timing is correct by Lars paper.Also sometimes stumbles on light throttle when warm.'77 350,edelbrock performer eps manifold,1406 carb,headers dual exhaust,open air cleaner,aftermarket cam specs not known.
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Joined: May 2006
Posts: 61
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From: NORWICH UNITED KINGDOM
Hi i am no expert and indeed just posted a simular problem on here. My 1970 with edlebrook performer carb and mainifold, would faulter and stubble with light acceleration when warm/hot. Some one posted it might be the carb pump adjuster on the side. I had it in hole 2. I moved it up a hole, top hole, and was same problem but worse. I moved it down to hole 1 and is lovely and smooth now. I now think I might have been over injecting fuel and flooding it. Trouble was I had two problems at the same time on my carb and i was confusing both. I also had the idle jets to lean and was lean over idle, resulting in a lean missfire, Olscarb helped with that one 
Racer
Joined: Apr 2006
Posts: 477
Likes: 43
From: Millbrae California
the 1406 has issues with a lazy accelerator pump and the idle channel restriction causes the air/fuel mixture to be lean at part throttle. the rods i use are 71/47 which are the #s on the rods. i do not know the edelbrock part # since we buy them thru a diferent source. we have the accelerator pump (that we had a custom spring made for us) for sale on e-bay that can be found as accelerator pump afb
the lean off idle can be cured if you slighty enlarge the idle channel restriction but only go out a few thousands of a inch at a time. for me to do make the changes the carb or primary venturi clusters would need to be sent to us.
the pop you hear in the exhaust may have been from a lean idle mixture and if making it richer helped you solved it
good luck henry @ oles carb
the lean off idle can be cured if you slighty enlarge the idle channel restriction but only go out a few thousands of a inch at a time. for me to do make the changes the carb or primary venturi clusters would need to be sent to us.
the pop you hear in the exhaust may have been from a lean idle mixture and if making it richer helped you solved it
good luck henry @ oles carb
Racer
Joined: Apr 2006
Posts: 477
Likes: 43
From: Millbrae California
to me, each carburetor has its good points and weak points.
for a application where you wants looks and drivabilty the edelbrock thunder and performer carbs are good, reliable and a good choke. i never go over 600-650 cfm because of a lean off idle problem that can not be fixed without about 2 or more hours of labor per carb. thier weak spot is cornering, the fuel bowl design causes one side of the carb to go rich and the other half to go lean during high G force cornering
a q-jet is a VERY good all around carb but because it only has one needle and seat proper fuel pressure maust be present at ALL driving conditions.
in the holley style carbs i like a mighty demon from barry grant because they are so easy to tune but i avoid any demon with a choke because i have had more than a few choke related problems with thier choke design
the older classic holleys are good but the new street avengers seem to need a lot of attention to get the air/fuel mixture correct. the new 4150HP carbs are good but are more expensive than a mighty demon and they still need some air/fuel mixture tweeking
hope this helps henry @ oles carb
for a application where you wants looks and drivabilty the edelbrock thunder and performer carbs are good, reliable and a good choke. i never go over 600-650 cfm because of a lean off idle problem that can not be fixed without about 2 or more hours of labor per carb. thier weak spot is cornering, the fuel bowl design causes one side of the carb to go rich and the other half to go lean during high G force cornering
a q-jet is a VERY good all around carb but because it only has one needle and seat proper fuel pressure maust be present at ALL driving conditions.
in the holley style carbs i like a mighty demon from barry grant because they are so easy to tune but i avoid any demon with a choke because i have had more than a few choke related problems with thier choke design
the older classic holleys are good but the new street avengers seem to need a lot of attention to get the air/fuel mixture correct. the new 4150HP carbs are good but are more expensive than a mighty demon and they still need some air/fuel mixture tweeking
hope this helps henry @ oles carb
Le Mans Master
Joined: Apr 2006
Posts: 5,403
Likes: 95
Originally Posted by 5day
Not wishing to highjack the thread, it seems that the edlebrook is not the ideal carb. Can anyone suggest what the idea carb would be for the corvette engine.
you would like to drink.
Drifting
Joined: Sep 2004
Posts: 1,959
Likes: 1
From: North Bend Ohio
Why Edelbrock chose to reproduce a carburetor with such obvious shortcomings is beyond me. I guess for getting you back and forth to work it's OK but it ain't no performance carburetor.
They should have put some research into making a refined Q-Jet. I would have liked to see them investment cast the bodies to cut down on the leaking plugs underneath. Or how 'bout making the airhorn in two sections so you could do jet, rod and float level changes faster. I would like to see the booster venturi removable like the 2G carbs.
'Course I would just like to see more tuning parts available. But, I guess that's asking too much.
BigBlockk
Later.....
They should have put some research into making a refined Q-Jet. I would have liked to see them investment cast the bodies to cut down on the leaking plugs underneath. Or how 'bout making the airhorn in two sections so you could do jet, rod and float level changes faster. I would like to see the booster venturi removable like the 2G carbs.
'Course I would just like to see more tuning parts available. But, I guess that's asking too much.
BigBlockk
Later.....
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Racer
Joined: Apr 2006
Posts: 477
Likes: 43
From: Millbrae California
the profit that is in reproducing and selling a afb or avs carb is very good, while a q-jet is a much more complicated carb to produce. add in that a q-jet is not as pretty as a shiney afb or avs and you have why the big E people push the thunder and performer carbs.
FYI edelbrock does not build the carbs but buys them from weber / magnetti marrelli
henry @ oles carb
FYI edelbrock does not build the carbs but buys them from weber / magnetti marrelli
henry @ oles carb
Safety Car
Joined: Dec 2004
Posts: 4,071
Likes: 0
From: San Diego CA
Originally Posted by BigBlockk
Why Edelbrock chose to reproduce a carburetor with such obvious shortcomings is beyond me. I guess for getting you back and forth to work it's OK but it ain't no performance carburetor.
They should have put some research into making a refined Q-Jet. I would have liked to see them investment cast the bodies to cut down on the leaking plugs underneath. Or how 'bout making the airhorn in two sections so you could do jet, rod and float level changes faster. I would like to see the booster venturi removable like the 2G carbs.
'Course I would just like to see more tuning parts available. But, I guess that's asking too much.
BigBlockk
Later.....
They should have put some research into making a refined Q-Jet. I would have liked to see them investment cast the bodies to cut down on the leaking plugs underneath. Or how 'bout making the airhorn in two sections so you could do jet, rod and float level changes faster. I would like to see the booster venturi removable like the 2G carbs.
'Course I would just like to see more tuning parts available. But, I guess that's asking too much.
BigBlockk
Later.....
I couldn't agree more. That right there would be a dream q-jet. If you didn't have to take the whole airhorn off to adjust the float, rods and jets it would be by far the easiest thing to tune.I'd freaking kill a man if edelbrock would put more tuning parts out for the M4M especially, too.
Melting Slicks
Joined: Mar 2006
Posts: 3,342
Likes: 7
From: Connecticut
Well, I beleive once you get a QJ running properly and leave it alone you have an excellent carb for all around use
I have owned many QJs and never had a problem until the one on my current Corvette (Which sat for 11 years) needed attention so I never even had one apart until recently.
I now have 2 great running QJ's and I still have the Holley Street Avenger which is a great carb as well.
As most of you probably know, I have posted my share of QJ questions... I finally have a fairly good understanding of what makes them tick and I think they are an all around great carb.......
To each his own
I have owned many QJs and never had a problem until the one on my current Corvette (Which sat for 11 years) needed attention so I never even had one apart until recently.
I now have 2 great running QJ's and I still have the Holley Street Avenger which is a great carb as well.
As most of you probably know, I have posted my share of QJ questions... I finally have a fairly good understanding of what makes them tick and I think they are an all around great carb.......
To each his own
Advanced
Joined: May 2006
Posts: 61
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From: NORWICH UNITED KINGDOM
I know my eddlebrook needs rejetting to get it right and as oles says may need the lean after idle sorted. I dont feel confident to attempt it myself and I am in UK and dont know any carb specialists near me. For a complete beginner with my problems could anyone suggest where I maybe could start. Do all carbs need to be tweeked like this in order to get them to work !
Melting Slicks
Joined: Mar 2006
Posts: 3,342
Likes: 7
From: Connecticut
Originally Posted by Kalway
there would be a dream q-jet. If you didn't have to take the whole airhorn off to adjust the float, rods and jets it would be by far the easiest thing to tune.
The only pain about it is the darn choke rod... which I leave off until Im satisfied with the tuning
Drifting
Joined: Jul 2002
Posts: 1,254
Likes: 1
From: Edinburgh
Originally Posted by 5day
I know my eddlebrook needs rejetting to get it right and as oles says may need the lean after idle sorted. I dont feel confident to attempt it myself and I am in UK and dont know any carb specialists near me. For a complete beginner with my problems could anyone suggest where I maybe could start. Do all carbs need to be tweeked like this in order to get them to work !
Racer
Joined: Apr 2006
Posts: 477
Likes: 43
From: Millbrae California
FYI, i did a tuning article in the june and july 2006 issues of Corvette Fever that they named tuning to perfection, it shows the tuning tools and methods i use for ignition and air/fuel mixture, plus the modifaction we do to cure the lean off idle problem on the edelbrock carbs
henry @ oles carb
henry @ oles carb
