Performer divider chopped = bad?
Thread Starter
Instructor
Joined: Jun 2013
Posts: 222
Likes: 0
From: Toronto Ontario
Performer divider chopped = bad?
While I'm shopping around for parts I came across this
He has chopped 1" off the divider along it's entire length. I've heard of people taking notches out of it, but isn't that a lot for a dual plane?
Is it worth investigating? I have a mild 1980 L48-auto, and I am putting a qjet on it in the spring. I hear talk of better top end... but this is a street car, all it usually gets to see is lower end. Torque is at the bottom end and it shifts around 5k anyways. Would a divider chop like that be good/acceptable or should I just keep looking?
The price is right... but not worth it if that chop is a terrible idea
He has chopped 1" off the divider along it's entire length. I've heard of people taking notches out of it, but isn't that a lot for a dual plane?
Is it worth investigating? I have a mild 1980 L48-auto, and I am putting a qjet on it in the spring. I hear talk of better top end... but this is a street car, all it usually gets to see is lower end. Torque is at the bottom end and it shifts around 5k anyways. Would a divider chop like that be good/acceptable or should I just keep looking?
The price is right... but not worth it if that chop is a terrible idea
Thread Starter
Instructor
Joined: Jun 2013
Posts: 222
Likes: 0
From: Toronto Ontario
The more I look into it, it seems that opening that divider up will open up the top end at the expense of low end and throttle response. Does that sound about right? Sounds like all the things I want to avoid!
Pro
Joined: Aug 2010
Posts: 698
Likes: 8
From: Stockholm Sweden
I think to modify the divider in an dualplane intake is something one take in considiration only if its been proved neccessery.
I dont think there is a general template for what result you will get, it all depends on what YOUR engins needs.
I dont think there is a general template for what result you will get, it all depends on what YOUR engins needs.
Pro
Joined: Aug 2010
Posts: 698
Likes: 8
From: Stockholm Sweden
I forgot to say..
On my own intake we saw the need for this action however we decided to put on an 1/2" spacer instead of cutting the divider.
This gives you a chance to se if you reach your goal and if no improvment the spacer can be removed again.
The basis are that if your engine is not happy with the manifold you have put on it, you propably have put on the wrong manifold from the beginning.
The reason i did this was due to lack of existing good manifolds that would clear the stock BB hood and i at that point didnt want to put a scoop on the car.
On my own intake we saw the need for this action however we decided to put on an 1/2" spacer instead of cutting the divider.
This gives you a chance to se if you reach your goal and if no improvment the spacer can be removed again.
The basis are that if your engine is not happy with the manifold you have put on it, you propably have put on the wrong manifold from the beginning.
The reason i did this was due to lack of existing good manifolds that would clear the stock BB hood and i at that point didnt want to put a scoop on the car.
Le Mans Master
Joined: Oct 2010
Posts: 6,929
Likes: 842
From: melbourne florida
2023 C3 of the Year Finalist - Modified
it was an old school way to get a little more high end power . that was back in the time that there weren't many choices in manifolds, unlike today. it would depend on what combination you have it may be fine. i once had a car (a vega)that overpowered the tires and without tubbing i couldn't get more tire under it, the car also was nosing over about 50 feet from the end of the 1/4 mile. by cutting the divider i cut the low end enough to let me peddle it out and pull on the big end. it gave me 2 tenths. in some cases it works in others not as well.
Thread Starter
Instructor
Joined: Jun 2013
Posts: 222
Likes: 0
From: Toronto Ontario
1980 Stock L48 350, no air pump or emissions
Factory shorty headers
true dual 2 1/4", no cat but mufflers are Midas specials
Planning for a Quadrajet on top.
Except for the exhaust, the Edelbrock C3BX intake, Holley 6619 emissions carb and open element air cleaner the engine is stock and mostly original. I talked to the guy with the ad and he said it worked great on his 327, but I have no idea how he drove it. He said he got a performance machine shop to do the work, but again that just means it might be well done. A notch across the whole top end is a lot more than the 2.5" they talked about in the old chevy horsepower book.
I wouldn't complain about gaining some top end performance up to 5200 but anything above that is wasted on an automatic weekend street car. I'm more worried about noticeable shortcomings at the low end. If it gains at 5800 but looses at idle-3500 then I'll definitely keep looking.
Factory shorty headers
true dual 2 1/4", no cat but mufflers are Midas specials
Planning for a Quadrajet on top.
Except for the exhaust, the Edelbrock C3BX intake, Holley 6619 emissions carb and open element air cleaner the engine is stock and mostly original. I talked to the guy with the ad and he said it worked great on his 327, but I have no idea how he drove it. He said he got a performance machine shop to do the work, but again that just means it might be well done. A notch across the whole top end is a lot more than the 2.5" they talked about in the old chevy horsepower book.
I wouldn't complain about gaining some top end performance up to 5200 but anything above that is wasted on an automatic weekend street car. I'm more worried about noticeable shortcomings at the low end. If it gains at 5800 but looses at idle-3500 then I'll definitely keep looking.
Last edited by brainsoft; Nov 23, 2013 at 10:51 PM.
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Burning Brakes
Joined: Apr 2007
Posts: 1,039
Likes: 62
From: Kona Hawaii
Went the other direction..Closed up the cut down divider on the air gap manifold.Low end torque increased as well as throttle response and MPG's.Also using a 4 hole carb gasket,spacer.Matt Gruber had a paper on this subject but the link doesn't seem to work:http://community-2.webtv.net/MATTGRU/carb/
After closing the gap,I would use less throttle ascending hills in my area.You can read this thread on the subject....
http://forums.corvetteforum.com/c3-t...r-gap-mod.html
After closing the gap,I would use less throttle ascending hills in my area.You can read this thread on the subject....
http://forums.corvetteforum.com/c3-t...r-gap-mod.html
2026 Loser of the Year
Joined: Sep 2013
Posts: 36,573
Likes: 7,016
From: New Or-leens Loo-z-anna
On my 350SBC/headers/HEI/Holley 600cfm, I have an un-cut divider intake. I changer from a divider-style carb/intake gasket to a plain square gasket---providing less than 1/8" air-gap between the carb and the divider).
I saw a noticeable decrease in torque immediately.
Like the other members said....Some engines need different modifications to run well, so buy something with a complete divider and use a divider spacer with divider gaskets (you can notch the spacer if you desire).....if things don't improve you can increase the notch size in the spacer---or even fill the notch back up if needed.
I saw a noticeable decrease in torque immediately.
Like the other members said....Some engines need different modifications to run well, so buy something with a complete divider and use a divider spacer with divider gaskets (you can notch the spacer if you desire).....if things don't improve you can increase the notch size in the spacer---or even fill the notch back up if needed.
Last edited by doorgunner; Nov 24, 2013 at 08:54 AM.
Melting Slicks
Joined: Sep 2011
Posts: 3,372
Likes: 215
From: Peoria Arizona
Seems like adding top end power to a basically stock '80 L48 driver is the wrong direction unless you're planning to drag race it. As you stated - it's a "weekend street car". There are plenty of those intakes around for a reasonable price without getting one that's been hacked up.
Thread Starter
Instructor
Joined: Jun 2013
Posts: 222
Likes: 0
From: Toronto Ontario
Thanks for the input guys, I figured I was thinking in the right direction. If it was a much smaller gap I may have grabbed it because I'm cheap but it is almost completely removed!
I'll keep on looking
I'll keep on looking