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#1
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dual plane intake with 4-7 swap
My buddy is fighting a stumbling problem on his 406. he currently has a edelbrock rpm, ported kre ds and a hydraulic roller with 4-7 swap, forged ohio crank and on e85. fairly new combo but not entirely.
Previously had same intake, non swapped cam, unported heads and pump gas and tad too much compression and his N crank paid the price. car had been 11.60s shifting it in his 65 gto. he has been playing with carb and timing, and even swapped carbs, and distributors. No results, except issue not as bad with less fuel (jetting etc). but car is now a dog and lean. No one considered the intake and the cam swap until now. has anyone run into a similar issue with dual plane and a 4-7 swap, where the dual plane is optimized for a different firing order? It makes sense that this is the problem the whole time. We are just looking for correlating experience. Next change will be a north wind or another single plane.
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1969 carousel red firebird 455, richmond 5 speed 1964 540 gto 1971 lemans sport convertible 1972 Maverick under slow construction |
#2
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I think it also effects the clocking of the headers?Tom
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#3
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i think that does apply for max hp if seeking every last drop. I guess with the scavenging effect, it could be pulling some charge into the exhaust before its being used, due to the lobe swap. This thing sits and idles fine, as soon as you jump on it it flutters
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1969 carousel red firebird 455, richmond 5 speed 1964 540 gto 1971 lemans sport convertible 1972 Maverick under slow construction Last edited by mysticmissle; 07-10-2020 at 10:49 AM. |
#4
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I have no experience but I just watched the Engine Masters do a Dino fest on it. They used a 572 Chevy.
The performance results were inconclusive but they did see it cause a large change in mixture distribution. May be the case in your friends car. It would probably take a lot of testing to figure out what’s going on. I’d think at least trying a single plane might be a good start. Murf Sent from my iPhone using Tapatalk Pro |
#5
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Id have to study it closer but i'd think a dual plane would like the 4 7 swap better. It's possible it's the issue but id be surprised. I am wrong a lot though
Last edited by slowbird; 07-10-2020 at 11:16 AM. |
#6
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If you stay in it, does it start to pop and crack out the exhaust?
Clay |
#7
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Was the cam installed properly? Any intake gasket leaks? Valve adjustment? Valve train issues with new cam?
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466 Mike Voycey shortblock, 310cfm SD KRE heads, SD "OF 2.0 cam", torker 2 373 gears 3200 Continental Convertor best et 10.679/127.5/1.533 60ft 308 gears best et 10.76/125.64/1.5471 Last edited by ta man; 07-10-2020 at 11:54 AM. |
#8
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no pop out the exhaust, lifters are a little noisy but 1/4 turn past zero lash, We have also considered an intake leak.
i cant speak to the cam installation, but he is pretty sharp young fella, and this was not the first time througe the process.
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1969 carousel red firebird 455, richmond 5 speed 1964 540 gto 1971 lemans sport convertible 1972 Maverick under slow construction |
#9
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Has the cam been checked to confirm that it was ground with the 4-7 swap. I know one person on this board who fought problems with his engine only to find out he didn't get the swap he paid for. If I remember right it was mainly sluggish, didn't pop or backfire.
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#10
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"Tanzi also noted that “to yield the greatest gains requires header design work....Matching primary tubes with regard to the intake manifold and cylinder head ports is also necessary. This usually relates more directly to applications that use a single-plane manifold, and tunnel ram manifolds in particular. In terms of fuel distribution, we see greater benefits with single-plane manifolds as compared to dual-plane manifolds, since dual-plane manifolds are less prone to
reversion and negative pulsation.” https://www.motor.com/magazinepdfs/032009_07.pdf .
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'70 TA / 505 cid / same engine but revised ( previous best 10.63 at 127.05 ) Old information here: http://www.hotrod.com/articles/0712p...tiac-trans-am/ Sponsor of the world's fastest Pontiac powered Ford Fairmont (engine) 5.14 at 140 mph (1/8 mile) , true 10.5 tire, stock type suspension https://www.youtube.com/watch?v=qDoJnIP3HgE |
The Following User Says Thank You to Steve C. For This Useful Post: | ||
#11
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Not to hi-jack the thread, but my new cam has the 4-7. And I believe 3/2. Swap. Do i need to worry about my header tube arrangement?
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#12
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I dont know about worry but if they were clocked properly for a std cam it could have some effect.Maybe a questions for the guys on SpeedTalk?Tom
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#13
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Imo no worries with a 4 into 1 collector, a 4-2-1 collector yes worry
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#14
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Thanks for the replies. Maybe " worry" was a little strong of a word. But I dont want to leave much of power potential on the table. I am assuming it will be minimal. But have no real experience with it.
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#15
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4/7 swap in mine. Had a dual plane first and it seemed to run ok for that season. Next season went to FAST 2.0 and ended up changing to a Northwind. Single plane seemed to wake it up in low end all the way thru top end. Happy with how it runs.
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1967 GTO, 467 roller motor, e heads ported, tremec T56 magnum 6 speed and 9" done. EZ EFI 2.0 with FAST dual sync distributor and separate nitrous system done. Track is at 4300 ft elevation. so far a best of 11.95@116. Suspension now getting dialed in...tubular front a arms with dual adjustable coil overs HR Parts n stuff rear bar and whole car lowered 3 inches.. |
The Following User Says Thank You to pokey1 For This Useful Post: | ||
#16
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You probably already tried it but my stumble problems almost always were the fault of small shooters or small accelerator pump/cam. I like the 50cc pumps.
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Runner Up Q16 Norwalk 2013! |
#17
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Check valve under the squirter sometimes gets stuck as well.. That could make someone walk in circles ..
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My Half AN Injun..... |
#18
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Got at least 12V going to the distributor? Cylinders not firing cause o2 to read lean.
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2023 Best ET Slip 60’ 1.224 330 3.186 1/8 4.784 MPH 152.07 1000 6.175 ET 7.347 MPH 189.92 Weight 3650 YouTube Channel --> https://www.youtube.com/channel/UC21...rWwgFdfTRqShGQ FaceBook Group --> https://www.facebook.com/groups/220092308823847/ |
#19
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Received an update from my friend. He thinks he found some improvement with the squirter cams and shooter size. He also believes the butterfly’s may have been a little bit too open. I assume out of the transfer slot.
He is going to put wide name on it and continue to tweak it
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1969 carousel red firebird 455, richmond 5 speed 1964 540 gto 1971 lemans sport convertible 1972 Maverick under slow construction |
#20
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Quote:
Last edited by Half-Inch Stud; 07-23-2020 at 08:39 AM. |
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