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#1
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Offenhauser 2x4 intake woes
I've been working on this system for a few months now and was looking forward to the install!
A little backround... 1963 lemans with a .060 '71 400 (412ci) stock 670 heads (rebuilt) 068 cam shaft. Aftermarket valley pan (Butlers) The valley pan is where things begin to get out whack! The 2x4 set up starts with a 5499 Offenhauser 2x4 intake and a set of 3300s (1962) afb carters, that have been clean and rebuilt with identical primary and secondary jets as well as matching metering rods. Everything seemed to be going fine till it was time to mount the intake. I ran into a couple of problems. Problem #1. Turns out that the pcv stack that is welded to the aftermarket vally pan has been placed 1/2" to far towards the rear... now the stack and the intake runner want to occupy some of the same space! Cannot mate the intake water port to the timing cover! Problem #2 I believe the thickness of the aftermarket valley pan and no dimple as the factory ones have, is the cause of this one! When I attempted to mount the 2x4 intake, I was unable to get the manifold to set flat on the heads. Again, it seems that the intake wants to occupy space that the valley pan occupies! The space that I refer to, is the heat crossover! The very edge of the exhaust crossover, on the bottom of the intake on both sides, rest on the valley pan and prevent the intake from resting on the heads about 1/8" or poss less, on both sides. So what is a man to do? I do not think the after markets valley pans (tomahawk) will allow a 2x4 Offey to mount correctly since they claim the tri power cannot be used! And if I purchase another Butler without the the pcv option....well that will fix problem #1 but not #2 ! So far my only solution is to keep my Butler valley pan and modify it! For proplem #1- remove the pcv stack and weld up the hole. Solution for problem #2- grind down some of thickness of the valley pan and or just grind away some of material (3/8" thick wall) on the exhaust crossover on both sides on the bottom of the intake. If anyone is running a 2x4 Offey intake with an aftermarket valley pan please let me know the particulars! Thanks Sent from my SM-N975U using Tapatalk
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87 GP le 455 200r4 3.42 rear |
#2
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You bought the wrong valley cover to use with that intake!Tom
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The Following User Says Thank You to tom s For This Useful Post: | ||
#3
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#4
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Agree with Tom S.
Tom V.
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"Engineers do stuff for reasons" Tom Vaught Despite small distractions, there are those who will go Forward, Learning, Sharing Knowledge, Doing what they can to help others move forward. |
#5
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Used what I had...had that valley pan for years on another engine combo and fit well with a 2 barrel intake that I was running on that engine prior. Found out the hard way, now I know!
Sent from my SM-N975U using Tapatalk
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87 GP le 455 200r4 3.42 rear |
#6
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Quote:
Sent from my SM-N975U using Tapatalk
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87 GP le 455 200r4 3.42 rear |
#7
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Franks Pontiac parts has the valley pan cover you need for 75 bucks.
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Wernher Von Braun warned before his retirement from NASA back in 1972, that the next world war would be against the ETs! And he was not talking about 1/8 or 1/4 mile ETs! 1) 1940s 100% silver 4 cup tea server set. Two dry rotted 14 x 10 Micky Thompson slicks. 1) un-mailed in gift coupon from a 1972 box of corn flakes. Two pairs of brown leather flip flops, never seen more then 2 mph. Education is what your left with once you forget things! |
#8
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Picture opens for me?It was also made to clear roller lifters,many stock pans wont.Tom
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The Following User Says Thank You to tom s For This Useful Post: | ||
#9
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I have and had the Offyl dual Quads and the stock Valley covers i used cleared.
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#10
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Quote:
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87 GP le 455 200r4 3.42 rear |
#11
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Valley pan
This would be it.
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Frank M. 75 Firebird 68 Firebird 400 RAIII 66 Chevy II 461 Pontiac in AZ |
#12
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Quote:
Just a thought but the tapatalk app is garbage and preventing you from seeing posted content to sell you woman's deodorant. |
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#13
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Thanks for the explanation!
Sent from my SM-N975U using Tapatalk
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87 GP le 455 200r4 3.42 rear |
#14
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You should have test fitted everything prior to final assembly.
Water crossover fitment, intake port fitment WITH gaskets, intake bolt fitment, distributor clearance, linkage clearance, fuel pressure regulator clearance (if used up top by the carbs/linkage), valley pan clearance, etc. I separated the water crossover on my 5499 and did some metal removal so I could run essentially any valley pan. It gives me great clearance and bolt hole alignment with the water crossover separated. I ground a little on the carb mounting plates for a little additional clearance too and blended the adapter plates to the intake plenum runners. This probably has no performance advantage, however. All of this was done before bringing it all together and final painting/assembly. Came together nicely. |
#15
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Hind sight is 20/20! Advice well taken.
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87 GP le 455 200r4 3.42 rear |
#16
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If you don't want to spring for a new valley cover, just cut the underside of the exhaust crossover like the other poster. It will cost you another set of intake gaskets with block off plates unless your gaskets came with them.
You can cut off the PCV boss off grind it flush and use a plastic/rubber body plug to seal it. Use a step drill to make a new hole wherever you want to accept a rubber PCV grommet (like the ones used on valve covers). Also, I think there is a poster in the classifieds giving away stock valley covers plus cost of shipping only.
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Triple Black 1971 GTO |
#17
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Thanks for all the comments! I have been diligently working around this problem and have achieved a positive outcome without total destruction of the valley pan and the intake!
Turns out the pcv stack just needed to be shortened just enough to use one of the teo baffles and the grommet. The intake was massaged in several places to achieve clearance with the Butler valley pan. By omitting the valley pan gasket I wss able to keep the valley pan as low ad possible. This gave me some extra room so clearance gringing on the intake would be at a minimum! After some hours of trial and fit, all is good! Now I can move on and tackle the other problems that are showing up! Sent from my SM-N975U using Tapatalk
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87 GP le 455 200r4 3.42 rear |
#18
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Nicely done!
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