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'68 390 Mods |
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Blue68SST
AMC Apprentice Joined: Nov/04/2014 Location: Mississauga, On Status: Offline Points: 123 |
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Blue68SST
AMC Apprentice Joined: Nov/04/2014 Location: Mississauga, On Status: Offline Points: 123 |
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As for the cylinder heads, I agree, the lower compression ratio works for the reasons you mention, as the car for me is a strong, reliable sunny day cruiser. I’m not looking for perfection or maximizing performance.
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White70JavelinSST
Supporter of TheAMCForum Joined: Aug/08/2012 Location: Minnesota Status: Offline Points: 4867 |
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I bought a 1970 390 several years ago. The oil pickup tube and screen that is threaded into the bottom of the block had rubber umbrella pieces packed inside it from sucking them out of the pan. Rubber umbrella seals are junk, unless you change them often enough that they don't deteriorate, get brittle, break up and end up in the pan. |
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70 Javelin SST, second owner, purchased 1972
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Ken_Parkman
AMC Addicted Joined: Jun/04/2009 Location: Ontario Status: Offline Points: 1815 |
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Have a look at the front of the intake where it is bolted to the head. the paper gaskets are about .060", and the valley pan about .025". You can usually tell; you can see if it is sheet metal. The PCV is plumbed into the front carb, so it really is entirely possible that is the oil problem. Not a perfect guarantee, but definitely likely. I stock the gaskets, but it is best to have both the factory baffle and the factory gasket. Baffles I do not have (actually I might have one, but I'm keeping it!), and are getting harder to find. The non EGR one should fit that intake although there are a couple different rivet patterns. Usually afternmarket intakes have both, but not sure about that intake. I always thread the holes and use small bolts with locktite instead of rivets.
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348AMX
AMC Addicted Joined: Jul/03/2007 Location: Massachusetts Status: Offline Points: 4165 |
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out of curiosity do the 60CC heads have less, the same, or more velocity than the high compression square ports? Edited by 348AMX - Dec/11/2017 at 4:07pm |
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67 Marlin
AMC Addicted Joined: Feb/21/2015 Location: Minnesota Status: Offline Points: 876 |
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The Offy doesn't come with the PCV baffle. But, it does have the little mounting holes. While I was checking, took some comparative photos and measurements. The AMC intake is the factory manifold for your 390. I think the hole between the carb mounts on the Offy is for the power brakes. The ports on both intakes are 1 1/16" wide, though the AMC unit narrows going toward the ceiling and floor. The AMC is 2 1/32 to 2 1/16" tall; the Offy ports are all 2 1/8" tall. |
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67 Marlin
AMC Addicted Joined: Feb/21/2015 Location: Minnesota Status: Offline Points: 876 |
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Here's another Offy photo. Have some questions, too, maybe answers can help the OP. 1. Is the hole, under where the rear carb mounts, where Offy intended the PCV valve hose to lead to? Or, did Offy intend for this to be a vacuum gauge connector fitting? It's threaded. My 1967 AFB has rear PCV and the OP's has them on the front. Since the power brake vacuum connector is between the carb mounts, maybe connecting to the front-side of the rear carb PCV would be super tight and make accessing the idle air screws difficult. 2. Why is front-side PCV preferential to the back of the carb? There's got to be a reason, otherwise Carter wouldn't have made the switch. 3. How does connecting to the front carb PCV act any worse than to the rear carb? |
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Blue68SST
AMC Apprentice Joined: Nov/04/2014 Location: Mississauga, On Status: Offline Points: 123 |
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Thanks 67 Marlin.
That really makes me wonder if I have a baffle on my intake. I suppose it’s worth the price of a gasket to find out......now I just need a baffle. The hole behind the rear carb has a threaded plug in it on my intake. |
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Blue68SST
AMC Apprentice Joined: Nov/04/2014 Location: Mississauga, On Status: Offline Points: 123 |
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I was checking out another thread for someone having similar oil consumption problems, and there was a suggestion to use a screwdriver down the pcv grommet hole to determine if there is a baffle on the intake.
If the screwdriver only goes down about 2 1/2 inches there is a baffle. More than that, there isn't. Makes sense. The 4 inch screwdriver went all the way in. The hunt for a baffle begins. |
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67 Marlin
AMC Addicted Joined: Feb/21/2015 Location: Minnesota Status: Offline Points: 876 |
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Why is the baffle so big? Why does it need to cover the entire center part of the intake? If it's just a PCV baffle, then isn't the only part that's really needed the quarter section in the upper left-hand of the photos, where the PCV valve is? Could someone just fab up a piece of sheet metal in that one place and meet the need?
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