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Guys,

I have OEM-style chrome valve covers on my 426 Hemi. The valve covers each have a filler tube with a push-on OEM-style breather. Obviously, they are not allowing the system to break enough because they constantly leak. After a hard acceleration, the caps almost push completely off!

What's the best fix? I considered leaving the one on the front driver's side and replacing the one at the rear passenger side with a PVC push-on cap like this: http://www.chicagoconnection.us/index.php?main_page=product_info&products_id=680

Help.
Cincylance

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The solutions is not easy or cheap, if you want to fix the problem, crankcase pressures at WOT and or upper(above 4000 RPM) RPM I use to race a 1963 M.W. 415 HP NHRA stocker that would blow the push on breathers off in the burn out box , It had the stock OEM piston in the motor, the top rings had .009 or more side clearances on the top ring land I ended up safety wiring the caps onto one of the valve cover studs on each side I didn't lose anymore of them after that The soulution is to replace the bad parts, maybe even having to bore the block also if there is enough cylinder wall taper Good luck

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Where can I buy some of these, like the one pictured?

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Took a quick look for ya,seems they come with a new set of covers,but can't find them individually sold.You can have mine in a month or so when I install new valve covers

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625 hp that's more race than street, you will get the vaccum pump when you get tired of fight the oil leaks and if your getting that much crankcase pressure your rings are not seating. vaccum pump probly pick up 40 HP on your deal

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Took a quick look for ya,seems they come with a new set of covers,but can't find them individually sold.You can have mine in a month or so when I install new valve covers

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Wow, I think I might take you up on that offer! From the pic it appears your new covers are already installed.

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Wow, that's tight! What body? Is it like a mid-60's a-body?

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625 hp that's more race than street, you will get the vaccum pump when you get tired of fight the oil leaks and if your getting that much crankcase pressure your rings are not seating. vaccum pump probly pick up 40 HP on your deal

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I am ignorant about what a vacuum pump actually does...even after reading over the website you posted in your original response. Actually, I'm ignorant about why there is excessive pressure in the crankcase. Is it a sign of a poorly built engine or a tightly built engine?

Thanks for the advice!

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You should do, or have it done, both a leak down test and compression tests to see what the ring seal is like both cold and warm Excessive crankcase pressure is what is blowing the breathers caps up My 518 C.I. pump gas B motor(400 block) would blow the tight fitting oil dipstick up out of the dipstick tube at WOT above 6000 RPM during a run in the 1/4 mile until I added a additional screw in breather cap and a addional PCV valve, one in each cast aluminum valve cover I used a vacume Tee to feed both PCV, they don't work at WOT but they do increase the idle vacume leakage which was a good thing in my case They definetly help suck any blowby out of the crankcase at idle or part throttle Being a Hemi(your motor) you may need to add two additional breather tubes to run four breathers or two breather caps and two PCV valves I did that(four breather caps) on the last blown street hemi motor I built for a custmomer, it had fabricated aluminum valve covers on it like shown in the pictures above It worked good, that motor made 927 HP at 7300 RPM with 7 lbs of boost (4.25 bore with 4.375 stroke, crankshaft scraper and windage tray) No oil leaks on the dyno If you do add two addiational breather tubes make sure and have oil baffles added under the tube holes also

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Thank you for the reply. This is a high dollar Ray Barton hemi built about 10 years ago, with approx. 4k miles on it. It's set up right, just has a lot of crankcase pressure when it's wound up. I'm going to start with breather mods first and see if that helps. Previous owner who built the car said he had luck just keeping the breathers clean, so I plan to start there.

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Nice ride!! Are you still on the westside??

Gonna stop by Willies on Weds nights this summer on Glenway ave where the old Texas roadhouse used to be?