[bdm6]

I have a 1964 283 chevy with 1958 heads. I am using old Cal-Custom aluminum valve covers. I am using cork gaskets, gluing them to covers with permatex #2. After engine gets up to temperature the gaskets started leaking and one blew out. My block is vented with a down tube at rear of block. the valve covers are not vented. Should they be?

[Blazin72]

How long did it take for the the engine to warm up and blow the gasket out? 5 mins? 20 mins?
Is the vent tube plugged? The underside of your valve covers are subject to the same pressures as your crankcase and lifter valley. You can also install a PCV valve in the valve cover and a breather in the other valve cover.

[docvette]

Doc here,

Does this 283 have the stock road draft and stock forward filler tube?

If so your vent or tube or both are probably plugged up or not up to the challenge of the fresh engine.

Install a PCV in the system you'll be glad you did. It will keep your engine , Drivetrain, Driveway as well as your oil cleaner longer...

Get a PCV valve and remove the road draft tube. Get a Grommet to fit in the block hole and around the PCV valve. Install it there.

Run the Vacuum host to any full manifold source, If you have a brake booster DO NOT Tee from it..you'll swamp the vacuum when you most need it. If need be, get a base plate spacer with a Vacuum tap on it and install that under the carb.Run your hose from it to your PCV.

Next get a VENTED filler cap for the filler tube, and install that.

When you go to install the new valve cover gaskets, two recommendations, One, OIL soak the gaskets before you put them on, this will expand and undistort them. Two, get some bolt spanner holdowns for the mount bolts, this will distribute the pressure evenly in case one of the covers is warped, and head off any leaks.

Doc

[red65mustang]

check simple first= the old covers are warped....set it flange down on a flat counter top...see if it "rocks", if yes than the cork is not compressing to a uniform seal thickness and pressure...
spanners ($10? Mr. Gasket?) may fix it....if not buy new covers

blow some compressed air thru the down draft tube with the motor off to be sure the system is open....if the draft system is plugged, usually the pressure causes leaks everywhere...mains/oil pan/intake/etc

to build enough air pressure to blow out valve cover gaskets = ??? the heads/block oil drain back holes are wrong ????

if all is really "happy" and correct....re-usable rubber/steel gaskets, NO glue, hand tightened dumb tall stand off bolts should seal fine.....that's your goal

[jimfulco]

VALVE COVER HOLD DOWNS (mr. gasket)

6395 gold iridite
6396 chrome
6397 black

Those are the "spanners" that docvette & red65mustang are talking about.