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Michael 9111 06-24-2012 07:40 PM

383 keeps blowing intake gasket
 
Fresh 383 keeps blowing intake gasket by distributor.

Michael 9111 06-24-2012 08:17 PM

I've ran this motor for ten years. All I did was freshen it up and put a different cam in it. I've used permatex for gasket and a rubber gasket that goes in the small holes on block and it keeps blowing out. Any ideas or suggestions. ???

68NovaSS 06-24-2012 08:38 PM

Sounds like you have excessive crank case pressure, are you running a PCV system? Did you have one prior to this upgrade?

Michael 9111 06-24-2012 08:42 PM

I got a PVC valve in one valve cover and a breather filter in the other valve cover. Both are good and not clogged. Same set up I've always used

68NovaSS 06-24-2012 09:16 PM

You're not putting RTV sealer on the rubber gasket are you? Could be squishing it out when the manifold's installed. Other than that, if the mating surfaces are dry, crankcase pressure is the only thing that could be pushing it out IMO.

Michael 9111 06-24-2012 09:18 PM

Yes I put rtv on gasket also. It don't blow it out at idle or revving it up. Just when I drive it down the street and romp down on it

68NovaSS 06-24-2012 09:25 PM

I would either install it dry with a dab at the ends or if you insist on coating the rubber gasket, let it setup/skin over before you install the manifold and cure for maybe 24 hours before you drive it. Sounds like it just slowly squishes out if the PCV is working/pulling a vacuum.

Michael 9111 06-24-2012 09:28 PM

I've always used just rtv on it in the past. It set for two days the first time it blew so I tried using it with a gasket and it did the same thing in the exact spot so idk what's going on

68NovaSS 06-24-2012 09:51 PM

IDK either, unless the manifold isn't sitting square in the valley, maybe a hair high on one side or the other.

Michael 9111 06-25-2012 07:57 PM

Fresh 383 compression
 
383 keeps blowing back intake gasket out. Ran compression test and all cylinders had from 120 to 145 of compression. I hear that's low but this motor always has had around that much. I didn't degree in the cam just lined up the dots. But it's still blowing intake gasket out. Any thoughts on any of this or opinions?? Any help is greatly appreciated.

dgcantrellsr 06-25-2012 08:16 PM

Quote:

Originally Posted by Michael 9111
383 keeps blowing back intake gasket out. Ran compression test and all cylinders had from 120 to 145 of compression. I hear that's low but this motor always has had around that much. I didn't degree in the cam just lined up the dots. But it's still blowing intake gasket out. Any thoughts on any of this or opinions?? Any help is greatly appreciated.

You need to run a PCV valve in one cover and a breather of some sort in the other or you got a lot of blowby somewhere.

Michael 9111 06-25-2012 08:18 PM

I have. A PVC valve in one valve cover and a breather in the other

68NovaSS 06-25-2012 09:24 PM

Please don't double post, you have two threads with the same question, they've been merged.

Michael 9111 06-25-2012 09:29 PM

I couldn't get my other post to pull up that's y I posted again

454C10 06-26-2012 05:26 AM

A full bead of rtv should not leak if it is done correctly. Use lacquer thinner to clean the surfaces (not paint thinner). After you bolt down the intake, make sure to stick your finger down the distributor hole and press the fresh rtv away from the distributor hole. Then give it over night to dry.

with a breather and pvc valve there isn't that much pressure under the intake even on a poorly sealing engine. so the rtv should hold if every thing is clean before putting on the rtv.

to check for engine blow by, start the engine, pull off the pvc and breather and place you hands/fingers over the valve cover holes for 5 or 10 seconds. then release one hole and see how much pressure has built up.

how many miles on the engine now. What did you do to freshen it up?

what compression and cam size?


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