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Hi, I have a 1987 Jeep Grand Wagoneer with the AMC 360 V8 engine. Sometime in 2011 I got tired of fighting / rebuilding the Holley 2BBL carb that was on it and decided to start fresh and put an Edelbrock Performer intake and Edelbrock 1406 carb on it. From the get go, the rear seal didn’t … well seal, so I had to pull it apart and thanks to other forum help who told me to get rid of the rubber gasket and use silicone, I had gotten it to seal. However about 2-3 months later the rear seal blew out again. Through different suggestion, with valley pan, with out valley pan, this type of sealer, that type of sealer, I have had this intake off more times than I would like to even think about. One of many suggestions was that the engine never seemed to (that I know of) have a PCV System, so a local mechanic friend of mine and myself designed a proper working PCV. I started having problems with that flipping Motorcraft Dura-Spark system, and it ended up sitting almost a year. It seems to leak in the same place every time which is the rear seal of the intake. I have done many Chevy Small blocks, and even some Ford V8s, and have never had such a problem. Any help you can offer on this would be greatly appreciated, thank you.
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Hi Eric,
I had a similar problem with my 390 in an AMX. I had a clogged up breather. On mine,the breather was the oil fill cap that went through the intake manifold. I can’t say for sure if the breather location changed between 72 and 87. What I learned was the breather is way more important than the pcv valve. A pcv valve is an emission device that allows some of the gasses from the crank case to be burned in the cylinders instead of venting to atmosphere. It also stops sludge build up by removing moisture. If you ran without a pcv you may have clogged your breather.
Pcv valves can’t vent the base constantly without causing a lean mixture in your intake. It only vents when an internal check valve is opened by pressure build up. When it vents it is only a small amount through a fairly small orifice. Very old cars didn’t even have pcv valves.The only change is that this engine originally had an EGR valve. I do have an aftermarket breather cap on it, I know it has flow, I just don’t know if it is sufficient tho.
The elimination of the EGR may be the culprit. That exhaust gas has to go somewhere and if the heads are designed to use one of the rear ports to feed the EGR this may be the reason that you keep blowing the seal back there. Modifications often come with issues like this. It’s often a question of trial and error. Keep us posted on what you find.
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