intake and idle

intake and idle

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By cbass139 - 12 Years Ago

I put the engine back together after putting in the pcv and it is running nice but I seem to have a small leak but I dont know what this port does. It is the port in the middle of the intake that is a different size then the other eight that obviously feed fuel to the cylinders? Also I can not get the idle to go any lower than 750, I was running it around 650 before this and really liked it there but it just wont go any lower. I tried everything, any ideas?

Sebastian

By GREENBIRD56 - 12 Years Ago

The center ports on each side are the "exhaust cross-over" that was intended to provide heating for the carburetor. It provides an exhaust passage across the engine from head to head beneath the carb. There is a "truck" gasket available that has a steel restriction at these ports - to limit the amount of heating and many use it for their passenger cars as well.

Try plugging the PCV inlet to the carb - see if that stops some of the "over speed" situation. If it does - you may need to find a smaller PCV - or orfice it down a bit (which is what I did).

By Ol'ford nut - 12 Years Ago

I believe you are talking about the exhaust port under the carb. Many restrict or plug it off to prevent burning the paint on the manifold and allow the fuel mixture to remain cooler, unless you drive in colder weather then it is needed.

After installing the PVC valve you might want to re-adjust you carb. air screws since that will be changed. This will affect your idle. I would re-check the timing also.

By oldcarmark - 12 Years Ago

That port can cause a vacuum leak.Plug the ends.You may need to play with the PCV size by either changing to a smaller one or restricting it with something in the hose.I ended up using one for a 4 cylinder 78 Fairmont.302 Ford was passing too much air.Fix those open ports first and than try it.As far as what Steve(Greenbird) mentioned about intake gaskets-I just cut 2 pieces of tin to cover the openings in tthe head.They go on before the gasket.

By cbass139 - 12 Years Ago

thanks guys, upon further review it was the valley pan that was leaking the fumes not the port. I fixed that and I had a gasket leak on the carb spacer so that was the idle problem. It is all buttoned up and running great. Thanks for the help as always. Wish I could add something some time instead of being the question guy all the time.

Regards,

Sebastian

By oldcarmark - 12 Years Ago

God to hear problem fixed.As far as valley pan leaks I fixed mine permanently when I rebuilt it awhile ago.I drilled and tapped 6-8 holes around the perimeter .Used machine screws to hold down the edges.The problem with the original design of the valley pan is that the torque limit for the 2 bolts that hold it in place is about 2-3 ft pounds.The more you tighten it ,the more it lifts at the edge plus the pan gets distorted over time.I did mine when I heard the suggestion from another member.