140 valve seals

[kgroombr]

I was putting new valve seals in a early Vega head (71-75). The intake seals popped down in place nicely and hold tight, but the exhaust seals are really loose. By really loose, they slide up and down with the valve. I have a few sets from different vendors, so I opened two others and those also fit really loose.

I have a few other heads so I tried them on the other heads and they only firmly fit on one of them. The only head it fit firmly on is a 71-75 head, They were loose on a 76 head and two other 71-75 heads.

The intake seals fit firmly on the exhaust side.

Anybody have experience with these. I am thinking that because of this oil is going to get under them and cause excessive oil burning. Should I use intake seals on the exhaust side? The intake seals are blue and the exhaust ones are black and I got information before that they are different because of the temperature, so I don't know if this would cause a problem.

Thanks,
Ken

[kgroombr]

After some searching I found the answer. It was posted in a forum. I was concerned as I was fairly sure that when I pulled the exhaust valve seals, I had to use use some force to pull them. Anyway, here is what I found:

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First you have to understand that there is Vacuum present on the intake guides that tends to draw oil down into the combustion chambers. But, on the exhaust side there is pressure. This tends to try to blow the oil back up the guide.

On older style engines I tend to use positive seals on the intakes and Umbrella or deflector seals on the exhaust. This allows better oiling to the exhaust. There are lots of arguments on this subject. Most citing the modern engines that use positive seals on both intake and exhaust. But, these engines were engineered for such use and have different exhaust and intake guide/valve materials. Not just plain old gray iron like the older stuff.