O-ring between fuel distributor and metering unit

Smog is coming up, and I want to make sure that I don't have any vacuum leaks that would cause my car to fail. Two years ago my car was running lean, and the technician had to richen the mixture past the FV swing to get it to pass, and I never quite figured out why because all of my vacuum lines are sealed.

Well, I recently discovered that there should be an o-ring between the fuel distributor and the metering unit. I looked underneath my FD to make sure it was there and it was, but it was crushed. I then ordered and installed a new o-ring and started the car. My mixture was completely off, and the FV not buzzing. I corrected the mixture with a dwell meter, but I can't recall the direction I turned it.

My question is, would a lack of a proper o-ring seal between the FD and mixture unit be considered a huge unmetered air leak? Because I wonder now if that was the culprit all along?

Attachment 57740

It wouldn't have to be a huge leak....I say that not because of semantics, but because a small leak will make it fail and that the adjustment it is so touchy that simply loosening and tightening the FD would probably require resetting it. Anyway, If the o-ring is the only thing that has changed since he set it, having to reset the dwell afterwards indicates it caused a significant change. So unless it is worse somehow and you compensated for it (unlikely, esp. if it runs well now), I'd say you nailed it.

(Make sure you check it with the adjustment hole plugged and the air cleaner etc. installed right before you take it;-)

Thanks Ron!

We'll see if that corrected the leanness problem when I take it in for smog next week. My oil smelled like gas as I was changing it last weekend.