I was about to ask a similar question, so lets see how this goes!
I have a Holley Ultra 750 DP on my 340. Had it on there about 9 years now (had to check, longer than I thought!), the car is driven regularly most of the year. I've replaced the bowl and metering block gaskets a few times, seems like that was more a result of taking the bowls on and off when I was tuning the carb. I recall having to change the accelerator pump diaphragm at one point because of a leak, think that was a few years ago. Little over a year ago I had a rich at idle condition just show up, which I finally tracked down to the needle and seat and/or the o-ring on the primary float. Had to change the gaskets as soon as I touched the float adjustment, those gaskets immediately failed when I loosened the lock screw.
Fast forward to this year and I had the same issue return, now the secondary needle and seat/o-ring. I probably should have replaced just the o-ring just to see if that fixed it by itself or if the whole assembly was allowing the leak. Really I should have changed them both when I figured out the primary needle and seat was an issue!
Obviously 8-9 years on a needle and seat assembly is plenty! But I was also curious if non-racers had an interval for changing gaskets/seals/o-rings in the carbs. For racers I would assume that the more frequent tuning would already lead to more frequent gasket and seal changes.
If it's running good, I don't take it apart.
That's definitely been my line of thinking, although with a couple of issues cropping up I'm beginning to think a more wholesale replacement of the gaskets/seals/o-rings might be in order at this point. Just curious if anyone else has a schedule for that or if everyone just deals with things as they fail.
