Thread: Thoughts on jetting.

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I did some more fiddling this morning. At 800 RPM idle, it's pulling about 17" Hg - solid, no fluctuating. In gear, I lose a couple hundred RPM, and the vacuum drops to around 13" Hg, but it fluctuates an inch or two. So, assuming that the power valve isn't blown, it should be about right.

After checking that, I drove about 10 miles on new plugs this morning, and they came out black as soot.

While I was trying to set the carb, I had trouble adjusting the idle. It felt like the secondary butterflies were open too far, and uncovering too much of the transfer slot. So, I pulled the carb to give it a quick once-over, and reset the secondary idle position.

While I was re-setting the secondary butterflies, I noticed something odd. When I opend the primaries, the secondaries would open with them for a bit, then they would snap shut. I pulled off the electric choke to get a better look. Check the photo below.

The link rod (A) and the bracket (B) are meant to keep the secondaries from opening further than the primaries will allow. I found that the link rod (A) was bent a little. As the primaries opened, the rod would hang up and pull the secondaires open, every time - even under light throttle. Looks to me like this would cause a very rich condition, and also would cause a bog because of the secondaries opening too early.

Whatcha' think?