FWD Honda Mini Stock - Hands-On Honda

I purchased 2 two-barrel to four-barrel adapters, bolted them back to back, and installed them under the carb. Instant plenum. Well, maybe there was a little benefit-it raised the rpm by about 1,000 before the problem occurred again. It looked like this engine might require a plenum somewhat bigger than my old 10-gallon hat. So I began to look elsewhere. I even changed back to a stock cam. No change in the extreme rich condition.

At this point, I was not looking for a cure but a fix. Surmising that the intake manifold was at fault, I looked for another way. First I drilled a 11/48-inch hole in the accelerator pump circuit. This would act as an air bleed into the float bowl. My thinking was the pump would overcome the air bleed and still get some squirt to the venturis. When this semi worked, I felt I was on the right track. However, the vacuum was still pulling fuel through the squirters at about 5,500 rpm.

I do not consider myself a carburetor man. After taking the carb off and apart for the 741st time, I removed the squirter. I turned the carb over and tapped it gently. Guess what? A pointed-end pin fell out of the hole under the squirter. This pin is part of a needle valve assembly. I suppose its weight would keep fuel from being sucked through the squirters under normal conditions. Nothing about this condition would be considered normal.

First I tried putting a spring on top of the needle to help it stay closed. But there is only about 0.090 inch of room between the squirter bolt and the pin. So there would be no spring on the pin to fix this. Rooting around in the nether world of Sleepy's Workshop, I found a 0.155-inch-diameter steel ball that came from some bearing I cut apart long ago. I dropped this ball in place of the pin. Then I installed half of a ball-point pen spring atop the ball. Instant improvement.

Then the pump didn't want to overcome the spring. To make adjustments, I stacked gaskets under the squirter. The spring adjustment needs to be where the pump can barely overcome it.

I'm down to 54 jets with a 25 squirter. The power valve is still the 2.5 that Bob Oliver sent with the carb, but this may be changed in the tuning process at the track. When I look in the throat of the carb at 6,500 rpm, fuel seems to be coming from the right places in the correct amounts. We'll know more after we check the plugs at the track. It has been an interesting problem to fix.