Hesitation upon acceleration issue

[1970 Problems]

QC,

This thread is all yours. Feel free to post all your quesitons, troubleshooting and findings here. I'm curious to see how this issue gets resolved without abandoning the stock carburator.

Maybe if someone has a detailed picture of the linkages on a stock '72 carb, we can use it to compare to our carbs.

Thanks.

Hey there. Reviving the forum. Did you ever get your hesitation completely gone? I have been trouble shooting the same things you have for a year and a half now. I tracked down a carb built the same month as my fj40(decmeber of 1970) I rebuilt it but I left that butterfly valve for the weighted secondary air valve out. It’s the small circle valve that is shaped really strangely. I put the carb back on without it and the car hesitates when you go to give it gas from Parked. I believe it’s the same issue that you had. Tomorrow I get my truck back from the shop where they had also been looking into the problem(had Experts look at it) but they haven’t fixed anything.

I believe that once I take the carb off and put the valve back in, it will work perfectly, but I have no idea.

 

[HKforte]

Hey there. Reviving the forum. Did you ever get your hesitation completely gone? I have been trouble shooting the same things you have for a year and a half now. I tracked down a carb built the same month as my fj40(decmeber of 1970) I rebuilt it but I left that butterfly valve for the weighted secondary air valve out. It’s the small circle valve that is shaped really strangely. I put the carb back on without it and the car hesitates when you go to give it gas from Parked. I believe it’s the same issue that you had. Tomorrow I get my truck back from the shop where they had also been looking into the problem(had Experts look at it) but they haven’t fixed anything.

I believe that once I take the carb off and put the valve back in, it will work perfectly, but I have no idea.

A slight hesitation is still there, but there was considerable improvement from playing with additional weight placement on the weighted secondary. A Carb rebuild and correcting the valve clearances during troubleshooting may have made improvements as well. I initially thought fuel delivery, timing, or insufficient spark were the culprits or at least part of the problem. I think running through the tune up process, and testing after individual changes are made, is a good idea.

Any updates after installing the carb?

 

[1970 Problems]

A slight hesitation is still there, but there was considerable improvement from playing with additional weight placement on the weighted secondary. A Carb rebuild and correcting the valve clearances during troubleshooting may have made improvements as well. I initially thought fuel delivery, timing, or insufficient spark were the culprits or at least part of the problem. I think running through the tune up process, and testing after individual changes are made, is a good idea.

Any updates after installing the carb?

Yup it works flawless now. That weighted valve is basically needed if you want no hesitation. My weighted valve was very sticky so we had to milk it out a tiny bit. Now the wait is smooth and correct. Currently installing a new oil pan gasket. The gasket has never been off so it’s giving me some troubles.

It ain’t work if it ain’t hard.