Earlier this year I acquired (paid too much for) a 78 Fj40 and began a DIY restoration. I was fortunate to have found a truck that was 100% original and have enjoyed resurrecting my 1970's mechanical intuitions. The main difference between 1970 and now is that its much more difficult to slide under and cram myself into tight spots on this truck verses the 68 Camero! I knew I should have kept that car!!
I've often used this site to help answer mysteries and so I thought I'd pay it forward and offer my insight into a vacuum leak that plagued me for several months, until the solution appeared. When I first started to go through the basic tune up portion of the project I had a persistent rough idle situation (failed CO emission test) which was not phased by 4 carb rebuilds, fuel solenoid replacement, timing adjustments, electrical system checks and numerous other refurbishments. I really felt I had left no stone unturned but knew it must be a carb related issue so I began the fifth tear down of the carb and noticed some peculiar gouges around many of the holes in the phenolic block between the carb and intake manifold. These gouges were somehow formed over time and were creating a vacuum situation at idle but as RPM's increased the problem subsided, likely overcome by increased air volume.
I JB welded the gouges, filed it smooth and flat, problem solved.
Lesson learned and emissions test passed. I hope this might offer one more solution option for someone having similar issues.
Thanks
I've often used this site to help answer mysteries and so I thought I'd pay it forward and offer my insight into a vacuum leak that plagued me for several months, until the solution appeared. When I first started to go through the basic tune up portion of the project I had a persistent rough idle situation (failed CO emission test) which was not phased by 4 carb rebuilds, fuel solenoid replacement, timing adjustments, electrical system checks and numerous other refurbishments. I really felt I had left no stone unturned but knew it must be a carb related issue so I began the fifth tear down of the carb and noticed some peculiar gouges around many of the holes in the phenolic block between the carb and intake manifold. These gouges were somehow formed over time and were creating a vacuum situation at idle but as RPM's increased the problem subsided, likely overcome by increased air volume.
I JB welded the gouges, filed it smooth and flat, problem solved.
Lesson learned and emissions test passed. I hope this might offer one more solution option for someone having similar issues.
Thanks
