3.2 missing on #5

[Hatari]

I had to remove my engine and trans a couple of weeks ago to have the 915 rebuilt. I guess the new tweaked 3.2 was a bit much for the old gearbox. Anyway, I got the trans back and reinstalled the engine and trans yesterday. Other than a small flat spot at lower RPM’s, the engine had been running flawlessly. The engine has 46mm PMO’s and I had spoken to Richard Parr about the flat spot. Richard sent a different set of check valves for the carb float bowls. I installed these while the engine was out. This was the only change in the engine from before removal to have the trans rebuilt.

Upon initial start-up yesterday, the engine roared to life as before hitting on all 6. After checking to be sure there were no leaks, etc., I started on a test drive. After about 3 miles, I noted that the engine was beginning to miss as if a plug had fouled. I pointed the car toward home and pulled in the garage. My immediate assumption was the change in the check valve had richened the mixture too much. This morning, I changed the check valves back to the original ones and installed new plugs. I noted that the old plugs didn’t look bad and were all burning about the same color…no real evidence of fouling. When the engine was started with the mentioned changes, it immediately was hitting on 5 cylinders. For whatever reason, it is not hitting on #5. To rule out a bad plug or wire, I swapped the wires on number 4 and 5 at the plugs and distributor. No change in getting #5 to hit. I pulled the air cleaner and noted that the injection nozzle on #5 is pumping gas and assume if this is the case, I should get some response under acceleration on all 6 cylinders, but this is not the case.

As mentioned, the engine had run perfectly prior to the removal/reinstallation. I now think that the condition which led me to the conclusion that the plugs were fouling yesterday was something else. The car has a new fuel tank and filters as prescribed by PMO so I doubt that trash has been drawn into the carb, but that is a possibility.

Any thoughts on this would be appreciated.
Jack

[yelcab1]

do a compression check on 5 and tell us what you find.

[Elombard]

I had webbers on my datsun race car a few years ago. I always noticed the the needle and seat would gum and stick a little after a few months lay over. Had to pull them and clean them/flush fuel through and then it would run better??

[john walker's workshop]

pull out the #5 idle jet and check for dirt.

[Hatari]

Thanks all. I actually discovered that the float windows on the right bank were unexplainably over full. I am adjusting this now and have spoken to Richard Parr...may have to replace the needle/seats.

At any rate, I think this is the problem.

Thanks again.
Jack