engine stutter of rebuild BT7 engine [tri-carb] above 2500 rpm

[Rob Glasgow]

I created a similar situation years ago when I over-oiled the OEM air filters after cleaning them. I somehow got enough oil on the wire mesh to restrict airflow and cause an over rich situation.

 

[mengels]

If you're getting that much oil in your rear air filter you should check your rocker shaft for wear. If it's spouting oil you're probably losing a PSI or two of oil pressure.

Bob,
I also wondered if there was an excess of oil coming from the valve cover vent, therefore I mounted a transparent tube. Until now it looks that there is no excess oil coming from the vent (it would be rather unfortunate if it did because the engine was totally overhauled a few thousand miles ago...). I guess it is due to mounting third party B quality air filters which I had to alter to fit the vent hose. The hose was probably too long and vented right onto the filter itself instead of into the body of the air filter.....
I replaced the air filters with the "original" Coopers....

 

[Deleted member 21878]

Maarten
one suggestion learned on this forum:
especially on tri-carbs the filter nuts are hard to get on and off. i drilled mine and put small cotter pins in them to hold them on. now if i want to remove, i can just pull the pins and they are off in a few seconds. once you drill, clean up the stud and you can still run a nut on them if you like later.

 

[vette]

Maarten, Remove the hose that goes from the valve cover vent to the rear carb. Put a 2" diameter filter on the "T" fitting of your valve cover vent as I show in the picture. Even if you don't want to keep running it this way this is a good test. With the filter installed drive your car for awhile. If the filter never gets saturated with oil then you don't have an over oiling problem. I have been running my BJ7 for more than 10 years with the hose removed from the rear carb and the 2" filter installed at the valve cover "T". I can cup that filter with my hand at anytime and my hand will stay oil free. I change it once a year. This method goes along way to help keep your rear spark plugs clean.
If your spark plugs are blackened first figure out if they are blackened by oil or soot from a rich mixture. Soot usually has a softer, dryer appearance on the plug, oil has a shiner, harder caking appearance. As I said earlier I thought your problem might be your carb setting and I said a lean condition might be causing it. But a rich condition can cause it too. Your problem may very well be just a carb adustment. but get that hose off the rear air filter.

 

[mengels]

Thanks for the few latest inputs....
In regard of the black spark plugs.... The oil vent hose is disconnected now in a more or less similar way as "Vette" did and I retuned / synchronised the carbs again starting with the tip from "Steveg" by dropping each jet 1mm from the bridge and fine tuned from there...
The car runs and drives fine now...

 

[Deleted member 21878]

Maarten
Where did you end up on the depth of those seats? i think mine ended up .074. not sure now why i ended up there. i looked back at my notes after seeing steve's post of .040.

 

[mengels]

I just measured it....I ended up at 0.67 ....the depth may vary from car to car because it's also dependend of needles and air filter used...

 

[vette]

I just measured it....I ended up at 0.67 ....the depth may vary from car to car because it's also dependend of needles and air filter used...

It's also dependant on the quality or lack there of of the intake stream / runners.