340 cast crank flywheel
First off:
You didn't say what model year your engine is, so make SURE your engine is an externally balanced one. Some people are under the mistaken impression that all '72 340s are externally balanced, they are NOT. Early '72s were still using up existing inventory internally balanced 340s, sometime mid year they began installing externally balanced engines. ALL '73 engines were external.
To confirm external balance, it will have a harmonic balancer with an external weight, labeled "use with 340 cast crank only" like this:
If it doesn't have this, it is NOT externally balanced. (Unless someone replaced your balancer with a plain internal one... which will cause an imbalance...)
If your engine is indeed externally balanced, it should be paired with a flywheel that has the rear face drilled like this:
It should not look like any of the following:
Internal balance:
External 360 balance:
B/RB cast crank:
Also any 5.9 magnum flywheel, no pic but they only came in 11" 143 tooth configuration anyway.
The use of ANY of these will cause an imbalance on a cast crank, externally balanced 340.
Apologies to any and all whose pictures I borrowed to illustrate my point(s).
First off:
You didn't say what model year your engine is, so make SURE your engine is an externally balanced one. Some people are under the mistaken impression that all '72 340s are externally balanced, they are NOT. Early '72s were still using up existing inventory internally balanced 340s, sometime mid year they began installing externally balanced engines. ALL '73 engines were external.
To confirm external balance, it will have a harmonic balancer with an external weight, labeled "use with 340 cast crank only" like this:
If it doesn't have this, it is NOT externally balanced. (Unless someone replaced your balancer with a plain internal one... which will cause an imbalance...)
If your engine is indeed externally balanced, it should be paired with a flywheel that has the rear face drilled like this:
It should not look like any of the following:
Internal balance:
External 360 balance:
B/RB cast crank:
Also any 5.9 magnum flywheel, no pic but they only came in 11" 143 tooth configuration anyway.
The use of ANY of these will cause an imbalance on a cast crank, externally balanced 340.
Apologies to any and all whose pictures I borrowed to illustrate my point(s).
