The importance of measuring bell housing runout.

skep419 said
I’m planning to swap to a 4 speed this winter. The 5.9 magnum that’s in the car isn’t drilled for the input shaft. I have a spare engine that I tore down on the stand and figured I could use it to get measurements to pre cut the input shaft. Got everything bolted up and my spare was drilled (completely spaced checking it first :BangHead:)
Hoping this old lakewood scatter shield comes out somewhat close when I measure the runout :thumbsup:.
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Hope your not going to use that threaded rod to indicate the locating bore on the bell housing/ scatter shield. It won’t give you a true reading in that position. Its going to drop cause of gravity. It will give you a true reading if you remove water pump and acessories and set timing chain cover face on the ground level to the bell housing mating face of the block if that surface is perpendicular to the axis of the crankshaft.

The farther out horizontally you stick an indicator, the more it will drop. The hole you are indicating will be off down to the floor from true position. This holds true for a magnetic base as well.

The face in your picture where the trans mounts to the bell housing/scatter shield needs to be shimmed perpendicular to the rotating axis of the crankshaft. This needs to be done before indicating and offsetting the dowels to get the bore on true position.

Trust me on this, I had a 45 year career as a tool and die maker and learned this experience running horizontal boring bars for 30 of those years.

You will find you will have to remove and re-install your bell housing/ scatter shield 4 times to get it dialed in, maybe more depending on how close you want it to be. Accuracy reduces frictional losses.