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Help to find center line

4K views 12 replies 7 participants last post by  1971BB427 
#1 ·
I have a 58 chevy truck the we bought without a motor or tranny so there was nothing to pull out It has old front mounts and we need to install side mounts how do I find the center line in other words It needs to be right on the center line of the crank. Never thought about it years ago we just put them in don't remember it ever being a problem. Thanks

Chris,
 
#2 ·
I have a 58 chevy truck the we bought without a motor or tranny so there was nothing to pull out It has old front mounts and we need to install side mounts how do I find the center line in other words It needs to be right on the center line of the crank. Never thought about it years ago we just put them in don't remember it ever being a problem.ThanksChris,
As long as the crankshaft is 90 degrees to the centerline of the rear axle, it will not be a problem. As long as you have room in the tunnel of the floor of the truck for the transmission and driveshaft, you are golden. I remember back in the 60's musclecar era, Chrysler Corp. moved some of their motors to the passenger side of the car by 3 inches off center in order for valve covers to clear brake boosters. But they kept the crank centerline perpendicular to the axle centerline and life was good.

Begin your work on a flat, smooth surface where you can drop a plumb bob from the axle to the floor, then make chalk marks on the floor that you can measure from, going to the front of the truck, where you will have dropped a plumb bob from points on the front frame or suspension. This is how you square up the whole mess, by reading it off the floor.

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#6 ·
Doesn't matter a whole lot if the engine isn't exactly centered to the chassis or at 90 degrees to the differential input flange, lots of vehicles come with the engine offset one way or the other and run the driveshaft at an angle as seen in the horizontal plane as well as the more typical vertical. So you've got some wiggle room on the installation.

Bogie
 
#7 ·
Dimensions ???

Chris, I found some old measurements from mine. From the centerline of the crankshaft down to the bottom lip of the front crossmember at the radiator support should be in the neighborhood of 5 1/2". I you're planning on using original style front V8 mounts, this distance is fixed by the mounts, but remember you'll have to use the early small 265/283 balancer(6") to clear the mounting tabs on the block.

With side mounts the centerline of the mounts should be around 10 1/4" from the top flange of that front crossmember. This should give adequate clearance for an HEI distributor.

The factory V8 engine placement is dead centered between the framerails.

On the rear view, the transmission tailshaft centerline should be somewhere in the neighborhood of 5 1/2"-6" below the bottom of the frame rail for 3 degrees down. You wil have to check this dimension and adjust the transmission or crossmember depth according to what transmission you use.

See my crude photo...Nolan
 

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#8 ·
Big crank pulley

I forgot to mention that from what I saw on the engine trial fitting, the big triple belt crank pulley's on some engines may not clear the frontmost crossmember. Mine fit fine with a serpentine belt setup. Engine may have to sit higher or farther back or a notch cut out in the crossmember to clear the big pulley. The dimensions I gave will clear an HEI distributor at the firewall. If you have to move it back, some massaging on the firewall may be needed. Nolan
 
#12 ·
Last time I did something like that, I mounted the motor-mounts to the engine, dropped it in and squared it up where I wanted the engine to end up, then tacked the mounts to the frame rails. Pulled the pins and lifted the engine back out and finished welding the mounts to the frame.
 
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