348 crank question

Hey guys. I am extremely excited to announce that I just bought a complete 348 to put in my 30 chevy coupe. while doing a little teardown over the weekend i found that the snout of the crankshaft did not have a hole with threads for a damper bolt, it just has a shallow countersink.
I have seen in several magazne builds of "w"motors that an SBC balancer and be modified and used but no mention was ever made of drilling and tapping the crank.
I'm pretty new to these motors and the help of an expert would be greatly appreciated

 

drill and tap it or have your local machinist do it for you. cheap insurance!

 

Chevys both 6 & V8 before around 68 were not generally taped. Some hi performance models were taped but not common. I drill them while still in the block. Start with a small bit and increase to I think .390 ? and tap to 7/16 NF, while drilling you can eyeball side to side and have someone watch the up & down from 10 Ft away, it works for me. I have taped at least 50 this way.
Van

 

My Neighbor drilled and tapped his 327 crank. He tapped a bubble level to the top of his drill and took it slow. That motor has been revved to the moon and no problems. That little 327 lasted two or three seasons in his stock car and several years in different street cars.
EDIT......
I was just sitting here thinking about it, and that motor lasted two or three seasons in his dirt car without a balancer bolt. Big solid lifter cam too. I rode with him in the truck he installed it in later and I can tell you he did not baby it. I saw 7500 on the tach over and over that night. I think the balancer eventually started to "walk" off the crank and that's when he drilled and tapped it. He did it with it in the truck.

 

My 58 motor in my coupe was already tapped but some Chevy motors were not, it is no big deal to do it yourself or if you are having machine work done have your machinest do it. It is a minor problem for what you may encounter later with doing machine work on these motors.

 

Thanks everybody for all the good advice! I figured it would be pretty minor just to drill and tap a hole in the crank with the hard work (finding the center) already being done at the factory.

Hey, while im thinking about it. annother dumb question, with the current set-up (no tapped hole) how do you install the damper? Do you just use a dead blow hammer till it stops or is there a more scientific way?

 

If you are going to drill & tap the crank you should go ahead and use a dampner installer you should be able to rent from most parts stores. OR you can knock the **** out of it with a hammer

 

If you are going to use a hammer to install the balancer it is best to support the back end of the crank, otherwise you are beating on the thrust surface of the rear cam bearing. you can stand the motor on end and put a block of wood under the crank flange, or if it's in an engine stand you can drive a wedge in behind it. It's also a good idea not to beat directly on the balancer. A block of wood or soft metal works here, too.