Quote:
Originally Posted by Verne_Frantz
The carb is the correct Rochester 4GC. I believe the crank and rods are the originals. Reportedly they did some "shaving" on the rods, so they are suspect. The pistons are new, but they are being cleaned and will be weighed. The valves appear to be new but I don't know about the other valve train pieces. I doubt any of those parts could cause a vibration. As I said before, the trans, flex plate, pulleys and balancer were removed and it was test run and still had the vibration.
When I talk to him again, I'll suggest the balancing. He should take those parts to another shop for that.
He said he adjusted the mixture screws using a vacuum gauge but I forgot to ask him what the readings were. There might be a leak which would cause the lean condition. I'll ask him if he has the correct PCV system hooked up. I want to know those things before making any changes to the carb.
Verne
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Verne, shaving on the rods? interesting. Maybe he meant polishing the rods and removing the flash and possible shot peen. But shaving could of meant lighting them up somehow. But if material is removed from a rod, you need a balance job on the crank and rods. His best bet would be to buy a good set of news rods on the market and lighter. Agree valve train should have nothing to do with this vibration problem. I always been big having an engine balanced anytime you have it apart for a rebuild or building an engine. You will be amazed how smooth they run. Racing engines are always balanced. IMO i highly doubt its a carb problem. You are right see what happens to his changes first before a carb rebuild. Keep me posted.