I have a freshly built 355 LT1 and took the car out for a test drive yesterday. This is the first time I brought the RPM up above 2800 but I thought I should run it a little harder to help the rings seat. Anyways, I didn't rev any higher than 5600. With that said, between 4300-5600 RPM, I experienced a vibrating phenomena.
I just put it on a lift with the inpection cover off and had some mechanics look for any noticable "wobbles" from flywheel, torque converter, and crank pulley. They thought the torque converter looked normal (we suspected it because I just had some work done to it by Precision Industries). After his own diagnosis, Scott said he "could feel more vibration towards the front of the motor than the rear." I don't know how you could feel any difference between front and rear but this guy used to build engines for Foley's Top Fuel car so I trust his opinions. He also said the harmonic balancer didn't look quite right and that he's willing to bet the culprit lies in the crank hub itself due to my method of installing it with heat and hammer rather than a hub installer. That hub was extremely difficult to get on the new crank and I actually had to file the "mushroom" off the front edge of the hub to make the balancer slide on.
Anyone have experience with this? Does the symptoms match the diagnosis? What is the PN for a 97 LT1 hub? What is the PN/cost for a LT1 hub installer? I couldn't get a regular sbc hub installer to work on it.
Thanks,
Michael

 

I hope the guy that built the eng. was aware that the TC gear on crank requires a notched key or a stock hub with no keyway will hit it. I use the Moroso puller/installer on hubs "BUT" I had a longer adapter made for the LT1's hub install. BTW I have had to change some customers cranks that had a bent nose due to a BFH. Danny Mc

 

I built the motor and I used the stock style timing chain set up (LT4 ED) and the stock hub with a new '97 LT1 woodruff key in the new crank so that shouldn't be a problem.

 

since you used a 97 woodruff key, did you also use the crank sensor reluctor? if you used the 97 key and no reluctor, the hub is bound up on the key, a 93-95 key needs to be used if no reluctor is used

also, if no reluctor is used , a 93-95 hub needs to be used

 

Yes, I used the reluctor so I did not have to change hub and key styles.