magilla,

I put a combo fuel/vacuum pump on my '54 GMC. I also had a time getting it to fit but I finally got the bolts started and it kinda popped into place as I tightened the bolts. It has worked fine ever since. I guess I just had to compress the arm against the cam. If I'd thought to turn the engine a little I'll bet it would have slipped right into place. Good luck with yours. Also, I had a problem with another fuel/vacuum pump before I put this one on. The vacuum side didn't work and it was making a funny weezing/whistling sound when I hooked it up to the wipers. After I took it off and replaced it with the afore mentioned pump I noticed the the screw that goes right in the middle of the bottom of the vacuum pump side had fallen out. Just needed a new screw in that spot and I could have avoided the hassle and expense of changing the pump, but, after it was out and the new one in I wasn't about to put the old one back in.