by rocketron » Wed Jan 21, 2009 9:10 pm
Hi David, years ago I had the local engine shop fit new cam bearings to an early 1071cc block. There was no way the cam would go in, despite several hours of good old fashioned hand scraping and polishing. Somehow the bearings were "swelled" up. I lost heart with this block and fitted a s/h 1300 with a 286 Piper, a head I'd ported myself, lcb and 45 Dellorto. This went like stink, was more than a match for many so called specialist built engines, and was hammered for nearly 60k, which included many rallies. It was a real cheapo. I did not change the cam bearings when the Piper was fitted.
Several years later, a friend offered to sort out the 1071 block, and with made up spigoted "drifts", whacked the old ones out and the new ones in and no line boring. He did loads of blocks after that! Seriously, try to determine by measurement whether they need changing. I've re-bored and re-built loads of mini engines, up to a 1437cc standard stroke "grenade", some had their cam bearings changed and some not, but not one failed. We built an over-bored 970s which was supercharged, had the cam bearings changed, just in case, and a local petrol-head fitted the old bearings to another block with no probs!
Should you decide to use an engine shop, ensure they're members of the Federation of Engine Re-manufacturers for a guaranteed job.
Regards, Ron