Roger60

Getting close to initial startup of my 67 330 4bbl hi comp rebuild. New rings, bearings cam lifters, heads redone, carb rebuild, everything. I have read that for initial start up you should run the engine at 2000 rpm for at least 20 minutes to break in the cam. I have rebuilt engines before and have not done this and never had a problem. Looking for any advice from those who know. Thanks.

MDchanic

In general, the best advice is to follow the cam manufacturer's instructions.

Those instructions will usually say to use plenty of cam break-in lube on the lobes, and break in for about 20 minutes, varying between 2,000 and 2,500 RPM, but they may say something else.

Be sure to have an oil pressure gauge and a temperature gauge connected during break-in.

- Eric

oldcutlass

Well Eric posted just before me, but here is how I do it.

First prime the oil system until you get oil through all the rockers. Use 4 qts of straight 30w and 1 qt of GM EOS. Follow your cam recommendations for break in. Usually that means pulling the inner valve springs if your running a more radical cam. starting the engine as quickly as possible and getting it to around 2000 RPM. Then varying RPM's between 2000 and 2500 for 20-30 mins. Then change oil and filter, drive for 500 miles and change oil and filter again.

joe_padavano

You've been lucky. Flat tappet cams are oiled by splash from the crank. The initial high RPM is to ensure sufficient about of oil is splashed up onto the cam for lubrication. Be sure to use a break-in additive in today's low-zinc oil.