Partial rebuild question.

[4.0blue98]

Can't seem to find my specific situation address on the internet. I've tried all sorts of searches but no luck.

Did a budget rebuild on a 326 Pontiac with heads disassembled and cleaned, rings, bottle brush honing, new rod and main bearings, but didn't touch the cam or flat tappet hydraulic lifters. Relatively new and looked great. the bits (valves (cleaned and lapped too), valve springs, pistons, lifters, push rods etc) were placed back in their original correct location.

Question is: what type of break-in would be appropriate? I have 10w40 Motul break-in oil in there now and have for 10 or 11 full temp heat cycles. When should I change the oil to the zinc containing regular flat tappet oil (I have 10w30 VR1 ready to go)?

All I see is immediate oil change after cam break-in and then mile increments. I believe the rings seated since no blowby and no smoke out the back, but really haven't run it under much load.

 

[gaz]

@4.0blue98 ,
To seat the rings I would, in the driveway in PARK:
• warm up to normal operating temperature
• then slowly spool up the engine to 2,000 RPM, moderating the RPM up and down +/-300 RPM slowly from 2k to 2,300 RPM to 1,700 RPM back to 2k and repeat, for 20 minutes
• change the oil
DONE

 

[scotts90ranger]

You're done, change the oil and operate as normal, everything special is for flat tappet cam berakin, rings will mostly figure themselves out on a hone and rering in short order assuming standard iron rings not molly rings...

 

[Uncle Gump]

While not scientific... I say change it and put some miles on it.

 

[4.0blue98]

This all sounds good to me. I've probably done the rpm variation while setting the timing and fiddling with the carb. Just put a new master cylinder in last week so probably do that oil change next Saturday. Then I'll follow @Uncle Gump and drive it!