About to break in my fresh 433" BBC in my '68 GMC

[nikwho]

Hello all,
I've just finished building my '69 427 (+0.030") for my '68 GMC. Engine is out of a '69 Camaro. It's got an all forged rotating assembly, 9.3:1 compression with a Comp Cams Xtreme Energy Cam (XE274). Has 291 heads with 105.9cc chambers, 2.19" intake and 1.88" exhaust valves. I bought 7 quarts of the Valvoline VR1 20W50 oil AND a bottle of STP ZDDP additive for the break in. I've set and doubLe checked the timing at 0° mechanically. Was planning on running the oil pump a bit, rotating engine 1/8 turn, running oil pump, rotating engine 1/8 turn, etc until I get back around to TDC on #1 the second time, dropping distributor back in, firing it up and revving up to 2,000-2,200 RPM, checking timing and run it there for 10 minutes or so. After 10 minutes, I was going to vary between 2,000-2,500 RPM for another 20 minutes. I am planning on removing the inner valve springs and run just the outers. I have a set of "tuning gauges" that I am going to hook up in the engine bay so that I can monitor everything.

Question. If at about 2,000 RPM, with an HEI distributor (I'm not sure if it's vacuum advance only or mechanical and vacuum advance?), what should I set timing to? Should timing be set at a specific RPM? Should timing be different during break in than normal operation?

I'm just getting nervous as the time approaches and want to give my new cam (entire engine) its best chances of survival! I've installed all new plugs and wires, checked continuity on all plug wires and believe that I've got all of my "ducks in a row".

Any help/advice would be greatly appreciated! If any flaws in my plan are apparent, by all means, let me know what I could do differently to have the best chances of success!

Thanks,
Nik

[Ewr101]

I wouldn't worry about dialing in the timing just yet. If it were me, I'd set the initial timing and then go thru the breaking procedures. After break in is done and your happy with it, then you can go back and set the timing and dial in its curve to how you want it. I just set mine a few weeks ago and it seems to me that there's steps with both break in and timing set up that could conflict. Plus I'd want to pay attention to the sounds the motor is making to pick up on any issues before the turn into problems.