I recently Built myself a 383 utilizing the Eagle kit with the 12cc dish KB pistones. I never plan on using a PA on it . The rings I used were speed pro Moly faced with a standard tension oil ring. I have now 275 miles on the motor. The heads were checked over thouroughly and valve seals were replaced I used the Fel-pro stock replacement gasket. For the first 100 miles I used dino 10-30 Valvolinethe car runs great has great power. at the 100 mile mark I switched to synthetic 10-30 valvoline. Since the motor seemed extremely sound and seemed to be sealing, (soot only on the base of the plug the electrode is clean) I took it out for some mile rpm runs, I went in 2nd gear from 3000 to 6000 rpms and let it coast back downto 3 then I would move it back up to six, not going WOT.around 5000 rpms the motor starts huffing out smoke. the smoke goes away after I let out and is not present at lower RPMs (as verified by riding behind in another car and duplicating the runs.) Should I be worried at only 275 miles or should I take measures and goto a differnt oil? or additive? I have rebuilt several motors in the past (at least 75 to 100 SBC) and it has never taken this long for the rings to seal fully (visibly)
What are you guys thoughts on this?

 

Well if you are running the engine up to 6 grand and letting it coast back down to three you are creating such a low pressure area above the pistons by coasting down through the rpms with the throttle closed that you are probably sucking oil up past the rings and oiling up the cylinders. It is not a very good idea to use your engine as a brake by coasting down from such high rpm's. You are essentially trying to rip the top of the piston off.

 

You could also still have a leak somewhere in your intake gasket to lifter valley area or maybe oil is loading up in your heads too for some reason? You could even possibly have your rings in upside down on the second ring. I've seen it before and fixed one like this 3 months ago. This will basically pump oil up instead of down.

 

I know the rings are in correctly, Its kinda funny cause I thought I had done it on one so I rechecked them all during assembly...lol.
I misstaded in my original post about the RPMs I was coasting down from , when I was doing those runs I was running from 2 to 4 I went to six a few times to see how it pulled above 5 and thats when it would smoke. I have done these kind of rns with every engine I have built and never had a single Piston problem (one is still running 20 years later ,it had cheap cast pistons).
I took it out again yesterday after work and it seemed to be doing better, I have a 1/4 marked off and from a dead stop I hit 118 once and a little below a few times. it seems to be clearing up quite a bit, maybe I just didnt be patient enough with it....lol
But nonethe less I have never had a new engine take so long to seal up good. I also was wondering what most of you guys use as ring piston and cylender prep on build-up.