All depends on what spring you have and what cam, its all about spring pressure and valvetrain weight.
Usually when I see things like your photo I find:
a. a chunk of piston missing
b. a piston that's crown was pulled up due to lean mixture
c. broken ring, and usually the piston...hehe
d. valve float
With the proper spec'd engine and components the 7000rpm limit is obtainable with the large stroke motor. I haven't seen excessive crank walk on the 69 windsors without a girdle but I usually install them if I plan to spin it high. Where's that combo make peak power and tq? What was the combo?
Peak tq is around 4300 and peak hp is 5800. I was shifting at 6200, though I would occasionally hit 6400-6500 in first gear. The only reason I went over that is because I missed a gear.
The combo is listed in my sig but I'll go ahead and post it again.
'69 block 420W 4.040 bore x 4.100 stroke, AFR 225 heads, custom hyd roller cam .600/.608 lift 240/248 duration 114lsa, Scorpion 1.6 RR's, Comp link bar lifters, Victor 5.8 intake, 80mm tb, 42# injectors, Kooks 1 7/8" headers, full 3" exhaust. Recently installed AEM EMS, converted to speed density, AEM cam/crank sensor, LQ9 coil packs.
The specs on the heads are here, Air Flow Research Cylinder Heads
If it was valve float would all the cylinders be trashed? I only have a problem with #8. It still runs decent, and still pulls good vacuum....or as good as it ever has anyways. Oil pressure is still good according to the stock gauge.
I didn't see a sig in this thread, might be the Google Chrome I am viewing through.
Nice combo
Sometimes with Valve float you only trash 1 cylinder, or 1 valve...#* might be bent. However once you get it apart you may find other damage in the other cylinders that is just not as apparent. Marks in top of pistons, etc... Depends on the PTV you had and the spring pressures. With the spark plug showing damage, something got tossed around in the cylinder, either pistons, ring or valve.
I've seen broken pistons and broken rings that didn't show up on a compression test or leak down