I am NOT a builder; but I think I designed at least one pretty good engine.
My Eddy-headed 367 has been running KB107s since 1999, and currently has over 100,000 miles on it.
In the beginning, this engine had a lotta trouble with running hot, that I could not solve. This engine was not assembled by me, on this first iteration.
Finally, I tore the engine down and sent the block out for honing a lil more skirt clearance ( the bore is reported to be 4.045 now) and got me some Plasma-Moly file-fit rings. I opened up the top gap to .032, and Second was .026 IIRC.
BAM ! instant heat relief.
I now run a minimum coolant temp of 207*F, on purpose, and she is impossible to overheat, running the same parts as when it ran hot.
On Day-1, my KB107s fell in .012 below deck.
I tried to run an .028 gasket for .040 Quench; but at the first scheduled tear-down, I found that the Fire-ring was migrating towards the valley and was only a short time from letting go. Good catch.
So I sent the block out to zero-deck it, to use the famed FelPro 1008s. The new Q was thus .039.
A couple of years later my cam spit off lobes, so on the Fourth inspection, I decked the block again, to get the pistons to pop up a lil to maintain the cylinder pressure with the new bigger cam. The new Q is about .032 with the .039 FelPros.
Cylinder Pressure on all three iterations was thus maintained at or nears 180psi. And all three iterations ran on 87E10 without detonation.
My car is a manual-trans car, so I do not have the option of a Hi-stall, so it has to perform right down to idle-speed. And with the high cylinder-pressure, it does. So much so that I have to retard the ignition below 700rpm to operate down there, without the power overwhelming the driveshaft.
If your pistons also drop in at .012 below-deck, and
if you also use the .039 gaskets with those closed chamber heads;
then your Q will be about .051..
They tell me that is about the maximum for Q to be, to still be considered a Quench-engine. And they say, usually talking about iron heads, that Q of this magnitude, occasionally elicits detonation on anything but best pump-gas. But I think with alloy heads, you should be fine.
As to balance; just get it done.
The KB107-Hypers are so light (502grams), that the Engine wants to rev like lightning. With decent springs, mine revs to a self-imposed red-line of 7200, and in the first two gears at WOT (with 3.55s), I can't hardly shift fast enough to not bang off the rev-limiter. Your engine will thank you for it.
With the Late-Closing Intake event of that Mutha cam, your cylinder pressure will not be very high even tho your compression ratio might be. That translates to a modest amount of sub 3000rpm Power. So try not to stall it too low.
The Desk-Top Dyno was Waaaaaaaaay off on my build, the car just barely got into the 12s (12.9@106mph). Which at 3650 race-weight, I think translated to 335 hp. That was with the Hughes HE2430AL cam;
270/276/110; 223/
[email protected]; and lifts of .538/
[email protected]. Great street cam, BTW! This combo ran a short time at 11.3Scr at 192psi. yes still on 87E10
I also run extra oil to the top end in an effort to cool the valve springs, and to help the aluminum roller-tipped 1.6 arms to survive. Since those rockers currently have over 100,000 miles on them, I think it must be working.
And I drilled the tops of my rods to try and grab some lube. And I slightly enlarged the spray-holes in the rods, that spray onto the cylinder walls.
Don't forget about the other Oiling Mods, and I highly recommend an extra capacity oil-pan to help cool the oil that is getting beat up pretty bad by all these mods. To support all that, I run a hi-volume oilpump, for which I had to modify the filter baseplate so it wouldn't blow the filter off. lol.
Good luck on your combo; It's getting to look a lot like mine except not the cam. I think you wouldda liked the 268 better...... but what do I know.
Happy HotRodding
EDIT;
BTW, take a good look at this graph, notice that, not including the baseline; below 3200rpm, nothing much changed. And that nothing really gets going until about 3800/4000. It's a good thing you'll be buying a TC.
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