New heads

to the OP:
These are my opinions, top to bottom, interspersed with my experiences.
................ just try to run the same 195psi with iron heads on 87E10, that can easily be run with alloy heads; good luck.
I mean making the pressure, to make the torque, to make the Power, is the whole point for the existence of an internal combustion engine.
So if yur not running the pressure up,
then you're missing the entire point of running alloys;
air-flow not withstanding.
Said another way;
If the pistons in your already-built short-block, are down in the holes, in the usual places, it will be impossible to make decent pressure with any head period, and so, IMO, spending good money on alloy heads is a waste.
I'm not saying impossible to make decent POWER, which is a function of rpm;
just impossible to make decent pressure.
At the best, with an Ica of 62*, the pressure will come in around 150/155psi; at the BEST! More likely is 140ish
Without the pressure, the bottom end will go soft, forcing you to increase the stall and the rear gear, in that order.
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Notta chance would I screw an engine together with alloy heads; and not address the Quench, and not run the cylinder pressure up to near the max, for 87E10, to enjoy both power and economy of operation, and the fun factor.
I mean 195psi versus 165 is a night and day different engine.
To get the pressure up with a typical 268* cam, with alloy heads, is gonna require the Scr to be in excess of 11.2/1 , maybe closer to 11.4, depending in the actual ICA.
For a 318, 11/4 is gonna require a total chamber volume of no more than 63.7 cc; and therein lies the problem, how to get down that low. To run the rock-solid-dependable Felpro .039s the pistons will need to pop up to get the Q down to say .030. But those pistons will need to then be machined for valve clearance.
Say the net on that is 5 less 2 is 3cc, and the gasket is 8.6 for a total of 11.6. Thus the heads have to be down at
63.7 less 11.6= 52.1cc
If you try to use the .028s chances are they will blow into the valley at this pressure.
In any case, this is gonna run the machining costs up, because nearly everything is gonna have to be machined and custom fitted together.
Whereas,
for iron heads to get to 160psi @9.7 Scr is nearly a bolt-together effort. Total chamber volume @ 3.94 bore is 76.1cc, (versus 63.7cc for the alloys), which is a huge deal. This allows ~64.5cc heads on the above block. Or with the pistons down at .057(11.2cc) and the .028 gaskets(6.2cc) now, the need to be ~58.7. A quick deck-swipe will bring that to a standard 60cc head, or at least close enough..
But in the end, she is still down 30psi from the alloy heads which bring the potential of increased airflow with the same cam.
I know
what I would do, and I know what I wouldn't do.
It's so much easier and cheaper to do with a 360, to get the same power with so much less cam, and then sip 87E10 at the rate of some 30% less, at hiway speeds, than the HO 318; and maybe a total of say 50% less if taken advantage of, by gearing the 360 to match the second-gear road-torque, with say 20% less rear gear.
And I guarantee that having a 360 under the hood, you will never say; " I shouldda built a 360."
With a 360,
What you save in machining costs, and not having to buy a higher stall convertor, nor big street gears, and not having to run 91 gas at every fill-up, and all the while idling down the hiway, will easily pay for a 360 short and some nice alloy heads, in less than 12,000 miles. At least that was my payback period, less than two summers.
If I was forced by circumstance,
to use a 318 block, I would likely bore it out to use a 340 piston, which already comes with a high-enough compression ratio, to use those sick .053 headgaskets that come in the gasket kits, which are accumulating in my rafters.......
hmmmmmmmmmmmmmmmmm maybe next winter.
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Facts, in my 367;
>I have run up to 195psi on 87E10, with no detonation.
>I have geared it to run 65mph@1600rpm and gotten 32mpg (USg) on a certain day-trip.
>The lowest pressure I have run is 177psi, with the engine now tired and having over 125,000 hard hard miles on her.
>Just 4* of later-closing intake valves is already noticeable.
I see
no reason that
> a sweetly built 318 cannot match this in every way except absolute power................. but is starts with having the pressure.
> Lack of Pressure is like a powerlifter not working out for a week or two, then coming to the station, loading up with his usual weight, and NADA.
Please coach, take off 10% and let me try again,
and still NADA,
please coach ........... take off another 10%
and so on.
> I know you have a 69 car, which should be a 9/1 Scr engine, but it's the piston height and chambers that made it a 9/1. Without knowing
where the pistons are, relative to the decks, and
the size of the combustion chambers, and
when exactly the intakes closes;
it's like watching a blind-man trying to find the loo, in a strange place. There's gonna be a lotta banging around in the hallway, and maybe he never gets there in time......