'68 318 to carbed Magnum 5.2: Check my checklist

txstang84 said
I can't answer with any certainty of course since I'm not there, but I used some reasonable numbers to calculate the estimate.

Std bore x stroke
0.045x4.15" gasket
0.040 deck clearance
10cc dish
72cc chambers

That netted 8.5, so I think it [and I can't stress this enough] should be about that. Fortunately, you have a 360 not a 318...you have some displacement to make up for those big chambers.

As far as potential for ping, as long as you tune the fuel delivery and timing correctly, and don't lug it, I think you'll be fine. People built up engines similar to this one for literally decades without issues so as long as you're putting things together with due diligence and setting it up correctly, you'll be fine.

That dial indicator setup should work just fine. Also consider since most pumps are selling ethanol blends, they have a better resistance to detonation since alcohols don't ignite as quickly as petroleum based fuels...you just have to tune for it.

I pulled out the dial indicator this afternoon. Pistons are down in the bore ~0.088", more or less. Assuming that I use Fel-Pro 1008 head gaskets on the existing setup:

Thus:
4.00x3.58 (bore/stroke)
4.18 (head gasket bore)
0.039 (gasket thickness)
72cc (CC volume)
-10cc (dished)
0.088 (deck clearance)

Gives me a CC of 7.77:1. Blech.

I'd be a lot happier around the 9:1 range.

Now, recalculating the above for SpeedPro H116CP pistons:
4.00x3.58 (bore/stroke)
4.18 (head gasket bore)
0.039 (gasket thickness)
72cc (CC volume)
-5cc (dished)
0.027 (deck clearance)

9.07:1. Sounds about right, but I haven't checked whether these pistons are within the same weight range as the stock pistons - I'd like to avoid having to rebalance the crank/rotating assembly.

EDIT: Word seems to have it that the H116's are similar in weight to stock and don't require rebalancing (Rumor? True? False? Anyone tried it yet?)

-Kurt