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  #11  
Old 06-13-2014, 12:06 AM
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Ford is vague about their numbers. The best way to know is to measure them.

Having said that, I've seen these heads go from 68CC to 72CC. Higher compression ratios use smaller chambers. All the early 352s and 332s I have seen, had machined chambers (with taper).
Regardless, as said before, figure what compression ratio you want, first. Then configure your chambers with the correct pistons, head gasket and gasoline. - Dave
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  #12  
Old 06-13-2014, 12:36 AM
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To know what to do and where you are going with CR on a rebuild, you have to know where the starting point is. That is why I consider cc'ing the chambers a must do point, for the overall plan, but wanted to know what the original numbers of an unmilled head were. It is hard to imagine a high compression head that is supposed to be 59-62 cc, coming in at 72 cc, unless someone relieved them or the valves were extremely sunken.
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Old 06-13-2014, 03:00 AM
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Ford advertised, early 352 engines had a whopping 9.6:1 compression ratio. It's plausible to know all your dimensions before the rebuild, but they will change dramatically before you are done.

If 9.6 is high compression, what is 10.5 or 11:1? Common for the day, but not this day.

I assume you will drive this car instead of keeping it a garage or trailer queen. I also assume you aren't building it to race because of its weight. Now we come to, what kind of gas do you want to burn? I will assume you would like to run on regular pump gas, since it cruises and does well on long trips.

To calculate CR, we need to know the bore, stroke, gasket bore diameter, gasket thickness, deck clearance of the piston, head volume and piston dome/relief. If we don't know what the exact piston dome/relief is but we do know the CR, it's easy to figure out.

9.6:1 using cast iron heads and today's reformulated gasoline is a disaster unless you buy premium gas or add octane boosters. If you want to use regular pump gas, either buy aluminum heads or lower the CR. Aluminum heads are not available for the 352 unless you want to pay through the nose which defeats the purpose of saving any money.

To lower the CR, either buy (20CC) dished pistons or open the chambers. New pistons will be larger which further exacerbates the high CR but aftermarket pistons usually come .020" shorter at the deck. Whatever you skin from the deck or head must be figured.

If you use flat top pistons, or nearly flat top, 60CC chambers aren't going to get it. 78CC chambers with flat pistons will give you 9.5:1 CR. I suggest you come down to 9:1 (like many modern cars and SUVs). I also suggest you use hypereutectic alloy pistons and moly rings (like modern cars and SUVs). Ever wonder why modern cars go 250k miles between rebuilds? They use modern-material components and low compression ratios.

CR is easy to figure, there are sites on the web where you simply plug in your numbers and it will come back with CR, chamber volume, total displacement vol., etc. Here is one:
http://www.csgnetwork.com/compcalc.html

Hope this helps. - Dave
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Old 06-13-2014, 10:13 AM
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I am familiar with the CR calculations, issues of octane, and means of reaching the objective. For the last engine I did the goal was to achieve as high a dynamic compression as possible, given the cam used, using 92 octane non alcohol gas, that wouldnt cause detonation. The prefiguring showed 175 to be the limit, and when it was all done cranking compression came in at 170. It has been working well since.
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