360 mystery breakdown
Also I definitely won't be putting it back together with the same camshaft, I know that was part of the issue all along; too little overlap for the cubes and compression = high cylinder pressure + shitty pump gas = POP!
Too little overlap is not the cause.
Too much Dcr is perhaps the first nail in the coffin, but the 32* at 3000 was the second ,a thin headgasket would have been the third, and not enough octane was the final. For you it is/was a combination factors, probably lead by lack of knowledge.1008s should have been successful; that they were not is a testament to the very high cylinder pressures that detonation can produce.
You don't need the Q to be that small. Do not sacrifice durability for Q. Just don't run Q between .050 and .080; I have read that this can actually create problems(no experience). Anywhere in the range of .035 to .045 should be fine, rather,it has been fine for me.
I did a quick check on what it would take to make 175 psi at 5000 ft and I came up with; Scr of 11.3,Dcr of 8.6/psi of 176.
8.6 is too much for iron heads and 87 as you have found out. It should have been a real ripper with sufficient octane.
I ran nearly this exact pressure a few years ago but with aluminum Eddies, on 87 no problem. I did it with a 270* cam and an ICA of 61*and a Q of about .025.and at 900ft. So you have all the ingredients. The recipe is good. This engine was crazy torquey, an awesome streeter.
With the .060 overbore, your cubes comes to 370.78 to make 11.3Scr, the total chamber volume needs to be about 73.74cc. With .042Q and a 1008 gasket,your pistons would need to be about .003 in the holes;which is .64c the gasket is 8.9cc and the KB107s are advertised with 5cc eyebrows. So far we are up to 14.54cc. Then 73.74 less 14.54 leaves 59.2 cc in the heads. That's pretty small. But that is what you need at 5000 ft.
There is certainly room in your Dcr for a bigger cam. If my calculations are close, the 55*ICA is a pretty small cam.I redid the calcs with a 64* ICA and with the same 11.3Scr, the Dcr comes in at 8.03/161psi. This will burn 91 for sure under full load,full timing. I think it might even be happy on 89 with a slightly delayed all-in. And it will be happy on 87 for day to day cruising, and for hiway.
So the 64* ICA is almost a magic number for you.
To get it, the math works out to a 276*/110 cam in at 106. Many other combinations are possible, but it just so happens that all the cam companies have something on the shelf like this. It is a very popular cam. It will not work with a stock TC, and it will not like less than 3.55s with an automatic.
Of course all my math is based on the very meager info spread out in all your posts,lol, so you know the old saying;"garbage in/garbage out".
Your results with different math will vary, WILL.
