Vacuum Secondary Conversion

4eighteener said

Here is the snip from hughes that I wanted to post earlier, but couldn't find. It is more to do with cylinder pressure, but does bring cylinder head materia in it too.
Perhaps it is a guide that is no longer relevant, the 165 for cast vs the 195 recommendations for aluminum heads, but probably one I will continue to adhere to until I see better information.
Anyway, I don't want to take over the op's thread on vacuum secondaries/distributors.
I was just hoping for clarification for my own benefit on cylinder pressure.
Perhaps someone will start a thread on cylinder head material vs cylinder pressure and people can post what they are running on what.
Unfortunately, I do remember engine building back in the 70's/80's/90's.

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Ok, I went to Hughes and found it.

That article should be called Horseshit because it's full of it.

I have never ever seen any correlation between cranking pressure and detonation. Ever.

I've seen 200 on the gauge and zero detonation and I've seen 150 rattle its bearings out.

My last engine was bumping 185 and zero detonation. And that was 11.75:1 on iron heads. When it goes back together it will be 12 or a skosh over that.

Again, you can build your stuff any way you want. The biggest killer of power is not enough compression. Compression is our friend.

There was a time when no one at the drag strip ever left below 180 degrees. Now no one does that. What did they learn? That hot oil and cold engines make more power, are far more detonation resistant and will live longer not running coolant temperatures that high.

We have guys on here who run 200 plus engine temps and they wonder why it will rattle its brains out at 10.5:1.

Head materiel means NOTHING when it comes to making power, reducing detonation or anything else along those lines.

You could learn this for yourself. Go build an 11.5:1 iron headed pump gas engine. See what you find.