Piston wrist pin
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Joined: Aug 2003
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Here's a thread that goes into some planning and should give some ideas.
https://www.f150forum.com/f10/bit-in...l-302s-276512/
Still doesn't address quench or dynamic compression ratio, etc. A lot more information toward the "parts swapping" end of things and not much toward the engineering end of things.
https://www.f150forum.com/f10/bit-in...l-302s-276512/
Still doesn't address quench or dynamic compression ratio, etc. A lot more information toward the "parts swapping" end of things and not much toward the engineering end of things.
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Joined: Aug 2003
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This looks like a real good thread but I'll have to finish reading it later. Done for tonight.
https://www.ford-trucks.com/forums/1...-upgrades.html
More future reading:
https://www.ford-trucks.com/forums/5...re-better.html
https://www.ford-trucks.com/forums/5...stock-cam.html
https://www.ford-trucks.com/forums/1...-upgrades.html
More future reading:
https://www.ford-trucks.com/forums/5...re-better.html
https://www.ford-trucks.com/forums/5...stock-cam.html
Cargo Master
Joined: Mar 2010
Posts: 3,342
Likes: 294
From: Laramie, WY
Those are good reads.
I covered some of this (quench) in my 5.8L Budget Build thread last fall; or at least I think I did? Might be worth a skim read. Spoiler; no dynamic compression planning; I just swapped recommended parts there. https://www.ford-trucks.com/forums/1...et-minded.html
Stock head gasket was 0.039", 4.100" bore, with E7's CC measured at 64cc and stock 351W pistons zero decked with 20cc dish, for a compression ratio of 8.8:1. Going over 0.050" squish is not advised, as the quenching effect falls off especially over 0.060" squish best I can recall. I'd make sure the block is trued up & zero deck it, pick your heads CC size (or mill stock heads a little--but watch CC volume!) and then use piston dish/flattop/dome to dial in the compression ratio around a stock-ish squish between 0.039" and 0.045". Contrary to what may seem intuitive, a loose squish can actually promote detonation. Check out my thread "Post-Mortem analysis" to see the result of 8.3:1 351W running pump gas with the pistons 0.070" in the hole and 0.050 head gaskets. https://www.ford-trucks.com/forums/1...-analysis.html
I covered some of this (quench) in my 5.8L Budget Build thread last fall; or at least I think I did? Might be worth a skim read. Spoiler; no dynamic compression planning; I just swapped recommended parts there. https://www.ford-trucks.com/forums/1...et-minded.html
Stock head gasket was 0.039", 4.100" bore, with E7's CC measured at 64cc and stock 351W pistons zero decked with 20cc dish, for a compression ratio of 8.8:1. Going over 0.050" squish is not advised, as the quenching effect falls off especially over 0.060" squish best I can recall. I'd make sure the block is trued up & zero deck it, pick your heads CC size (or mill stock heads a little--but watch CC volume!) and then use piston dish/flattop/dome to dial in the compression ratio around a stock-ish squish between 0.039" and 0.045". Contrary to what may seem intuitive, a loose squish can actually promote detonation. Check out my thread "Post-Mortem analysis" to see the result of 8.3:1 351W running pump gas with the pistons 0.070" in the hole and 0.050 head gaskets. https://www.ford-trucks.com/forums/1...-analysis.html
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Dynamic compression is a good topic. Low RPM motors can have detonation issues cause you're packing in the maximum charge at low rpm and the engine is under a load, towing, whatever. Engine builders can tweak the cam specs to reduce detonation. It is counter-intuitive. They go the other way with the specs. More cam to lessen the charge at low rpm to reduce detonation. I think they use overlap but overlap might not be right. I remember it's backward of what I would think. Custom cams are cheaper than people think and can work around some other issues like this.
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One thread talked about Cometic making any thickness head gasket you want. They can also make the squish band any bore size. One thread said a bore matched squish band can reduce detonation. New one on me.
Lead Driver
Joined: May 2011
Posts: 5,808
Likes: 457
The cylinder deck creates a sharp edge that will generate a hot spot (just like any sharp edge in the cc) which an oversized hg exaggerates. Tight bore means it minimizes that hot spot created by the deck. Normally a sharp edge would just be chamfered.
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