Sunken Valves!!
Thread Starter
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Posting Guru
Joined: Aug 2005
Posts: 1,036
Likes: 1
From: NE Ga
ok new news, plopped one of the 1131 silvolites in on the new 390 crank with everything in as if to run and we got .025 deck clearance!! i thought a 390 would come out somewhere around .014-.016? is that just a fe block that has been milled alot?? do i have any options now? sounds like nothing but premium or a power robbing egr for me. am i right?? .025 deck clearance+.020 head gasket is still not enough quench to get me to low grade fuel right? is there anything i can have done to my heads while the machinist has them?? i know milling them more won't work b/c it's the thickness of the gasket and the deck clearance but come on!! help me once again kurt!
Post Fiend
Joined: Jan 2003
Posts: 8,600
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From: Iowa
Well, you're closing in on usable quench. That's close enough. If you had the block decked .005" you'd be at .040", which is widely regarded as useful.
The theoretical deck clearance with those pistons is .030". I think Silvolite has some generous tolerances in regard to compression height. This is why it's important to check them.
If you've got the time, it may prove beneficial to check all eight pistons.
I really think you'll be able to control any pinging with careful tuning of the timing.
The theoretical deck clearance with those pistons is .030". I think Silvolite has some generous tolerances in regard to compression height. This is why it's important to check them.
If you've got the time, it may prove beneficial to check all eight pistons.
I really think you'll be able to control any pinging with careful tuning of the timing.
Thread Starter
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Posting Guru
Joined: Aug 2005
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Likes: 1
From: NE Ga
well i know you're not my machinist but do you have a rough estimate as to how much a machinist would charge to deck my block some more? if i were to deck it, how much would you go? just .005 or would you go a full .010? thanks
Thread Starter
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Posting Guru
Joined: Aug 2005
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Likes: 1
From: NE Ga
hey also what was that site with the information on explaining quench?? my dad has always understood the higher compression=premium gas. he doesn't understand quench andhasn't heard of it till i told him about it from you and i still really don't understand it. also, out of my 8 pistons, can the deck clearance vary from piston to piston? how much? thanks
Post Fiend
Joined: Jan 2003
Posts: 8,600
Likes: 4
From: Iowa
You might as well go the full .010". I would test fit the cylinder heads, valve covers, and intake manifold first to assure you wont have any fitment problems. I really doubt you will though. Oh, and I dont know how much it will cost; I'm not a machinist! Pick up the phone and give him a call!
Here's the link:
http://www.popularhotroddingweb.com/...power_squeeze/
Here's a good quote from the article:
"By cutting the quench clearance the burn rate and quality improve to the point where the motor gains compression and is less likely to detonate even at the higher ratio involved."
Read the whole paragraph on combustion chamber dynamics.
Deck clearance can vary since not all pistons are the same, connecting rods can stretch with usage, and the stroke on the crank journals might not be exactly equal.
Here's the link:
http://www.popularhotroddingweb.com/...power_squeeze/
Here's a good quote from the article:
"By cutting the quench clearance the burn rate and quality improve to the point where the motor gains compression and is less likely to detonate even at the higher ratio involved."
Read the whole paragraph on combustion chamber dynamics.
Deck clearance can vary since not all pistons are the same, connecting rods can stretch with usage, and the stroke on the crank journals might not be exactly equal.
Thread Starter
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Posting Guru
Joined: Aug 2005
Posts: 1,036
Likes: 1
From: NE Ga
ok starting to make some more sense, now where can i get some of this thermal barrier coating stuff? is it just spray on or do you have to buy the valves with this already made into them? also, any ideas at all as to a cold air intake system for a '73 f100?? anything at all? thanks
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Post Fiend
Joined: Jan 2003
Posts: 8,600
Likes: 4
From: Iowa
I think you have to buy valves with it pre-applied. I could be mistaken though. The best thing you can do now, is polish the heck out of the valves and the combustion chambers. Make 'em mirror smooth.
I've done a lot of thinking on a cold air induction. Haven't actually got around to doing something though. You may find this interesting:
http://www.ramairbox.com/
I've done a lot of thinking on a cold air induction. Haven't actually got around to doing something though. You may find this interesting:
http://www.ramairbox.com/
