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when i order my heads, i am debating on 64cc or 70cc heads, 64cc will give me 10:1 and 70cc will give me about 9.5:1, this is a daily driver, but i am shooting for about 420 hp. my question is how reliable is 10:1 for daily driving? the cam i will be running with the heads is 234* duration intake and exhuast and .488" lift intake and exhaust. thanks for the help
greg
 

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I had a 90 GMC TBI that I put a 406 in, with roughly 10 to 1. Still had all the sensors and injection hooked up, and it ran fine. Had all kinds of power down low and all the way up the rpm range, all on 87 pump gas.
 

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The small block I had in my S-10 ran great. No problems with unreliability. (Drove it 6 hours one way to school for 2 years no prob.) I ran 93 in mine, but that is just me! Shouldn't be a problem as long as it is tuned properly and the cooling system is up to snuff!
 

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there should be no problem at all as long as you don't ping.

what comp. does your cam call for? what's the valve over-lap? you lose comp with valve-overlap. so putting in a big-ol cam sometimes lowers your comp.

go ahead and run the 10:1 i say. and maintain the cooling system and you shouldn't have any problems except for traction.:p
 

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BowtieRed said:
any way to change compression w/o new heads?
pistons.

having the old heads cut down at a machine shop.

takeing out the big bumpy-bump cam and installing a stock one. but changing a cam is not the way to adjust compretion.
 

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any way to change compression w/o new heads?
You can get your heads decked, that will bump it up a little.
you can deck your block.
change the stroke
over adjust your lash :flipoff2:
get heads worked a little
change cams
many ways(build up deposits)


Charlo
 

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1/2 point of compression won't net you all that much horse power. But it could make a big difference in what gas you will have to run.

What is the rest of your combination? Rod lenght, Cast or Alluminum heads? Duration? Stroke?
 

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HeyBeerMan said:
1/2 point of compression won't net you all that much horse power. But it could make a big difference in what gas you will have to run.

What is the rest of your combination? Rod lenght, Cast or Alluminum heads? Duration? Stroke?
I agree no reason to push the envelope on being pump gas friendly. 10:1 would give maybe a few more ponies, but really risks getting detonation expecially if you haul loads.
 

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Discussion Starter #10
my motor has stock legnth hardened rods, stock stroke, cam duration is 234* lift is .488" (that is the cam i was thinking about, not set in stone). i will tow with this truck maybe twice a year, that's about it. aluminum heads. 114* seperation on the cam. thanks for the input. i'm still doing the research now.
greg
 

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hawaii500_1999 said:
well with that cam you can run 10:1 easy, (it will bleed a lot of it off), and with aluminum heads the pinging issues aren't near as bad.
I was thinking the samething. But its got 114 lobe sepertation.
With 5.7" rods it might be close. waddya think?
 

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i was thinkin a 10.1 compression ratio with a 280 cam- how will that do, lot of stress on the transmission eh?
 

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That isn't really daily driver engine specs.

You can run 10:1 with a cam that large and burn 93 and not have any valve ping. The cam should bleed off enough pressure, I know if it has 110 of sep it will.

You will be doing good to get 8 MPG. That is about what I get with mine, so it sits in the yard a lot.

You plan on running a stall?

You should probably run 93 whether you get 9.5 or 10 to 1.
 

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with aluminum heads you can get away with more comprestion.the aluminum disapates heat much faster then Iron and it is said with aluminum heads you can get away with about one more point of comprestion...:D but still the idea of running 87 octane is not a good thought to me..
 

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BowtieRed said:
any way to change compression w/o new heads?
shave the tops of the pistons but then they have to be rebalanced or install dished pistons or go with a thick felpro head gasket they range from 30- 80 thousands another thing is have the heads pocketed with a step cut
 
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