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Author
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Topic: Safe CR ? Cleveland
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73torinoqcode
Gearhead Posts: 403
From: Buffalo,NY,USA
Registered: Jun 2003
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posted 01-08-2005 01:49 PM
   
I am doing a 4V Cleve OC headed engine and was wondering what a safe streetable CR is? I want to run it on Pump Premium. I was looking at the TRW pop up pistons that say 10.2:1 with my heads. Is this safe? Does anybody run these pistons with OC heads? I know the OC heads are more prone to detonation than the CC heads. I just dont want to sink a bunch of money into it and have problems.
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steve'66
Gearhead Posts: 9104
From: Sonoma,CA,USA
Registered: Mar 2000
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posted 01-08-2005 06:53 PM
That depends on your cam choice. I think you'll be fine with a 240 degree duration @ .050 cam. SteveW
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89_coupe
Gearhead Posts: 228
From: Ontario (Upstate), NY
Registered: Mar 2001
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posted 01-09-2005 12:40 AM
Since we have Sunoco stations up here which many have 94 octane gas at you should be fine (I'm near Rochester). It may run fine without any detonation using 93. As long as you advance curve is not too agressive and initial timing, I don't see a problem with 93. I have run 12.5-13.5:1 compression on the street with 93 octane gas for many years without any issues. I do use race gas at the track though.------------------
Kent '68 Falcon wagon stock 289
'65 Fairlane 500 wagon 10.5:1 351W
'78 Fairmont wagon 10.5:1 302
'76 Pinto wagon 392 stroke
'01 Focus SE DOHC 2.0L
'04 Explorer XLT 4.6 3.73 trac lock Pinto 392W 15:1, Iron Pro Topline 64/215s ported to 237cc, angle milled .115" to 52.5cc chambers with 2.08/1.6 valves, ported Super Victor, 1.72 rockers, Isky solid roller (290/300 adv, 256/266 at .050", .650" net lift, 108LSA/108 ICL), Crane Pro Series solid roller lifters, 9375 1050 Dominator, Victor water pump, billet 9 key timing set, custom 1 7/8"-2" step headers, 3.5" H-pipe and Hooker Aero Chamber mufflers, C4 w/9" 5000 stall, 4.30 gears, 28/10.5/15 MT ET Drags, 3200#s w/o driver.
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Toronado3800
Gearhead Posts: 903
From: St. Louis, MO
Registered: Jul 2001
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posted 01-09-2005 04:03 AM
How about trading the power you gain with .2 compresson points for the power you gain with 2 degrees of advanced timing and being safer at around 10:1? Of course you can always use thicker head gaskets if you get pre-detonation.
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kid vishus
Gearhead Posts: 6220
From: middle of NC
Registered: Oct 2000
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posted 01-09-2005 09:20 AM
Since I have ran OC cleveland heads on the street and used those same pistons, here is what I would do. I would polish the chambers, flat mill the heads down to 70 cc's, (there is more than enough material to get them there, the last set I used were milled down to 67 cc's) zero deck the block, and use flat tops. The domed pistons really mess up the flame front inside the chamber which doesn't help the detonation problems any. You should still end up around 10-1 (maybe just under it) with a better burn (more efficeint) which will more than make up for the loss of .2 -.5 compression. Even then, you will still need to choose your timing curve carefully.It can be done. 
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