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| Is 9:1 CR enough for a 260 duration cam? https://slantsix.org/forum/viewtopic.php?t=6573 |
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| Author: | relic-lover [ Fri Aug 15, 2003 8:14 pm ] |
| Post subject: | Is 9:1 CR enough for a 260 duration cam? |
This is a bit backwards ! I have already bought the cam and am now deciding what instructions to give machinist for the rebuild of my 170. Does a 9 to 1 static compression ratio (mill about .040 off the head/block) make sense for a 170 with a cam with the specs : for .050 numbers 210 degree duration (both intake and exhaust) .290 lift at cam (both intake and exhaust) - 10 degree overlap advertised numbers 260 degree duration .435 lift 40 degree overlap Plan to run a 390cfm 4bbl on h pak with stock torque converter in the 904. Plan stock (or .20 over) pistons, stock valves (with hardened seats), hope to gasket match and pocket port the head. Balanced crank. Exhaust will be a cut rear manifold and a front Dutra into a Y pipe and Turbo style muffler. I am looking for good drivability, reliability, and uniqueness more than power. Probably will never see over 5000 rpm. Advice? Opinions? |
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| Author: | DusterIdiot [ Fri Aug 15, 2003 8:33 pm ] |
| Post subject: | Dig up last Hpak thread.... |
If you dig up the last thread reed started, you'd find that the cam has a short enough overlap per Doc for street use.... I'm not sure about the carb though, currently I'm having my Hpak plenum 'split' to help make the thing more streetable. I have a 390 cfm to start with, but I think I may have to move up the chain a bit. You might think about breaking in the engine with a super six to start with just to make sure it all works first, then swapping over to the Hpak since no-one has a true 'this is gonna work for you' formula on it. At least that way you can rule out any problems with your engine, get an idea of what the vacuum looks like at various speeds depending on your driving habits, then swap the Hpak on and start reading plugs and making your adjustments. (I estimate it will take quite a few idles, and runs down the block to get the powervalve and jetting correct...then I gotta worry about the secondaries, and hope I chose the right metering plate on the rebuild) Good luck, -D.Idiot |
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