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#1
12-19-2002, 02:41 PM
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I have a 400 XH code engine with #48 heads and according to the book 10.0:1 compression. this is in a driver. What would I need to do to run on 93 octane with no additives? Appreciate any imput you might have.
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#2
12-19-2002, 02:41 PM
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I have a 400 XH code engine with #48 heads and according to the book 10.0:1 compression. this is in a driver. What would I need to do to run on 93 octane with no additives? Appreciate any imput you might have.
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#3
12-19-2002, 06:21 PM
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Have the same combo in one of my cars keep the engine temp low, play with plugs, jetting and timing it should run fine.
jeff --------------------------------------------------------- "...And on the seventh day God raced his GTO!" ---------------------------------------------------------  
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--------------------------------------------------------- "And he Asked, Who Owns This Car? With The Peace Sign, Mag Wheels, and the Four on the Floor?? --------------------------------------------------------- |
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#4
12-20-2002, 10:40 AM
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What about putting in hardened valve seats to eliminate the use of lead, is this not really necessary or am I thinking of something else.
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#5
12-20-2002, 12:43 PM
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New Brighton, your right up the road from me! Never a bad idea to have the seats installed. Even if you don't we seldom don't see any problems as long as the engine is not ran hot, overheated, detonation, excessively strong springs, ran lean or combinations of the above. Have observed a few sets of heads with the valves nearly pulled thru them, always one or more combinations of the items mentioned above.....Cliff
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If you can read this, thank a teacher. If you can read this in English, thank a Veteran! https://cliffshighperformance.com/ 73 Ventura, SOLD 455, 3740lbs, 11.30's at 120mph, 1977 Pontiac Q-jet, HO intake, HEI, 10" converter, 3.42 gears, DOT's, 7.20's at 96mph and still WAY under the roll bar rule. Best ET to date 7.18 at 97MPH (1/8th mile), |
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#6
12-21-2002, 04:06 AM
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Agree with above. To be more specific:
Run the coldest plug that won't foul out. Keep engine temps down below the 190 degree range. Run a 180 or colder thermostat. Jet the carb slightly rich. Just enough to give the plugs a good brown color (not black, or fouled). Duct colder air from outside the engine compartment to the carb. Block the exhaust crossover passages in the heads. Keep careful tabs on your timing. If you experience light throttle pinging, unhook the vac advance. If it goes away, try an adjustable vac can or one rated for fewer degrees of advance. If you ever hear pinging at WOT, get out of it! WOT pinging/detonation is when things break. If WOT pinging is a problem, retard the timing a couple degrees or slow the curve way down. 
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---------------------------- '72 Formula 400 Lucerne Blue, Blue Deluxe interior - My first car! '73 Firebird 350/4-speed Black on Black, mix & match. |
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