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Old 09-11-2019, 12:35 PM
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Cliff R Cliff R is offline
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Join Date: Nov 2000
Location: Mount Vernon, Ohio 43050
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Ported vacuum does EXACTLY the same thing when you drive your car as manifold vacuum, timing from the VA is "all-in" unless you are coasting or at idle, so running cooler wouldn't even be part of the equation unless you spend a LOT of time idling.

Anyhow, the engine combination should not want, like, or need as much timing as you are using at idle. Having it at 28 degrees initial timing tells me that the engine is not happy with the camshaft at it's current compression ratio. Maybe the carb needs a little help as well, or the distributors vacuum advance needs a light spring in it?

A 10 to 1 compression ratio 455 with a 231/239/110 cam should idle just fine with 10-12 degrees initial timing and no additional timing from the VA. It should also idle fine well below 900rpms, that is a pretty high idle RPM, it should settle in nicely around 750rpm's and drop may 50 rpms or so when placed in gear.

In most cases when we see a big RPM drop when the trans is placed in gear the distributor is retarding the timing slightly.

I've also tuned a few engines where they were trying to run a LOT of timing at idle and the throttle plates were so far closed the idle was "stable" when the trans was placed in gear and engine loaded slightly......Cliff

PS: the Morel HR lifters run much better with less oil under the plungers that more. I started adjusting them up from bottomed out vs down from zero lash and they run a LOT quieter......

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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),