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Tech Question
Art Pesaturo, Wellington, FL, 1970 Plymouth Duster 360
I have a 1970 Plymouth Duster with the following: The engine is a 360 with a Mopar Purple Shaft 292 duration, 0.508" lift cam, ported and polished heads, .30" over 10.5:1 Keith Black pistons, Mopar Performance aluminum intake manifold, Edelbrock 600cfm 4-barrel carb, MSD electronic ignition, lightened flywheel, ceramic coated Thorley headers, and dual FlowMaster exhaust. 350 plus horsepower. Runs on 93 octane pump gas. Has a 4-speed manual transmission and 3.91 SureGrip positraction rearend.
Living in southern Florida and given the above what weight oil should I use?
Also, what kind a spark plugs and what gap? Lastly, what degree should the timing be set above or below TDC?
Your input would be greatly appreciated.
Art, if the engine bearing clearances are all stock, i.e., tight, I'd go with synthetic 10W30 or mineral 15W40. If the oil pressure drops below 15 PSI at 1,000 RPM, then go heavier -- say, 20W50.
My personal recommendation on plugs: Bosch Platinum 4218, gapped at 0.035"
The timing's a bit trickier. Hold the revs at 3,000 RPM, with vacuum advance hose removed. Set timing to 33 deg BTDC. This should result in about 15 deg. BTDC at idle. If it's not between 10 and 20, the distributor advance mechanism needs to be reworked. It should not begin to advance until at least 200 RPM over idle speed, whatever that may be, or the idle will be unstable.
Next, while held at 3,000 RPM / 33 degrees, temporarily connect the vacuum cannister to manifold vacuum. Timing should advance at LEAST 10-12 more degrees. If less, stop "notch" on vacuum cannister arm must be modified.
Now, while at curb idle, reconnect the vacuum cannister to ported vacuum. There should be no change in spark advance or idle RPM. If there is, the carb needs to be reworked.
By the way, I really hope that .30" overbore is a typo! And, please, drop that Chebby rear end nomenclature!
Rick
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