Timing my 235, the manual states to set timing with BB at the pointer. When I do this the truck lacks power and idle RPMS go down. If I set the timing where it was,since no degree marks for retard or advance I can only say about 1/2 inch below thw pointer. The manual doesn't say to disconnect vacuum at carb and block. Any thoughts guys..could the distributor be off a tooth?
The flash of your timing light lets you know where your #1 is firing in relation to the crankshaft position. If it will line up on the BB your ok even if not in the exact factory location. You can drop the distributer in in any location and move the wires so #1 is over the rotor with the #1 piston in the firing position, of course when the next guy works on it he'll cuss you out. The engine will always sound better if advanced a little from the factory spec but can detonate or lose torque if done to any extreme. What we do on one that is overly lazy like you describe yours is run it till it's at it's running temp, then advance in increments till it pings when you accelerate in high gear at about 20 mph, then back off a couple degrees. Now kill it and start several times to make sure it doesn't "kick back" at the starter. This is a much more common situation on engines with timing chains that become stretched than it is on a gear driven setup like yours.
Print out Kevin's advice and follow it to the letter as it's spot on and is in fact , the GM factory way of setting the timing in the field . This is called the " Throttle Ping Test " and ensures the most powerfull -and- economical orperation of your engine . Of course you knew to do a _HOT_ valve adjust before fiddling with the timing or caby...? RIGHT ? . Make sure the spark plugs all have .035" gap , MINIMUM . -Nate
RE: Valve Adj. & Timing 235 If it was the 2st. time you've adjusted them , it's time to go back and re-check as they'll often close up a bit . -Nate
