The Stovebolt Site Forums The Shop Area Engine Shop '64 chevy 230 L6 Timing

I bought this truck from the original owner. With the paint job, it's almost back to showroom condition. Engine compartment needs a liitle sprucing, but that's not the current issue. I need some advice regarding the timing. The engine has 178k miles on it. After adjusting the lifters (3/4 turn past zero lash), carb. rebuild (manual choke) and replacing intake/exhaust manifold gasket, I got around to checking the timing setting. At idle it was 10 BTDC (at the "A" on the plate with vacuum advance blocked). When revved, the timing went off the scale. Is this normal? Timing was then set to 4 BTDC, but again, when revved the mark went off the scale! Is the mechanical advance s'posed to take it that far? Generally, the old 230 runs fine, but there is a little spark knock when running a steady 55 mph and some engine hesitation when accelerator is depressed. Also used the vacuum gage technique to check timing. Hooked it up to the intake manifold where the PCV ties in. Vacuum was a steady 18" Hg at idle and a slight advance brought it up to 20" Hg. But when the light was put on and the engine revved, timing advanced off the scale again! So, specifically, at idle, what should the timing be set at? Does the mechanical advance take it that far? Do I have a clue? Thanks.

Mike,
Short answer, mechanical advance can move the mark off the scale. Some distributors can have up to 20 degrees mechanical advance,depending upon application.
The hesitation and spark knock could be caused by other things. A lean carb, vac. leak, bad accel.pump , low float level, weak fuel pump come to mind. How do the plugs look? A white/very light gray indicate it is lean.
I dont have a manual in front of me, but I seem to remember that Automatics time at 10 BTDC and Standards at 4 BTDC

I have a 65 with the 230 also. I was having a good bit of spark knock, especially when giving it a little gas while cruising along at about 55 MPH. Carb adjusted, and I have been using a lead substitute in my gas tank. I took it by my mechanic buddy's garage, and the timing was only off slightly, which he fixed. Still had a bit of spark knock.

I took it back by and he gave me a can of GM Top Engine treatment/cleaner. Poured about half the can down the carb, keeping it running, then increased the flow until it shut off. Let it sit for about an hour, cranked it back up, then finished off the can. Lots of smoke starting back up, a trip down the highway to "blow it out," and no more spark knock.

Maybe a similar treatment will help you out. By the way, he has been a mechanic for about 30 years, and said that the GM cleaner was the best he has tried. The only brand he keeps in stock now.

Mike