The Stovebolt Site Forums The Shop Area Engine Shop Timing? How Much?

My 235 (1960, 12 volt) runs great until you flog it, then it bogs down and sometimes backfires. I know that most backfiring is from lack of fuel, but I think I've covered everything so I'm not sure.

Here's what I've already done.
- timing is slightly advanced (the flywheel BB is just about out of the timing hole to the left)
- carb is rebuilt, float is right on, throttle valve is 1.75 turns out
- cap, rotor points and plugs are all new and gaps are to spec

I have not checked fuel pressure.

Also, someone told me to disconnect and plug vac advance for timing. I haven't tried it since I haven't seen this in any shop manuals.

I love fixing things but when I think I've covered all the bases and still can't get it working right, I come to you guys.

Any help would be great.

Hy Lode51, put a vacuum gauge on the engine and see what readings you get. Only 7 1/2 - 10" of vacuum will advance timing 7 1/2 - 10 degrees, while centrifugal advance starts at 700 engine rpm. It would seem that maybe we should be disconnecting the vacuum advance while setting the timing, even though it doesn't mention doing that in the manual. Why don't you try it and see how it runs, let us know please.

Lode...backfire richen up the mixture a tad? Timing on the BB is a good starting point left of the window is advance there is a pointer at the middle of the window for the BB set up and to the right of the window is retard. Mine runs best a little advanced but I have an HEI. Don't worry, there will be an expert along anytime now.

BILL, if you are reading this help the lad out.
Steve

My manual for a 54 235 says to disconnect the vac. advance to set timing. Does your vacuum advance work?

yes the vacuum advance works.

I've seen and heard that there are marks on flywheel to see how advanced I am. I've cleaned it up and can't see anything.

When you guys say advance the timing a little, have I gone far enough? The BB is just visible in the window.

YEP....Disconnect the vacuum line and plug it with a golf tee. Two marks on fly-wheel triangles and BB's very small BB's the triangles are for valve events( I was told). Far left of the window is advanced. How much advanced only the old pros can tell you and each circumstance is relative.

Hey thanks for all the help!

when I disconnect the vacuum advance, and plug the hole, do I just pull the line of the carb, or off the advance?
do I plug both holes or just the one going to the carb?
This is new to me.

The vacuum advance line is between the carburetor and the vacuum advance unit. The vacuum is created in the intake manifold/carburetor. If you disconnect the line at the carburetor, you need to plug that "hole" in the carburetor. If you disconnect that line at the vacuum advance unit, you need to plug the open end of the vacuum advance line.

When your engine's idle is at normal idle RPM (around 500 RPM), that line does not have to be disconnected in order to set the timing. However, as long as you plug the vacuum line, it will not hurt taking this additional (unnecessary) step.

USA 1954 Truck Shop Manual instructions for setting timing. The same instructions are shown in the 48-51 Truck Shop manual.

1960 Truck Owner's Manual - ignition timing

Lode51, I'm in the middle of doing this my self...I had to really clean the fly wheel...crawled under and used a wire brush. There should be a triangle ...hash marks then a small circle...stamped into the flywheel. I used white paint and highlighted them so I could see them better thru the inspection hole next to the atarter.
I didn't have the UDC or TDC mark other folks had talked about. Good luck.

Having reread my shop manual Tim is correct , there is no mention of disconnecting the vacuum line. My 2 cents have worth have devalued the same as RIM stock.

So, once you figure out how to connect that vac gage, loosen the dist. and adjust to highest reading, that's where your engine likes to be.