VCCA Home Forums TECHNICAL - GENERAL Mechanical - Engine, Trans, etc 235 ignition timing

My 56 Chevy Belair with a 235 motor appears to have a miss in motor unless timing is retarded to ATDC. How can this be possible.
Help! Please.
Regards

The first thing I would do is test the compression.

When the timing is set to specs do you hear a pop-pop-pop back through the carburetor or a pop-pop-pop in the exhaust?

I agree with Gene about checking the compression.

One other item to check is whether the outer ring on the harmonic balancer has rotated due to the rubber failing. You can check that by turning the engine over by hand until #1 piston is at top dead center. Stick a piece of 1/4” wooden dowel in the spark plug hole as an indicator. Then look at the timing marks.

The timing marks are on the flywheel and not the balancer,

Thank you Gene! I could not remember if they had moved them to the balancer on '56 235.

Compression is 100 across the board.

Setting timing at BTDC, run-up is rough but no pop from carb that I hear. I was checking timing at flywheel BB as I don't have any timing marks on the harmonic balancer.

Gene is correct. The timing marks for your engine are on the flywheel.

Make sure you aim the timing light as parallel to block as you can when you look back towards the flywheel. If you have too much angle it will give a mis-leading reading.

Here is a long shot thought to consider. Has there been work done that would change the timing gear setting between the crankshaft and the camshaft?

Thanks, but no work has been done except cylinder head replacement.

Now that we know that the head has been removed there are a few other items to consider.

What clearances did you use for adjusting the valves when the head was re-installed?

I wonder if there is a leak where the intake manifold bolts to the head. Also check the exhaust manifold as well as carburetor mounting.

Has the head been re-torqued after the new head gasket was installed and the engine run for a while?

I would check the compression. Note - the engine has hydraulic lifters.

You could also have a sticking intake valve caused by bad gas.