Can the TDC pin be off by 90 Degrees?

[Ray in La Mesa]

I had an engine 40 years ago that had a timing gear with the timing pin hole 180" off from where it should have been, manufactured that way. Took me a while to figure it out, finally set engine at TDC #1 and timed it. That's when I discovered the problem.

[bbrocksr]

Originally Posted by Tablemaker

Ever since I got my 31 A from my father, it has been “Running” without the exhaust/intake manifolds flush minted to the block. In other words, the engine was been running without a flush seal on the third and fourth cylinders.

After installing a brand new pair of intake/exhaust manifolds, with copper gaskets, I now have backfire during acceleration and deceleration.

I suspected the car needed to be timed. I’ve timed the engine without relief. I now suspect that the timing gear could be off by approximately 90degrees.

I followed some advice to identify TDC for cylinder 1 (by taking off all spark plugs and watching the four cylinders rise and fall)

What I’ve found, is that the timing pin more closely aligned to TDC for cylinder 2. *AND*, if I set the timing according to when cylinder 1 is physically at TDC WILL CAUSE massive backfire.

I’m at a loss in how the engine even runs using the timing pin (since #1 cylinder in already at the bottom of the stroke) and why I cannot even get the engine running when I use what I know to be TDC for #1 according physical inspection.

Can anyone help me get my fathers car running the way it should?

Many thanks,

Did you bolt the new manifolds together and straightedge the gasket surfaces for alignment? If they are not it will suck air and backfire, Bill