Regarding a 351w and with all things being equal, is it possible to have the timing pointer at 0 degrees with the distributor rotor pointing to the #1 tower and the #1 cyl not be at TDC on the compression stroke? Or, put another way, knowing the cam and crank were properly aligned when timing chain was installed, can the dizzy be installed with rotor at #1 tower after aligning crank pointer to 0 degrees and being able to conclude #1 cyl is at TDC compression stroke? Or maybe I'm missing something. Thank you.

 

The distributor doesn't care which terminal on the cap is #1, this is an arbitrary designation. So long as the correct firing order is maintained from the "#1" terminal starting point, it will work fine.

It is possible though for example if the distributor gear roll pin were to shear, the rotor will now point somewhere, anywhere, other than where it would ordinarily be.

 

I appreciate that info. So with dizzy removed from the equation does 0 degrees strictly mean TDC for #1 cyl and the stroke for #1, whether it's intake or whatever, then being determined by position of the distributor? I'm getting ready to start motor after a rebuild and knowing motor is at 0 degrees can I just install dizzy pointing at #1 tower and know my timing is going to be close enough. It sounds like the answer is yes. Thanks for the info. My brain is getting foggy and I feel myself getting lazy having spent so many hours on this and am looking for the easy answer. A swift kick in the rear oughta snap me out of it.lol

 

No, if I'm reading what you're asking. There are two TDC events for each cylinder, one at the end of the compression stroke, and one at the end of the exhaust stroke.

So what usually (well sometimes anyway) happens is the distributor mistakenly gets installed with the rotor pointing to #1, the balancer and pointer on "0", except, the #1 piston is actually on the exhaust stroke. It will actually be the #6 piston that is on the compression stroke in this situation. Whenever the "0" mark is aligned with the pointer, either #1 or #6 piston is at TDC. If #1 piston is on the compression stroke, #6 valves are at overlap. If #6 compression, #1 valves are at overlap.

Make sure balancer is serviceable, just to be sure. Use a piston stop tool to find true TDC and verify for certain the "0" mark on the balancer is accurately placed. Old balancers are notorious for slipping.

Once you get a little familiar with all that stuff though, there's no problem. I just remove the #1 spark plug and roll the engine over by hand while stuffing a finger in the spark plug hole. When air starts rushing past I know for a fact it's coming up on the compression stroke. Line up the "0" mark with pointer.

The distributor rotor should be aligned at this time with the #1 terminal position of the cap. Now normally an engine wants something like say, 12° BTDC initial timing. If the balancer is set to 12° BTDC and for example, has contact ignition points, there's a method where the distributor is rotated back and forth to trip a test light between ground and the movable point arm, as the breaker points open, the spark plug will fire.

This way the engine is now pre-set to 12° BTDC ignition timing before ever trying to actually fire it up. It's important to avoid messing around, the engine needs to fire up immediately and spool up to 2500 RPM for camshaft break-in. Fill the carb bowl with fresh fuel, a known, good carburetor, fresh battery, etc. Even more ignition advance than normal is really what you want once it first fires.

Retarded ignition timing runs excessively hot. Glowing red hot engine manifolds. A newly fired engine is tight clearance already. So I've read a lot of engine builders will advance the timing once it fires up, to around 20° or 25° BTDC or so for the 20 minute cam break-in. It won't hurt a thing and runs a lot cooler.

 

If the balancer's outer ring has slipped, yea it's possible

 

I appreciate it guys. Engine was 180 out. There are lots of things I'd rather do than pull the #1 plug. I got it fired up thankfully although there was some black smoke coming out of the exhaust. I'm hoping things just need to settle in. I hope.

 

I always put them in about ten degrees or so before tdc. If you put one in at zero you will probably end up having to jump it a tooth so the advance can will be more at the 6 o'clock position, where it belongs.