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alexiskai · 10-23-2019, 08:22 AM

Thanks for the pointer to fordgarage.com. Here is a relevant chart from the site:

Note that, because the camshaft rotates 1:2 with the crankshaft, all these values are 1/2 the crankshaft values, e.g., at 2000 engine RPM the Nu-Rex is advancing the timing to 29° at the crankshaft.

So it looks like the B distributor and the Phillips/Nu-Rex aftermarket product have pretty similar advance curves, with the B curve starting from a more advanced position. This may reflect the 4.6:1 standard B engine compression. If that's true, then the Nu-Rex timing at idle with a HC is more retarded than optimal, but as Synchro said, not a big deal.

As Vince states on fordgarage.com, "The Model B is a higher compression (cylinder pressure) engine which uses more initial spark advance, and lower maximum advance compared to a Model A. This is consistent with the operation of the B engine and the need to protect it from the effects of running too far retarded or over-advanced."

I wonder whether, given that the B curve continues to advance above 2000 rpm while the Nu-Rex curve does not, it would still be advisable to add some manual advance if one were running at 50 mph+ for long periods (assuming no overdrive).

Per these instructions, the Phillips auto-advance originally came with a "spark lever lock" attachment that you used to clamp the spark lever in place once you had driven around and performed your fine-tuning.

10-23-2019, 08:22 AM	#20
alexiskai Senior Member Join Date: Apr 2018 Location: Mebane NC Posts: 2,355	Re: Hi compression head and stock ignition Thanks for the pointer to fordgarage.com. Here is a relevant chart from the site: Note that, because the camshaft rotates 1:2 with the crankshaft, all these values are 1/2 the crankshaft values, e.g., at 2000 engine RPM the Nu-Rex is advancing the timing to 29° at the crankshaft. So it looks like the B distributor and the Phillips/Nu-Rex aftermarket product have pretty similar advance curves, with the B curve starting from a more advanced position. This may reflect the 4.6:1 standard B engine compression. If that's true, then the Nu-Rex timing at idle with a HC is more retarded than optimal, but as Synchro said, not a big deal. As Vince states on fordgarage.com, "The Model B is a higher compression (cylinder pressure) engine which uses more initial spark advance, and lower maximum advance compared to a Model A. This is consistent with the operation of the B engine and the need to protect it from the effects of running too far retarded or over-advanced." I wonder whether, given that the B curve continues to advance above 2000 rpm while the Nu-Rex curve does not, it would still be advisable to add some manual advance if one were running at 50 mph+ for long periods (assuming no overdrive). Per these instructions, the Phillips auto-advance originally came with a "spark lever lock" attachment that you used to clamp the spark lever in place once you had driven around and performed your fine-tuning.