383 woes
. Stock spec is 2.5 BTDC +/- 2.5. I'm wondering if the intermediate shaft is off one tooth. .
1---Forget stock timing specs
2--The intermediate shaft has nothing to do with it, so long as you can set the timing, and don't have the vacuum can in an awkward position or jammed up against something.
3--Have you checked that the mechanical advance is working?
Set the idle timing to AT LEAST 10 BTC OR MORE if the engine will handle it on startup, and doesn't ping. You can also get a good idea from the vacuum gauge.
THEN see how much mechanical advance you have at high RPM.
I ALWAYS check the timing marks for accuracy with a piston stop. This is the ONLY accurate and practical way to check TDC.
You can easily "figgure" this by measuring around the balancer with a small tape, and work out how many degrees per inch that is, then mark the balancer for at least 40*. Then you can use dividers to cut that in half for 20 marks, and again for each 10.
MOST factory stock distributors in the "smog" era from 68 and worse, later, have long, slow advance curves which are NOT helpful for performance. But if something is wrong like a sticky/ rusted mechanical advance, it's all that much worse.
