Okay, I always ran about 13 degrees initial timing on my old 302. It always ran nicely that way, and from what I remember, I think the total timing was 38 degrees (which is basically max). Well, when setting it to 12 deg. initial on this new motor (same distributor), the total goes to 42 deg., which is obviously too much. This engine "wants" more timing, as with 12 degrees, it wouldn't even break the tires loose, and after advancing it more, it'll do a burnout now, and the throttle response is better. So my first question is: What changed to cause the total to be more @ 12 initial with this motor versus the old motor (with the same distributor)? And my second question is: Why is more than 38 degrees total, harmful to the engine? It starts easily and there is no noise or "pinging" under a load. It also does not "diesel" when the key is turned off...
My first answer is are you sure of TDC? Not all balancers,and or crankshaft key ways are created equal. If you are not looking at true numbers then you may be slow on the timing. Verify that tdc is where its supposed to be. Second question, 38 degrees is not harmful to the engine,AS LONG as it does not detonate, My motor runs down the highway with no load at 48 to 52 degrees, Just depends on the weather. Now as soon as the engine goes under any load timing is pulled down to 25 and is never allowed to go any higher. If it doesn't rattle you can run 60 degrees if that's what the motor wants, But like i said in the first answer, be sure to verify TDC.
Mine runs 48-50 with the advance vacuum hooked up at 2500 rpm. It likes it that way. That is with about 15 at idle. Of course, I only have 8:1 compression so I can get away with all kinds of advance...
Thanks. So I need to verify. I replaced the original balancer with a new one made by Pioneer (basically, a stock-type replacement balancer). The marks only go to 40 BTDC, and 10 ATDC. I "think" the #1 piston was at top dead center when I stabbed the distributor. I could feel the top of the piston with my finger, and it fired right up on initial start. No backfiring or anything. I actually lined the pointer up with the 6BTDC mark, per my Chilton's manual, and pointed the rotor at #1 terminal for the cap. Should I have lined it up at "0" instead?...
Go to comptition cams web site and learn how to find TDC, Its in their how to degree a cam forum.Where they talk of a degree wheel just substitute your balancer. You can fabricate a piston stop from a old spark plug.
Yeah but how difficult can it be? If both valves are closed, and you can feel the top of the piston (and the marks on the balancer line up with the pointer), shouldn't that be sufficient?...
Why don't you just keep advancing the timing until you get a ping, then back off a few degrees. Not sure what your compression is, but I can crank my distributor all the way until it hits my upper radiator hose and it never pings, so I keep it right about there. Runs great, no pinging. That is why I run 15* initial...
Because "pinging" can be occurring even when you're not actually hearing it. My comp ratio is around 9.5:1 ...
T.L. I agree with being absolutely positive on top dead center. Yes, pointing the rotor at #1 does put you in the ballpark. But you are most certainly needing exact at this point. You are right on about not hearing pinging. You could be right on TDC,, but then again 10 degrees or so can be error, so best to check. I do know you can get more than 38 degrees total advance, and have been told I can go up to 60 total on my motor. But I have left mine at 13 degrees initial and 38 total since I put it in 1992. I am running 10.5:1 compression so we are a little different. Keep us posted. Dan
at the dyno last Monday the guy checked my initial it was 20 degrees, t/a was 55 degrees .i was having no ping so i left it there. ... ...
hey is the motor a new rebuilt and if so what kind of timing chain setup did you use. It might have a multiple indexable chain gears on it and they might be set up to advance or retard the timing. you will have to find out tdc of engine and check the degree of cam
It's a stock-type replacement timing set with steel gears instead of nylon. It only goes on one way. It's made by DynaGear (which is owned by Cloyes). Dots were lined up and that was it...
You can't just stick your finger in the plug hole and know if the piston is at TDC. You need a piston stop and a degree wheel if the heads are installed. If the heads are off you use a dial indicator. You're dealing with thousandths of an inch here. Even when the piston is at the top there is a period of dwell time where the crank rotates a few degrees but the piston doesn't move. TDC is in the center of that dwell range. All kinds of things decide what the engine will tolerate for ignition timing; CR, cam overlap, combustion chamber design, air/fuel ratio, the list goes on. Ideally you want ignition timing such that you develop maximum cylinder pressure when the piston is between 12*-15* after TDC on the power stroke. That's where you get the most leverage on the crank. On a small block Ford that's usually between 32* & 38* advance. On a lot of engines you can figure what initial timing the engine likes by bringing the engine up to operating temperature, advancing the distributor 2*, shut off for a couple minutes to heat soak, then trying to restart. If it starts right up repeat the process of advancing the timing and heat soak/restart. When you reach a point that the starter begins to labor or you get a backfire through the carb, back of the timing two degrees. That's where your motor likes initial timing. I have seen on a low compression motor where this method didn't work. We had nearly 40* of initial and the thing kept firing right up.
