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Now that I've got my leaky carb situation solved I'm looking at fine tuning ignition timing. I managed to find the sticker that was on my valve cover and what caught my eye is that it says engine RPM at 550 and 6* BTDC. My truck is auto trans. Anyway, I've been reading guys setting anywhere from 10-14*.. this truck is fresh rebuild bone stock.
Just wondering your thoughts.
You could experiment with running more initial timing but the best setting to use depends a lot on the advance curve that's in the distributor. Also keep in mind that running more ignition advance does not necessarily give you better performance. Many times the opposite is true.
Thanks Dave this is in line with my thinking too... I understand if a new cam gets installed all sorts of parameters may change.. but I know I've got stock, so while right now it's running ok at 10* I think I"m going to retard to 6* and run. This motor is on a run stand right now so no trans load or "real world" driving. I think I'll time to 6 and drop it back in the truck and see. At least it's a good starting point I suppose
You'll just have to experiment. But in the meantime make sure to degree out the balancer to about 40 degrees and double check the pointer. What you're looking for is the setting that gives the best performance and that probably isn't the maximum amount of timing that you can run without pinging. I'd probably start out at around 35 degrees or to total timing without the vacuum advance hooked up and see how that does.
What Dave is talking about is what we used to call peaking. and it is the best way to set timing.
Your initial is just that, a starting point. if it starts good and idles that's your initial. now you need to check the curve with a dial back and get your best performance and economy before you get detonation. if your curve is close you can peak it out and it still starts and idles good. if it doesn't you have to distributor tuning to do.
Another thing. You never want to tune up the timing without regard to the duty cycle of the engine. What I started doing on my circle track engines after everything else was done for that season, mixture, lash, timing you name it I would do a few pulls where I would hold and go. With the engine at full temperature coolant an oil I would set it up to hold wide open at around 5500 rpm for 15 seconds and then go to 7200 at 300 rpm/sec rate to double check the timing requirement. Usually the best was not near as much as what most people would run in a flat top piston 350 with a 2 barrel carburetor. I usually ran around 28 degrees total.
so on the distributor tuning topic... that would involve either altering the spring/weights or simply new dizzy? I've never done that before (though understand the idle vs determining 2500 rpm max timing value).
You will have to mess with the weights, springs and the length of the limiting slot to get the curve that you want. Who knows, it might be just right already.
ok so I'm gonna get it dialed in starting at 6* with a smooth idle, up to 2500 and see what that looks like, then put it back in the truck and go for a drive.... thanks!
I've never had a dial back light but it could be handy if the balancer isn't degreed out far enough. You'll need to rev the engine till the timing stops advancing to see what you've got. I've checked timing at 6000rpm before but you shouldn't have to rev it that high.
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