FE Power Forums
FE Power Forums => FE Technical Forum => Topic started by: Yellow Truck on May 19, 2019, 02:06:46 PM
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I have the 445 running, but decided to go back and check pre-load (just a precaution), then play with timing and idle settings. Initial timing was last set at 3,500 feet, now at sea level (well, 8 ft above sea level). Initial was around 18, so pushed up and got a happier engine until around 24-25 degrees (as predicted by Drew and a few others on another thread), but at 25 total shows 45 (with a timing light and someone on the throttle looking at the tach).
Going to dial back mechanical advance, question is - what is wise for total timing?
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Apologies for bad typing - corrected it to read 24 - 25 degrees initial timing.
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I would expect that engine to be happy with 34 total max, assuming a tight quench. That is with vacuum advance disconnected and certainty that it isn't still advancing with RPM
If at that total, it likes more initial than that, limit total and add a little more initial. However, 45 with mechanical alone is likely too much and it'll start rattling or hurt it if you let it stay there
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Thanks. I'll start there. I was thinking 36 max but would rather try less. I had been running 18 degrees initial but it was labouring a bit at idle. 18 degrees initial would have been around 38 degrees total. No vacuum advance.
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Welld the slots to limit the mecanical advance
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No animals were actually hurt to test this metaphor, but after advancing the timing to 28-30 degrees initial and limiting it to 34-35 total it is running like a scalded cat. Idle is smoother, vacuum is up around 10 inches, and it is happier up and down the RPM range. Running at 2,000 in second and it snatches the tires loose at 35 mph, and pulls hard right up through 6,000.
Shut down is ok (runs on a little), and it isn't fighting to start.
I quote a small range for timing since I think the timing mark is 2 degrees advanced on the harmonic balancer - I marked it when I advanced the cam but it was a few years ago and I don't really remember.
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Good to hear, can you idle it lower to stop the run-on?
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Ross, I think I can, right now it is a little wheeze or one fire so not terrible. I got lucky when I moved here and one of my neighbours is an old guy who has been tuning Holleys and sprint cars for 4 years. As the engine kept responding to more advance he kept telling me he runs all the sprint cars at 36 degrees advance, period, so not to worry about it liking almost 30. I'm not going to run a vacuum advance.
After helping with this he wants my carb next week to do some tweeking on it, should get the idle down a little, and he thinks it needs a larger pump jet, he doesn't think it cracks hard enough. Meanwhile truck needs to do some work. Need to pick up some garden supplies and get working on the flower beds.
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All my FE's run 40 total. Usually about 20 initial. Race car or hot rod. Give it all she wants.
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IMHO That chamber won’t need that much at WOT just asking for detonation without a gain. Although having some vacuum advance come in wouldn’t hurt mileage. Big factory chambers need the extra, so you have to do it. Likely likes the fast timing and early initial due to cam design. Maybe Brent, Barry or Blair will chime in with more BBM dyno time
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FWIW, 'back when' it was standard procedure to run a performance Ford---one that came from the factory with no vacuum advance, like my '64 427 or my '65 HP Mustang---with the mechanical advance in the ten degree slot (For 20 total degrees) and dial in 18 of initial. I played with my '64 a bit and it definitely ran best at 20 and 18 for a 38 total. 260 Sunoco was mandatory.
As a short side story, I let the guy at the station put the gas in one day and he gave me a load of 190. I pulled out into the street and a block or so away put my foot in it. When the 190 got through to the carbs I had instant detonation. It hammered the ring grooves tight on the rings of one piston and I immediately started a massive trail of smoke. I had to replace that piston and its rings to stop the oil burning.
KS
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If the run-on won't go away, you can always try shutting it off in gear. The idle is lower in gear, and the convertor seems to cause enough drag to keep it from happening....sometimes.
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As you increase base timing you will want to reduce throttle opening at idle to get the speed back under control.
Usually run-on (aka dieseling) is caused by too high of a closed throttle airflow setting.
The timing is not the direct cause of the run-on - - because the ignition is "off" when you turn off the key. :)
If you cannot get a decent idle speed and eliminate the run-on you might consider adding an idle stop solenoid such as the one common to cars in the 70s/80s.
Solenoid is "up" with "key on"and is used to set running idle speed. When you go "key off" the solenoid is de-energized and lets the throttle blades close up.
I would expect that engine to be best with 34-36 total, but once they are running you feed it what it wants to eat.....
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I just noticed I said my neighbour Percy has been tuning sprint cars for 4 years, I meant to type 40.
I have no vacuum advance and don't think I'll bother. I did test initial timing all the way up to 40 and it didn't really change from 28 degrees to 40, but since it ran the same at idle at 28 I took it back there. It had been on the narrow slot in the distributor which was giving us 45 degrees total (not experienced enough to know how many degrees the narrow or wide slots are), so we had to put a bit of pipe over the post and epoxied it in. That is giving us around 34-36 degrees total and it seems happy. It also means that testing it at 36-38 will be a bunch of work so I think I'll just leave it. Again - I give the timing in a range since I think the marks are 2 degrees advanced so it overstates the timing, but I'm not absolutely positive.
The dieseling is pretty minor right now, and killing it in gear doesn't make a difference since it is NOT an automatic. I think we can make some adjustments on the carb to get the idle down a little and possibly close the throttle a touch. It was set up at 3,500 feet and hasn't really been revisited since we got to sea level.
Percy is SBF guy and his buddies are mostly GM and SBF guys, and they are quite astonished at the quality of the replies I get here on this forum.