I have been looking a bit into setting base timing. How much advance can you set it at on a stock 2f before it starts pinging on regular gas? I know factory is supposed to be like 7 degrees. Has anyone tried 15 or 20?
Timing advance (1 Viewer)
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My F engine likes around 11 - 12 degrees advance. Beyond that and it'll start pinging. I would think 15 to 20 would be pushing it.
JohnnyC
Long ago TLCA# 2231
I'm at 12-14* ... on a 74' F and a half
I've always been advanced beyond the 7 - I just don't know how much 
- (on a desmogged 2F)
- (on a desmogged 2F)
Just swap your plug wires over one position on the cap and then re-time it. That way your diaphragm won't hit the oil filter.
1911
chupacabra
It all depends on local and environmental conditions. For example, at altitude it will take much more advance. If you have higher compression (or sometimes just carbon build-up on your head) it needs less advance. If it's fully de-smogged, it needs advance sooner than the stock advance curve.
I live at only 900' of elevation, and my 2F is completely de-smogged, running a big-cap FJ60 distributor that has been re-curved (for de-smog) by Jim C. My base timing is 10-12 degrees BTDC, but with my (stock for 1980 US truck) high-altitude compensation system still intact, it will be way up there at full advance over 5,000' elevation.
But the real answer to your question is, you can run as much advance as your engine in your location will take without pinging under load. That is how I time all of my older vehicles with distributors - no timing light, just keep advancing the timing a bit at a time until it just starts to ping under load, then back it off to the last setting before that. Use a dial-back timing light if you want to know exactly where that ends up being.
Clockwise?
Yes I know. Speaking of plug wires on dissy
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When I first put Ruftoys on the road in 1986, I had to take it to a smog ref. Before failing me on the visual for not having a NOX device, he ran the obligatory baseline checks. With virtual horror, he told me I had 28 degrees of advance at idle. My engine did not ping, I had no timing light, and no idea. I immediately invested in a good timing light.
My point is I have not used the 'as much advance as your engine will take' method knowingly. If I overly-advance, it is only during tune ups, if needed, to establish best vacuum for making carburetor adjustments.
Soooo, why are you asking? What's your vacuum at 7 degrees? 10 degrees? 13 degrees?
Best
Mark
www.marksoffroad.net
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Mark is the man, if ur having to increase timing to "make it run happier" you may be masking a problem,
I try not to set more then 13* at base timing,
These are just old tractor motors,
I try not to set more then 13* at base timing,
These are just old tractor motors,
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I am asking because I have a idea of what factory max advance is at during cruise and at 0 vacuum, but was curious how much farther people are pushing it. Im making an advance curve for my tbi 2F.
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Being unfamiliar with Fool Infection, I have to ask, wouldn't a knock sensor take care of that?
Off the cuff, my '76 2F FJ60 dist. desmogged at 1000 ft seems to like it with a bit of advance. I get 18-20 in of vacuum at idle. I advance until the BB mark on the flywheel is just visible in the window opening, rather than on the pointer in the middle of the window. This gives crisper acceleration at speed, seat of the pants of course. No idea what the degrees are.
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I would have to add a knock sensor circuit. I never did because I questioned if the 2F is too loud and rattles for a knock sensor. A knock sensor could back off timing a programmed amount of degrees if it senses pinging. Basically it's a 3 dimensional graph. For every 500 rpm and 2 inches or so of vacuum I enter how many degrees I want the ignition spark to be. I am at 5000 ft elevation. So at high rpm, low vacuum I'm running 37 degrees total advance. At high vacuum low rpm( cruising light load) I'm running around 52 degrees total advance. At idle, I'm running 16 degrees total advance.
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Very interesting. Thanks for the explanation. I can imagine now where ANY solid lifter engine could potentially effect a knock sensor. But I never would have thought of it before.
I learned something new.
So, if you can't use a knock sensor, how about a timing profile that accounts for change in temperature? High temperatures definitely effect the knock equation. When the motor in Ruftoys was fresh, it definitely had knock issues once I hit 190 degrees.
I learned something new.
So, if you can't use a knock sensor, how about a timing profile that accounts for change in temperature? High temperatures definitely effect the knock equation. When the motor in Ruftoys was fresh, it definitely had knock issues once I hit 190 degrees.
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Haha well only the wise realize the more you know the more their is to learn. You know a lot sir and its nice you continue to try to learn. However I am not certain the 2f makes enough noise to confuse a knock sensor, but I didn't want to go through the effort to wire up a knock sensor circuit and risk an issue.
Yes good question about temperature and timing, their is a couple of different graphs the ecm looks at to get total timing. You have your base timing curve graph as I described, and you have another one that you program how much you want the ecm to reduce or add timing to the base map based on temperature of the engine. From what I have read somehow toyota had a way to compensate for high altitude by adding up to 6 degrees of additional timing. Do you know if that is a correct rumor and how they did this?
You should consider adding tbi to one of your motors with a EBL ECM just to mess aroung with if you have time. Its pretty interesting stuff and provides quite a bit of flexibility to making the motor do different things when you want it too. I just have the factory gm ecm, and its pretty cumbersome to program. My 2f runs pretty good now, but once in a while I get a wild hair and try to refine how it runs a bit.
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I still have nightmares about the Downey TBI that Jim horsed around with on my cruiser 15 years ago. EVERY time I took the truck out, it came home on a hook.
A carburetor has never left me stranded.
A carburetor has never left me stranded.
I used to have a tbi setup . I ran it for over a decade . It had a knock sensor , I insulated it from the block with a piece of rubber as per an article I read at some point . Over the years it ran really well , never left me stranded on the trail but it never really ran perfectly all of the time . I did have a speed sensor hooked up for a while and it didn't help . I never really got into tuning the prom or ecm . It seemed to run well enough for me not to bother trying to get every little wild hair that happened occasionally . Most of the issues I had were from running an HEI distributor . It used to chew up the magnetic pickup inside occasionally . I tried different distributors (toyota electronic) over the years and they never ran as well as it did with the DUI unit . From my understanding , the ecm controls the amount of advance by using the knock sensor in relation to retard the timing . 15 degrees is its capability iirc. If you don't have a knock sensor , you will have a trouble code and it won't run closed loop (all sensors responding as they should) FWIW I used to run my timing anywhere from 12 to 18 degrees via timing gun with the spout wore unplugged . Most of the time closer to 12 . I have since moved on and now run a 3fe . It is all toyota and runs better than it ever did with a TBI .
