2F timing help needed

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Jan 22, 2019
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I’ve been attempting to time my 2F and have a few questions. Here is the relevant info: 2F from FJ60, HEI distributor with vacuum advance, recently adjusted valves, setting timing at 700 rpm’s, static timing with vacuum advance port plugged, and living at 400 ft above sea level.

My basic question is when setting timing, should I aim for max vacuum or a particular mark above tdc?

If I max vacuum, I can get a stable 17 in Hg with timing about 18 degrees above tdc. Runs fine at this setting. If I retard timing to what I’ve read is about right at my elevation (9 degrees), the vacuum drops to about 13 and there is a hesitation upon acceleration. It runs fine, just not as stable upon acceleration. Also, after setting timing I readjust carb by drop down method, which doesn’t really yield much adjustment or vacuum change since it’s more or less dialed in.

Thanks in advance for those tech guys that can help me figure out what to do.

Cheers,
Mike
 

pjohnson

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I ran my DUI on a 75 2F at about 12 degrees. Fwiw.
 

1911

chupacabra
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I’ve been attempting to time my 2F and have a few questions. Here is the relevant info: 2F from FJ60, HEI distributor with vacuum advance, recently adjusted valves, setting timing at 700 rpm’s, static timing with vacuum advance port plugged, and living at 400 ft above sea level.

My basic question is when setting timing, should I aim for max vacuum or a particular mark above tdc?

Personally, I wouldn't use max vacuum to set timing. I set mine by running the maximum advance it will take without pinging or knocking while accelerating under load. Takes a few iterations to get it spot-on but worth it IMO. On my de-smogged 2F, running an FJ60 distributor recurved by Jim C., at about 1,000' elevation, that ended up being at least 10 degrees BTDC for me as I recall - maybe a little more; it's been a few years.
 

Pighead

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I run an early 2F with a 60 dizzy and a custom single diaphragm advance mechanism from @4Cruisers. I advance my timing to the best vacuum then back it off a couple degrees. I'm at about 15*BTDC right now.
 

77mustard40

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Personally, I wouldn't use max vacuum to set timing. I set mine by running the maximum advance it will take without pinging or knocking while accelerating under load. Takes a few iterations to get it spot-on but worth it IMO. On my de-smogged 2F, running an FJ60 distributor recurved by Jim C., at about 1,000' elevation, that ended up being at least 10 degrees BTDC for me as I recall - maybe a little more; it's been a few years.
I’m running a similar set up, I think I set mine at 8*. Haven’t checked it in years.
 

micruz60

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I run an early 2F with a 60 dizzy and a custom single diaphragm advance mechanism from @4Cruisers. I advance my timing to the best vacuum then back it off a couple degrees. I'm at about 15*BTDC right now.
You are a mile high, right. . .?
OP: 18 degrees seems a bit much but if vac is 17, and it seems good; but 9 degrees is sluggish, so try 12 degrees, maybe 11, sweet spot? -not exact interpolation, these are analog timing set-ups, you will be going back and forth with regard to lean-drop idle and best timing. HEI dizzys can be challenging as you try to use factory settings. . .
 

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