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By MrHavard - 13 Years Ago
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Hey Guys, This is my first post here on this site, although I have read this page off and on for a while now. I am a little confused by the timing on my engine and was hoping to get a little clarification. My Father-in-Law and I rebuilt the 292 in my '60 F100 about 18 months ago. When we rebuilt the engine my Father-in-law set the timing for me and I never gave it a second thought because the engine runs really well. It is basically a stock rebuild except we had the cam reground to an RV cam, it has a 4 bbl Holley carb and headers. I am also running a stock rebuilt distributor. From my research I have found that the manual says timing should be 4-6 degrees btdc. I have seen some people say that timing should be 10-12 degrees btdc. When I checked my timing with a dial back light I found that it was approximately 20 degrees btdc. Is that crazy? Should I dial it back closer to 12 degrees? I set it to approx. 4 degrees btdc and drove it around the block, it seemed to run a little rough so I set it back to 20 and parked it for now. I have heard that you really need to use a vacuum gauge to time a y block correctly. Is that true? Thanks in advance for your input
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By GREENBIRD56 - 13 Years Ago
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Glad to meet you Mr Havard - hope you hang around. We have some help and some fun here!  Did you check the timing with the vacuum line to the distributor on or off? If you check that line - at idle - does it have vacuum or none? If you don't own a vacuum gauge or a digital volt meter (to accompany your timing light) - good idea to get your hands on them - if you are going to troubleshoot and diagnose your own vehicle. Engines set-up for "live" manifold vacuum and with that line connected to the distributor -often have pretty high advance showing at idle. The Y engines do like to have at least 10° "initial" advance - with no vacuum advance applied - and at low idle so the mechanical advance is nil.
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By charliemccraney - 13 Years Ago
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If the damper is original and not rebuilt, the ring may have slipped and you can't know exactly where it is. Therefore, the indicated 20 degrees may be about right.
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By Ted - 13 Years Ago
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And did you check the total timing with the vacuum advance unplugged? This is typically performed by running the engine up in rpm until the advance curve finds its stopping point. Besides the intial timing, there are several other timing attributes worth looking at. The total amount of advance curve (both mechanical and vacuum) needs to be examined as well as the speed of the curve. If in doubt about any of this, just ask and we’ll see about clarifying your questions.
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By MrHavard - 13 Years Ago
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GREENBIRD56 (7/30/2012)
Glad to meet you Mr Havard - hope you hang around. We have some help and some fun here! Did you check the timing with the vacuum line to the distributor on or off? If you check that line - at idle - does it have vacuum or none? If you don't own a vacuum gauge or a digital volt meter (to accompany your timing light) - good idea to get your hands on them - if you are going to troubleshoot and diagnose your own vehicle. Engines set-up for "live" manifold vacuum and with that line connected to the distributor -often have pretty high advance showing at idle. The Y engines do like to have at least 10° "initial" advance - with no vacuum advance applied - and at low idle so the mechanical advance is nil. Hi, I did check the timing with the vacuum line off at the carb. I don't own a vacuum gauge however so I guess that is my next tool purchase.
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By MrHavard - 13 Years Ago
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charliemccraney (7/31/2012)
If the damper is original and not rebuilt, the ring may have slipped and you can't know exactly where it is. Therefore, the indicated 20 degrees may be about right. I have heard that recently, the 10 degree mark on my damper is right about center of one of the spokes of the damper and Ive heard that should be right.
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By MrHavard - 13 Years Ago
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Ted (7/31/2012)
And did you check the total timing with the vacuum advance unplugged? This is typically performed by running the engine up in rpm until the advance curve finds its stopping point. Besides the intial timing, there are several other timing attributes worth looking at. The total amount of advance curve (both mechanical and vacuum) needs to be examined as well as the speed of the curve. If in doubt about any of this, just ask and we’ll see about clarifying your questions.I checked the timing without the vacuum attached, but I didn't check it while running the engine up in rpm. I will try setting it to about 10 and check that this weekend. Thanks for all of the replies!
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By GREENBIRD56 - 13 Years Ago
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Sounds to me like your father-in-law has already done a bit of "timing tune". I'm thinking the engine still has its "ported vacuum" system in place and he has simply turned up the initial to get it running smooth. Many here have got their similar systems set up at maybe 14° initial - but then they have limited the total advance on the other end. The upper end shouldn't get to much beyond 36° of total mechanical advance.
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By oldcarmark - 13 Years Ago
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Maybe the damper has shifted.Are they the same on trucks as the passenger car-timing marks on the damper?
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By Riz - 13 Years Ago
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I have the exact same thing with my 63 292 i was adjusting the timing with a vacuum gauge i am running a mallory mech dizzy--as i was getting crap gas mileage and slow throttleand waiting for it to ping and when I put the timing light to it i was sitting at 20* I have just been listening for a miss or knock. I chalked it up like the others have said to a slipped damper. I was
Taught by an old school mechanic to give an engine as much advance as makes it happy. I don't think I am in any danger of detonating the engine, but who knows. I did back it off to about 18* to be on the safe side. Starting requires a little ritual of throttle position, but I am running a 3x2 with original 94s. So that is to be expected
Also.
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By Riz - 13 Years Ago
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With that advance it also holds right at 15# of vac at idle.
I was chasing a small internal carb vac leak from one of the carbs.
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By MrHavard - 13 Years Ago
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GREENBIRD56 (7/31/2012)
Sounds to me like your father-in-law has already done a bit of "timing tune". I'm thinking the engine still has its "ported vacuum" system in place and he has simply turned up the initial to get it running smooth. Many here have got their similar systems set up at maybe 14° initial - but then they have limited the total advance on the other end. The upper end shouldn't get to much beyond 36° of total mechanical advance. My distributor is connected to timed spark vacuum port on my holley, which I disconnected when I ran the timing light. the full vacuum ports are plugged. I'm going to try setting it down to 12-14 degrees this weekend and see how that goes.
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By oldcarmark - 13 Years Ago
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Old time mechanics use a vacuum gauge to set up timing.Disconnect vacuum hose.Advance the distributor slowly until maximium reading on gauge,Turn it back slowly until vacuum reading starts to drop.Set the timing halfway between highest reading and where it starts to drop.Road test for ping under load.Back off timing slowly until it doesn't.
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By MrHavard - 13 Years Ago
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oldcarmark (8/1/2012)
Old time mechanics use a vacuum gauge to set up timing.Disconnect vacuum hose.Advance the distributor slowly until maximium reading on gauge,Turn it back slowly until vacuum reading starts to drop.Set the timing halfway between highest reading and where it starts to drop.Road test for ping under load.Back off timing slowly until it doesn't.Thanks for the tip Mark. I'll try and get a hold of a vacuum gauge.
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By oldcarmark - 13 Years Ago
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I have found my vacuum gauge very useful over the years.You can tell a lot about what is going on with the motor by watching the needle.A very inexpensive useful diagnostic tool in your toolbox.
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By Riz - 13 Years Ago
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A vac gauge is probably the best $20 investment I made. Most normally will measure pressure(oil, gas) as well.
An extra length of vac hose through the firewall grommet and I will occasionally run on a drive with the gage stuck on the dash. It can give you a lot of info on what is happening in the engine under load and through the throttle range. The engine is basically one big vacuum pump. I have found a lot of issues with timing and carb issues (flat spots, hesitation, rich/lean conditions transmission shift points for AT, etc) by watching what the gauge does during a drive.
I actually thought about mounting one permanently, but only have the 1 spare manifold port for a future PB booster.
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By oldcarmark - 13 Years Ago
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I have one next to my other underdash gauges.Tee into vacuum line to distributor.
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By Ted - 13 Years Ago
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A permanent vacuum gauge where you can see it is a great idea. Here’s what I did on my ’55 Customline. 
One gauge for manifold vacuum and the other gauge is used to monitor the vacuum to the distributor. I’m using ported vacuum as the vacuum source for the distributor and at idle, there is no vacuum going to the distributor.
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By oldcarmark - 13 Years Ago
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Thats a nice setup Ted.I am curious about the manifold vacuum gauge.What does that tell you and why would it be different than the distributor vacuum reading?In other words what would you be looking for with the manifold vacuum gauge?
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By pegleg - 13 Years Ago
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As he told you it's for ported vacuum which is influenced by the air velocity thru the carb. The other is simply manifold vacuum.
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By Ted - 13 Years Ago
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oldcarmark (8/3/2012)
Thats a nice setup Ted. I am curious about the manifold vacuum gauge. What does that tell you and why would it be different than the distributor vacuum reading? In other words what would you be looking for with the manifold vacuum gauge?Frank has it right. The ported vacuum and the manifold (direct) vacuum are two completely different vacuum signals. While the direct vacuum comes from the intake manifold or any place sourced under the carburetor, the ported vacuum signal is being pulled from within the carburetor at a position located just above the throttle plate when it’s in the idle position. At anything above idle, the port is exposed and gives increasingly more vacuum signal to the distributor as the throttle blades are opened. Hole sizing on the ported vacuum is also a player on the amount of signal from this port. After 1/3 throttle position, this particular vacuum signal starts dying away thus keeping the engine away from detonation under the heavier throttle loads. The separate gauges helps me to monitor exactly how much vacuum signal and aids in modifying carb hole sizing and the tuning of the vacuum pot on the distributor for the appropriate amount of vacuum advance. Steve has elaborated to a more eloquent degree on the vacuum differences yesterday in another post. Here’s the link. http://www.y-blocksforever.com/forums/Topic73727-3-1.aspx
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By carl - 13 Years Ago
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Ted That is the first 55 Customline i have seen with a 150 mph speedometer,but knowing how you build horsepower it dont surprise me Carl
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