351w HO timing

[Fordboy300]

Hey Guys, could someone explain to me how to set up timing on my dads f250 I just bought a timing light the other day and I've never used one before but I'm always open to learning new things. The reason I bought a timing is because I'm planning on replacing the intake manifold with a edelbrock and the distributor is a tooth off so number one is where 3 is and so on

When I got the timing light I was so eager to use I hooked it up to my 86 f150 with a 300 six and it's at 10 degrees advance if I said that right. It was pretty cool seeing that.

 

[myrl883]

10 degrees is going to be pretty close. As far as setting timing goes, you want the engine at a slow idle so that you know that there's no centrifugal advance, and disconnect the vacuum hose to the distributor. Then rotate the distributor to line up the marks on the balancer and the pointer. If your truck still has the VECI decal, timing specs will be listed on it.

[Pete Whitstone]

A lot of people like to set timing on the "top" end and kind of ignore what the timing is at idle. By top end I mean with the distributor fully advanced, as it is when the engine is running above 2500 rpms or so. 351W engines like about 33 or 34 degrees total timing, from what I've been able to research.

But in order to set the engine for total timing, there are some things that are different from setting it for idle timing.

First, leave the vacuum advance plugged into the distributor. At these RPMs it may not be affecting timing at all, it really depends on where on the carb you are plugged in. That's kind of a whole other subject that I won't go into here, but run a test timing it at 3500rpm both with and without the distributor plugged into the carb. If you get the same timing reading either way, then you know that the carb is not influencing timing up at these RPM. Make sure you cap off the vacuum leak at the carb when you do this. In other words, disconnect the hose at the carb end, not the dizzy end, and put a vacuum cap over the carb nipple.

Second, some manufacturers put timing marks on the harmonic balancer all the way out to 40 degrees or more. If yours has this, you are all set. If not, then there are a couple ways to address this. One is to buy some "timing tape" from Summit or Jegs and stick it on your balancer. This will provide the marks all the way out to the higher advance numbers. You have to line up the zero marks with your existing zero mark, and you have to buy the right size according to the diameter of your harmonic balancer.

If you don't have the marks on your balancer, and you don't have the timing tape, then the other way to deal with this is a feature that may be on your timing gun, called a "dial back". This will either be a knob, or a setting within the "menu" of a digital gun, in which you can retard the flash at the gun by a set number of degrees. So in this scenario, if you want to set total timing to 33 degrees, you would dial the gun back by 33 degrees. Then time the engine at 3500 rpm or so, and if the "zero" mark lines up when the gun flashes, then you know you are at 33 degrees total timing.

Hope that makes sense.

[Fordboy300]

A lot of people like to set timing on the "top" end and kind of ignore what the timing is at idle. By top end I mean with the distributor fully advanced, as it is when the engine is running above 2500 rpms or so. 351W engines like about 33 or 34 degrees total timing, from what I've been able to research.

But in order to set the engine for total timing, there are some things that are different from setting it for idle timing.

First, leave the vacuum advance plugged into the distributor. At these RPMs it may not be affecting timing at all, it really depends on where on the carb you are plugged in. That's kind of a whole other subject that I won't go into here, but run a test timing it at 3500rpm both with and without the distributor plugged into the carb. If you get the same timing reading either way, then you know that the carb is not influencing timing up at these RPM. Make sure you cap off the vacuum leak at the carb when you do this. In other words, disconnect the hose at the carb end, not the dizzy end, and put a vacuum cap over the carb nipple.

Second, some manufacturers put timing marks on the harmonic balancer all the way out to 40 degrees or more. If yours has this, you are all set. If not, then there are a couple ways to address this. One is to buy some "timing tape" from Summit or Jegs and stick it on your balancer. This will provide the marks all the way out to the higher advance numbers. You have to line up the zero marks with your existing zero mark, and you have to buy the right size according to the diameter of your harmonic balancer.

If you don't have the marks on your balancer, and you don't have the timing tape, then the other way to deal with this is a feature that may be on your timing gun, called a "dial back". This will either be a knob, or a setting within the "menu" of a digital gun, in which you can retard the flash at the gun by a set number of degrees. So in this scenario, if you want to set total timing to 33 degrees, you would dial the gun back by 33 degrees. Then time the engine at 3500 rpm or so, and if the "zero" mark lines up when the gun flashes, then you know you are at 33 degrees total timing.

Hope that makes sense.

Thank you man. Truly appreciated. I'll have to read like two more time for it to click in. I've seen a couple videos on YouTube of Thunderhead289 his vids are helpful as well.