Please help!
I found the timing marks on my 1984 ford f150, 5.0 liter. But what do i line these up to?

What I found was the grid that looks like a ruler. I marked my spot which is 8 degrees behind top dead center.

I check it with the timing light and I see my mark, but what do I line this up to?

I have lookup everywhere on my pulleys for another timing mark but cant find it.

According to my repair manual on v8's there is not this other mark?

What do I line the grid up to?

Thanks in advance,

Kristi

 

There should be a triangle shaped pointer bolted to the timing cover somewhere under the water pump.

 

Thanks Franklin2,

Maybe you pointed me in the right direction. I will see if I can find it when I get off today.

I wonder if its possible that someone removed this when they rebuilt the engine?

I sure hope not.

Anyways thanks again Franklin2 for your constant wealth of information in this forum.



I will let you know how it turns out.

 

I just checked and there is definitely no timing pointer. I guess whoever rebuilt the engine did not put it back on!?

I timed the engine just by backing off the timing until the engine stopped pinging under a load, and this works I guess..


Is there anyways I can get it more exact without that triangle timing pointer. I can see my grid just fine with my timing light, but I just need something to line it up to.

Is there another way to time it?

The only other thing I can think of is go to the junkyard and find one that has the timing pointer, and then pick a spot on the engine and do a measurement from that point. I could transfer this measurement to my truck, and it would probably work.

Is this the right idea or is there an easier way?

Thanks

 

Sorry about the slow response, but I finally did fix my problem. Turns out the timing point was missing on my engine. I went to the junkyard and by luck they had an 84 that was also a 5.0 just like mine. When I looked at that engine, I could see plain as day the timing pointer. I removed the timing pointer from that engine(only 2 bolts holding it to timing cover) and bolted it on my engine. After that, timing my engine was a breeze. The pointer is about 4 inches long and on the right edge of it, there is the word TIME stamped into it. I just lined my mark on my grid with this mark and bingo I was done.

I was beginning to think that I was crazy, because I knew the timing marks shouldn't be that hard to find. I guess when someone rebuilt the engine, they didn't put the pointer back on.

Thanks again Franklin for your help.

Kris

 

Kristi,

Glad to hear you got your pointer issue fixed and can now time your motor. It seems like you may be a bit new at some of this, but if not don't take this wrong.

There are a few acronyms that may be helpful in your mechanical pursuits. When referring to ignition timing there are three:

BTDC: Before Top Dead Center
ATDC: After Top Dead Center
TDC: Top Dead Center

This refers to the point, in crankshaft rotational degrees, in which the park plug actually fires with regards to the location of the piston on number one cylinder in its compression stroke. Whatever point it happens for the number one cylinder it happens for the others thus the reason we only need to set it for number one.

So, as in your case, if you set yours at 8 degrees BTDC then you are having the plugs fire when the crankshaft is 8 degrees before the piston has reached the very top of the compression stroke. Most all engines have the plugs fire BTDC because of the time that it actually takes the combustion to reach its maximum energy point. If you set it to fire too early (in this case more than 8 degrees BTDC) then it reaches that maximum point as the piston is still traveling up in the compression stroke and the combustion is trying to push it back down. The pinging noise you hear is the rattle of the piston and valves during the combustion.

Setting it to fire the plugs too late, closer to TDC or ATDC, will cause the combustion to reach its maximum when the piston is already headed back down on the power stroke and you will not maximize the power out of the engine.

There are many things that affect the best timing for any motor and the spec provided by the manufacture is a conservative setting to not have pinging on most all lower grades of pump gas and also get reasonable power from the motor. It is a compromise setting.

If you use premium gas you should be able to set the timing at more degrees BTDC and not have it ping. The reason this works is that higher octane gas takes longer to burn (octane slows the burn rate) and thus needs to be ignited earlier in the compression stroke to get maximum burn. And, as you have probably figured out, the early the spark occurs the more power the motor produces.

What you did by timing it by ear was actually a valid method assuming you can hear it ping over all the other noise a truck makes. I normally time a motor that way and after reaching the point where I don’t think I can hear any more pinging I back it off a couple more degrees just to be safe (using the timing light to make sure I don’t over do it!).

BTW, the 8 degrees setting is the timing at idle speed only. As the engine speed goes up the timing occurs earlier in the combustion stroke to compensate for the increased speed in the piston travel. Maximum ignition advance is normally in the range of 38 degrees BTDC at around 3,000 RPM.

I hopes this helped, but if you already knew all this please don’t take offense. It took me many years to learn the little that I know - with the help of many people - so if I can help some one else I hope to be able to.

Good luck and ask questions,

Mark

 

Just FYI...

An "acronym" is an abbreviation for several words that can be pronounced as if it was a word itself, like SoNAR, LASER, SCUBA, ****, VelCro, Yuppie, HMMWV (Humm-vee), ROM, and WORM.

BTDC, ATDC, & TDC are just plain old abbreviations.

(Give yourself extra points if you know what all those acronyms stand for without looking them up! )