6.5 deg BTDC vs. 8.5 deg BTDC

[Dave 001]

Concerning timing a 7.3........Why are people setting their injection timing at 8.5 deg BTDC when the factory recommended setting is 6.5 deg BTDC? Just bought a Ferrett/Actron set-up and going out to check timing now. Truck starts OK down to about 20 deg F. Below that and starting gets rather hard. There's no place to plug in at work and temperatures are heading back into the single digits.

Thanks.

Dave

 

[freebird01]

because when these trucks were originally designed and built they were made for the older diesel fuel. they seem to run better...have better economy and more power at 8.5-9.5 btdc on the new ULSD

 

[icanfixall]

Your posting is partly correct. Factory setting are 6.5 to 8.5 degrees advanced. Thats a large spread. As posted above the new fuels react differantly in our engines. so its been found that a 9.0 to 9.5 degree advance setting will run better. Give us better fuel mileage and more hp. My engine runs best at 9.4 degrees advance. My timing meter is the kent moore j33300-a and it can give me the 9.4 or 9.5 advance if thats what I want. The meter has a microprocessor in it that does all the timing and rpm work for you. All you do is read the digital display and adjust as needed. No timing lites are used but you can if you choose to. they also wil time by the luminosity probe method too. They are a very versatile meter designed for ruff use. I have been renting them to members of this forum for many years now. The industry threw us away long ago so we have to repair or time our engines ourselves. This is the main reason I invested several thousand dollars in this timing meter rental program. I feel it benefits all members well. I'm always looking to make it better too. But to set our timing to 6.5 advance is leaving plenty of mpg and hp on the table.

 

[FORDF250HDXLT]

oem timing specs,each method.i run 7 BTDC/pulse.
when i used a lumy meter,i ran 6 ATDC.

 

[hce]

You have a timing meter, play with different settings.

 

[icanfixall]

Reciently with the metr rental program I started suggesting the members time their engines to several different degrees advance. Make a new mark for each degree of timing change. I suggest 8.5. then 9.0 then 9.5 and finally 10.0. Then you wont need a meter to make any known timing adjustments. Just make a map of the different degrees of timing you have made up. Now these new marks are only good as long as the same pump is on that engine. You can remove the pump. work on the engine and return the pump to any of those known degrees of timing and be confident that its correct without a meter. now if thats not cutting me out of more meter business I don't know what it but its a fair idea. We all try to help each other along in this forum. This is my thanks for being part of the program. I'm surprised nobody else thought of this long ago.

 

[riotwarrior]

Meters do make it real easy to change timing and Gary's idea of marks for several different timing settings is a great one; one of which I just may do myself. I think I'll do a combination of centre punch/cold chisel/centre punch/cold chisel so it would look like this

0 | 0 | thus I could do 8.5 / 9.0 / 9.5 / 10 and not get confused by dot dot dot dot if all center punched set lowest timing then punch, adjust for more adv, then chisel, adjust for more advance then punch etc...

This is just me thinking outloud in print here about this and wonder what you all think this makes the most sense to me, so when I replace a pump I can REDO those marks in same spots/timing once again, as I have a meter! I can also do this for other's whom stop by for an adjustment.

Any thoughts...suggestions...

I know that the new engine cackles really hard when first fired up and loud as hell, so sounds like set high for advance, and I'm going to check that once I get my engine all sorted out installed and so forth.

Al

 

[dunk]

Mine was at about 6.5* and getting poor fuel economy and felt real slow. Set timing to 9* and next two fill ups gave me 10.56 and 12.6 MPG. Still feels real slow, but definitely has a lot more low end grunt and takes less pedal to keep it moving once up to speed. So it seems to me more timing increases efficiency up to a point, just like on a gas engine. Slower burning fuel compared to what was around when these engines were designed makes sense as to why they respond well to more advance then original spec.

If you advance timing too much you'll reach a point where you lose efficiency as the combustion will be pushing down on a piston that's still coming up. Of course damage will occur. In a gas engine you'll hammer rod bearings and break rings, and I'd imagine you'll get similar results in a diesel. Somewhere before that point is ideal for power and economy. My understanding from what I've read here is much past 9.5* and you risk damaging glow plugs from the added heat. Maybe 10*, 11*, or more is optimal for performance and economy as I believe other engines without glow plugs run more advance, but with these engines it seems we are limited by how much heat the glow plugs can take.

Personally once I get a few more fill ups and MPG recorded to have an accurate and stable trend I'll try advancing to 9.5* and then 10* and get a stable MPG trend at those settings as well. Not sure I'd run more than 10* given the apparent risk of glow plug damage, not unless I was thinking of pulling the heads soon anyhow in case any plugs get damaged and don't want to come out nicely.

 

[Dieselcrawler]

at the 2011 rally, mel and I played with my timing while on the dyno. now, stock factory turbo pump with 110000 on it, and brand new BB codes just installed. set to 8.5, mad decent power. set to 9.5, power gained 20 hp, torque gained 15. set to 10.5, torque stayed same, hp lost 15..... ever since that day, I set every truck I time to 9.2-9.6. if it is withing that range I call it good.

 

[riotwarrior]

at the 2011 rally, mel and I played with my timing while on the dyno. now, stock factory turbo pump with 110000 on it, and brand new BB codes just installed. set to 8.5, mad decent power. set to 9.5, power gained 20 hp, torque gained 15. set to 10.5, torque stayed same, hp lost 15..... ever since that day, I set every truck I time to 9.2-9.6. if it is withing that range I call it good.

Very useful, quantified data that really helps make a point. Thanks!

 

[FORDF250HDXLT]

at the 2011 rally, mel and I played with my timing while on the dyno. now, stock factory turbo pump with 110000 on it, and brand new BB codes just installed. set to 8.5, mad decent power. set to 9.5, power gained 20 hp, torque gained 15. set to 10.5, torque stayed same, hp lost 15..... ever since that day, I set every truck I time to 9.2-9.6. if it is withing that range I call it good.

but where did you gain it? wot/max rpm? did the curve look the same,or did you actually loose towing hp off the line/in the mid where you drive most often?
there are other drawbacks to running on the high end too;
higher noise pollution from the engine.
increased turbo lag.
reduced towing performance.
reduced fuel economy while working the engine.
higher cylinder pressures.

 

[Dieselcrawler]

will have to dig, but I belive I still have the sheets. peak HP was at 3200 each pull iirc.

 

[Dave 001]

Guys, Thanks bigtime for the help. Its been really cold here and I was having serious concerns over whether or not the van was going to start when I had no place to plug it in (a.k.a. work). It was 3 deg this morning and the engine started right up (not plugged in).

My factory manuals (from 1988) show a timing spec of 6.5 deg BTDC. As FORDF250HDXLT pointed out, later engines had the timing advanced a little more...hence the reason for my question.

The timing on the engine had obviously never been set. It was 1 or 2 deg ATDC (yes, AFTER TDC). And whoever the hack was that worked on it before never tightened up the bottom two injection pump nuts....only the top ''easy to get to" nut was tightened. I set the timing to 7.5 deg BTDC and had a very hard time getting the injection pump turned that far. I'm gonna make an injection pump turning tool (once the weather gets better).

I can't believe the thing ran as good as it did. I've grossed over 13,000 lbs and it pulled just fine. And I average 18.5 MPG. I'm curious what this thing is going to feel like now when towing and what my mileage will be. It now sounds like a Diesel. It has one heck of a crackle that it didn't have before. The tail pipe no longer stinks or makes your eyes tear. I should have bought that timing meter setup long ago. I also raised the cold idle up to 875 RPM....it was only about 775 RPM having been set by ear.

Again thanks for the help and the quick replies....Monday was the only day I had to mess around with the timing and Tuesday night the temperature started dropping again. Thanks.

Dave

 

[freebird01]

I sell a pump wrench just for turning the pumps

 

[ToughOldFord]

I sell a pump wrench just for turning the pumps

Price and pics?