6.9 timing Where did the 8.5* come from

tvrrproto48

Registered User
Joined
Jul 10, 2022
Posts
9
Reaction score
1
Location
Nevada
I have read at several blog sites, "book specification for dynamic timing is 8.5* BTDC". Where is this 8.5 coming from.

I have an 85 F250 with ATS turbo I inherited from my dad. 132k original miles. It smokes a lot and was a little difficult to start. I replaced injectors and it ran smoother but still cranked a lot to start not as much when hot but not like the single revolution required from my Mazda diesel.

I replaced the glow plugs with 12G as I was told they are self regulating and won't swell. With less than 100 miles since doing this the engine died on a trip to town.

I replaced the ip but still would not start. Replaced all rubber hoses within the engine compartment. Replaced the fuel return with a 7.3 kit. I had set the timing with the cast marks placing the new pump in the same position as the old. Have finally stopped all air leaks. After 2 or 3 cycles of 30 second cranks it will start but only with the throttle to the floor and rpm's have to be held above 1k for a minute and slowly lowered or it dies.

Bought a DTI 3300S timing setup. Using the pulse adapter and timing light I set the pump to "8.5*". It is still hard to start. It no longer has a lop at idle and runs up smoothly but still has a lot of smoke even after fully warmed. Shutting it down and immediately restarting still has to crank with at least half throttle and patience. I have seen this 8.5 thrown around on the web for years. Where did it come from? The factory manual says between 4* to 7* depending on elevation and cetane. That is for magnetic probe which I haven't tried yet because it doesn't come close to fitting the hole and with the luminosity probe.

I'm sure at this point it is a timing issue. Just not certain which way to move it. Oh and the 12Gs that never can swell. With less than 100 miles 2 okay, 1 split, 2 bulged and the other three still trying to get them out of the holes. Will have to pull the heads and break off the tips to get them out.

Jeff

 

NeverHave-I-Ether

Full Access Member
Joined
Jan 18, 2022
Posts
304
Reaction score
207
Location
Texas
The 8.5 degrees for timing is for N/A engines I believe. Turbo models are between 7.5-4* as you mentioned. That's the way I remember it.

Never-Have-I-Ether
 

tvrrproto48

Registered User
Joined
Jul 10, 2022
Posts
9
Reaction score
1
Location
Nevada
The Ford official shop manual I have is from 1985, same as the truck. Turbo didn't come out til the 7.3. And I have reread the instructions with the ATS turbo install and there is no mention of changing the timing.

Jeff
 

tvrrproto48

Registered User
Joined
Jul 10, 2022
Posts
9
Reaction score
1
Location
Nevada
I should have mentioned, we determined the old pump was dumping fuel out around the advance lever. But was told that alone would not have shut the engine down. Also before my dad passed away the truck was driven once a year for several years to get smog-ed and licenced. That was for probably 10 years after he went blind. I do remember it getting harder to start back then.

Jeff
 

Jesus Freak

Full Access Member
Joined
Apr 3, 2022
Posts
1,487
Reaction score
1,156
Location
Crestview, FL
Hey, just a thought, but I don't think you've mentioned the actual mechanical fuel pump. It has a check valve in it that if it's compromised will let fuel drain back to the tank and create a situation like you're discribing. Mine did that.
 

IDIDIDIhoDhoDhoDO

Registered User
Joined
Dec 3, 2021
Posts
26
Reaction score
12
Location
Earth
You are setting the timing at 2000 rpm and not at idle right?

I have the ferret timing adapter and I have found that the best timing for me is 10 degrees. When doing a little reading about timing these engines it was mentioned that diesel fuel nowadays, because of the reduced sulfur and maybe some other factors, I'm not sure, requires more timing than the fuel available when these engines were new.

I am also at a pretty high altitude, around 7000 feet, so that might affect why my engine likes 10 degrees as well, but 10 degrees at 2000 rpm (12 degrees with the cold advance on) with the fuel I get around here seems to be the sweet spot in my truck.
 

Big Bart

Tow&Slow
Joined
Dec 22, 2020
Posts
1,481
Reaction score
922
Location
Newport Beach, CA
I have read at several blog sites, "book specification for dynamic timing is 8.5* BTDC". Where is this 8.5 coming from.

I have an 85 F250 with ATS turbo I inherited from my dad. 132k original miles. It smokes a lot and was a little difficult to start. I replaced injectors and it ran smoother but still cranked a lot to start not as much when hot but not like the single revolution required from my Mazda diesel.

I replaced the glow plugs with 12G as I was told they are self regulating and won't swell. With less than 100 miles since doing this the engine died on a trip to town.

I replaced the ip but still would not start. Replaced all rubber hoses within the engine compartment. Replaced the fuel return with a 7.3 kit. I had set the timing with the cast marks placing the new pump in the same position as the old. Have finally stopped all air leaks. After 2 or 3 cycles of 30 second cranks it will start but only with the throttle to the floor and rpm's have to be held above 1k for a minute and slowly lowered or it dies.

Bought a DTI 3300S timing setup. Using the pulse adapter and timing light I set the pump to "8.5*". It is still hard to start. It no longer has a lop at idle and runs up smoothly but still has a lot of smoke even after fully warmed. Shutting it down and immediately restarting still has to crank with at least half throttle and patience. I have seen this 8.5 thrown around on the web for years. Where did it come from? The factory manual says between 4* to 7* depending on elevation and cetane. That is for magnetic probe which I haven't tried yet because it doesn't come close to fitting the hole and with the luminosity probe.

I'm sure at this point it is a timing issue. Just not certain which way to move it. Oh and the 12Gs that never can swell. With less than 100 miles 2 okay, 1 split, 2 bulged and the other three still trying to get them out of the holes. Will have to pull the heads and break off the tips to get them out.

Jeff

Jeff,

Some things to rember.

Timing - 8.5* @ 2000 rpm is the gold standard for both turbo and non-turbo when using injector pulse method. (Engine warm and IP advance off.)
1) However some of the IP builders sometimes recommend other settings when you buy their IP’s.
2) Many members prefer 9.5* @ 2000 rpm.
3) You can play with yours and also try 10* and 7* and see what works for you.
4) Lummy method was the early method, it used the flash of the combustion. Your DTI is using the pulse of the injector line. So different results. Also with lummy centane was a factor in what you set the timing to.
5) 6.9 engines where not factory turbo, so usually you have to turn the IP fuel ratio up when adding a turbo.

Smoking mainly when cold is often injectors or from a long cranking to get the fuel system re-primed. Other reasons you may have smoke all the time are your timing is way off, your engine is having a issue like a leaky valve seal, stuck rings, too much blow by, a bad cdr valve, etc.

Try pulling the Fuel filter off, pouring out the diesel, filling it with ATF. Run for 35-45 seconds and shut off and let sit over night. If the smoke lessens the next day then likely your injectors need to be rebuilt.

Now when you crank your engine for 60 seconds and then it fires off you will get a big cloud of white smoke. But once that diesel burns off it should not continue to smoke.

Since your dad only ran it once a year you could have some stuck rings, they should clear up after you put on some miles.

If after setting the timing and doing one or two rounds of ATF treatment your truck does not start warm in 5 seconds likely you still have an air leak somewhere.

Lastly the IP and injectors should be rebuilt every 100,000 miles. They should be done together. You mention you replaced the IP but not if new or used. Or if from one of the 4 companies recommend on this site. (See tech article below.). So if you continue to have starting and running issues you may want to send the IP and injectors in for testing.

Here are some tech articles I highly recommend you review. Let us know how things progress and we can help guide you more once we understand more about your issues, testing, and results.





 

danda

Registered User
Joined
May 17, 2022
Posts
46
Reaction score
1
Location
CA
Where did you get the replacement injectors and are they new or reman?

I ask because I was having long crank times (10+ secs after 24 hours). After sealing up the fuel system in a bunch of ways, still long crank. I pulled the injectors, pop tested, and found they were leaking at only about 1000+ PSI.

I ordered reman injectors off ebay. They arrived with obviously used nozzles (carbon deposits visible, etc). Fortunately I pop tested them before using, and they were just about as bad as my old ones.... leaky at low pressures and pop totally inconsistent.

I finally got a reman set from Russ with new nozzles. Pop tested them, and totally consistent with no nozzle leaks.

After installation, my crank time after 24 hours is about 3-4 secs. Still longer than I would like, but a dramatic improvement from before. At least I don't have to worry about draining the batts and killing starter now.

I also heard from forum members that even brand new Delphi injectors may have quality control problems, which Is why I went with Russ instead.

So anyway, I relate this story because I'm quite certain if I had installed the injectors I got from ebay, I would've still had long crank times.
 

tvrrproto48

Registered User
Joined
Jul 10, 2022
Posts
9
Reaction score
1
Location
Nevada
The injectors are GB rebuilds from Rockauto. I have used the brand in every injected engine I own and never a problem.

Temporarily replaced the hose from the tank line to the lift pump (new pump) from the ip to return line and the small bleed line on the filter head with clear line. Satisfied there was no air filtration after ten minutes of running. Replaced the clear line from the tank line to lift pump and replaced the fitting at the filter head with a 90* without the small nipple. Ran it again til no air showed and left it overnight. All clear hoses were full the next morning. Started it after the usual 2 minutes of cranking and no bubbles showing.

Other than the three glow plugs I could not get out the glow plugs are new the glow plug circuit has been tested all hoses replaced except at the tanks the lift pump is new the injectors and ip are rebuilt from companies I trust. The cold idle and cold advance have been tested.

At this point the only variables I see are the 3 old plugs and timing. It idles smooth after a few minutes but smokes constantly white to light blue on start up to bluish black on punches. The hardest thing is starting it.

Jeff
 

Big Bart

Tow&Slow
Joined
Dec 22, 2020
Posts
1,481
Reaction score
922
Location
Newport Beach, CA
Some more thoughts.

1) Glow plugs are needed to effectively start these engines cold. (Even in summer.) Sounds like the 12g’s burned up, any chance your glow plug controller is a old mechanical one and and it stuck on? IE they stayed on and burned up? FYI another glow plug eater is when your timing is considerably off. So if you are down 3-4 glow plugs it will be harder to start cold, but should not be a big factor when the engine is hot. If you have a working block heater use it and see if the truck will start right up. If so it’s likely a glow plug issue not an air issue.

2) Double check your timing and make sure you are 8.5 btdc at 2000 rpms. You want to use the hole towards the left side of the timing tab (Passenger side.) as that is TDC. There are two holes, one is 0 or TDC and the other is 20* ATDC and is the hole the magnetic probe goes in if not using a timing light. You set the timing advance to 8.5* and line up the mark on the damper with the center of the left hole which is TDC. Just a reminder you adjust the IP with the engine off. Leaning the pump to the passenger side advances, to the drivers side retards it.

3) The fact you have a rebuilt IP, rebuilt injectors, and new return lines, and have to have to crank so much even when the engine is hot is leaning me towards you also have an air issue.(Maybe at the tank switch valve or at the tank.)

There is drain back and there is air intrusion. Drain back tends to be the lift pump valve or leaky return line part lets the fuel drain back down to the tank over say +6 hours. This makes it so you have to crank and refill the fuel system. But generally if you wait five minutes and test, the truck starts right up as the drain back is usually a small hole/gap and it takes hours to drain back. You said you truck is also hard to start warm, which generally is not a drain back issue.

But air intrusion is where the system sucks air before the lift pump and causes odd running issues even after it starts. The best way to test this is hook up a 5 gallon gas can with diesel in it via a line directly to the lift pump. Then the only variable is the lift pump, which you replaced. Run it, shut it off, and try to restart it. Rinse and repeat. If no problem starting anymore when the engine is hot, you know you have a fuel system leak between one or both tanks and the lift pump.

4) These trucks have several supply side issues.
a) The fuel gauges are giving out at this age or on the way out. So confirm at the pump you have at least half a tank In each tank while doing your testing.
b) Part of the pickup in the fuel tanks break off, often called a shower head, now that tank sucks air when you are say 1/4 tank or less.
c) Then fuel tank selector valves are also failing for many. These can be tricky to diagnose. Basically they get stuck in between tanks and cause running issues.

Now some words for the wise-

1) Many members have tried and many have failed buying IP’s and injectors at parts stores or online. So if all the other tests and repairs don’t fix your issues, have your IP and injectors tested by one of the vendors shared above so you can rule out it is not yet again another IP or injector issue.
2) Never assume any new or rebuilt part is good and works. Every week some member here gets burned by a faulty new or rebuilt part. You may have got stung this month with 12g’s that should not have ballooned/mushroomed. But maybe your lift pump is or has gone bad or is allowing for drain back. Maybe you got a bad IP out of the box, but most of us do not have a IP tester to know. My point is don’t assume because you replaced it is good.
3) If your batteries and/or starter are marginal and your engine rotates slowly when starting. This also can be a reason your truck starts poorly.
4) You have done a lot of good work, but it sounds like all of it was recent. So more things that may be impacting you. So be sure to double check that work and make sure those components are working or you did not miss something. Such as your remaining glow plugs are coming on at start so your getting the heat you need. But they are not staying on more than 8-20 seconds. That your DTI was set correctly and you used the TDC hole for the timing. That all your injectors are popping within spec of 1,850 +/- 50. That your lift pump is giving you 4-6psi at the filter head and not letting the fuel drain back.

Keep with it, you will figure it out. Know many of us were in a pain funnel when we got our trucks trying to figure out what was wrong with them. Still having issues after fixing or adjusting several things. Keep us informed and ask questions as they come up.
 
Last edited:

tvrrproto48

Registered User
Joined
Jul 10, 2022
Posts
9
Reaction score
1
Location
Nevada
I think I stated this before, new lift pump with clear hose between pump and hard line from tank and finally getting it started worked the air out of that line and ran for five minutes. No bubbles. Sat over night still full of fuel and no bubbles.

With all the new lines and forgot to mention new sleeves on hard line from pump to filter to ip. I am 99.999% certain it is not an air problem. Typical cold start (65*) in the morning is two or three 30 second cranks. After the temp gauge shows normal I can shut it off and within seconds a restart is one or two 30 second crank if I don't press the throttle. With throttle down and hot engine I can get it started with a 15 to 20 second crank.

I'm sure the three "old" plugs are a factor but shouldn't be when hot engine. I'm convinced it has to be the timing. Using the DTI, engine held at 2000 rpm. Pump readjusted to 8.5* is where I'm at now. Idles smooth, runs up smooth but not very snappy. Hard to start and white to light blue smoke at start changing to light blue to grey with black when throttle snapped. It almost seams like an overfuel but this pump has not been turned up for turbo. Broke allen wrench trying to adjust it so left it.
 

tvrrproto48

Registered User
Joined
Jul 10, 2022
Posts
9
Reaction score
1
Location
Nevada
If the glow plug controller was stuck on wouldn't the glow plug light also stay on? Typical glow plug cycle is 10 seconds on followed by on off on off cycle for several seconds and then occasional on off till temp comes up. It has been like that for as far back as I can remember.
 

tvrrproto48

Registered User
Joined
Jul 10, 2022
Posts
9
Reaction score
1
Location
Nevada
I plan on one day building up a new glow plug harness and change over to the 7.3 controller.
 

Forum statistics

Threads
89,955
Posts
1,103,649
Members
23,013
Latest member
yseguy

Members online

Top