I had a friend of mine tell me that you can advance the pump timing by turning the pump a nickel's distance to get more power out of these things. Is this true? And which way would I turn the pump?


Thanks

 

A nickel's width would be a huge amount of advance.
To much advange and you will have a diesel version of spark knock, which can cause the diesel version of same the damage.
Top of the IP to the passenger side is advancing the timing.
The width of the timing mark on the IP is probably to much change unless your IP is real high mileage.

If the engine starts to sound like a Power Stroke rattle, you have gone to far.
Also the engine must be OFF while the bolts are loose on the IP.
IP damage will result if it is running with the IP bolts loose.
No turning the IP while the engine is running like you do the distributor on a gasser.

Also if you do this, don't expect a huge gain in power.
Some gain, yes, but it will not suddenly be a Power Stroke.

 

Theoretically .015 inch movement at the timing mark is one degree of timing. The problem is there are +/- 2 degrees or more of play that can accumulate between gear wear and play in the mounting bolts. ie. you can loosen the bolts, advance the mark .015" and have the timing retard 1 degree or advance as much as 3 degrees after you re-tighten the bolts.

I just advanced the timing on my truck using a pulse adaptor and timing light. It took me the better part of a day to get the timing set to 8 1/2 degrees BTDC because evertime I loosened the IP to make a small change I never knew what was going to happen. I finally got lucky and hit within a half degree of the setting I was looking for and I may have just been unlucky but the timing can bounce around everytime you loosen the bolts.

The final IP timing on my truck was 8 1/2 degrees BTDC. At that setting the timing mark was advanced .o3o inch (.030" = 1/32 inch) from the static timing position but, because of the variances listed above, the timing for another IP advanced the same distance could vary as much as 5 degrees from the setting I got.

 

OK, here's a brief history. 8 1/2 degrees BTDC appears in quite a few web references (mostly forums on other diesel sites) as the max safe advance for the 7.3 IDI, which is where I came up with the setting. Power was excellent, milage went to about 13 mpg moving 14,000 lbs of camper and truck down the road at 65 mph.

The engine held for about 4,000 miles. She blew late at night on a flat stretch of highway at low rpm going about 55. I haven't pulled the engine yet to see what happened as she is setting about 800 miles from home and I'm hoping it's just the head gasket but I felt lucky that she didn't blow climbing one of several mountain passes.

Question 1. What effect does an increased cetane rating have on ignition timing? I added Power Service which claims to increase the cetane rating by 4.

Question 2. The timing was set at sea level on a warm day while most of my driving was 4,000 to 5,000 ft with passes over 8,000 ft. What effect does elevation/ air density have on ignition timing?

 

Higher cetane rating means less ignition delay from the time the fuel is injected.
Higher numbers autoignite easier. So this could have the same effect as advancing the timing slightly.

Altitude has no effect on the IP, but also you have to consider the air density is less at 5,000 feet. On turbocharged engines this lower pressure makes the turbo spin faster due to less exhaust restriction and less air going into the turbo. The faster spinning turbo should produce very close to the same boost levels, so this should not be a factor.

Were your EGT and boost readings about normal?

 

What were your pyro temps when your engine went ?

David

 

when i time my motors, i do it purely be ear. high milege pumps will wear and slow the timing down. i like to turn it to the passenger side of the truck untill it rattles when idling, tighten the pump and slowly speed the motor up, when the motor hits somewhere around 1500 or so the rattle should lessen and it should go away completely when you goose it. take the air cleaner off to hear the rattle better. a rediculously large crescent wrench over top of the whole pump makes a good timing adjuster wrench. do this preferrably when the engine is cold so you dont burn your hands off when loosening the bottom nuts. grind down the round end of a 9/16 wrench so it is thin enough to fit between the manifold and the i.p. nut when the nut is loosened a little, its tight but is not impossible

 

i have had a shop do the timing on my truck and i watched as he did the timing with a light while it was running just like on a gasser, and i have timed several trucks while they are running, i have never heard of injection pump damage occured from doing that. i would say you have a better chance of winning the lottery than i.p. damage from timing it while running.

 

She went real quick. I heard the change in the engine and felt the loss of power. I was running at about 1800 rpm. engine temp was normal, Boost was about 2 lbs. Which is normal for my non-wastegated turbo at that rpm. EGTs were about 450 -500.

She went all at once and lost power instantly. I glanced at the gauges as I headed for the side of the road and everything was normal. She blew the soft plug/block heater plug so by the time I reached the side of the road the temp gauge was pegged to the right and I shut her down and got a tow off the road.

The next morning I replaced the plug, refilled the radiator and started her up. She was missing but held water just fine till she reached operating temp and I shut her down and topped of the radiator. I started her again to pull out from under the camper and as I released the clutch she sounded like something fell apart inside. This time I opened the radiator and watched the water drain down into the block.

The timing was set using Snap-on's pulse tool and a timing light. I should note that after I added the Power Service I could hear a difference and thought she was advanced too far. I didn't have the timing tools with me so I borrowed some wrenches the next morning and reset the timing to the static mark thinking I could retime at home after the trip. After resetting to the static mark she climbed 2 mountain passes which were climbed in second gear at about 2800 rpm. During those climbs boost was 8 - 9 and EGTs were 950 - 1000 and the temp gauge was in the high normal range. She blew about 150 miles after the last pass.

 

Sounds like it started with a blown head gasket.
The compression pressure is probably what blew the soft plug out.

As it built pressure in the cooling system as it warmed up, it probably hydrolocked the engine while it was running. That is probably the sounded like something fell apart.

Time for some teardown to see what the "fell apart" sound actually was.

 

I'm planning a trip to tow her home but will be winter before I have time to pull the engine. Actually, I'm looking forward to it. Must be my more masochistic side. What's the gambler theme? "Don't play if you can't afford to lose"?

Anybody playing with timing, adding turbos, modifying intakes, filter systems, and exhaust, etc/ to get the most out of the outdated design of these IDI's is a gambler in the worst way.

But dang! it sure is fun! lol I might try a more reasonable timing next time. maybe 6 1/2 degrees instead of 8 1/2. Or maybe doping up the fuel with Power Service "before" setting the IP timing. Or maybe setting the timing when she's taking in cool dense air. Maybe the answer is to use a combination of all 3?

Anyone thats going to mess with getting the max performance out of these engines had better be in love with em! She was kind of running like a powerstroke before she blew up. lol ...... and while she's in the shop an update to 6X6 might be in order.Too bad I'm not a mechanic or an engineer.

TD

 

i added a turbo on my idi a few years ago, it was all homebuilt and not very pretty at all, but it did work, dave and a few other people on here helped me out quite a bit with my design, its a crying shame that the only turbo i had to put on it was a junker.. it was all wallered out. i have a few pictures and planned to add a few more pics, but the camera went south before i could get the pics developed. anyways i had a pyro and boost, i had 15 psi and 1,200 temp at the highest i could get it. it would slip the clutch at 3,600+ rpm the best mod i ever did to that truck was to put a 4,000 rpm governor spring on it and i would recommend it to anyone that is not too afraid of high rpms. its hard to find but worth doing, and if u dont like it, then shift earlier..... but try it and you'll love it i promise. look at my avatar, that was taken sitting still in neutral. i think i revved up the engine 3-4 times. tell me if you have seen any other idi make that much smoke.....