special or custom tools for true TDC?

[NOMOFO]

Can y'all share your experiences with custom made or acquired "rare earth tools" for determining the error in your timing pin? I now have a dial indicator and a magnetic base. I will be changing injectors so will be able to use injector hole. Tried searching but the archives are offline for awhile apparently. It would be helpful to me and hopefully others to centralize all of these ideas in one topic. TIA, Bob

 

[Paychk]

I would submit the easiest way would be to roll the engine to the timed position (use the timing pin as it is currently adjusted) and adjust the # 1 exhaust valve to zero lash, then back the engine up 1/4 turn counter-clockwise. At this point crank down the exhaust valve 2 turns, the object is to cause the valve to contact the piston GENTLY, when you roll the engine forward MANUALLY . Mark the balancer in line with some convient object (RPM sensor on newer motors or a temp installed pointer) then crank the engine in the opposite direction nearly one complete revolution. GENTLY contact the piston again with the valve using the same amount of pressure on the turning tool, make a second mark on the balancer. Split the difference between the marks and that is top dead center. Re-adjust the valve and press on.

Advantages: no tools other than simple hand tools. Only way to do it more accurately is to do the same thing with a degree wheel attached.

Disadvantages: recommended to pull all injectors, this vents the compression and eliminates it's influence on the stopping points of the engine.



PS this is the suggested method from the repair manual.

 

[Tim1]

Hey bob, is your fear that the timing pin is not the true Tdc because the pump has been changed or that the factory may have set it wrong? I really don't understand your concern about the exact moment of TDC. Maybe I'm missing something! Please clear this up for me as I'm going to set the timing real shortly too. Thanks Tim

 

[NOMOFO]

Thanks Alan. Is that from Dodge or Cummins engine manual? Sounds reasonable to me but I think I would rather have a dial indicator involved. There have been mentions of tools fabbed that create a piston stop that go down the injector hole (Power Wagon from that great post on timing quite awhile back) and a tool that forces [overcomes spring pressure (Keeno/Jannety)] a valve down apparently without adjustment or disassembly then measuring it's movement with an indicator as piston contacts it. Hopefully details on these and all other ideas keep coming for comparison.

Tim, the factory settings have been widely known here to be off as much as five degrees. Apparently not too critical for valve adjustment but quite so for accurate pump timing. Checkout the recent post on pump timing where Keeno has a hyperlink to Power Wagon's dissertation on timing. He mentions the regularity of these things being off. Paccool also mentions somewhere that Wentland found his off by several degrees. All the Big Dogs seem to agree that the real fine tuning really means a lot. It is just my intent to be as precise as can be. So if the most precise tools and methods should present themselves... ... .....

 

[Paychk]

This method is from the Dodge manual, as for other methods that measure the movement of the piston, those have long ago been given up on and the positive stop method prefered. The reason for this is when a piston has stopped moving in the bore, the crank can still rock back and forth and not move the piston. This movement of the crank may only be some minutes and seconds of a degree, but it still is movement. The positive stop method on the other hand eliminates the bearing clearances, piston rock and crank movement that can influence direct reading off the piston. As in my previous post the only way to make this method more accurate is to attach a degree wheel to the front of the engine and take your readings from the degree wheel (usually 18 inches in diameter) and that would entail alot of disassembly of the front of the motor. If you have need of more information you can look at any of the performance engine building books that cover any brand of engine and they all refer to this method. After all an engine doesn't know the name on the outside it just knows converting reciprocating motion to rotary.

 

[Harlan]

Timing

I am just going out to the shop to find TDC on my engine. My methed is to come up on compretion stroke and at close to TDC I remove a intake valve spring and let valve sit on top of piston. Back crank up a little (put close pin on valve stem so it wont drop into cylender. ) role moterover till you are . 050 befor TDC, Mark crank dampener and continue on till you are . 050 ATDC and mark dampener agen. The center between these Two marks ,is TDC.

The main reasen I go this way is that there is no chance of bending somthing. and you do not have to role the moter all the way around. Just a few % BTDC and a Few % ATDC.

Harlan

 

[Tim1]

Hi Harlan, do you think it would be possible to make an adapter for our new DI to bolt to to go in the injcetor hole to measure the piston TDC? Basically a bolt drilled and tapped to accept the timing adapter the correct length. Seems it would be a little easier than taking the valve apart. Always thinking! Tim

 

[Power Wagon]

The reason for checking the timing pin, is that on occaision, the timing pin has been close to 3/8 of an inch off in the position of the dampner perimeter from true TDC on vehicles I"ve worked on. On others, it was dead on. That's far enough to make someone's truck go from running GREAT to weak, smoking, and sick.



The easiest way to find TDC is to mark the dampner at a little wasy below TDC. Like, the piston being . 250" down on each side of TDC, marking the dampner at each point, and then accurately splitting the difference to find the true tdc.

 

[Power Wagon]

Originally posted by Tim1

Hi Harlan, do you think it would be possible to make an adapter for our new DI to bolt to to go in the injcetor hole to measure the piston TDC? Basically a bolt drilled and tapped to accept the timing adapter the correct length. Seems it would be a little easier than taking the valve apart. Always thinking! Tim

Where I worked, we took a core injector, cut the top off a little, and drilled it all the way through, tapped it, and put a section of threaded rod through it. It's held in place with the retaining nut, just like an injector is, and the rod can be run in and out by hand, and it has a locknut, to ensure consistency. it touches the piston near TDC, and we rotate the engine by hand using either the alternator pulley or the bolts that hold the dampner.



We used a magnetically mounted pointer to accurately locate the points on the dampner.

 

[NOMOFO]

Hey thanks all. I like the injector/ rod approach and not messing with or contacting valve. Perhaps a rod of softer metal than piston too so as not to risk dinging it. No experience in this type of operation hence no developed soft touch. Just being intensely careful.

Regards, Bob

 

[Tim1]

Powerwagon, 1\4" before and 1\4" after, split the difference, Perfect. The core injector is a real good way to measure the travel and I can do this. Thanks for all the good info you are sharing on this site, glad to have you aboard!!!! Hope to see you at the get together. Tim

 

[Harlan]

Timing

Tim1= The injector with rod will work just as good as a dial indicater. I had the dial indicater and no injecter core so went that way. It is amazing what comes out when we all get are heads to geather on a problem.

Called Piers to day and orderd my injecters and he was very helpful on setting my pump timing and some mods for interear

pump work. Said if I had any problems to call back. It is very nice to have fallow up help like that from a top of the line man. I work with big deasels and when you by parts and have problems all they wont is for you to bring it to there shop at $90. 00 per hr.

And some times it is 100=200mile one way trip. But not to rap all shops, some are vary good about helping you out when you are intruble and long distence.

Harlan

 

[Mel Fuelling]

Anyone wanting to verify injection pump timing should first verify

TDC because the timing pin may be as far as 5 degrees off, and

unfortunately its also a royal P. I. T. A. to reach and to work with.



The two most commonly used methods of accurately determining

TDC are:

1. Positive Stop Method. Use immovable object to stop

piston travel near TDC and scribe H. Balancer or mark

degree wheel, then reverse direction of crankshaft

rotation and repeat. 1/2 the distance between scribe

marks is TDC. The immovable object part is a little more

difficult on diesel applications



2. Dial Indicator Method. Position D. I. in a solid holder with

stem inline with and bearing on the piston. This method

is made more difficult by the fact that the injector bore

is at an angle with the cylinder bore. This angle can be

minimized by holding the D. I. with an adjustable

magnetic base and using a 3" stem extension to reach

down through the injector bore to the piston, keeping

the D. I. as vertical as you can and still contacting the

piston without dragging on the sides of the injector hole

into the combustion chamber. Use a dowel rod to find

an approximate TDC while rolling the crankshaft over,

then use the D. I. to find an accurate TDC. Mark the

H. Balancer or a degree wheel when the gauge needle

stops moving(or @ . 050") and again when it starts

moving. Halfway between is an accurate TDC.



The injector core tool seems like a good way to avoid

a side load on a stem extension.



The valve on piston method that Harlan describes is one

that I'd like to try next.



A degree wheel is one way to mark and transfer data

points, but its dominance in gasser timing is because it

has complete 360 degree markings that allow intake and

exhaust events to be verified for each cylinder, usually

using a dial indicator to measure . 050" of valve lift, but I

am skeptical that it offers any increase in absolute

accuracy at the end of the day to verify TDC.



All of these tools and methods are capable of delivering

acceptable and similar levels of accuracy. They can also

produce errors if not done carefully. We all have

different resources and experience that will lead us to

use the method and tools that we are most comfortable

with.



Accuracy does make a difference.

 

[Tim1]

Mel and Harlan, was you TDC off when you checked it with both methods? Just curious, I ran into some snags in my schedule with family, but will be timing soon. Damn good posts!!!!!! Tim

 

[Mel Fuelling]

Tim1,

My timing pin was right on, but it has so much pin drag even

after removal, cleaning, and lubing that it is difficult to use even

after moving the Vacum/Power Steering pump back out of the

way. I scribed TDC on my H. Balancer so that it will be much

easier to find/verify in the future. I'll just use my timing pin to

verify that the H. Balancer hasn't slipped. (I haven't heard of

this with the 5. 9 but I encountered outer balancer ring

separation on 70's F**d gas motors making me suspicious ever

since)



I did not verify TDC with the positive stop method on my pickup.

I am very comfortable with and confident in the results I got with

my dial indicator. I have compared them in the past and I will use whichever method that seems most appropriate for the project in front of me. I will ususally trade certainty of results

for ease or speed of completion, but in this case either will give

excellent results.



I'll always start with an O. E. M. shop manual, but when you have

a chance to learn about proven field expendients from so many

experienced different sources as we do on many websites, it really makes it worth my time to look and learn. Imagination and

experience are powerful tools.



What year are your seats out of? How did you adapt them?

 

[Tim1]

Mel, the buckets are out of a mid 80's chrysler that fold forward. The drivers is electric and the passengers is manual. I used some 1x1 tubing to level the seats out (2 pieces toward the door) and drilled through the floor pan. The center console I got from the local speed shop( baxters Auto Parts) and it sits pretty high. I'll stop by there and see if I can get some numbers, as I looked for a long time to find the right one. The seats have folding arm rests. As you know, the bench seat is awfully uncomfortable. These seats make all the difference! Tim

 

[Tim1]

Hey Mel, let me redo my post. When I bought the sears, they were setting on the floor in the wrecking yard and the fella tole me that was what he thought they were out of. Could be a Laberon. The seat is 25" wide from the door to the plastic latch that folds the seat forward. The back is 23 1\2" high not including the headrest. I used 2x2(not1x1) tubing 15"long on the side with the door. Thats 4" total rise and on the inside I used a 2x2 with a 1 1\2"tube on the front only. The console is made by Bestop and is 9"wide and 231\2"long. The front height is 9" where the drink cups set and the flip top is 12 1\2" at the rear. Real nice arm rest. Of course they don't carry them anymore. This job took a whole weekend to do by myself! By the way mel, since I already installed new injectors with new copper gaskets, I'm thinking of trusting the TDC untill I change the valve springs for a ehaust brake, then I'll use the valve method. Tim