Adjusting injection pump timing without setting cam timing

[nazrat]

I've measured the timing chain stretch and ordered the correct woodruff key. While I wait for it to arrive (special order) I was going to set the pump timing. The way I see it the crank turns which pulls on the timing chain on the driver's side around the injection pump and the vacuum pump (and in my case the hydraulic pump for SLS) then up and over the cam, then past the tensioner and back to the crank. Because the tensioner is after the cam, and the injection pump is before the cam, I should be able to set the injection pump timing before the new woodruff key arrives. It will be one less thing to do once the key arrives.

-Tad

[OMEGAMAN]

You are correct there's no reason why you can't adjust that pump now and the cam later.

[Brian Carlton]

Since you know the stretch, the spec for the IP timing should be adjusted to compensate for the stretch. IMHO, about 1/2 the stretch should be added, or subtracted from the spec (depending on which method you are using).

For example, if the stretch is 4 degrees and you use the RIV tool, the setting would be 13 ATDC. The normal spec is 15 ATDC and you advance the timing by one-half of the stretch.

The amount to adjust (1/2 the stretch) is just an estimate presuming that the IP is 1/2 way up to the camshaft. In reality, it's probably closer than 1/2 way.

[Diesel Giant]

Hmmm... sounds like a nice pictorial to do....

[TimFreeh]

Originally Posted by Brian Carlton

Since you know the stretch, the spec for the IP timing should be adjusted to compensate for the stretch. IMHO, about 1/2 the stretch should be added, or subtracted from the spec (depending on which method you are using).

For example, if the stretch is 4 degrees and you use the RIV tool, the setting would be 13 ATDC. The normal spec is 15 ATDC and you advance the timing by one-half of the stretch.

The amount to adjust (1/2 the stretch) is just an estimate presuming that the IP is 1/2 way up to the camshaft. In reality, it's probably closer than 1/2 way.

Next time you have the head off a 61X engine put a dial indicator on the number 1 piston and see if the TDC marker actually identifies the true TDC position. You may be surprised at what you find.

[sailor15015]

Originally Posted by Diesel Giant

Hmmm... sounds like a nice pictorial to do....

Oh please do. That would be great. I love your pictorials.

[LarryBible]

Originally Posted by TimFreeh

Next time you have the head off a 61X engine put a dial indicator on the number 1 piston and see if the TDC marker actually identifies the true TDC position. You may be surprised at what you find.

Tim,

It would be very difficult to locate TDC with a dial indicator. It is more accurate to use the positive stop method. Rig a positive stop that will stop the piston about 1/4" from the top of its travel. Put a degree wheel on the crankshaft snout and turn the engine one direction until number one hits the stop and note the degree wheel position. Turn the engine all the way in the opposite direction until the piston hits the stop again and note the degree wheel position. TDC will be halfway between the two positions.

You can do the same thing with a dial indicator by measuring the position down the bore in a similar method, but it is difficult to do.

On the MB engine, this should not be done with the timing chain installed since it's a no no to turn the timing chain backwards.

Just wanted to clarify.

Have a great day,