Most definitely.

TF was the originator of this info and few believed him.

It's right on the money.


The difficulty in accepting this premise is tied to the understanding of "starts in second".

It must be carefully explained, and very meticulously verified, that the vehicle sits at a dead stop in second, and, before it has any forward movement, the trans performs a 2-1 shift. One could actually make the argument that it is starting in first, if "starting" is considered the forward motion of the vehicle.

All,

I have finally received my new primer pump and just installed it on the vehicle and I was able to check the injection pump timing. I was a little confused by the write up that I found, but I think I performed it correctly:

1. Removed the #1 injector line
2. Rotated the engine through the intake valve open & close, through the compression stroke, and through exhaust valve open & close.
3. Used a paper towel to dry out the visible fuel in delivery valve #1.
4. Pumped the primer several times till i could here the injection pump bypass valve opening.
5. Rotated the engine through the intake stroke (intake valve opened & closed).
6. Continued rotating through the compression stroke till about 40° BTDC.
7. Slowly rotated the crankshaft until my helper noticed fuel starting in the number delivery valve.

Please let me know if I performed the procedure incorrectly.

So the car injection timing shows 15° BTDC! 9° retarded! No wonder the car is a little sluggish off the line.

I am kinda wondering if I performed the procedure correctly, since it is so far out of time. Is it common to have the injection pump timing out this far or does the injection pump have enough adjustment to bring the timing back to 24°?

Would it be best if I checked the cam timing next? Or just adjust the IP timing and don't worry about the cam timing?

Any help is greatly appreciated!

Thanks,

Keith


BTW - Just to clarify, I noticed someone mentioned the banjo bolt being dirty. When I first got the car I cleaned that bolt out and pulled the switchover valve off to maker sure it was not clogged also.

if you are correct, something's gotta be up.
I'd pull the cam gear, and verify there is not a offset key first, then perform the 2mm lift method of checking chain stretch. if the chain checks out, then likely the IP has been replaced, or timed incorrectly.
hard to believe it's out that far in only 200K miles... perhaps the odometer is off?

Checking via the drip method is notoriously inaccurate for those not well versed. The determination of "welling up" can easily vary by five degrees or more.

On the '85, the preferred method is to use the A-B lights and verify the IP timing within 1 degree with perfect accuracy. The operator has no possibility of skewing the result.

This approach is far simpler than the 2mm valve lift method which required some additional skill.

So I have a cheap haynes manual from my old 85 300D w123 and it pictures the use of a special drip line which attaches to the injection pump number 1 line, after removing the two components inside the delivery valve and reinstalling it (if I remember correctly). The spec is to adjust the pump until there is 1 drip/second. Would this be a more accurate method? Of course I want to get the timing as close as possible, but I noticed that the A-B light costs around $250 after my quick search online. Plus the procedure for the A-B light says set the specification to 14°? My car specifies ~24°.

Just to clarify, the 2mm valve lift only indicates chain wear only, correct?

It is a notoriously inaccurate method for those who are not very well versed in exactly what to look for. Additionally, it's inaccurate, by definition because the specification of 1 drop per second has no defined fuel pressure. If the pressure is higher, the flow rate increases..........and the converse.





Check the rental forum. IIRC there were a couple there for rent, although I haven't checked lately. Finding someone with this light would be to your advantage.

The spec is 15° ATDC with the A-B lights.


The 2mm valve lift method indicates the timing between the camshaft and the crankshaft. You might make some assumptions of the relative timing of the IP based upon your findings of the camshaft timing, but those assumptions won't allow you to adjust the IP to any accuracy.

However, if you do find the camshaft timing to be significantly late, you might consider the addition of a Woodruff key to advance the camshaft. Unfortunately, this accomplishes nothing for the IP.

Thanks for your responses, I have PM'd the member with the A-B timing light for rent, so that will be my next step.

Just to help me understand better, would the fuel pressure during this "drip method" be regulated by the bypass valve on the injection pump? Could you maintain a certain fuel pressure by doing this? Adjust the pump, pump the primer till the bypass opens, record value, adjust the pump, pump the primer, etc...until you reach the proper adjustment?

You could only maintain the bypass fuel pressure if you could pump like a madman so that the pressure remained at the bypass level.

Under normal circumstances, you don't continually pressurize the system and the pressure falls throughout your attempt at garnering the elusive 1 drop per second.

You might be successful in your scenario whereby the test occurs after the IP is set in order to verify.

IMHO, the entire process is fraught with inaccuracies.............YMMV.

If you are referring to the 15 degrees BTDC injection timing, that is very typical of a previously untouched IP. As I have stated here a number of times, I suspect that the typical 616/617 engine on the road is 8-10 degrees retarded.

In my opinion, the exact timing of the drips is not terribly critical. The point is that the IP is at the position just prior to "no flow." It's like shutting off your kitchen faucet, where you go from full flow to off, but stop just shy of completely off. The difference between X drips/sec and Y drips/sec is relatively insignificant when compared to full flow versus "dripping." The range of positioning between full flow and no flow is very small.

interesting.
do you agree with my point about checking chain stretch and if there is a woodruff key?
I find that when the IP timing is heavily retarded, the timing chain needs replacement.
if it lines up correct, then there's likely an offset key installed, and it, and the chain need to be replaced, if not all the gears as well...

Yes, I am refering to 15 BTDC timing.

So does this mean that the IP has enough adjustment range to get the pump back into the correcting timing position?

Finally, I am going to do some more reading on this drip method. I understand the A-B light is the most accurate, but for the time being, I would like to experiment with the drip timing method. It will probably take another week to rent the A-B light.

Since I do not have the drip tube, can I use the number 1 injector line positioned off to the side somewhere to act as a drip tube?


Thanks.

It's very possible that it will not.

I guess I will have to try it out. If not, I would assume the next step is to check for excessive chain wear?

At this point, chain wear is, for all practical purposes, an unrelated issue. If you want the IP timed and you run out of adjustment, you just remove the IP, index it and reinstall it in the center of the adjustment range. Then time as normal.