Cam timing expert help needed! - Page 6 - PeachParts Mercedes-Benz Forum

Stevo · #76 07-01-2006, 10:32 AM

Quote:

Originally Posted by Brian Carlton

Bubba doesn't know how to loosen the mounting bolt and adjust the IP without taking the bracket off. Naturally, he can't get it back on.............

That bolt/bracket is truly a bugger, Ive heard of cutting a slot down to the top hole in the bracket to make it easier. Once I had my wife get up there with her tiny "girl hands".

leathermang · #77 07-01-2006, 10:47 AM

"As a side note, I wonder if significantly advanced timing could cause excess blowby. My reasoning is that with the timing advanced your causing the ignition to happen while the piston is still on its way up."

If you were dealing with a gasoline engine at 8 or 11 to one compression ratio it would be different.
But the heat to cause ignition in your car comes from about 21-1 compression ... so that is not going to happen much before TDC on the compression stroke.. also, spraying fuel into your engine early will just cool that air as compared to advanced ignition in a gas engine ( already loaded with vaporized gasoline ) and whose mixture can be ignited by a too soon pop of the spark plug.

"I can see this"
!! Really !?!
You must have one of those quartz windows installed in your engine.. like the old " Color Tune" which allowed seeing the color of the combustion going on in the engine while it was running...

"I can see this forcing more gas past the rings than a properly timed engine would."
That 21-1 ratio is pretty tough on the rings in the first place... they are made very well and little actual pressure hits them due to the tight piston to wall specs on our engines...

Stevo,
"and usually make a big mess."
PUT A TUNA CAN UNDER THE DRIP TUBE !!!! LOLOL

Stevo · #78 07-01-2006, 11:09 AM

Stevo,
"and usually make a big mess."
PUT A TUNA CAN UNDER THE DRIP TUBE !!!! LOLOL
[/QUOTE]

You could, then another one when the first one gets full, real handy

Endust · #79 07-01-2006, 03:33 PM

Leathermang Im disappointed. All the info about the timing and the no drip tube had you commentless. However posing a simple question about possible blowby got you in full attack mode! Yeesh...not to mention that fact that there is sufficient compression at the 6 degrees of extra advance Im talking about. Based on your theory it would't matter how we timed our engines since ignition could only happen at TDC. Obviously not the case. I didnt say I was positive but it seemed like a valid question. Must be a sore spot!

leathermang · #80 07-01-2006, 04:11 PM

I think you are confusing the word timing ...
When dealing with gas engines it means when the spark plug sparks....

When dealing with our diesels it means when the fuel is injected...

But there is only a certain parameter of piston travel at which the air , due to compression, is hot enough to fire the fuel put into the chamber... and burn it properly to create power to be transferred to the piston fully during its next stroke.

And some of the computation as to the best time has to do with the condition of certain things in the engine.. mainly that of the precombustion chambers, the radial holes, the pintel ball, and the injectors.... less than good dispersion can need to be compensated for in the timing to get optimum power and smoothness.. although bringing those things up to snuff is the preferred way..

Endust · #81 07-01-2006, 08:00 PM

Well, I took it for a drive. The vibration is pretty much gone. Smoke is much less. Power is way up off the line. The idle is lumpy and the engine moves around a bit more but the vibes are not there. Just have to R&R the injectors now and Im hoping for a smooth runner.

I also did the milivolt check, it was between .56 and .60 across all 4 cyl. Not too sure what that means yet, but Im gonna go peruse the milivolt thread to find out.

leathermang · #82 07-01-2006, 09:56 PM

Now will you tell me what, if anything ,you did to adjust the engine mounts when you put them in ?

Endust · #83 07-01-2006, 10:22 PM

The 2 front mounts don't have an adjustment. They are fairly strsight forward. However, the front engine stop and his parther the trans mount were a diff story. The front engine stop has a tool that sets the spacing. Easy enough to fab up since the dimensions are in that evil FSM. There is a bolt on the trans mount and on the FES that need to be adjusted. Really just loosened and a rock of the engine. Sadly, when I did all this work I was expecting miracles and I got nothing. We all know why now after this thread but at the time I was quite disappointed!

ps..one other bit that should go in this thread. The engine is quite smooth in idle after the highway thrashing I just gave it. No more lumps. However, the cursed nailing from #4 injector is back. Only when cold and only at idle. Little bugger taunted me before until I broke down and put a new nozzle in it. Then it was fine for weeks. Now its back to its old tricks. Gonna see what a few days of my work commute does to it.

barry123400 · #84 07-02-2006, 09:41 AM

Endust, I have been away to the cottage so missed the few last posts until now. Your milli volt readings sound wrong. Perhaps you are reading milli amps? The milli volt reading is usually displayed as say 10.5. or 6.9 for instance. There is a decimal point between the last two didgits. I would read them again and check your meter scales. The milli volts are still going to indicate if everything is good or otherwise. Readings of .56-.60 just do not sound right to me. Glad to hear you have made some progress. All so far has not been in vain as you have helped a lot of members understand the limitations or interpretation difficulties using the well up method. The milli volt method is always advisable to indicate if one cylinder is performing in a destructive context as well as indicating what is going on in general. Always simple things first like swapping # 3 and #4 injectors positions if knock is still there after a day or so. Gotta be easier than pulling pre chambers I think you will agree. For other members reading this thread . Amateur mechanics like myself should never underestimate the milli volt system. Once all the variables are considered or eliminated by test it is almost infallable in my opinion. In some cases there are quite a few variables to consider and eliminate. In other situations practically none. It also can save you a bundle of money and time. The most important component is it does locate the problem or problems and helps you resolve them. Even verifys you have solved them after if you wish. I still feel it will eventually become a primary service tool especially for the seemingly obscure problems on 123 type engines. I know I must sound like a nut case and do not mind that senario if the end result is the majority eventually use it as a helpful tool. Just would be a shame to loose the milli volt system to posterity or if only a handful land up using it. For me it is a given that I will use it until I no longer can work on indirect injection diesels. There are already a few others out there that have the same attitude as myself I believe.

mplafleur · #85 07-02-2006, 02:58 PM

That rear IP bolt was placed there by some demented MB engineer. I'd just as soon as leave it off as well.

I have an electronic injection timing tester. It reads the injection pulse through a transducer clamped around the #1 injection line. You fire up the engine and point a timing light at the balancer. Adjust the timing of the light until the timing on the balancer is at TDC and read off your injection timing from the display on the tester.

Question:

The book says timing should be 24 DBTDC. But this is using the drip method. What should it be when the pulse actually occurs?

Brian Carlton · #86 07-02-2006, 03:21 PM

Quote:

Originally Posted by mplafleur

Question:

The book says timing should be 24 DBTDC. But this is using the drip method. What should it be when the pulse actually occurs?

14° BTDC

mplafleur · #87 07-02-2006, 04:00 PM

Quote:

Originally Posted by Brian Carlton

14° BTDC

No wonder I have no power at 24°.

But I get good fuel consumption. I've been getting close to 26 mpg.

Adam, get back here!

Brian Carlton · #88 07-02-2006, 04:22 PM

Quote:

Originally Posted by mplafleur

No wonder I have no power at 24°.

But I get good fuel consumption. I've been getting close to 26 mpg.

Adam, get back here!

When you can consistently get above 30-31..........then call me.........

Supposedly you can get better fuel economy with slightly more advance........2°or so.......but, I have not attempted to prove it.

mplafleur · #89 07-02-2006, 10:56 PM

I've retimed the IP. I connected the timing tool and started the car. The rpm was a little high at 880, so I readjusted it down to 750. Much better. I always thought it was too high at the stop lights.

I then loosened the two nuts that I could get at and removed the injector lines at the injectors. I hoped that the remaining nut was not on tight enough that I couldn't rotate the IP. I put a breaker bar between the IP and the block and sucessfully rotated the IP. I checked the timing (see pic) and it was 14.0°.

I noticed that the 0° timing mark was not very readable, so I remarked it with a wax pencil and checked the iming again. I was actually set a 14.1° - 14.2°.

I tightened the nuts (both) back down and took out the car for a test drive. I do have more power and less smoke when stomping on it, I believe. I'll recheck the mileage after a few tanks.