Knock...knock ! Help please

[veggie]

Hi All,

I have been experimenting with various speeds to run my listeroid for two reasons.
1] Sound control in a residential neighborhood
2] I only need a maximum of 800 to 1000 watts to charge a battery bank for 2-3 hrs. each day.
   ( 55 amps X 12 volts = 660 watts + 20% for losses = 792 watts )

I have been swapping pulleys and belt combinations to get 1000 watts of power when fully loaded and at a reasonably low speed.
The magic speed for the engine/generator seems to be 465 rpm.
The system has gone very quiet EXCEPT FOR THE DIESEL KNOCK !      It stayed.
Wow ! the ignition sounds like a guy hammering on an anvil with a sledge hammer.

I don't think I'm anywhere close to the point where the engine is in a hammer/detonation mode.
Many other members have run at speeds lower than this.

My question to everyone is in regards to injector timing and injector spring setting.

A] When I first got the engine 2 years ago, the Lovson factory suggested I loosen the injector spring screw by 1/2 turn if I wish to run the engine slower. Does this make sense ?

B] And what about injector timing. Has anyone been able to control knock by retarding the timing ?


cheers,
veggie

[rcavictim]

Veggie,

Sometimes people have reduced knock by installing a doorbell.  

Seriously, if the factory suggested backing out the pressure screw on the injector two turns why not try it.  If it doesn't help it is easily cranked back in, no?

I pounded out and completely disintegrated the small timing side crankshaft main ball bearing on my JD175A by operating it slow without retarding the injection timing.  If you continue to run that as shown in the video I predict a broken crankshaft or something else in short order.

If you back the timing advance off too much it will get hard to start.

Good luck.

Rob

[bschwartz]

If I understand it correctly, adjusting the spring on the injector adjusts the injection pressure, not timing.  I retard the timing by lowering (screwing down) the plunger under the IP.  As Rob said, you will know you went too far (retarded timing) when it is hard to start.  This quieted down my knock quite a bit.

[billswan]

A] When I first got the engine 2 years ago, the Lovson factory suggested I loosen the injector spring screw by 1/2 turn if I wish to run the engine slower. Does this make sense ?

Why not try it, 1/2 turn will lower the injector cracking pressure quite a bit. But it will not alter timing much if at all.
I see that your engine is direct injected, looks just like my 16/1 metro.

If you want to inject later go with what bschwartz posted........

Billswan

[Tom Reed]

It doesn't make sense to me, by lowering the injection pressure the injector would open sooner and advance the timing. Lowering the bolt under the IP will retard the timing which sounds like the correct thing to do to reduce the ignition knock.

[veggie]

Thanks fellas,

I will start with the bolt under the IP.
Any experience as to how sensitive that IP adjustment is.?
Should I go 1/4 turn at a time?  1/2 a turn, full turn... or ?

thanks,
veggie

[bschwartz]

I don't think its too sensitive.  1/4 to 1/2 turn at a time should be fine.  The worst thing that could happen is if you go too far, it just won't start.

[Ronmar]

The pressure delivered to the injector is a factor of the cam lobe driving the IP.  If you lower the injector pop pressure, the IP output will reach that lower pressure at an earlier point in time, and will advance the injection sligthtly in relation to the crank position...

As mentioned on the other forum, check your flywheel gib keys.  A loose wheel manifests itself, at least initially, as a loud knock in coincidence with the power stroke at low RPM...



"You picked a fine time to leave me loose wheel...   This time I'm a fearin the road rash won't heal" 

[veggie]

*** UPDATE ***

Thanks for all the help fellas.!
Made a huge difference.
I removed the IP pump and lowered the IP Tappet by one full turn.

- Started easily
- Made 10% more power
- AND almost eliminated the diesel knock !!
- Noisiest items now are the roller mains and the gen head 

http://www.youtube.com/watch?v=GNAKS0e06zg

Happy camper  

[mbryner]

Nice!   I'll remember that when I run at low RPM's again.   Thanks for this thread.

[Horsepoor]

Which solution did you implement? Retard timing, alter I.P. pressure or both?

[veggie]

Which solution did you implement? Retard timing, alter I.P. pressure or both?

IP timing.
One full turn clockwise on the IP tappet.

[rcavictim]

Glad you got it worked out!

[veggie]

*** UPDATE #2 ***

Well....I couldn't "leave well enough alone" and played with the settings a bit more.
I retarded the timing by another 1/2 turn on the IP tappet. (for a total of 1.5 turns)
and also reduced the injector pressure by 1/4 turn taking the pop pressure down from 220 BAR to 175 BAR.
(3030 psi to 2625 psi)

Got some nice results...

- Very quiet combustion
- No loss in power
- Still easy to start

Even under full load the engine is smooth and quiet with minimal thumping on the power stroke.
http://www.youtube.com/watch?v=RBqzEL3W9JA

I am happy with the results at this point an will leave these settings in place.

veggie

[TimSR2]

OK now have have me going.  I'm going to be pulling some pump shims out of my noisy, and slow running SR2 just to see what happens. Excellent topic, thanks!