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+--- Thread: Modding the timing device (/showthread.php?tid=7739)
Modding the timing device - firen456 - 05-12-2017
Hi,
is there anybody who changed the springs in his timing device? The springs in the 606.962 device are weaker than the springs of the 606.910 device. I think with a superpump, in my case a 8mm, the tourqe the pump needs to be driven is much more than with 6mm elements. The timing device will advance sooner till the max advance. Changing the spring-rate would help to solve this problem in my opinion. Has anybody already tried different springs in this timing device or extended the travel? Anybody gained experience with this so far?
Regards
RE: Modding the timing device - R-3350 - 05-12-2017
yes i did it on my 617 it can be a bit tricky to tune properly depending on the cams you are running any pre-chamber mods and any porting done to the head. my advice is pull the springs and take some measurements and order a few different ones with different spring rates and try them out and see what it does.
RE: Modding the timing device - barrote - 05-12-2017
What is the problem with the original device? Why do u need a diff advance rate?
As is my understanding the N/A engines are much more sensitive to advance than turbo ones. Mostly cause of the part load condition.
I suspect that jerking and engine shaking is directly related to the timming device wrong setting when a manual gearbox is used and clutches are week.
I have done some reserch and found nothing except that when pre cup mods are done the engine need more advance range.
But still fighting with the best solution...
RE: Modding the timing device - Hercules - 05-13-2017
(05-12-2017, 09:38 PM)R-3350 yes i did it on my 617 it can be a bit tricky to tune properly depending on the cams you are running any pre-chamber mods and any porting done to the head. my advice is pull the springs and take some measurements and order a few different ones with different spring rates and try them out and see what it does.
Please tell where springs could be found.
RE: Modding the timing device - Hercules - 05-13-2017
Did not know where lighter springs could be found,so this was my mod. of the timer.
Each of the base spring roll pins,(4) i ground off 1/2mm,than 1mm from stop pins (2), than re leaved the housing a small amount
so the stop pins would do the stopping of advance , not the housing.
Results; Noticeable improvement off idle through mid rpms.
Results will very according with other mods done.
30,000 mi plus,timing set at 26-27 degrees.
RE: Modding the timing device - firen456 - 05-13-2017
(05-12-2017, 09:38 PM)R-3350 yes i did it on my 617 it can be a bit tricky to tune properly depending on the cams you are running any pre-chamber mods and any porting done to the head. my advice is pull the springs and take some measurements and order a few different ones with different spring rates and try them out and see what it does.
Yes, that was my thought also. I pulled the springs and did some measuring. But where to start? How much spring rate did you add in the beginning? Can you give me a practical value how much spring rate you added? Like +15% for example?
I wanna change the springs because the engone is nailing during the range of the timing device. There is no/little nailing in idle and with rising enginespeed the nailing gets more till about 2k7 where it is gone. I will also try to avoid the nailing by retarding the pump, but the dynamic effect of the nailing gives me the impression that the timing device advaces too early.
RE: Modding the timing device - Hercules - 05-14-2017
I could be wrong,but is not the advance done through rpm with the weights over coming the springs and pressure of
injection pump. If this works this way than increased pressure from injection pump would mean less advance and
higher rpms needed to advance.
RE: Modding the timing device - starynovy - 05-14-2017
Yea it is not only RPM dependent but also load because more fuel pump injects more power it draws therefore springs are more compressed.
RE: Modding the timing device - firen456 - 05-14-2017
Yes, you are right. So higher torque from bigger elements causes later advance. This would mean that my pump is set too advanced when it's nailing in part-load. So I'll try to get this right before changing the springs.
RE: Modding the timing device - R-3350 - 05-14-2017
this is exactly why i got a few different springs to try out. i also have a few sets of limiter pins i ground to various lengths to try different advance settings. i got my springs from Mcmaster Carr after measuring the stock ones i took a guess as to the stock spring rate and ordered a few sets around that number. once you get used to pulling the vac pump its not that hard to swap springs quickly (at least on an OM617 which has a slightly different advance mechanism)
RE: Modding the timing device - led-panzer - 05-24-2017
I'm trying to get a better understanding of this. So we would want a higher spring rate for a modified pump? Or a lower one?
RE: Modding the timing device - firen456 - 05-25-2017
Harder springs will let the device advance later.
RE: Modding the timing device - mischa56 - 05-25-2023
My OM605 with 7.7 Elements does have the same symptomps. Good idle with no/ just a bit nailing. Nailing above idle till approx. 2500rpm.
I try to summarize the chat and my thoughts.
-stiffer springs will advance timing later
-lighter weights will advance timing later
I am unsure about the following theory:
Because of bigger elements the device advance later
what do you think?
In this case the springs should be softer.
Kind Regards
RE: Modding the timing device - mischa56 - 05-25-2023