Modding the timing device
Modding the timing device
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
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.
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...
(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.
(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.
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.
(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.
(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.
Yea it is not only RPM dependent but also load because more fuel pump injects more power it draws therefore springs are more compressed.
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)
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?
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