I am trying to set the timing on my M series And having the following problem as can be seen in the attached photos. When the rotor arm is pointing to cylinder number 3 the crank pulley is way off of the 6 degree mark. I can’t swing the distributor anymore as it is on it’s furthest point already. Points gap is set perfectly. Distributor is set fully retarded. Looks to be about 22 degrees Off of TDC. Is there any adjustment internally within the distributor. Car has had cam work previously but the cam timing marks are all pretty close. Image Unavailable, Please Login Image Unavailable, Please Login
A few questions: 1. when was the last time the car ran relative to the cam work? I ask because it would help a lot to determine when the problem started. 2. with cylinder #3 at tdc compression stroke are you sure you are checking the correct rotor position. I say this because the Dino distributor cap has an odd snake of path that you need to accurately trace from looking at the inside. Is it possible you are trying to line up to the wrong terminal? 3. is the advance mechanism seized? You can check this by removing the distributor, holding the rotor and turning the input shaft to see if the advance is activating.
Good time to service the often neglected advance mechanism. I use Bosch distributor grease. I believe the drive flange that engages the cam is adjustable also.
Thanks for the swift response Rob. Car is running. Have traced the path of number 3 terminal, rotor arm is pointing at the 4 o’clock position. Have reset the Timing To 10 Degrees. I have a severe off idle flat sport that disappears at higher revs. Distributor orientation is now central to the bolt.
Thanks for the swift response Rob. Car is running. Have traced the path of number 3 terminal, rotor arm is pointing at the 4 o’clock position. Have reset the Timing To 10 Degrees. I have a severe off idle flat sport that disappears at higher revs. Distributor orientation is now central to the bolt.
Ok now we are getting somewhere. Assuming you are able to confirm the 10 degrees of advance at idle have you tried to see if the advance mechanism is working by accelerating the engine and watching the timing marks move. If you have a timing light where you can dial in the advance you can chart the advance curve by measuring and recording in 500 rpm intervals to say 3000 rpm. If it is advancing then you should be ok otherwise your advance mechanism will need servicing. Other than that a problem that disappears at higher revs can point to carburation issues. If the problem disappears after about 3000 rpm (the point around which the main circuit kicks in) then you may have an issue with your idle circuit. A slightly blocked idle jet could do it and these are easy to pull and clean with some compressed air. This is assuming the car ran well before and does not now. If you are not sure the last time it ran well then maybe your idle jets are the wrong size, idle mixture is set wrong, or the throttle plate speed screws are out of adjustment.
Thanks Rob, I will check the advance as suggested. I am going to do Adrian’s Dinoplex conversion soon so will rebuild the distributor then if necessary. I think I wii take the carbs off and give all a thorough cleaning. I really appreciate your help on this. Thank you
As a start don't take the carbs off just yet. It could be a plugged idle jet which you can do in place with minimum work. Here is a link to a photo of the carb showing exactly where the idle jet is: http://dino246blog.blogspot.com/2014/08/carb-tuning-1-weber-dcnf-carbs-and.html Just unscrew it, pull it apart from the holder and put it up to the light to see if it is clogged. Then clean and re-install. Super simple.
I can only second Rob,s suggestion to check the idle jets. It takes 2 minutes per jet and all you need as a screwdriver. I've cleaned mine twice after 4 years of driving and I found a blockage both times. I find it good to drift the jets with one of the hairs from from steel brush, sometimes the foreign object tends to get stuck and can not be removed with air only. Good luck, Peter
