Title: The ignition coil did it!
Post by: Anders Dinsen on December 14, 2008, 03:09:55 pm
The ignition coil was at fault. I have smacked my head hard against the wall for not recognising this before and spending countless hours fixing things that didn't need mending!!! :-[
But on the positive side, I've got a really well running setup now :D I have just changed idle jets from the 45F8 to a slightly richer 50F9, and this has removed any hesitation in low revs. It can now run in 5th at 50 km/h or 1500 rpm, and can even pull out of it without stumbling. That's very good, actually!
Main jets are down from the original 150's to 140 now. I'm going to try even smaller main jets, but have to order them first, and I think I'll also throw in a set of 34 venturis to see the difference. I'm not going to rev this engine above 6000 rpm, and since the Holbay cam is actually not that demanding, it shouldn't affect the top end performance much.
Here's the link to my log sheet: http://tmp.dinsen.net/murena/jetting.html
I managed to get in touch with the guy with the business where Lennart had his car on rollers - the hourly rate is not too bad, and if I bring my own jets and have a good idea of what I want to try out, it shoulnd't take more than two hours to get it right.
I was a bit worried about fuel seeping out of the float chamber due to the inclination of the carbs. The DCOE's aren't that well suited for inclined setups like this, and the fuel could be going out through either the accel pump jets or the starter circuit. Counting the number of pumps made by the fuel pump to prime the float chambes gives a good indication of the reduction, but it actually seems acceptible. There's also no real smell of fuel in the engine room, so I'm not that worried any more.
Here's a photo of the defective coil (the black one). Notice that it reads "ballast" - this could mean that it's a 9V coil intended to be used with a ballast resistor, so it has probably been overloaded. This is a coil that Roy gave me with the car, and while I have no reason to beleive that he knowingly gave me the wrong coil, these coils are getting more difficult to find, and the shop may simply have given him the wrong one.
The other coil in the photo is new - I'm making a new engine loom with it and the ignition module in the photo.
(http://gallery.dinsen.net/d/11720-2/DSC_3330.JPG)
But on the positive side, I've got a really well running setup now :D I have just changed idle jets from the 45F8 to a slightly richer 50F9, and this has removed any hesitation in low revs. It can now run in 5th at 50 km/h or 1500 rpm, and can even pull out of it without stumbling. That's very good, actually!
Main jets are down from the original 150's to 140 now. I'm going to try even smaller main jets, but have to order them first, and I think I'll also throw in a set of 34 venturis to see the difference. I'm not going to rev this engine above 6000 rpm, and since the Holbay cam is actually not that demanding, it shouldn't affect the top end performance much.
Here's the link to my log sheet: http://tmp.dinsen.net/murena/jetting.html
I managed to get in touch with the guy with the business where Lennart had his car on rollers - the hourly rate is not too bad, and if I bring my own jets and have a good idea of what I want to try out, it shoulnd't take more than two hours to get it right.
I was a bit worried about fuel seeping out of the float chamber due to the inclination of the carbs. The DCOE's aren't that well suited for inclined setups like this, and the fuel could be going out through either the accel pump jets or the starter circuit. Counting the number of pumps made by the fuel pump to prime the float chambes gives a good indication of the reduction, but it actually seems acceptible. There's also no real smell of fuel in the engine room, so I'm not that worried any more.
Here's a photo of the defective coil (the black one). Notice that it reads "ballast" - this could mean that it's a 9V coil intended to be used with a ballast resistor, so it has probably been overloaded. This is a coil that Roy gave me with the car, and while I have no reason to beleive that he knowingly gave me the wrong coil, these coils are getting more difficult to find, and the shop may simply have given him the wrong one.
The other coil in the photo is new - I'm making a new engine loom with it and the ignition module in the photo.
(http://gallery.dinsen.net/d/11720-2/DSC_3330.JPG)
Title: Re: The ignition coil did it!
Post by: krede on December 14, 2008, 03:48:39 pm
Im glad you forked out the money and bought a proper coil and not some cheap no name crap from Biltema ;)
Title: Re: The ignition coil did it!
Post by: RazorbackNOR on December 15, 2008, 03:51:27 pm
Krede, Anders is not "THE" Biltema guy, just because half his car is Biltema parts now... ;)
Title: Re: The ignition coil did it!
Post by: krede on December 15, 2008, 04:21:54 pm
Perhaps not... but he's getting there!! :D
Title: Re: The ignition coil did it!
Post by: Anders Dinsen on December 17, 2008, 10:15:55 am
Haha :D
It seems one of the carbs have a fuel leak, as the rightmost plug was fouled when I checked it yesterday. The others were nice tan on the insulator. Recovering from a cold now, I haven't spent time trying to find the problem yet, but I have a few ideas of what to look for. I hope I can diagnose it with the carb still on the engine...
Otherwise it's really running well - tractable, does 50 km/h in 5th without complaining (and my garbox has been modified with the heavy 5th), and revs freely. I'm up to 150 main jets now, as the 140 turned out to be too lean - it was hestitating on the motorway 110 km/h in 5th, where it's running right in the critical point where the main system takes over from the slow run (idle and progression).
Log sheet is updated: http://tmp.dinsen.net/murena/jetting.html
It seems one of the carbs have a fuel leak, as the rightmost plug was fouled when I checked it yesterday. The others were nice tan on the insulator. Recovering from a cold now, I haven't spent time trying to find the problem yet, but I have a few ideas of what to look for. I hope I can diagnose it with the carb still on the engine...
Otherwise it's really running well - tractable, does 50 km/h in 5th without complaining (and my garbox has been modified with the heavy 5th), and revs freely. I'm up to 150 main jets now, as the 140 turned out to be too lean - it was hestitating on the motorway 110 km/h in 5th, where it's running right in the critical point where the main system takes over from the slow run (idle and progression).
Log sheet is updated: http://tmp.dinsen.net/murena/jetting.html
