Carb conversion rough idle and misfire
Discussion
Hey guys. I fitted a brand new 59d dizzy today (going to get it recurved to suit my need soon but for now it’s fine) the car runs perfectly, much more smooth idle and doesn’t seem to hunt anymore. Although when I tried to set the timing with a light it was advanced to roughly 40°, way below the gauge to see how advanced the timing is.... may be a stupid question but if the cam was installed one notch wrong would the car still even run?? Although i triple checked everything I did when rebuilding the engine but I can’t think of why the timing would be so “advanced” but still run perfectly. If I try to retard the timing to where it’s even on the gauge the car cuts out. The timing light is a cheap product so could this be affecting the results I’m getting from it or is that unlikely? Also where the timing is set now the car runs great, idles and Revs up perfectly. I’ve just set the timing by ear now and found a spot where the engine seems to be the happiest. Any help much appreciated. Cheers guys.
Are you getting cam timing and ignition timing confused.
If the cam timing is out by one tooth it will probably still run but badly and you are unlikely to get it to run right no matter what you do. Can't remember my A Series days but one tooth out may cause valves to hit pistons. (There were some engine builders that set cam timing out to actually gain power but that is on a very limited engine spec and not for you).
Have you rechecked compression? Plugs out, foot on the accelerator, spin engine over a few times to check compression is OK and the same across all 4 cylinders. Post your readings please.
High tick over. An A Series should tick over at 800 -1000 no matter what cam.
Carb, never played with the one you have but a HIF44 on a decent manifold should work a treat unless you've a 286 or 296 cam
Have you got an air leak at the manifold? Sucking in air would make the mixture weak, cause running on and high tick over.
Vacuum advance. remove it from the dizzy and blank the hole - too much advance can cause problems but also what are you setting the ignition timing at? And static or at a certain revs?
If you are suffering from Dieselling (Running on) don't continue to use it, you'll hole a piston or destroy piston rings (been there etc).
And I can't see 6psi as being too much, a little high but within acceptable limits.
If the cam timing is out by one tooth it will probably still run but badly and you are unlikely to get it to run right no matter what you do. Can't remember my A Series days but one tooth out may cause valves to hit pistons. (There were some engine builders that set cam timing out to actually gain power but that is on a very limited engine spec and not for you).
Have you rechecked compression? Plugs out, foot on the accelerator, spin engine over a few times to check compression is OK and the same across all 4 cylinders. Post your readings please.
High tick over. An A Series should tick over at 800 -1000 no matter what cam.
Carb, never played with the one you have but a HIF44 on a decent manifold should work a treat unless you've a 286 or 296 cam
Have you got an air leak at the manifold? Sucking in air would make the mixture weak, cause running on and high tick over.
Vacuum advance. remove it from the dizzy and blank the hole - too much advance can cause problems but also what are you setting the ignition timing at? And static or at a certain revs?
If you are suffering from Dieselling (Running on) don't continue to use it, you'll hole a piston or destroy piston rings (been there etc).
And I can't see 6psi as being too much, a little high but within acceptable limits.
Skyedriver said:
Are you getting cam timing and ignition timing confused.
If the cam timing is out by one tooth it will probably still run but badly and you are unlikely to get it to run right no matter what you do. Can't remember my A Series days but one tooth out may cause valves to hit pistons. (There were some engine builders that set cam timing out to actually gain power but that is on a very limited engine spec and not for you).
Have you rechecked compression? Plugs out, foot on the accelerator, spin engine over a few times to check compression is OK and the same across all 4 cylinders. Post your readings please.
High tick over. An A Series should tick over at 800 -1000 no matter what cam.
Carb, never played with the one you have but a HIF44 on a decent manifold should work a treat unless you've a 286 or 296 cam
Have you got an air leak at the manifold? Sucking in air would make the mixture weak, cause running on and high tick over.
Vacuum advance. remove it from the dizzy and blank the hole - too much advance can cause problems but also what are you setting the ignition timing at? And static or at a certain revs?
If you are suffering from Dieselling (Running on) don't continue to use it, you'll hole a piston or destroy piston rings (been there etc).
That’s great cheers mate, I was worried I had reinstalled the camshaft incorrectly, but if it could cause valves to hit pistons or to run badly then it should be out of the question, as it is running quite well only on the crankshaft pulley the timing seems to be way out although running well. I haven’t checked compression yet although the cars only done 50000 miles, I will check this ASAP and post what I find. The car was idiling nicely today at around 1000 which I could never get it down to without cutting out with the old dizzy so that’s good. I’m not too sure if there is a leak although I did spray some easy start around the carb a few weeks back and there seemed to be no change in rpm which makes me think it’s okay, I’ll have another proper check ASAP. I’ve been setting the timing at idle speed. I’m not using the car at all at the moment due to the issues going to get it all sorted before it goes back on the road so hopefully won’t damage the engine in anyway. Cheers for all the help I’ll get back with my findings hopefully soon.If the cam timing is out by one tooth it will probably still run but badly and you are unlikely to get it to run right no matter what you do. Can't remember my A Series days but one tooth out may cause valves to hit pistons. (There were some engine builders that set cam timing out to actually gain power but that is on a very limited engine spec and not for you).
Have you rechecked compression? Plugs out, foot on the accelerator, spin engine over a few times to check compression is OK and the same across all 4 cylinders. Post your readings please.
High tick over. An A Series should tick over at 800 -1000 no matter what cam.
Carb, never played with the one you have but a HIF44 on a decent manifold should work a treat unless you've a 286 or 296 cam
Have you got an air leak at the manifold? Sucking in air would make the mixture weak, cause running on and high tick over.
Vacuum advance. remove it from the dizzy and blank the hole - too much advance can cause problems but also what are you setting the ignition timing at? And static or at a certain revs?
If you are suffering from Dieselling (Running on) don't continue to use it, you'll hole a piston or destroy piston rings (been there etc).
Callump said:
Skyedriver said:
Are you getting cam timing and ignition timing confused.
If the cam timing is out by one tooth it will probably still run but badly and you are unlikely to get it to run right no matter what you do. Can't remember my A Series days but one tooth out may cause valves to hit pistons. (There were some engine builders that set cam timing out to actually gain power but that is on a very limited engine spec and not for you).
Have you rechecked compression? Plugs out, foot on the accelerator, spin engine over a few times to check compression is OK and the same across all 4 cylinders. Post your readings please.
High tick over. An A Series should tick over at 800 -1000 no matter what cam.
Carb, never played with the one you have but a HIF44 on a decent manifold should work a treat unless you've a 286 or 296 cam
Have you got an air leak at the manifold? Sucking in air would make the mixture weak, cause running on and high tick over.
Vacuum advance. remove it from the dizzy and blank the hole - too much advance can cause problems but also what are you setting the ignition timing at? And static or at a certain revs?
If you are suffering from Dieselling (Running on) don't continue to use it, you'll hole a piston or destroy piston rings (been there etc).
That’s great cheers mate, I was worried I had reinstalled the camshaft incorrectly, but if it could cause valves to hit pistons or to run badly then it should be out of the question, as it is running quite well only on the crankshaft pulley the timing seems to be way out although running well. I haven’t checked compression yet although the cars only done 50000 miles, I will check this ASAP and post what I find. The car was idiling nicely today at around 1000 which I could never get it down to without cutting out with the old dizzy so that’s good. I’m not too sure if there is a leak although I did spray some easy start around the carb a few weeks back and there seemed to be no change in rpm which makes me think it’s okay, I’ll have another proper check ASAP. I’ve been setting the timing at idle speed. I’m not using the car at all at the moment due to the issues going to get it all sorted before it goes back on the road so hopefully won’t damage the engine in anyway. Cheers for all the help I’ll get back with my findings hopefully soon.If the cam timing is out by one tooth it will probably still run but badly and you are unlikely to get it to run right no matter what you do. Can't remember my A Series days but one tooth out may cause valves to hit pistons. (There were some engine builders that set cam timing out to actually gain power but that is on a very limited engine spec and not for you).
Have you rechecked compression? Plugs out, foot on the accelerator, spin engine over a few times to check compression is OK and the same across all 4 cylinders. Post your readings please.
High tick over. An A Series should tick over at 800 -1000 no matter what cam.
Carb, never played with the one you have but a HIF44 on a decent manifold should work a treat unless you've a 286 or 296 cam
Have you got an air leak at the manifold? Sucking in air would make the mixture weak, cause running on and high tick over.
Vacuum advance. remove it from the dizzy and blank the hole - too much advance can cause problems but also what are you setting the ignition timing at? And static or at a certain revs?
If you are suffering from Dieselling (Running on) don't continue to use it, you'll hole a piston or destroy piston rings (been there etc).
How far out is the timing mark on the pulley? My 1330 A Series was set at about 6 degrees static IIRC. Aldon distributor vacuum advance disconnected IIRC
Got rid of my last hateful crock of s
t about 6 or 7 years ago and have been trying to erase the memories ever since.Have you tried asking on the Mini Classic forum on PH you might get more recent knowledge.
Skyedriver said:
Someone with more recent memories of the A Series will be able to confirm if valves and pistons will collide.
How far out is the timing mark on the pulley? My 1330 A Series was set at about 6 degrees static IIRC. Aldon distributor vacuum advance disconnected IIRC
Got rid of my last hateful crock of st about 6 or 7 years ago and have been trying to erase the memories ever since.
Have you tried asking on the Mini Classic forum on PH you might get more recent knowledge.
Did some more research and pretty sure the piston wouldn’t collide with the valves and wouldn’t even run so I’m pretty sure I could rule this out which is a big relief. The timing mark is about an inch below the timing gauge when idling (so maybe 40° of advance) as the lowest on the gauge is 20° of advance. I asked on the classic mini section a while back but seems to be pretty inactive. The car seems to run quite well and revs up nicely although the revs do drop quite slowly...? I still need to take the car for a drive but if I were to just advance the timing untill I get pinking then retard untill the pinking goes away would this be my best bet of getting the timing sorted as with the timing light it’s way outHow far out is the timing mark on the pulley? My 1330 A Series was set at about 6 degrees static IIRC. Aldon distributor vacuum advance disconnected IIRC
Got rid of my last hateful crock of s
t about 6 or 7 years ago and have been trying to erase the memories ever since.Have you tried asking on the Mini Classic forum on PH you might get more recent knowledge.
Okay so got a new “performance” non ballast coil on today. This allowed me to retard the timing down to 10~12° From the original “40°” at idle. The car runs much smoother now but still not perfect, rpm still hunts and sounds still slightly rough. A new fletcher su manifold arrived today and a 1 1/2 hs4 su coming soon. Hopefully this will fix my issues. Cheers guys for all the help.
catman said:
Don't forget that such a drastic change of the timing could mean that an adjustment of the carb will be needed. Have a try at slowly screwing the mixture screw in or out, when warmed up. It will probably make a difference.
Cheers mate, got the colour tune onto the carb today and got it running perfectly, but the Nikki carb has now sold 
and my new su arrived today. Even though it is now running well glad to have the su going on now much simpler and many more parts available.Gassing Station | Home Mechanics | Top of Page | What's New | My Stuff