running rich....not sure why.
Thread Starter
Instructor
Joined: Apr 2018
Posts: 181
Likes: 6
From: Orlando, FL
running rich....not sure why.
Ive been running rich with carbon fouled plugs, smoky exhaust and stinging eyes.
Ive got a 850 carb, and dialed all 4 idle mixture screws to 1/2 turn out from closed, 800 rpm at idle and fairly smooth for the cam. If I close the idle screws any more the idle gets chuggy and wants to die.
Mild cam. MSD ignition. 17 mech advance and close to 30 with vac advance connected at idle.
Could a weak spark cause this? When I reinstalled the plugs I reduced the gap from .045 to .038 and did put anti seize on the threads. I was still having the rich issue before tho.
Thanks
Ive got a 850 carb, and dialed all 4 idle mixture screws to 1/2 turn out from closed, 800 rpm at idle and fairly smooth for the cam. If I close the idle screws any more the idle gets chuggy and wants to die.
Mild cam. MSD ignition. 17 mech advance and close to 30 with vac advance connected at idle.
Could a weak spark cause this? When I reinstalled the plugs I reduced the gap from .045 to .038 and did put anti seize on the threads. I was still having the rich issue before tho.
Thanks
Thread Starter
Instructor
Joined: Apr 2018
Posts: 181
Likes: 6
From: Orlando, FL
Thread Starter
Instructor
Joined: Apr 2018
Posts: 181
Likes: 6
From: Orlando, FL
floats are good. I did put some new gas in but do that regularly. 93 oct. Im just trying to think of causes with the low spark. Ive read that anti seize can cause a grounding issue with the plugs but wasn't sure if that translates to weak spark / running rich.
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Le Mans Master
Joined: Oct 2010
Posts: 6,914
Likes: 836
From: melbourne florida
2023 C3 of the Year Finalist - Modified
Crack open the secondaries and make sure your transfer slot isn't open too far. Cracking the secondaries open a little may make adjusting you mixture screws work better
Dr. Detroit
Joined: Mar 2012
Posts: 10,093
Likes: 4,017
From: New Braunfels Texas
Try to crack front and back throttle blades evenly...then re-adjust the idle screws.
Having a large carb has zero to do with running fat at idle......you could have a 1000hp or Dominator on there and you can still tune the idle circuit......
If the rear blades are closed...the idle will not adjust....it needs a little air going past the transfer slot.....
I see you have a Demon so the rear throttle adjustment should be up top......crack it open....decrease the primary blade to get your idle rpm down and re-adjust.
Jebby
Having a large carb has zero to do with running fat at idle......you could have a 1000hp or Dominator on there and you can still tune the idle circuit......
If the rear blades are closed...the idle will not adjust....it needs a little air going past the transfer slot.....
I see you have a Demon so the rear throttle adjustment should be up top......crack it open....decrease the primary blade to get your idle rpm down and re-adjust.
Jebby
Le Mans Master
Joined: Apr 2011
Posts: 6,284
Likes: 1,170
From: Hermosa
That throttle bracket looks a little wonky to me. Does not pull straight, may give you issues later if not now. Not necessarily related to your issue.
What you got there is a cam with 70* of overlap. And lots of lift.
A cam with that much overlap is going to want lots of timing and some bypass air to get it to idle. What Jebby and 79l82 are suggesting is what I believe you need to do on a Holley to get bypass air.. or drill the secondaries. On the timing jack that up to 36* or there abouts, maybe even more, with vacuum at idle. Adding bypass air and enough initial timing will clean up your idle issues.
What you got there is a cam with 70* of overlap. And lots of lift.
A cam with that much overlap is going to want lots of timing and some bypass air to get it to idle. What Jebby and 79l82 are suggesting is what I believe you need to do on a Holley to get bypass air.. or drill the secondaries. On the timing jack that up to 36* or there abouts, maybe even more, with vacuum at idle. Adding bypass air and enough initial timing will clean up your idle issues.
Dr. Detroit
Joined: Mar 2012
Posts: 10,093
Likes: 4,017
From: New Braunfels Texas
That throttle bracket looks a little wonky to me. Does not pull straight, may give you issues later if not now. Not necessarily related to your issue.
What you got there is a cam with 70* of overlap. And lots of lift.
A cam with that much overlap is going to want lots of timing and some bypass air to get it to idle. What Jebby and 79l82 are suggesting is what I believe you need to do on a Holley to get bypass air.. or drill the secondaries. On the timing jack that up to 36* or there abouts, maybe even more, with vacuum at idle. Adding bypass air and enough initial timing will clean up your idle issues.
What you got there is a cam with 70* of overlap. And lots of lift.
A cam with that much overlap is going to want lots of timing and some bypass air to get it to idle. What Jebby and 79l82 are suggesting is what I believe you need to do on a Holley to get bypass air.. or drill the secondaries. On the timing jack that up to 36* or there abouts, maybe even more, with vacuum at idle. Adding bypass air and enough initial timing will clean up your idle issues.
Jebby
Tech Contributor
Joined: Aug 1999
Posts: 14,365
Likes: 6,345
From: At my Bar drinking and wrenching in Lafayette Colorado
Also, that 110 LSA cam is never going to run "clean" at idle... There's a really good reason that the factory performance cams are all in the 114-range. A 110 LSA cam needs lots of compression and a lot of timing.
Lars
Lars
Thread Starter
Instructor
Joined: Apr 2018
Posts: 181
Likes: 6
From: Orlando, FL
Thanks for the info!
Ill adjust the blades and see how much I can dial it in. If need be after Ill look at the "idleeze".
With that cam whats the ideal initial and overall timing I should run?
Ill adjust the blades and see how much I can dial it in. If need be after Ill look at the "idleeze".
With that cam whats the ideal initial and overall timing I should run?
Dr. Detroit
Joined: Mar 2012
Posts: 10,093
Likes: 4,017
From: New Braunfels Texas
Jebby
Le Mans Master
Joined: Oct 2010
Posts: 6,914
Likes: 836
From: melbourne florida
2023 C3 of the Year Finalist - Modified
I have a 110 lsa with a 750 double pumper and outside of the cam being a bit rowdy the idle isn't that bad.
You should be able to get it to idle pretty good. I agree more timing will help overall performance . I've been texting with 40 total and it's been an animal but still not sure I'll leave it that high.
Good luck keep us posted.
You should be able to get it to idle pretty good. I agree more timing will help overall performance . I've been texting with 40 total and it's been an animal but still not sure I'll leave it that high.
Good luck keep us posted.
Le Mans Master
Joined: Apr 2011
Posts: 6,284
Likes: 1,170
From: Hermosa
Total timing is different. That's timing with mechanical fully advanced + initial, vacuum does not come into play for total timing.
For total timing it's gonna depend on the heads more than anything.