Nismo_Gizmo Posted March 18, 2011 Share Posted March 18, 2011 I am getting about 6MPG right now and there is carbon on my bumper next to the muffler, that's how rich we are talking. This is an L28 with what I believe to be dual stock carbs. It runs really strong, sometimes. Other times it doesn't seem to be warmed up, and when killing the choke, it will sometimes stall. The previous owner took a lot of care in this car and told me he had just balanced and tuned the carbs, so I am thinking that this could be a problem with the Dizzy, or timing? If I can't get this solved soon, it's going to accelerate the engine swap that I've been planning because it's going to pay for itself at the cost of my current fuel economy. Thanks in advance! Quote Link to comment Share on other sites More sharing options...
steve260z Posted March 18, 2011 Share Posted March 18, 2011 I would first check the carbs regardless. Are they SU Carbs? Make sure the adjustment nuts are not turned too far down resulting in a rich mixture. Among other how to sites, here's one: http://www.sonic.net/~kyle/su.html Quote Link to comment Share on other sites More sharing options...
Nismo_Gizmo Posted March 18, 2011 Author Share Posted March 18, 2011 I would first check the carbs regardless. Are they SU Carbs? Make sure the adjustment nuts are not turned too far down resulting in a rich mixture. Among other how to sites, here's one: http://www.sonic.net/~kyle/su.html Thank you for the quick reply! I will read through this and check out how mine is set up when I get out of work. I'm pretty sure that these are indeed the same carbs that I am running. I will let you know how everything looks. Quote Link to comment Share on other sites More sharing options...
Nismo_Gizmo Posted March 18, 2011 Author Share Posted March 18, 2011 Thank you for the quick reply! I will read through this and check out how mine is set up when I get out of work. I'm pretty sure that these are indeed the same carbs that I am running. I will let you know how everything looks. Do I have the buy a sync tool? I wanted to try to do this tonight and I don't want to wait for shipping. I'm pretty sure that no where nearby sells these. Maybe I can do the oil in a clear hose trick? This didn't work on my motorcycle because of the space available. Quote Link to comment Share on other sites More sharing options...
ezzzzzzz Posted March 18, 2011 Share Posted March 18, 2011 (edited) A length of heater hose held to your ear is surprisingly effective for tuning. Just place the hose end to the side of the airhorn. You'll hear the flow differences distinctly with maladjusted carbs. Keep balancing until you can't discern that difference and you'll be good to go. I've done this and later checked with a unisync tool and it was really close to dead-on. That said, I would be surprised if that was your major problem. It sounds more like over pressurization of fuel (do you smell gas strongly under the hood with the engine off but in the run position?) or ignition timing way off like the distributor isn't advancing. Totally forgot that it could easily be the fuel enrichment circuit (e.g. sticking nozzles on the carbs). That would explain why it runs great at times and sucks at other times. Be careful checking that because the levers are relatively easy to bend. Edited March 18, 2011 by ezzzzzzz Quote Link to comment Share on other sites More sharing options...
Nismo_Gizmo Posted March 18, 2011 Author Share Posted March 18, 2011 A length of heater hose held to your ear is surprisingly effective for tuning. Just place the hose end to the side of the airhorn. You'll hear the flow differences distinctly with maladjusted carbs. Keep balancing until you can't discern that difference and you'll be good to go. I've done this and later checked with a unisync tool and it was really close to dead-on. That said, I would be surprised if that was your major problem. It sounds more like over pressurization of fuel (do you smell gas strongly under the hood with the engine off but in the run position?) or ignition timing way off like the distributor isn't advancing. Totally forgot that it could easily be the fuel enrichment circuit (e.g. sticking nozzles on the carbs). That would explain why it runs great at times and sucks at other times. Be careful checking that because the levers are relatively easy to bend. I don't smell gas when the car is not running, no. When it is running though, you can smell it in the car. My clothes always smell like fuel after driving it, and the hatch has been sealed, so I think its coming from the firewall. How would I go about checking the timing? Something is telling me that the problem is related to the distributor. Quote Link to comment Share on other sites More sharing options...
steve260z Posted March 19, 2011 Share Posted March 19, 2011 Have you pulled the plugs? Are they carbon fouled? If so that can confirm the car is actually running rich. Do you have a timing light? If not they are fairly cheap. Sears/other parts stores. But you need a timing light. I'm sure there are many posts on checking the timing either here or on Zcar.com (no need to repeat the procedure here.) Its straightforward. Quote Link to comment Share on other sites More sharing options...
NewZed Posted March 19, 2011 Share Posted March 19, 2011 Does the L28 use an electric fuel pump (the PO would have had to install a mechanical otherwise). Your fuel pressure could be too high. Quote Link to comment Share on other sites More sharing options...
Recommended Posts
Join the conversation
You can post now and register later. If you have an account, sign in now to post with your account.