October 12, 20186 yr comment_559446 3 minutes ago, Patcon said: What are you doing up or have you been up all night? I open up a restaurant at 5:30a.m. Leave at 11 a.m. when they "open" Pretty sweet job as I'm a morning person. Edited October 12, 20186 yr by siteunseen Link to comment https://www.classiczcars.com/forums/topic/60072-misfiring-while-cruising/?&page=19#findComment-559446 Share on other sites More sharing options...
October 12, 20186 yr comment_559447 20 years ago I'd be trying to go to sleep, staring at the ceiling fan. Link to comment https://www.classiczcars.com/forums/topic/60072-misfiring-while-cruising/?&page=19#findComment-559447 Share on other sites More sharing options...
October 12, 20186 yr comment_559448 4 minutes ago, siteunseen said: I open up a restaurant at 5:30a.m. Leave at 11 a.m. when they "open" Pretty sweet job as I'm a morning person. I am up to go look for Bambi's big brother...? Link to comment https://www.classiczcars.com/forums/topic/60072-misfiring-while-cruising/?&page=19#findComment-559448 Share on other sites More sharing options...
October 12, 20186 yr comment_559470 what kind of gearing are you running? Im seeing an issue on my Z where the car falls flat on its face in 4th gear, running a 3.36 and close ratio gearbox. It used to occur in 3rd gear @4k rpm, but I was able to tune that issue out, im starting to thing its the gearing thats "bogging" down the car if thats possible. Think of your gearing as a torque amplifier - it merely amplifies your engine's characteristics. So if you are bogging down @4K you have a power flat-spot that a long diff will make more prominent. L24s were renowned for having a flat spot at or just before 4K rpm - one way to "tune"' it out is to have a 6-3-2 exhaust header with long primaries and long collectors (the 2 bit) as per the Nismo or Janspeed design. The theoretical ideal (rule of thumb) is around 90cm primaries and 50cm collectors. See this fine bit of engineering ... http://www.datsun-zstory.com/echappements/headers/headers-race-sport/ Changing your diff will surely reduce the effect but the flat spot is still there. I just realised why you guys are getting such low revs, you are using an auto 'box, right? Apologies to the OP for taking the thread off track. Link to comment https://www.classiczcars.com/forums/topic/60072-misfiring-while-cruising/?&page=19#findComment-559470 Share on other sites More sharing options...
October 12, 20186 yr comment_559478 1 hour ago, AK260 said: Think of your gearing as a torque amplifier - it merely amplifies your engine's characteristics. So if you are bogging down @4K you have a power flat-spot that a long diff will make more prominent. L24s were renowned for having a flat spot at or just before 4K rpm - one way to "tune"' it out is to have a 6-3-2 exhaust header with long primaries and long collectors (the 2 bit) as per the Nismo or Janspeed design. The theoretical ideal (rule of thumb) is around 90cm primaries and 50cm collectors. See this fine bit of engineering ... http://www.datsun-zstory.com/echappements/headers/headers-race-sport/ Changing your diff will surely reduce the effect but the flat spot is still there. I just realised why you guys are getting such low revs, you are using an auto 'box, right? Apologies to the OP for taking the thread off track. I need to solve my black fouling at idle issue first before getting into this kind of stuff. I was thinking if using ngk bp5es plugs which are hotter will avoid the fouling at idle. Link to comment https://www.classiczcars.com/forums/topic/60072-misfiring-while-cruising/?&page=19#findComment-559478 Share on other sites More sharing options...
October 15, 20186 yr comment_559635 On 10/5/2018 at 2:31 AM, AK260 said: Spot on! Also try it on the coil to dizzy cap cable - which is where the majority of my issues lay. It looks like your engine earth strap is next to your oil dipstick. Thick black wire goes from block to body. Your coil has positive and negative low tension connectors. One is 12v from your ignition switch and the other is the 0v that the dizzy breaks / makes as it operates. Also you have low tension connectors at your distributor - look at those too. These connectors tend to corrode. Especially in the UK where we are constantly humid. IMHO plug fouling at idle is a red herring here and given your photos they look OK. I had an L series that drank a lot of oil and the plugs were not just sooty but also wet and black - it never backfired or missed when cruising or on power. So your plugs for the sake of trouble shooting this issue look fine. Would swapping to bp5es which is hotter plug solve the fouling issue at idle? Link to comment https://www.classiczcars.com/forums/topic/60072-misfiring-while-cruising/?&page=19#findComment-559635 Share on other sites More sharing options...
October 15, 20186 yr comment_559636 22 minutes ago, jalexquijano said: Would swapping to bp5es which is hotter plug solve the fouling issue at idle? it would mask it, but not solve the underlying problem. Link to comment https://www.classiczcars.com/forums/topic/60072-misfiring-while-cruising/?&page=19#findComment-559636 Share on other sites More sharing options...
October 15, 20186 yr comment_559641 @jalexquijano I don't think you need hotter plugs yet. Some of the plugs are looking good. Let's figure out what's wrong with the others. Have you installed the new wires yet? Link to comment https://www.classiczcars.com/forums/topic/60072-misfiring-while-cruising/?&page=19#findComment-559641 Share on other sites More sharing options...
October 15, 20186 yr comment_559643 Waiting for them Link to comment https://www.classiczcars.com/forums/topic/60072-misfiring-while-cruising/?&page=19#findComment-559643 Share on other sites More sharing options...
October 17, 20186 yr comment_559762 [mention=28721]jalexquijano[/mention] I don't think you need hotter plugs yet. Some of the plugs are looking good. Let's figure out what's wrong with the others. Have you installed the new wires yet?Agreed! Plug fouling at idle could be caused by other things like mix, lack of vac advance, etc. Get her firing well first and then sweat the other stuff later. ;)Is it safe to assume you've already changed your cap and rotor? Link to comment https://www.classiczcars.com/forums/topic/60072-misfiring-while-cruising/?&page=19#findComment-559762 Share on other sites More sharing options...
October 18, 20186 yr comment_559777 @AK260 Jalex installed a new Bosch cap and rotor a few weeks ago. Link to comment https://www.classiczcars.com/forums/topic/60072-misfiring-while-cruising/?&page=19#findComment-559777 Share on other sites More sharing options...
October 18, 20186 yr comment_559780 5 hours ago, AK260 said: Agreed! Plug fouling at idle could be caused by other things like mix, lack of vac advance, etc. Get her firing well first and then sweat the other stuff later. ? Is it safe to assume you've already changed your cap and rotor? Thats done already. Link to comment https://www.classiczcars.com/forums/topic/60072-misfiring-while-cruising/?&page=19#findComment-559780 Share on other sites More sharing options...
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