atx_s130 Posted February 8, 2007 Share Posted February 8, 2007 ive been tinkering with mine a lot but it seems i got it to un ok at 14 btdc but it should be 10btdc any theorys? it only letme rev to about 5500 b4 it runs out of power and backfires. im not unhooking my vacume advance when i set it with a light should i be? Quote Link to comment Share on other sites More sharing options...
atx_s130 Posted February 8, 2007 Author Share Posted February 8, 2007 my bad more info its an 81 280zx non turbo Quote Link to comment Share on other sites More sharing options...
naviathan Posted February 8, 2007 Share Posted February 8, 2007 According to the manual you should be disconnecting the vacuum advance, however it shouldn't make a difference as it's hooked to a ported vacuum line which only applies vacuum when the throttle is opened. So at idle it shouldn't make a difference. Other possabilities are that the crank pully has spun on the balancer moving your mark or the base plate under the dizzy could need adjusting. There are two adjustment points on the stock dizzy that can be moved. Quote Link to comment Share on other sites More sharing options...
atx_s130 Posted February 8, 2007 Author Share Posted February 8, 2007 oh got any diagrams of both points. also im gonna check but i think its pullin constant vacume this z has some stupid problems from the previous (15 year old) owner Quote Link to comment Share on other sites More sharing options...
spotfitz Posted February 8, 2007 Share Posted February 8, 2007 oh got any diagrams of both points. This may help. You can see the other bolt for adjusting in this image at the bottom left side of the mounting plate. http://autozone.com/images/cds/gif/medium/0900823d801d1299.gif Quote Link to comment Share on other sites More sharing options...
atx_s130 Posted February 9, 2007 Author Share Posted February 9, 2007 asuming perfect camtiming ect. would the vacum advance bet centered or more towards the spark plug cause i have to rotate my dizzy clockwise as far as it will go for it to run decent but it still spits and retarding it just feels wrong ya know? Quote Link to comment Share on other sites More sharing options...
atx_s130 Posted February 9, 2007 Author Share Posted February 9, 2007 ok well i adjusted it more and its running much better feels more powerful. but when i hit it with the light it say 28btdc!!! so im guessing my harmonic balencer is off or somthing cause it wouldnt run for ♥♥♥♥ at that setting also i noticed it runs better without the vacume advance hooked up. ok so i goes fine through first gear catch secon around 550 a little stutter(open header i can hear what its dooing. then in third at 5500 it let out 3 not back fire but like the sound of firecrackers underwater(detonation maybe) any advice? Quote Link to comment Share on other sites More sharing options...
ktm Posted February 10, 2007 Share Posted February 10, 2007 Have you adjusted your valves or at least checked them? Quote Link to comment Share on other sites More sharing options...
atx_s130 Posted February 11, 2007 Author Share Posted February 11, 2007 they looked fine when i had the valve cover off but im not an expert Quote Link to comment Share on other sites More sharing options...
ktm Posted February 11, 2007 Share Posted February 11, 2007 You adjust them by first measuring the gap between the lobe and the top of the valve assembly. The lash should be adjusted while the engine is 'hot', but as a first attempt, adjusting them cold is fine. The gap should measure 0.08 intake/0.10 exhaust when cold and 0.10 intake/0.12 exhaust when hot. Adjusting your valves is actually quite easy. I suggest doing a little bit of reading here, on Zcar.com (yes, there is some good basic info there) and Classiczcars.com for basic maintenance tips. Image courtesy of Blue from Zcar.com. You really, really do not want to be running 28 btdc with your vacuum advance hooked up. I had 17 deg btdc on my L24 at idle and 36 deg btdc (iirc) at 3000 rpm. Quote Link to comment Share on other sites More sharing options...
datsunlover Posted February 11, 2007 Share Posted February 11, 2007 A 'maybe' here... if someone has removed the dizzy at some point, it may be a tooth off.. if that is the case, there won't be enough rotation of the actuall unit. The quick fix is to rotate all the plug wires over one position on the cap (direction depends on which way you're trying to go; redard or advance) but I would still check the valve lash first.. you'd be suprised the diffrence it can make! For the record, I'm running close to 26* btdc but I have the vacum advance removed. Not a good idea for a FI car, but my SU carbs seam to deal with it. It idles a bit high, but I don't mind. Quote Link to comment Share on other sites More sharing options...
atx_s130 Posted February 11, 2007 Author Share Posted February 11, 2007 ill check the lash this wed. at school. and update yall after that. i knwo either my rings or valve seals are bad cuase i get fuel in the crank case and burn oil its getting worse about a quart a week....but i found another motor so i might just swap it cause the one i found is a 0 mile riebuilt Quote Link to comment Share on other sites More sharing options...
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