perspectiveshifting Posted July 28, 2015 Report Share Posted July 28, 2015 So, after the long process of an engine and transmission swap, I'm having trouble focused around the carbs and timing of my Z. Without going into too much depth, I went from the stock 2.4l engine and a stock automatic transmission, to a slightly later 2.8l with it's already connected 5 speed manual transmission from a newer, but very rusted Z. After the swap, the car started up and ran, albeit very poorly. I was able to get it across town and back to throw an exhaust on it, and upon its return, tried to tweak the fuel to air mixture on the carbs, with little luck. After a few days of the car getting worse with my misguided tampering, I decided to retrieve the carbs from the previous engine, my logic being that I knew they had worked well and were in sync, and thus would give me a better starting point. The car barely ran at all after my carb swap, and after attempting to reset the timing, failed to start at all. After swapping the thoroughly dirtied plugs out and trying to correct my timing errors, the car still refuses to start. It turns over, and will give me their occasional backfire to show its still trying, but I can't get much better than that. What steps should I take to appropriately troubleshoot what the main source of my problem is? I'm still very new to working on cars, so any severe mistakes in my process that can be pointed out to me are helpful for me going forward as well. Thanks in advance for any advice! Quote Link to comment
datzenmike Posted July 28, 2015 Report Share Posted July 28, 2015 Am I reading this right? The L24 and the L28 both have carbs? Because all L28s were EFI. So someone has previously swapped it to carbs? If so, did you have it running before you swapped the engine.. so do you know if this engine is even running properly???? Maybe this engine is crap. Need more info. First thing.... the jetting for a 2.4 liter is not going to be the same for a 2.8 liter. Carb sync. is lost as soon as you swap to a different engine. 1 Quote Link to comment
banzai510(hainz) Posted July 28, 2015 Report Share Posted July 28, 2015 Isnt there a Z car place up in Everett take it there Quote Link to comment
perspectiveshifting Posted July 28, 2015 Author Report Share Posted July 28, 2015 Hey king rat, thanks for the response! The 2.8l engine had carbs on it when I got it, the same su carbs as on the 2.4l engine. The previous owner had rebuilt it, so it very well could be a modification they chose to make - I didn't even realize it was abnormal. The engine I swapped in was running heartily in the rusty car it came in before I swapped it over, so I know it's usable, assuming I didn't ruin it somehow in the swap. It's good to know that the jetting could (or should, from your explanation) be inadequate for the new engine, so I'll try tweaking that more a well. Quote Link to comment
banzai510(hainz) Posted July 28, 2015 Report Share Posted July 28, 2015 did you use the same distributor assemble? Maybe you put soemthing in wrong. Even with the wrong carbs it shoudl be soemwhat drivable I heard of 240 z carbs on 280 motors before put a timming light on it? 1 Quote Link to comment
perspectiveshifting Posted August 6, 2015 Author Report Share Posted August 6, 2015 Finally got it to start after playing with the spark wires a million different ways. It starts fine and is idling at about 750, but sits comfortably at 550 with no choke before warmed up. The only issue is, my timing light is saying it's advanced 55'... I've attempted shifting the spark wires (while maintaining their order) both directions, and the car refuses to start no matter how I rotate the dizzy in any position other than that one, and it also refuses to run in the current wire configuration if I rotate the dizzy too far clockwise. It's currently turned as far the setting screw will allow counterclockwise, which seems to give the closest to "good" performance. My assumption at that point was that the handmade timing mark I've been going off of was inaccurate, so I removed the valve cover and first plug to verify where TDC really was. The timing mark, as far as I can tell, is accurate, so I'm at a loss for how to progress further. My question at this point is what would allow the timing mark to be so seemingly inaccurate, or, if it is accurate, why such an extreme timing advance seems to give me the most usable performance? I've attached linked pictures of how my plug wires are currently attached, as well as the view with the valve cover removed at what I believe to be TDC. Let me know if I can provide any more information or pictures, and thanks! http://imgur.com/M0IXuex http://imgur.com/Ro25Ly7 Quote Link to comment
banzai510(hainz) Posted August 6, 2015 Report Share Posted August 6, 2015 save this https://vimeo.com/19077890 half way in vid I install a distrubutor. piston will be at TDC and the lobes will be in the 10 and 2 o clock position)on 4 cyl).On number 1 . then install dist and where this lands it should be on Plug 1 and go in the CCW fire order. watch vid and make sure timming plates are in the middle position. is this a simple basic light? if yes then I assume it would not even run at 55 deg but Im not familiar with the 6 cyl L motors but should be almost the same I dont know what the fire order is I assume you have a book Quote Link to comment
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