Med Center Z Posted February 16, 2013 Share Posted February 16, 2013 Hostory My z sat for 8 months in my garage. Installed 40mm webers H7 models (completely overhualed). Installed rx7 fuel pump (producing 4psi on gauge). Installed 81 280zx distributer. (Replace oil driver and gear) If relevant this is a 3.1 l28 with a V07 crank, Cam - 290/.505, 266/.490, F54/P90 Took spark plug on cylinder one out and set motor to TDC, checked to see if cylinder one is at the top of the block deck and it is. First two Cam lobs are upright on both sides and valves are closed. Motor tries to start but won't. I did a conpression test and I can't get conpression over 70 on any cylinder. I addvanced my timing to 50 degrees and the motor will idle. I'm stumped and frustrated... Quote Link to comment Share on other sites More sharing options...
skirkland1980 Posted February 17, 2013 Share Posted February 17, 2013 You would need a leak down tester to see where the leak is, if any. Quote Link to comment Share on other sites More sharing options...
NewZed Posted February 17, 2013 Share Posted February 17, 2013 Kind of sounds like you might have your timing light lead on the wrong plug wire or your distributor is off. If it starts and idles, you're probably in the ~20 to~ zero degree advance range. Move the timing light lead from plug wire to plug wire until you get a reading in that range then set it to 10, for starters. The cylinder that you're measuring timing on is then your new #1. If you have an adapter on your cylinder pressure gauge you'll get much lower pressure readings. If it runs you probably have much more than 70 psi cylinder true pressure. The gauge volume becomes part of what's being measured and affects the number. Just look at the difference between cylinders, if they're close, don't worry about it. Quote Link to comment Share on other sites More sharing options...
WEBEZEEed Posted February 17, 2013 Share Posted February 17, 2013 You might also check and verify that your valve lash is correct. Quote Link to comment Share on other sites More sharing options...
Med Center Z Posted February 17, 2013 Author Share Posted February 17, 2013 Still having the same issue I think a leak down test is next. Here is a short video. I checked valve lash its fine. also if its relevant behind the crank pulley there is a small medal backing plate that is loose witch is concerning to me.. Quote Link to comment Share on other sites More sharing options...
skirkland1980 Posted February 17, 2013 Share Posted February 17, 2013 I don't see the video link. Quote Link to comment Share on other sites More sharing options...
beermanpete Posted February 17, 2013 Share Posted February 17, 2013 You said you replaced the "oil driver and gear". Does this mean you took the oil pump out? I suspect you have the timing wrong, as New Zead has already said, due to installing the oil pump gear out of time. If this is the case, you can fix it without retiming the gear. Put the engine back at TDC in the #1 cylinder (compression stroke) and look at the distributor rotor. Put the #1 plug wire in the cap at the closest position. Install the other plug wires following the firing order (1-5-3-6-2-4) in an anti-clockwise direction. If still does not start up try turning the distributor while cranking. Make sure to loosen both adjusting clamp screws so you get the full range of adjustment possible. Quote Link to comment Share on other sites More sharing options...
Tony D Posted February 18, 2013 Share Posted February 18, 2013 If you advanced the spark 50 degrees, in essence you changed the tower firing position one lead. There is only 60 degrees between towers, and with normal firing at idle being 10-15deg BTDC, you only actually have 45-50 degrees separation between terminals. If you advanced your timing 50 degrees, you are right in line with then next terminal firing position! (Megasquirt taught me this when I had 50 degrees in some higher rpm low-MAP positions. Car revved up, snap throttle closed and the spark jumped to the next terminal, running terrible coming down! Oh man...) Quote Link to comment Share on other sites More sharing options...
Med Center Z Posted February 18, 2013 Author Share Posted February 18, 2013 Seems that my I-phone 5 wont attach the video. I put it on you tube Chanel here is the link. I don't think the motor was at TDC when took the Oil Pump out and changed the Oil drive and gear. Quote Link to comment Share on other sites More sharing options...
skirkland1980 Posted February 18, 2013 Share Posted February 18, 2013 Was the engine running in the video or was the starter on? I'd get the distributor set right and change the spark plugs and it may likely run. Once all the fuel on the rings dries the compression should bump up to normal...hopefully Quote Link to comment Share on other sites More sharing options...
NewZed Posted February 18, 2013 Share Posted February 18, 2013 It's fun to guess, with little information, but if you really want some good ideas you need to add more. "My z sat for 8 months in my garage.Installed 40mm webers H7 models(completely overhualed).Installed rx7 fuel pump(producing 4psi on gauge).Installed 81 280zx distributer.(Replace oil driver and gear)" Did it run before you parked it 8 months ago? What else did you remove when you installed the Webers? and the fuel pump? and the distributor? Assuming it ran well when you parked it, odds are you just made a mistake when you did the distributor work. No reason for your rings to get messed up over 8 months. If you don't reset the distributor to factory specs. then you'll have to work around it and make it work based on principles. You'll probably understand your engine much better if you do things the second way. Or you could just start from scratch. There's a drawing the 1981 Engine Lubrication chapter showing orientation at cylinder #1 TDC. It seems to be the only drawing, for some reason, in the '81 FSM. You can at least check orientation to see how far it's off. As for the loose medal backing plate witch is concerning - maybe a promiscuous, decorated, female military member who practiced the dark arts used to own the car. lol Quote Link to comment Share on other sites More sharing options...
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