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modified 73 240z not starting

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Posted (edited)

Hello All,


I own a 73 240z. Im having problems getting the rebuilt motor to run. And would like some advice and help.


Motor Specs:

81 280ZX lower block with standard size flat top pistons, rebuilt.

73 240z heads cylinder cleaned, rebuilt and valve change. the camshaft is a Schneider 274F. (The head was "decked" bottom resurfaced)

an E12-92 equiped distributor.

SU carbs with 73 intake manifold (Unknown yr of SU's).

header in 6 - 2 outlets(No muffler yet).

82 280ZX 5 speed transmission.

Mechanical pump.


The car has been hesitant to start but doesn't. I rebuilt the carbs and found one of the jets was seized. i did change the jets with new ones from Walker rebuild kits. I sized the floats according to the walker guidelines, but once installed no pressure was going into the empty float tank. I resized the floats and tested by blowing throw the fuel inlet for passage and also while installed. I filled the float tank slightly with fuel and installed everything. The float sealed due to the fuel inside the tank. Did the same for the rear carb. I had a difficultly  understanding camshaft timing, then found an hybridz post MSD video that helped. The initial pics are the cam set at 2nd notch with the dash slightly to the left of the groove. Both 1st cylinder lobes pointing in a v pattern at TDC. Upon cranking, motor was hesitant, but didn't start. No starter fluid used. No backfire or smoke from carbs or exhaust. The 2nd pics posted are the same setting, but set to 1st notch with dash slightly to the  left of the groove. A whine upon cranking. Had to use starter fluid. It would bob and backfire on both the header and carbs. Rear carb backfires loads, sometimes spits sparks!! The front carb hesitates when fluid is sprayed and the rear backfires and sometimes out of the front carb.The carbs are turned 2 revolutions down from the  top flush. I drained the float tanks twice and there was fuel inside. 


Now, I need advice and help before I burn this beauty!! Any advice on using schneider 274F cam? how to set cam timing for such cam. Cant upload the videos, Ill try to attach them.














Edited by Datz44

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My problem with a similar setup was the EN12 being wired incorrectly and not receiving power and the rockers being out of adjustment not allowing for compression. 


With starter fluid you can bypass the fuel portion for now, but you still need spark and compression. Compression is easy to check, turn the engine over by hand, with the valve cover off and you should be able to hear the compression. Check the valve lash and adjust as necessary. Then you will have to check the ignition wiring. I will say some of the wires that can be made out in the background look a bit rough. I recall the diagram I found at first was wrong. I think I pulled from near the ballast resistor, I think we had to use a multimeter to find the correct ignition wire to the EN12 so that it would have the correct power and voltage.

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Posted (edited)

The distributor drive is off by 180 degrees?


You can easily check this by removing the distributor cap and see where the rotor is pointed when you're on tdc #1 and also seeing if the cam lobes for that cylinder are pointing up instead of downward.

A field fix would be marching the plug wires around until #1 sits in the cap where the rotor is pointed 


Edited by HowlerMonkey

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