I'm hoping to get some help and I'm new to the forum. I've searched this site as well as the web to find the answer to my problem and I haven't found it. I recently purchased a 70 240Z that had an engine that wasn't running well because of valve and rocker issues.

I bought an engine from an 82 280ZX and installed it this week. I took the SU carbs (which were working fine) and intake from the 240Z and installed them on the 280ZX engine. The engine came without a distributor so I purchased a rebuilt Cardone to install.

My problem is that when I start the engine, the RPMs immediately start climbing even though I am not pressing the gas pedal. I started it 6 or 7 times and then had to shut it off almost immediately because the RPMs just kept climbing. Here's what I know and what I am thinking:

I installed an electric fuel pump to replace the mechanical pump on the 240Z. It's a low pressure pump designed for carbureted engines. It seems to be working fine.

When I installed the new distributor, I noticed 2 things: First, I can't tell if I have an E12-80 or E12-92 ignition module because where it is stamped on the outer case of the module it has been scratched or gouged so I can't tell if it say 80 or 92. It has 2 connectors on top and doesn't have a connector or a little "ear" sticking out on the side like the E12-92's I've seen pictures of. Second, my rotor was not pointing where it should have been when I installed the distributor but since the distributor slot is offset I didn't think there was any way I could have installed it wrong. But, when standing on the driver's side of the car looking at the distributor, the rotor was pointing at approx the 3 o'clock position when I had #1 piston at TDC. From what I have read, the rotor should actually be somewhere around the 7 o'clock position. The distributor wouldn't go in any other way so I installed it the way it was. Then I read a couple of posts on one of the forums where guys said they had the same problem but the engine still ran fine. Others said they had to change the spark plug wire connections on the cap to match where the rotor was. So, I did that. I put #1 spark plug wire where the rotor was at TDC and then continued the firing order. Didn't work. It backfired like crazy, so I went ahead and put the spark plug wires in the "correct" positions, with the #1 wire at the 7 o'clock position. It fired right up but the RPMs immediately started going way up and I shut her down. Same thing every time I've started it.

I also followed the instructions in several forum threads for wiring the 280ZX distributor into the 240Z harness. I removed the ballast resistor and connected its two wires together. I connected "C" on the ignition module to the "-" side of the coil and used a "y" connection to connect the "ignition on" lead from the harness to the "B" side of the module and also to the "+" side of the coil.

I'm thinking maybe I do have an E12-92 ignition module and this is causing the problem. Does that make sense? I can't think of what else would cause something like this. I haven't been able to time the engine because I have to shut it down almost immediately after I start because of the rising RPMs.

Any feedback will be appreciated.

 

Hi, don't know if you're still with us but your problem is the BDD valve. It is located on the bottom of the throttle body. This valve opens on deceleration to give air to the engine to keep it from being to rich and backfireing, smog stuff. In your case the valve is stuck open. That causes the engine to rev up even with the throttle closed. The opening is in the TB just before the butterfly, Plug it with silicone. The engine will stabilize now. Next is your distributor drive shaft was installed 180 off. To correct that you need to take the shaft out through the bottom of the oil pump, rotate it and remesh the gears. Not that difficult. Your #1 should now be at the 9 oclock position. Reposition your spark plug wires and you know the rest. Sorry I didn't notice you before, good luck.