Zark

Just finished putting in new stainless steel fuel lines, pressure regulator and hoses. That is an Aeromotive regulator, it does a great job of providing steady pressure to the carbs.

Enkie Compe 16x7 with Hankook Rs-3 205/55

We will put the oscope on the HEI and ZX distributors to analyze the signals to the ICM and post the results here. It will have to wait until Christmas break. I was using a coil with 0.4 ohm primary resistance with the HEI and I am still using it with the e12-80. I also ran 10 gauge wire from just behind the ignition switch through the tack and to the coil to reduce the voltage drop. To make the tack work I formed a new loop of #10 wire to replace the much smaller gauge white wire that is the loop on the original harness. I just laid the white loop to the side. I used spade connectors on the little #10 loop because it would have been very difficult to form the loop in a continuous piece of #10 wire. Previously we had done other repairs to the tach to make it work. I suspect the weak link in the tach are the two transistors. If you have a problem with the tack I might be able to help.

Yep, it is easy to get carried away in writing a post and make your opinions sound too factual or set in concrete. On the other hand I suspect many are expressing opinions based on what they think is going on and I have no big problem with that. I will add this. I had the HEI in first because the ZX dizzy was minus the ICM. I had a stumble from 2000 to 4000 rpm that I could not resolve and I suspect the stumble was still occurring all the way to 6,500. So after working with the carbs, coil, and timing I decided to buy the e12-80 ICM. I also tried it with and without the vacuum advance. I got a used Nissan ICM from a Z restoration shop in Escondido, CA. It is a simple thing to switch between the two ICMs. I left the HEI in so I could switch back and forth between the two. The e12-80 just made it run much better by the butt-o-meter and the idle was smoother. I still had a slight stumble with the e12-80 so I decided to try the hotter plug and since then It is running great, smooth acceleration through the whole range. I feel ready for the hill climbs I skipped this summer. To complete the picture I need to describe the engine better. Original 24L rebuilt and balanced E88 head ported and polished Intake manifold smoothed and polished to 120 grit Comp cam with a 260 grind, running about 3.5 degrees advanced at 0.050" open on the intake valve MSA 3-2 header Original SUs with thinner needles recommended by Dave at Z-therapy, can't recall the letter designation Now maybe the HEI would work better in a stock set up. My oldest son is an electrical engineer with just two terms to graduation and he does have a real nice tetronix scope. Since I have the HEI running in my old cruiser and the e12-80 in the Z I should get him to compare the AC signals from both distributors. Of course my two boys want me to start over with mega squirt and injectors or better yet six motorcycle carbs. Ugh.

Here is the a link to the article. I agree with NewZed, don't make your choice based on just what I said. There are others that have recommended the e12-80 over the GM HEI for ZX distributor. I am sure you will find them. There are many internet threads by motorcycle guys concerning the using the 4-pin HEI. There area also threads on retrofitting older Chevy 235s from point to the HEI. I have a 1970 Toyota FJ-55 land cruiser that I put an HEI distributor in and it was great improvement. I have tried both the GM-HEI (Pertronix and Standard) and the Nissan e12-80 on my 24L and the Nissan module makes the engine run much better. In my experience the HEI did not work well with the ZX distributor and I would not recommended. http://www.scribd.com/doc/54217408/4-Pin-GM-HEI-Module-Notes I agree plug temperature choice is function of the combustion process. Again what I said above about the plug choice is based on my experience. Obviously the hotter plug in my engine was fouling less. Generally accepted knowledge, come on. Post #8 makes no sense.

I had problem with ignition momentarily cutting out on me after upgrading the ignition in my 72 to electronic with a high powered coil. I found that the spark plugs were carbon fouling. So I switched to a one step hotter plug. The problem went away completely. I went from the stock NGK BPR6E to the BPR5E.

The one on the left looks like a 280ZX dizzy and the one on the right looks like the 260 dizzy. I have a 24L with a performance cam, header, ported and polished head and polished intake manifold. I put a 280ZX dizzy in it that I got at a junk yard minus the ICM. So I went with the HEI 4 pin module which is easy to get and install. But I was not happy with its performance, it just was not stable enough. In my research on trying to make it perform better I found a very detail article on how the GM HEI 4 pin module functions. It was on a motorcycle forum. One problem is that the reluctor on the 280zx dizzy has what are called ramps ahead of the spikes. These ramps definitely play a role in form of the AC signal generated and used by the ICM to control the dwell time. The GM-HEI reluctor has simple sharp spikes on it, no ramp. The AC signal generated by the 280ZX dizzy is not the signal that the GM-HEI was designed for. So I removed the GM-HEI module and put in a used Nissan e12-80 ICM. It made a big difference, much better performance through the entire rpm range. I would stick with the e12-80 module. It looks like you have the correct Nissan module on the 280ZX dizzy. If it is the e12-92 module replace it with the e12-80. I also found that with either module I needed to run a hotter plug, NGK BPR5EGP. The colder 6 would carbon foul easily.

Here are some photos of my orange 72 Z. This orange changes depending on the angle of the light source. It is about three years old now. The car was originally white with red interior. I am the second owner, I have all the original paper work including the dealers window sticker. The original owner hit a jackpot in Reno and promptly went to the Datsun dealer in Reno and purchased it. Those are the wheels she had the dealer put on it.

Thanks for the check

I have checked my cam timing using an indexing wheel and a piston stop to get TDC, and find that the valve timing is retarded about 3.5 degrees due to chain stretch. I have a Comp street cam, 260 and standard cam sprocket. My question is do holes #2 and #3 on the cam sprocket advance the cam in 4 degree increments. In other words, #2 hole is 4 degrees advance and #3 is 8 degrees advanced. This is how I interpret the FSM. Am I right? I have searched this site and found no clear simple answer. Also searched the web and found some contradictory explanations.

On the right side when sitting in the seat.

My boy and I painted his 240 with R-M UNO-HD a two part single stage paint over PPG primer D822. This was our first paint job and we were very happy with how it went and the end result. Very high gloss and after two years outside in the rain of the Willamette Valley it still looks like new.

I have a 72 240z that I recently replace the original dizzy with a dizzy from a 83 280zx that I got at a u-pick yard yard for $60. I took it all apart and cleaned it up, it was in great shape except for one thing. I had to make a new bearing for the breaker plate assembly, the plastic cage that holds the three ball bearings is commonly busted. I used the 4-pin HEI ignition control module. I got two modules from the local auto parts store, a Standard for $22 and a Pertronix D2000 for $46. So far I am not sure if there is much difference in performance between the two, I need to make a series of timed runs with each. It is very simple to change them out. Overall I am very happy with the 280zx dizzy/HEI combination. It makes a great difference in acceleration and the engine runs smoothly up to 6,000 rpm. That is as far as I have taken it so far. Attached is a drawing with notes. Be sure you replace the coil with one that has a low resistance. I am using a Pertronix Flamethrower III coil. I did a lot of research before making this change and some of the best info I found was on Chevy hot rod sites that discussed replacing points with an HEI distributor. I also have a 1970 Toyota FJ55 Land Cruiser which has an engine that is a metric version of the Chevy 250 straight six. It makes a very big difference putting in the HEI distributor. Distributor conversion drawin....pdf

I still suspect the coil may be the problem. It does not take very long to damage a coil running it at 12V, a short burn as you would say could do it. I have done it. You may have an intermittent short in the winding that is temperature sensitive. Maybe the energy the the coil is put out now is so slow low that spark at the plugs is quenched as the compression in the cylinder increases and that is why it tries to run way advanced. I would pop a another coil in there and see if it is a fix. Maybe you still have the old one lying about.

It is not clear if you have the ballast resistor in the circuit or not. If it is not in there then a stock 1.5 ohm coil and the points are going to get fried. I restored a Z a few years back that had been sitting in a field for about 15 years and I thought I had the fuel tank very clean before I put it back on but I did not. After I got it back on the road I had to change the fuel filter quite often for awhile due to very fine rust plugging up the filter. Might check your filter and replace it. After 15 years there is going to be a lot gunk and rust in the tank.