ckurtz2

Ok I am going to keep stock cam. Didn't do injectors after all, because I think I found the real problem.... So the gas was old, sitting since December, so I swapped it for new gas and also replaced the filter I had running in the back. Put about 8 gallons in. The previous filter sure did do it's job. The first thing I ever did to the car was clean the tank with nuts, bolts, muriatic acid, and vinegar to shake all the rust out. I also cleaned out the pickup and return tubes with solvents which were clogged at the time. I then put a little filter between the fuel pump and the tank to make sure any pieces of rust or gunk I missed were caught Now here is where things get interesting. The car starts and idles beautifully without a miss when cold, or after sitting for about 30 minutes. Now I wondered what the hell was happening, and I knew it must be somehow fuel, even though the fuel pump bench tested wonderfully when I put it on the car. I went and looked at the little filter I replaced and here is what I saw. What the hell, is what I thought. I thought that the fuel pickup must be semi clogged, but that is not the case. When the car turns off it fills up instantly. That is when I noticed this when the car is off. This bubbles subside after about 20 to 30 minutes. When I start the car and watch this filter the stream is consistent and powerful to the filter. Then after running for a little bit the stream starts to spurt again with less power. Like there is air getting stuck in between. Have you ever seen this happen? Is somehow air leaking into the system? What is going on here, I am all eyes and ears. I am thinking there are rust holes in the pickup causing air to surge in or something like so.

I think I am with you on this one. In the name of science though, my friend and I are going to rewire the injectors anyways tommorow morning. If something changes then miracles are possible. If not, then you can use my forum post as proof to debunk anyone in the future who thinks that their injector wiring is wrong.

So you think that it is possible if the wires are connected backwards it can lead to issues? All six of mine are wired the exact reverse of this by accident. I tested by seeing which side of the connector was getting voltage when on the car, and the opposite side had voltage as apposed to this thread. No idea how I messed this up, as I thought I was careful. https://www.atlanticz.ca/zclub/techtips/injectors/connectors/index.html Regarding the cam, I will stick to stock, but I think I am going to use the internally oiled one. @Reptoid Overlords, ok interesting. maybe the header is just causing more noise to pass through. I might try one of those special tools to see exactly where the sound is coming from.

Another update after a hard day's work. The Datsun has won again. Did a valve adjustment, some of the specs were crazy off. Mostly tight, but definitely not at what I set it to before. Redid the oiler gaskets with new proper ones. Realized that I didn't even have a gasket in the middle:( Anyways, fired it up, cold it was quieter, but once warm it was louder than hell from the valvetrain. I am thinking it's time for a new cam, internally oiled, and probably a hotter cam as well. So that's loss number 1 Number 2 I slapped on the potentiometer trick. Man that thing works like a charm to lean and richen the mixture. Quite a masterpiece, whoever came up with it. However, it did not fix the miss. The miss did go away when I had the potentiometer at about 3/4 rich. However, my eyes were watering from unburnt fuel, and it sounded like a vacuum out the back. With slightly more fuel I was able to get vacuum up to about 17 at idle, and it still ran fine. Still has a stumble though. Are you positive that fuel injectors can be wired backwards with no ill effects? With good fuel pressure, vacuum, electronics tests, I really don't know what the miss could be caused by. I checked to see if the EGR thing was rotted through by plugging the holes, but nothing changed when I did. I am starting to think it is spark related. Is there a spark control module? Is it somehow possible for this to cause a miss? On a positive note the suspension, brakes, wheel hubs, shocks is almost completely out and ready to be cleaned and rebuilt. Just stuck on the spindle pins for now.

Wow, thanks for all the replies! Do you think it is ok to keep running that cam for now? So I think the issue with it's oiling efficiency is that I half assed the gaskets. I used a cork type gasket instead of rubber, because it is what I had at the time. You can see the cork is sopping wet, because it is obsorbing the oil and I am sure letting some leak out. I am going to find a rubber sheet somewhere and make new ones, hopefully that will help. None of the galleries were clogged. New valve adjustment coming up as well. The car is a 1/77 280z. So I am not sure when they switched to an internally oiled cam. This is what the car had when I got it, and it was a pretty unmolested car. Is an internally oiled cam better? Anyhow, decided to switch things up today and got started on the brakes and regreasing wheel bearings. Lemme tell yah, that rear nut on the rear stub axle is a real enemy. Haven't figured out how to defeat it yet. I am thinking a punch to open up those crimped edges, and then an impact at maximum uggah duggas. Oooh the fun... I have the potentiometer coming in tomorrow. I will try the new gaskets and see if it quiets down the motor. Then I will fit in the potentiometer and see what fun it brings. The weird thing is that the spark plugs all look slightly carbon fouled. However, the car ran on crazy advance for a while so I won't be surprised if that caused that. The ground electrode was slightly white, while the center electrode was black.

@zclocks Mine has a very minute wobble. Just another problem to add to the mix. Ok, so I took a ton of photos and a video. I think my wipe pattern is ok-ish, but I may not understand the concept completely. Enlighten me. Also, the cam has score marks on it in certain places, does this mean I am screwed and need a new cam. I think I narrowed it down that my spray bar just isn't providing enough oil, however the engine wasn't turning fast either. Some holes in the bar had virtually no oil coming out, while some had decent spray for such low rpm. In addition, sometimes the oil looked like it was just spraying straight down. Does anyone know how to disconnect and make no spark get to the coil. It was really annoying watching the spark arc when cranking.

I will. I'll get photos and such to show everyone as well. Just getting dark here, so it will be tomorrow. I just found that at 18deg BTDC it seemed to run best, I didn't wan't to go higher. Lower the idle dropped and got a little rougher. I could raise it with the idle adjustment screw, but it still seemed to stumble more. The sticker on the hood says 10deg BTDC, which I assume is what it ran from factory. I can bring it back down to around there if you advise that.

@zclocks my bad. Not sure where you saw that, but it is plugged now. Must have forgotten earlier when I was trying to figure out which vac port I could connect to.

@zclocksThanks for the morale boost. Definitely need it. Yah, I have no idea what is going on with the valves, but clearly it has issue. I will pop off the cover again tommorow and post my findings. It is just a spray bar that I had to make custom gaskets for. Thanks @Zed Head for the tip. So it turns out at 1k rpm I am getting 16Hg of vacuum. Maybe a little low, but the oil pan also pisses about a 1/5 of a cup of oil every night so I am sure that could be considered a small vacuum leak. I connected the gauge to the brake booster fitting on the intake. Another good thing to note is when I rev it to full throttle the vac pretty much goes to 0 and when I let off it shoots to about 25

Copy. I will go figure out a way to hook up the vac to that and update you. The AC fitting was too small for it and the brake booster was too large

Ok, took a breather for most of the day, but went back at it this afternoon. I was still iffy of my timing light being correct saying 40deg advanced cause I stepped on it yesterday😬. I borrowed another to make sure. Turns out is was right, and I backed it down back to about 18deg BTDC. Now the timing light is much more stable and not bouncing everywhere, so I don't think I need that rebuild. Though I will probably get it done anyways in the future. The chop chop chop is gone, and it hasn't spit out the intake since. The gentleman who let me borrow his timing light also let me borrow the vac gauge, because mine was broken. The results were unsettling. It seems I have like 3Hg of vacuum when idling. A good thing to note is I hooked it up at the T fitting coming off the throttle body, I just disconnected the dizzy advance and hooked it up. Not sure if this is an ok port to use. Now, what could cause such low vac? Could it still be a low fuel issue due to the control unit drifting in resistance. Overtightened valves maybe? I'm not sure where to go from here. I am thinking maybe of smoke testing the engine. Which speaking of that, what is a good way to go about that on these cars. I know lots of questions. Anyways to bring everyone more face to face with the problem I have I made another video so you can see what I am seeing.

I can get one from partsgeek or rockauto. I am just worried those will be lousy rebuilds. What do you think of this company? http://advanceddistributors.com/wordpress1/

Does anyone know who makes good remanufactured distributors for these cars? I am going to go through the process of testing it, but I would like to have a backup plan if it fails

Exactly, haha. Resist the haircut by all means🙃. Yah this car is an evil girlfriend, she keeps digging all the money out of my wallet with a smile, then coughs and sputters it right back at me. Thank God she hasn't got ahold of a credit card🤣 Like I tell everyone who asks about my car. She has an attitude problem and nothing I do pleases her, but in time she will turn round. Or cough a piston through the hood.

Another update. Re fired it up, really struggled this time. Back to sounding like its cammed with chop chop chop. In addition, the volts on the dash read now about 2, but at the battery i get about 12.6. Dash used to be accurate before. I am hoping that is a problem I can ignore for now. I will start going through the distributor. I haven't gone through the internals yet so it should be good to go through. Yip, I believe it. Car has to put you through hell before it starts to give anything in return. I still think I am going to do that potentiometer trick though. Can't hurt.

Interesting and scary. I will dig into some research about this. Another odd thing I noticed. The timing light shows the pulley mark is bouncing around about 4 deg each way. Man I swear this car is going to be the end of me haha.

haha. I have the timing dial set at its max 60deg, and I barely got the light to flash with the notch on the crank pulley. Before I could get it marked on the pulley at a reasonable advance. I guess what I am saying is could I have set the distributor a full cycle out. I had TDC set to when piston #6 was on its compression stroke and not #1?

Thanks! Getting closer. So I put back on the dizzy and fired it up. The lifters seem annoyingly loud, and I am wondering if my spray bar gaskets I made just aren't working well, or are these engines just pretty noisy up front. Anyways. Let it warm up no more misfires out the intake! Still stumbles though when idling. Every few seconds you can hear the exhaust kind of stumble. Now here is where I am stumped. The timing light is reading 60 degrees advanced or something weird like that, what could this mean? The dizzy may have spun round a few times when off the car, does that matter? Or could I have missed completely TDC because it has to go two cycles? Is this even possible? If it is how do I make sure I don't do it twice when i repull the shaft.

Roger, thanks. I will check out that wipe patter as soon as I can. I also just redid the oil pump, already had the sway bar removed from when I did it last so no biggy. I noticed that I could never get the shaft aligned if I lined up the dots perfectly on the shaft, because I would have to twist the pump on for clearance to get it in. The tang would always be pointing almost perfectly at 12:00. So I just barely offset the dot and twisted it in. This is what I got and I think it is near perfect. What do you think?

One step closer. Pulled dizzy at TDC and it definitely seems off a tooth? Even if it was wouldn't me timing the engine compensate for this when I twisted the dizzy, and it won't explain the weird miss and stumble I have? Here it is. First photo is where the rotor was pointing at TDC with the dizzy timed. Does it look right? Second photo shows the shaft. @Reptoid Overlords thanks for watching closely! So close to the finish line, I think...

Ok so here is the plan. I am going to check the dizzy shaft tommorow and make sure it looks proper with the engine at TDC. Next, because my car is a 77 cali model I am going to disconnect the altitude switch under the dash and see by some miracle if that does something. After that I think it is time for the potentiometer magic to happen. Regarding the pot tweak, which pot should I get. I was looking online and there are so many options within the 1kohm limit I don't know which is best. In addition, do the bullet connectors have a certain size on the water temp sensor. I need to buy some connectors for the pot that match the water temp sensor's bullet connectors. Thanks for hanging with me over this tedious process thus far!

@Reptoid Overlords thanks for the confirmation photo! My chain is definitely stretched, but the #3 cam pulley position compensated. Mine may be running a tad more advanced then yours, but it looks to be in spec as well. I wish my cam sprocket looked as clean as yours! 😎

What do you mean by wipe pattern? It definitely doesn't look amazing. There are some burn marks and light scratches to the eye, but over the finger everything feels smooth. I never did anything to the cam, just took it off and plopped it back in. I refired up the car. Much quieter up front with less valve train noise. I definitely tightened it closer to the tight specs on the hot valve adjustment guide. I just let it idle and listened from the back end. The chop is erratic which leads me to believe it is not cammed. The plugs look great, except for plug number 2 and 1 which had a little bit more carbon deposits. I pulled the injector connector from cylinder 2 and I swear the car barely changed in behavior. Ran a tad worse, but not as much as the other cylinders. May just be placebo and me wanting to find the culprit though. So after letting it idle for a while I went to give the car about 3/4 throttle straight away. Essentially opening up the throttle body quickly to see how the car reacts. The only thing consistent I have noticed is that after sitting idling for a few minutes and I hammer the gas, there is always a pretty big missfire out the intake. This I think is the biggest clue we have thus far. Which leads me to believe it may be running a tad lean still?

Just did a valve adjustment. A lot of them had way to loose of clearance. Only one I didn't need to touch. Weird cause I already did the adjustment once. I would say it was a warm adjustment. I also agree it sounds cammy, but I don't know why. Everything seems stock under the valve cover, but I don't know how to tell if it is an aftermarket cam. In addition, sometimes it smoothes out like when cold, so it makes me think it is just missing or stumbling. I rotated the engine clockwise carefully until I got to TDC. I have it on mark 3, so obviously the chain has wear. However, it looks like at this position the cam is advanced still. Is that ok? This is where the crank pulley lines up and how the cam timing marks look correlated to it.

I am going to go ahead and do a hot valve adjustment. I have the car warming up now. Revs perfect cold with almost zero bobble. Warmed up a little bit and when I pumped the throttle it gave a nice intake backfire. I want to make sure it is not the valves fault. I will also take a photo of where the cam lines up at top dead center.