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About blownalcohol

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  • Location
    ABQ, NM 87110
  • Cars
    1982 Datsun 720 King Cab 4x4, 86 Nissan reg Cab 720 4x4
  • Interests
    Hopeless Gearhead
  • Occupation
    Automobile Technician
  1. I pulled the number 4 fuse out and it was plastic welded from behind. There was nearly a volt voltage drop over the fuse and lots of heat. The fuse box looked nasty and after pulling the fuse box back I could see that the insulation on the Y/r power wire for for the fuse #4 ignition circuit was melted some too. After studying the wiring diagram for a while I found that right next door to the #4 fuse is the #3 fuse which provides a dedicated circuit for a rear window defogger option that my truck is not equipped with. Since this circuit was serving no purpose I snipped the #3 yellow wire about 12" out from the fuse box and cut the Y/r wire from the #4 fuse right at the fuse terminal. After cleaning up the melted portion of the Y/r wire I spliced the #3 yellow wire from the fuse box to the harness end of the Y/r wire. Every thing is working properly now. Thanks once again for pointing me in the right direction.
  2. Well its warming up so I am working out bugs in truck 2. Its a 720 2dr 4x4. A little bit of a Frankenstein as I have utilized a lot of ST stuff from the local u pull and pay. I upgraded to a cluster with clock, tach, gauges and I upgraded to a center console with voltmeter and oil pressure gauge. It also got a tilt column and upgraded to intermittent wipers. I have a factory manual and wiring diagrams, I did have to install a different oil pressure switch and add a wire to a section of under hood harness for the console gauges but everything else was pretty much plug and play. Everything seems to work fine except except for one annoyance. If I have the lights on, and turn signal on the alt light pulsates dimly in relationship to the flasher. You can only see it at night. If the truck is stationary and the emergency brake is on the brake warning light in the cluster is on but if you turn on the turn signal the warning lamp will pulsate in and out, bright dim, again in relationship to the flasher. The voltmeter in the console also reflects a significant voltage drop that correlates with the flasher. I replaced the alternator without even checking it because I figured I had a bad diode in the rectifier. But that fixed nothing. I wanted to put a 60 amp in it anyway so that's done. I have checked the charging system at the battery with a Sun VAT 40. Its charging at as much as 60 amps and voltage is steady at 14-14.5. The VAT-40 doesn't show the same voltage fluctuation at the battery that I see from the gauge in the console. I have checked every ground I could find, I've had more than one cluster of the same type in it, The 4 way flashers do not have they same dramatic effect as the turn signal does. That seemed odd to me so I've tried different flashers too, it changed nothing. The battery never goes dead and it starts every time. All of the exterior lights work fine, no hiccups. I have a lot of work in this truck and would really love to solve this little annoyance. Anyone been there? Need a fix.
  3. Since no one came forward with a valve spring recommendation and virtually nothing shows up for a lowly Z24 engine with a Google search I started digging. I went to Rock Auto, looked up a stock valve spring for the Napz in an 85 720 2.4 and clicked on the buyer's guide. According to the Rock Auto buyers guide this spring fits a lot of different Nissan engines. So what models showed promise for aftermarket performance parts? The 300zx or the 200sx are both listed, how about them? I searched performance valve springs for a 1985 300zx and a 200sx. They both came back to an Isky Part # 7005-8 performance spring through CarID. Then I searched the ISKY parts number and found them through Summit. https://www.carid.com/isky-racing-cams/valve-springs-mpn-7005-8.html?singleid=84035380&url=80639190 https://www.summitracing.com/parts/isk-7005-8/overview/ It is not a double spring as the OEMs are. If the pics are correct it does have a damper spring. I can't find an OEMlbs per inch or coil bind spec in my manual to make comparisions. I found these too but the metric specs confuse me compared to what I remember from the old days racing domestic stuff. At first look they don't seem to be much more than stock. They are double springs though. https://thmotorsports.com/supertech-performance/supertech-valve-springs/sprh1021dsr20/i-252853.aspx Thoughts?
  4. I pulled the donor head off the engine today and tore it down. I inspected everything and the head appears to be ion great shape. It was on a running engine that smoked so I was concerned about valve guides and stem wear but they show no appreciable wear. The biggest concern I have is that there is not an overabundance of material that can be removed. After looking at the head I estimate that the casting in the valve bowls is only 5-6 mm thick. Here is a picture that shows the bowl from the gigantic water jacket as viewed from the rear freeze plug. There is not a lot of port floor material either. The water jacket extends under the intake floor to the intake manifold as seen in this picture. Working the short side radius will be limited due to this. I'm not sure how much I'll be able to raise the roof. It would be nice to see a cross section of this head. I live in the mountains and the butt dyno will be in the form of a couple of hills. As I said, I'm not trying to make a hot rod. It would be nice to bring this 86 4 banger a little closer to a present day stock performance level. I've been thinking about throwing some head studs at this thing in favor of head bolts when I finally swap out the finished head. I'm going to mill the head at least 1 mm as Mike suggested would more than that be crazy? Also, Mike thought valve springs might be in order. Since I've got it pulled apart now is the time. Can you recommend a proven product that won't be too much spring? I'm concerned about over doing it with a stock valve train. I don't see this engine exceeding 4500 RPM except by accident. Here are some exhaust port pics for future comparison.
  5. Are these the pistons that I've been reading are free floating and will need valve reliefs cut in them before installing in the Z-24? I was thinking about them but balked a little with the machine work and having to check clearance with clay, the whole assemble, disassemble, reassemble... Don't know if I'm up for that with this engine. That said, I worry about taking too much mass out of a head on an engine that is know for its blown head gaskets. How much can be safely milled? I do not wish to build a head that will not work below 2500 RPM. I would be happy with a conservative enhancement of the existing power band. I'm thinking about slightly opening and blending the valve pockets into the runners while smoothing out the short side radius on the exhaust side. I plan to polish the exhaust side runners and open them to match the OEM gasket. I plan to open the intake side slightly, matching the gasket while working a venturi into the intake side runner. I'll leave the intake runners a little rough without polishing to maintain turbulence. Maybe I'll polish and cc the chambers as well as knock down any sharp edges that might create hot spots. I have done this before with domestic V-8's and been very happy with the results. Maybe the single biggest improvement to the engine I've made without replacing parts. I have a 455 Olds that I built in a 66 C-10 that I used to race. A real torque monster. The exhaust radius is a real problem with the Olds head. I've been reading that the Z 24 suffers in the same way and that the exhaust radius is a bottleneck. That's what got me to thinking about working on this extra head I have. Maybe applying what I've learned from the Olds head would net me some improvement in the Nissan. I have time tools and some ability but not an endless supply of cash. All that said, I haven't worked on a Z 24 head in this respect. I have no experience improving performance in 4 banger outisde of a few bolt ons we've all read about. That is why I'm asking for pointers before I jump in.
  6. The idea is to possibly increase fuel mileage so no 38/38. I thought about the 32/36 and have read all about it. Worked on them a lot back in the day and I know they are decent carburetors. My Hitachi is working well and it will pass emissions. I think the AIS, carburetor and the cat are the largest factors in its ability to do that. Do you have any thought on this Hitachi progressive linkage mod?
  7. I'm thinking of doing some conservative pocket porting, gasket matching and exhaust runner work with a 3 angle valve job on an extra Z24 head I have for my latest 4x4 project. The engine runs good but suffers from all of the power issues associated with this engine. Since I plan to throw some rings, head gasket and timing components at this unknown mileage engine anyway why not try to unlock a little more power? I'm not trying to build a monster, just unlock a few more ponies and maybe even some economy by improving head flow. Bottom end is strong, doesn't use oil, maintains good oil pressure with no noise other than some timing chain slap on a cold start that readily disappears. Are there any areas in the head that demand extra care around water jackets or other cavities? I don't want to ruin the head by grinding through. I've read a lot about cams and the interference issues due to a high lift. Comp cams offers what looks like a conservative application. Does anyone have any input? http://www.compperformancegroupstores.com/store/merchant.mvc?Screen=PROD&Store_Code=CC&Product_Code=88-123-6&Category_Code=Z2024 Any input or personal experience is welcomed.
  8. My other car is a POS too! LOL. Wife drives the new one, I like my old trucks. 2 720 4x4's an F250 4x4, and my baby a 66 Chevy C-10 Short Wide 4x2 that bastardized a bit with a big block Olds 455.
  9. I will not argue that a large vacuum leak will do all the things that you indicate but as you also argue it depends on the size of the leak and the condition of the fuel mixture. I have great respect for you and your exceptional knowledge of this manufacturer. I concluded after reading the post that it was safe to assume that this is not a well tuned engine, Perhaps a better more correct term for me to have used would have been un-metered air in place of vacuum leak. Suppose for a moment that the idle mixture screw plug has been knocked out and the idle mixture screw turned out to obtain a smoother idle. Then we see that all of the exhaust emission components have been disabled. It is not outside the realm of possibility that his engine is running rich at idle. Given a very small external vacuum leak like a cracked hose or a leaking gasket, idle can increase. That said, I was actually thinking of my experience with my own 82 720 4x4. Consider the age and wear in the OEM carburetors. Worn throttle plates and increased air flow through the primary venturi because of them will cause increased idle speed. My 82 will not idle below 1000-1100 RPM, idle screw backed all the way off, throttle cable free and all other variables normal without reducing timing, shutting down the mixture screw and destroying the idle quality. The butterflies are just worn out.
  10. Ditto, 620's were everywhere 20 years ago. LOVE those old ones but you can't find anything around here anymore, if you do they want an arm and a leg for something that needs a ton of work but you can't find parts for. So because I live in the mountains and wanted a 4x4 720 was the one for me. 720's while they too are disappearing from the yards are still workable.
  11. Living in the south west is a plus if your going to be playing with old cars but 720's still rust! The cabs and beds hold up pretty good but the front floor pans rust away. The sun burns up the windshield gaskets and the floor boards stay wet, that's my theory anyway. I had to hunt a long time around here to find good used floor pans for both of my projects. I finally found them from a couple of California trucks that found their way to the Pick a Part here in Albuquerque.
  12. Possible vacuum leak? Small amounts of air going by the throttle pates will increase idle speed. Is the timing over advanced? Another thing that comes to mind. My 82 has a lot of wear around the perimeter of the butterflies in the carburetor. Even with the idle screw backed all of the way off it idles at 1000 to 1100 rpm due to the amount of air getting by the butterflies in the closed position. Wow just noticed how old this post is.... maybe it will help someone anyway :D
  13. 96 up. I liked the headrests better on the newer ones and used 2001. I think the newer model ones may be easier to find in decent condition too depending on the climate in your area. MX71 and I were discussing the possibility of the 96-99 seats having different brackets and he claims they have the correct profile without modifying anything. I'm still not sure about that. When I was doing the research I found posts recommending 96 up, 96-99 and one showcasing the 2002. Take your tape measure with you and compare or use your original seat rails/brackets providing your truck is equipped with buckets. Another note is that if you are putting them in a regular cab the seats reclining functions will be more limited depending on how far you have to side the seat back to drive, even so it still beats the hell out of OEM. IMHO
  14. What can you buy for $3200.00? Not much, besides do you really want to be driving the same thing as everyone else? I don't know about your neck of the woods but these old trucks are getting scarce around here. Parts are going obsolete. That makes you hone your skills, figure out alternatives, make things work, be creative. Yes its a hobby and I like the challenge. If you have a nice 4x4 720 you probably won't pass another one every 5 minutes. I like that too. You could do a lot worse things with your $3200.00.
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