ErickwithnoK Posted June 19, 2017 Author Report Share Posted June 19, 2017 ...and you get 2 sets! More colors available too, green makes 5 more HP! No resistor needed for the matchbox! A new coil is cheap, you don't need 1,000,000 volts. Making my own wires sounds interesting but I wouldn't know what I'm doing. I'd love to get rid of the ballast thing, not sure how to wire things without it or what I can cut out of the harness and throw away. Quote Link to comment
banzai510(hainz) Posted June 19, 2017 Report Share Posted June 19, 2017 the ballast is for points and a point ohm coil. to keep it from getting HOT. or points arching. NGK wires are fine. I have no proplems with them. some tacks are wires in series and others in Parallell. Quote Link to comment
distributorguy Posted June 19, 2017 Report Share Posted June 19, 2017 All tachometers just grab the negative coil signal, so they know each time the coil fires. I've never seen anything different. NGK wires are better now, but I have a set from a few months ago that are 7K Ohms per foot. That's not ok. Yet an MGB set I have are 700 Ohms per foot. Different wire altogether, but still blue. You have to check what you get to verify if its good or just passable and functional. You want more than that if you plan to drive an trust things. Otherwise the coil will run hot and eventually fail. For that matter, I have a perfect NOS set of original 1979 plug wires here. I wouldn't wish them on any of you. Well, maybe Mike. LOL!!! They have 17,000 Ohms of resistance and WILL run poorly with a very hot coil. Quote Link to comment
Crashtd420 Posted June 20, 2017 Report Share Posted June 20, 2017 Distributorguy, what is the ideal resistance valve on the wires and plug? And it also seems to be mentioned Ohms per foot, ... So if you had 14,000 ohms on a 2 ft long wire.... would that be viewd as 7000 ohm per ft.... Is that the standard in a sense? 1 Quote Link to comment
distributorguy Posted June 20, 2017 Report Share Posted June 20, 2017 You want less than 5000 Ohms per cylinder. Best case scenario, 800-1500 Ohms, per. Remember the coil wire adds to each cylinder as well (not part of my equation). 7000 Ohms per foot is bad. 1400 not 14000 is what you want. Quote Link to comment
Crashtd420 Posted June 20, 2017 Report Share Posted June 20, 2017 Thanks.... so sounds like less is best.. I run bosch wires with ngk plugs... guess I will see how they measure to be sure.. Quote Link to comment
datzenmike Posted June 21, 2017 Report Share Posted June 21, 2017 So I've tried it where I put my wire on the distributor and the negative on the coil. The tach is functioning, but it seems like about half speed. What I would guess to be 6k rpm is showing as 3k on the tach. All tachometers just grab the negative coil signal, so they know each time the coil fires. I've never seen anything different. NGK wires are better now, but I have a set from a few months ago that are 7K Ohms per foot. That's not ok. Yet an MGB set I have are 700 Ohms per foot. Different wire altogether, but still blue. You have to check what you get to verify if its good or just passable and functional. You want more than that if you plan to drive an trust things. Otherwise the coil will run hot and eventually fail. For that matter, I have a perfect NOS set of original 1979 plug wires here. I wouldn't wish them on any of you. Well, maybe Mike. LOL!!! They have 17,000 Ohms of resistance and WILL run poorly with a very hot coil. This 1200 tach needs to be between the coil and the distributor or in line. I already said this. Later ones could simply be connected to the coil for the signal. This is the inductive type and the signal has to flow through that loop on the tach from the coil to the distributor. Quote Link to comment
distributorguy Posted June 21, 2017 Report Share Posted June 21, 2017 Interesting. Some British cars do this on the positive side. I assumed he had an aftermarket tach fitted. Quote Link to comment
ErickwithnoK Posted June 21, 2017 Author Report Share Posted June 21, 2017 I believe that's how I have it wired: between the coil and distributor. Could resistance in the plugs and wires be my issue still? Quote Link to comment
ErickwithnoK Posted June 21, 2017 Author Report Share Posted June 21, 2017 It's on the coil negative and the only blade connector on the distributor. To attach it I disconnected the wire on the distributor, but didn't disconnect anything on the coil side. Quote Link to comment
datzenmike Posted June 21, 2017 Report Share Posted June 21, 2017 As I previously stated you may have to reverse the wires so current flows in the opposite direction. Quote Link to comment
kgrantkey Posted June 30, 2017 Report Share Posted June 30, 2017 I had an l16 stock and l18 stock. Same with my l20b. The best mod I made that gave me more performance was a bigger carb. I don't race it just drive it. Of course I've done the alt upgrade and electronic ignition. Put a 720 brake booster and master cylinder to help my drum brakes stop, and did that because I kept getting bad master cylinders from the parts stores. I do wish I'd kept my 79 king cab. More room and front disks. Quote Link to comment
ErickwithnoK Posted December 23, 2017 Author Report Share Posted December 23, 2017 Reviving this thread. My motor is in a different place than it was this summer, I took all of your advice and chose to wait to build a motor on the side. And I'm ready to move forward with building an l20 for the truck. I bought a 5 speed and an l20b block (bottom end complete, no head) for 180 bucks :thumbup: , and an engine stand for 20. The block has been sitting on the stand for several months now, untouched. I also recently grabbed a complete 620 dash off craigslist from a non-datsun guy for waaaay too cheap, and traded it for an a87 peanut head with a supposed reground (street?) cam and a set of SU's with a manifold. The 5 speed is in, the SU's are up and running, and now I have no excuse not to build the l20 and a87 motor on the side as a winter project since I can still drive my truck. Today I got real ambitious and took apart most of the block I had on the stand. All the peripherals are off, everything but the crank and the freeze plugs are out. Today I used air tools for the first time. GAME CHANGING... I live in the greater Portland area, and am wondering if someone can recommend a machine shop for me? Price is definitely a concern and I would like to do as much as possible in my own garage for the experience and satisfaction. Also in need of a cherry picker... Planning on 280zx flat tops, deck the head and block, hot tank, hone the bearing journal, new seals and gaskets, and if anyone knows of a place to buy rebuild kits for the SU's, I'm having trouble finding one. Cheers guys. [/url]">http:// [/url]">http://http://s1253.photobucket.com/user/erickwithnok/media/Mobile%20Uploads/20171123_074206_zpss6ks0sbo.jpg.html'> Quote Link to comment
datzenmike Posted December 23, 2017 Report Share Posted December 23, 2017 Time to get a divorce from Photobucket. Get it down to just the block and a machine shop can hot tank it, bore the block for you and hone to exact size with the correct finish, but I would supply the pistons marked for the cylinders you want them in. A good shop will measure them and bore to get the correct ring clearance rather than just boring to 86mm. Discuss the type of rings you want to run. With a perfect bore like this, you can run chrome or chrome/molly for long life. The head should be checked out and a small fly cut is ok but blocks seldom need it. You can check the combustion chamber size before milling, in case it's been milled before. Stock is 45.2cc give or take for an open chamber head and 41cc for a closed chamber. You should at least replace the valve guide seals. That's it for the block and head. The rest a backyard mechanic can do or the part is so small it's easily sent out. Quote Link to comment
wayno Posted December 23, 2017 Report Share Posted December 23, 2017 Someone should tell him what the compression ratio is gonna be with flat top pistons, open and closed chamber, he might need to rethink the piston choice. 1 Quote Link to comment
datzenmike Posted December 23, 2017 Report Share Posted December 23, 2017 #1 Stock L20B compression .......................................................... 8.4 #1 with closed chamber head......................................................... 8.9 #1 with flat top 86mm bore pistons.............................................. 10.11 #1 with flat top 86mm bore pistons, closed chamber head......... 10.87 Block not decked and both heads un-shaved. Compression would be much higher is anything was milled down. If you decked the block 0.020" or about 1/2 a mm (about the thickness of 4 sheets of newspaper) and if you did the same to the head, the resultant increase would raise the compression to 11.2. Again this would be way higher if the head was already milled. I would find out your planned compression first then increase the combustion chamber size by removing the shrouding around both valves with a grinder to lower the compression back down. You can also relief grind the block around the valves out to the edge of the gasket ring but staying above the top ring land.. Quote Link to comment
ErickwithnoK Posted December 24, 2017 Author Report Share Posted December 24, 2017 Mike, I would prefer to do as straightforward of a process as possible since this is my first rebuild. Would the dished 280zx pistons reduce compression enough to run regular or premium pump gas? Quote Link to comment
Crashtd420 Posted December 24, 2017 Report Share Posted December 24, 2017 Dished pistons will reduce the compression ratio.... but you will get the most benefit out of the peanut head with the flatops, because of the quench area mostly.... 10.87 isn't to bad, with mine the thought of it scared me at first but once I fired my high compression L16 my fears went away... And as mike stated you can unshroud the valve area in the head, even prep the spark plug area to gain ccs.... On my w53 peanut is was able to increase it from 41cc to 43cc... it sucked to do accurately but can be done with patience and time. Or money.... yes you will wanna run premium, i run 93. Quote Link to comment
Crashtd420 Posted December 24, 2017 Report Share Posted December 24, 2017 And i think premium 93 octane is easily good up to 11 to 1 cr.... above 11 i think it's either creative tuning or you need higher octane.... Quote Link to comment
wayno Posted December 24, 2017 Report Share Posted December 24, 2017 If you want a driver that you can fill up anywhere you need around 9.0 compression ratio, otherwise your likely going to have to get creative, like welding up the metal piece inside your distributor to keep it from advancing so far, this will keep it from knocking/pinging, but you have to get it just right, I will be welding up one side(short side) 1mm, I just have not got around to it yet, but I have not started the engine yet either. You can build it and start changing things to make it run properly like I am going to do, as i built mine already and then mentioned the compression ratio to my machinist, he made a face, it was not a good face, I am guessing that I am at 10.9 or higher CR(flat tops/closed chamber head). I started asking about it and got some suggestions from a couple guys that have built race engines, read this thread in the link below. http://community.ratsun.net/topic/72985-z20-build/ Quote Link to comment
flatcat19 Posted December 24, 2017 Report Share Posted December 24, 2017 Blah, blah, blah...engine math...yawn. Be careful where you use power tools. If it had a measurable tolerance, remove and torque down by hand. If it is a sealing surface, torque by hand. I just rebuilt a Camry(2009) 2.4 liter motor yesterday. I use 5 different torque wrenches to assemble one as per the repair manual. And that ain't even for my car! When I assembled my L, I brought home 3 "way too nice for a Datsun" torque wrenches. 1 Quote Link to comment
datzenmike Posted December 24, 2017 Report Share Posted December 24, 2017 Is this A87 a closed chamber head??? I just read A87 on the last page. Can you confirm if open or closed? Quote Link to comment
ErickwithnoK Posted December 24, 2017 Author Report Share Posted December 24, 2017 It's closed chamber. I definitely plan on trading in my harbor freight click style torque wrench for a bar style wrench so I can be accurate. Unless someone has a different recommendation. Wayno I wanna stay away from race motor thing a because it's my first rebuild. Welding inside my distributor sounds a little intimidating and hopefully if I choose the right hardware, unnecessary. It seems like the determining factor is whether or not the block or head have been shaved. I can measure the head with my calipers I think but the block is definitely too tall for that. What should the head height be? Are there other piston options with more or less bore and lower CR? Quote Link to comment
datzenmike Posted December 24, 2017 Report Share Posted December 24, 2017 #1 Stock L20B compression .......................................................... 8.4 #1 with closed chamber head......................................................... 8.9 #1 with L28 dished 86mm bore pistons.......................................... 8.6 #1 with L28 dished 86mm bore pistons, closed chamber head....... 9.12 There are no other pistons available you can use without also changing the rod lengths to compensate. Quote Link to comment
ErickwithnoK Posted December 24, 2017 Author Report Share Posted December 24, 2017 L28 dished it is then! Thank you Mike for doing the math for me. Should I rely on the machine shop for bearings seals and head components or source them myself? Is rock auto head stuff junk? Quote Link to comment
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