josh817 Posted January 11, 2009 Share Posted January 11, 2009 Alright so you guys are going to help me figure out what the hell happened to this motor before my customer bought it. Not only did it run lean/detonate, it also has what seems like a wide variety of ****ed up internals. So this is what happened. I have a new customer, he wants a hot street motor, I said I can build and install in his car for him to drive off when he arrives for $3500. Ok so everyone is happy, I get the motor and tear it down with the intention to rebuild big as a 2.3L, big cam, high comp, headers, etc. motor. I see why it needs a rebuild. One of the cylinders had a problem with firing it appeared and the bearings were shot to hell. Upon further inspection it looks like the little set notch in the bearings had broken off on one. I know if anyone ever heard of an oil change/filter because these bearing look yucky big time. Ok so from my 3.1L motor I had 2 KA24 pistons left. My plan was to bore the block out to 89mm and use a set of the KA24's in there. My dad comes up and checks out the pistons and wow good thing we checked, the pin height on the KA24 is much smaller than the piston from the motor. Like over 4mm smaller. So I pull out the How to Mod your Datsun Motor book and it has all sorts of charts with numbers for all the Datsun motors. This is where things get messed up. I already knew this motor was hot before I did anything to it, it had 88mm bores instead of 85mm, already had a .495" 290º cam, header, cylinders were notched (don't know if thats stock), lightened flywheel, etc. So we know these pistons are 3mm over bore, but hey look the pin height is 41mm rather than 38.1mm. Hmmmmm I said to myself in a sly manner. So then I decided to put the crank back in and one rod with its piston. At TDC the piston is just under/flush with the deck. Well how can this be if its 3mm too tall? So I check the rods. The rod journals should be like 50mm or something like that, these are 52mm... The small end of the rods have bushings too and I didn't think Datsun made them with bushings, I know mine weren't but those were 240 rods. So then I check rod length, they SHOULD be 145.9mm but are they? Hell no, they're like 142mm or some **** like that. So then I think and I tinker and hey, my 18mm socket is kind of loose on the rod bolt, let me get a 17mm socket. Uh oh it doesn't fit, wait a second... whats between 17 and 18mm .... 11/16"... >_< DOAH! I KNEW THOSE LOOKED HUGE! By this time I'm going ape ****, especially when I tried to take the rings off one piston and the oil ring happened to be one piece, never seen that before... To further explore I thought jee these rods fit on the crank, which should have 50mm rod journals. Well that too is messed up and it has 56mm rod journals and the mains were too big also. So now I say ok the crank fits in the block, I check the block and the mains on the block have been align bored too! RAH! I shouted, when will it ever end! You have to understand that the more stuff isn't what it should be, the more I spend to make it right, meaning that $3500 isn't going to be much profit by the end of the day. I need to pick up a Haynes manual for the motor and I can double check the numbers but these seem so far off and so consistently wrong I wouldn't be surprised if whoever built this motor built it from scratch or something and no wonder it broke down. Who knows, maybe the things like rod bolts and larger mains and such were all part of like a racing setup for added strength... Now we guess what happened to the motor and whats inside it... What we know Rods: -142mm, proper center to center length is 145.9mm -11/16" cap nuts -52mm big end, proper is 50mm-ish -Bushed small end Crank: -56mm rod journal, proper is 50mm-ish (I think, may be 51mm) -66mm Main journal, proper should be like 62mm I believe -Fits in block and rods fit on crank Block: -Notched cylinders -Over sized mains -88mm bore -Pistons have a one piece oil ring -.495" 290º cam -Lightened flywheel -Header Pictures are of the car, damaged piston which I'd like to say was detonation because on twin SU's 2 pistons would be raped but only 1 was, damaged rod and main bearing (all them were that bad), notched cylinders, head gasket which leads me to believe it may be stock to notch since the gasket doesn't look cut unless it was made specifically, valve cover, cam, and rods because I liked how beefy they seemed to be I almost wanted my own set. Quote Link to comment Share on other sites More sharing options...
blue72 Posted January 11, 2009 Share Posted January 11, 2009 Z22 Rods? Quote Link to comment Share on other sites More sharing options...
josh817 Posted January 11, 2009 Author Share Posted January 11, 2009 Nope, connecting rod journals for all cranks and rods are the same from L13 to LZ24. The only center to center lengths Datsun made was 133mm 130.2mm 145.9mm and 152.45mm. Quote Link to comment Share on other sites More sharing options...
hoov100 Posted January 11, 2009 Share Posted January 11, 2009 is the HTML code broken as all i see is a wall of words. seriously though, paragraphs are your friend and ours as well. Quote Link to comment Share on other sites More sharing options...
josh817 Posted January 12, 2009 Author Share Posted January 12, 2009 So can anyone see the pictures? Quote Link to comment Share on other sites More sharing options...
blue72 Posted January 12, 2009 Share Posted January 12, 2009 I don't have any problem seeing the pictures. Nope, connecting rod journals for all cranks and rods are the same from L13 to LZ24. The only center to center lengths Datsun made was 133mm 130.2mm 145.9mm and 152.45mm. So you're saying your rods have 142mm center to center length, not 145.9? I thought you were referring to them the other way around, so I mentioned the Early Z22 rod because its supposed center to center is 145.9mm. The L20B rod is right in the same boat too. Now I have to troll around and find a rod that fits your measurements. Hmmmm..... Haven't played with any R or U series engines yet. Just as an update to your list of rod lengths, to fill in the gaps with some you didn't have: L series rods alone have center to center lengths of 130.35, 133, 135, 136.6, 138.5, 140, and 146mm, plus two that I haven't tracked down yet. Also, the late L20aE, late L24E, and late L20ET rods had smaller rod journals than the rest. Quote Link to comment Share on other sites More sharing options...
josh817 Posted January 12, 2009 Author Share Posted January 12, 2009 This setup in here looks to be a hot setup meant for strength too. This rod has standard (non metric, whatever you want to call it) rod bolts that are pretty beefy, bushed small, and over size big end to fit the over sized rod journal on the crank. Its an L20B crank that I can tell from the counter weights and how they have wedges cut out of them for balancing, but the journals are all too big so it seems like maybe they welded them up and polished. I'm weary of my measurements so I want to triple check them but being millimeters off isn't a mistake to me. NOTE: Nissan rod bolts have an oval/half circle head to their rod bolts, these are full circle heads and the bolts are pressed in, with 11/16" nuts. Also note the oil hole at the top. This may have been done if a stock rod was bushed to provide oil to the pin, it doesn't look like it was added though... However if you look closely, you can see on both sides of the rod there were oil holes that looked to be filled in and ground down. My L24 rods from the stroker, in the middle of lightening and polishing. Note the small end shape and the rod bolt heads that are semicircles: I've come up with a different and better plan. Since its a street application and the customer is a police officer, he probably won't want to be doing high speeds rather than having a fun through the turns on a nice day car. With that said, I think I will do the combination of a Z22 crank, KA24 89mm pistons, and L20B rods. The crank is is barely counter weighted plus it is a 92mm stroke rather than 86mm stroke. This should give him an almost 1:1 rod/stroke ratio plus the bigger stroke will open up some torque hopefully. PS: If you can't see the pictures please visit my photobucket. I keep all my Datsun stuff there so maybe you can find useful things as well as the pictures in this thread. Thanks! http://s14.photobucket.com/albums/a333/josh817/Customers/Datsun%202000%20Roadster/ EDIT: Does anyone know how to read the number on the rod? What do these numbers mean by any chance to possibly identify what rod this could be. I double checked my measurements and these are in fact 145.9mm. Good thing you double, triple, and I like to make it a habit of quadruple checking everything before buying... Rod bolts are still something with of a standard size. Bolt measures 11mm at the threads and 10.25mm at the non threaded portion. Big-end is measuring a confirmed 55mm and according to the books the rod journals on the crank should be 49.961-49.974mm. You think bearings take up 5mm? I think no. Quote Link to comment Share on other sites More sharing options...
blue72 Posted January 12, 2009 Share Posted January 12, 2009 Is your crankshaft cast with the number U60? Quote Link to comment Share on other sites More sharing options...
josh817 Posted January 12, 2009 Author Share Posted January 12, 2009 I'm not sure. I looked for cast marks and didn't find anything but it was a quick look over. It has these wedges on the counterweights: Quote Link to comment Share on other sites More sharing options...
johnc Posted January 12, 2009 Share Posted January 12, 2009 The only center to center lengths Datsun made was 133mm 130.2mm 145.9mm and 152.45mm. Nissan Motorsports also sold a U20 rod with a C2C length of 144mm. Part number 12100-25500. I can't match that -25540 part number with anything in my collection of old Nissan Motorsports catalogs. Quote Link to comment Share on other sites More sharing options...
josh817 Posted January 12, 2009 Author Share Posted January 12, 2009 Perhaps this is the reason why all the lower end bearings are shot... That doesn't seem like enough of a hole for oiling to me. :/ Maybe I'm just crazy. I probably am. I believe on our L6 rods they have big lump things I guess you could say with the oil hole in them, helps sling oil up onto the cylinder wall however when I polished my rods I got rid of the lump but kept the hole open for flow. The hole was probably the same size, maybe a little bit bigger than on this rod. Quote Link to comment Share on other sites More sharing options...
blue72 Posted January 13, 2009 Share Posted January 13, 2009 Did some researching, and a lot of what you have looks like standard U20 stuff. From the FSM: U20 1982cc I-4 5 Main Bearing Crankshaft Engine Bore = 87.2mm Piston Wristpin Diameter = 22mm Engine Stroke = 83mm Crank Journal Diameter = 62.942mm – 62.955mm Crank Pin Diameter = 51.941mm - 51.954mm Rod length = 144mm Here are some screen captures of the FSM itself: Connecting Rod One piece oil ring Factory notched cylinder bores Here's a chart that shows oversized piston options including 88mm You might get more help over at 311s.org Quote Link to comment Share on other sites More sharing options...
josh817 Posted January 13, 2009 Author Share Posted January 13, 2009 Did some researching, and a lot of what you have looks like standard U20 stuff. From the FSM: U20 1982cc I-4 5 Main Bearing Crankshaft Engine Bore = 87.2mm Piston Wristpin Diameter = 22mm Engine Stroke = 83mm Crank Journal Diameter = 62.942mm – 62.955mm Crank Pin Diameter = 51.941mm - 51.954mm Rod length = 144mm I agree with some of the stuff but things like bore and stroke... Should be an 86mm stroke and 85mm bore stock... I mean unless the U20 was a unique casting from Nissan? All my research says L20B but just like our L28's, there are different castings... I agree with the wrist pin size, not sure what to think about the crank journal sizes, and the rod lengths should be 145.9mm... unless like I said the U20 was a unique motor. Also, unless the pin height of the piston was something similar to the one from this motor (42mm+) the compression ratio for those sizes is 7:1. I can't argue with the pictures though... Its clearly obvious that something was different about this motor... It may just be in my best interest to start from scratch so this customer doesn't have a blown motor. These are the numbers I was going off of. We need TonyD in here or something... This is too strange for me... Quote Link to comment Share on other sites More sharing options...
Cobra_Tim Posted January 13, 2009 Share Posted January 13, 2009 U20s and R16s dont share much with the L series. You do know you have a U20 there right? Quote Link to comment Share on other sites More sharing options...
josh817 Posted January 13, 2009 Author Share Posted January 13, 2009 Yah the block reads U20. This is kinda sucking because I have no idea what will fit what now... Was the U20 not a division of the L20B or is the L20B in like the Datsun pickup trucks? Made an account at Ratsun and hopefully I'll get some answers. Quote Link to comment Share on other sites More sharing options...
johnc Posted January 13, 2009 Share Posted January 13, 2009 U20 predated the L16/18/20 and there is not much commonality. http://www.gordon-glasgow.org/Evil_L.asp Quote Link to comment Share on other sites More sharing options...
josh817 Posted January 13, 2009 Author Share Posted January 13, 2009 Ah yes.. lovely... I did some reading and saw that they are 2 different things and now I feel like a dumb ass for thinking "Well the L series motors had the same setups, just 2 extra cylinders is the difference but hey look durrrrr this doesn't look like an L series..." Pretty much like asking if an L28 is an RB26. Alright well thanks guys for the help and hey, I guess if anyone is interested in this block, crank, and rods, give me a yell... Admin, care to delete this thread now? Quote Link to comment Share on other sites More sharing options...
Cobra_Tim Posted January 14, 2009 Share Posted January 14, 2009 Ah yes.. lovely... I did some reading and saw that they are 2 different things and now I feel like a dumb ass for thinking "Well the L series motors had the same setups, just 2 extra cylinders is the difference but hey look durrrrr this doesn't look like an L series..." Pretty much like asking if an L28 is an RB26. Alright well thanks guys for the help and hey, I guess if anyone is interested in this block, crank, and rods, give me a yell... Admin, care to delete this thread now? I think my uncle has parts if you need them. We raced his vintage roadster and one of the BRE roadsters for several years. We know a thing or two about the U series Quote Link to comment Share on other sites More sharing options...
gira Posted January 14, 2009 Share Posted January 14, 2009 PS. The U20 engine is known for beating the bottom end bearing to death. Don't rev it up to high. That engine has a super heavy crank that seems like it should be built for a tractor trailer, but the harmonics beat the crap out of the bottom end. Quote Link to comment Share on other sites More sharing options...
Cobra_Tim Posted January 14, 2009 Share Posted January 14, 2009 That engine has a super heavy crank that seems like it should be built for a tractor trailer Thats cause it is Quote Link to comment Share on other sites More sharing options...
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