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| L18 engine build advice please http://www.ozdat.com.au/forum/viewtopic.php?t=3936 |
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| Author: | fr3ak [ Tue Dec 07, 2004 12:21 pm ] | |
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I just went and had a look at an l18, l20b and an l16. The l18 and l20b both have the same counterweights. the l16 doesn't have as many.
When i read-up about this, it seems it's the drill holes for the oil on the crank which makes them die. It's not that the crank will fracture, but the oil cannot lubricate the bearings at such high rpm because it is forced out under centrafugal force. No oil = breakage. It also says this only happens at 7500rpm. My "wannabe" race car will not rev to 9000rpm. So i'll do the best i can to get the most out of it BEFORE 7000rpm and therefore avoid problems... What recommendations on a cam to work great with a max engine speed of 7500rpm? Specs too please! |
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| Author: | thomas [ Tue Dec 07, 2004 12:51 pm ] |
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Chris, what do you mean by fully counterweighted? and I'm not sure what you mean by 6 bolt either. could you explain this please? Thomas. |
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| Author: | banzai510(hainz) [ Tue Dec 07, 2004 4:54 pm ] |
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thomas, There are weight inbetween the rods The L16 is not as fully counter weighted as the L18 or the L20. Get some nissan books it will be in there. As for the 6 bolt L18 cranks are very rare and mostly racing. The stock L18 came witha 5 bolt crank. This is how many bolts hold the flywheel on. all stock L16/18 have 5 bolt flywheel cranks L20s have 6 bolt flywheel cranks. L16 have 200mm flywheels L18 have 200mm flywheels in the cars ,Trucks have the 225mm L20 200mmm cars, trucks 225mm These are in the states and should maybe have the same in Austrailia. The L20b was not sold in Japan. Mostly Aussie and the USA |
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| Author: | Tazholio [ Tue Dec 07, 2004 7:41 pm ] |
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if the oil is getting "flicked" off the crank, causing damage... wouldnt that happen to all cranks? Yet there are plenty that are capable of higher RPM's... maybe look into why they are... different oil? i dunno |
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| Author: | Bondy [ Tue Dec 07, 2004 8:13 pm ] |
| Post subject: | L18 build cost |
Fr3ak, Bought the head cam and carbies from a Group Nc racer here in Brissy, Max Davies (although i think he sold car a bit later).  Cost was the best $800 i ever spent, but don't know what the individual costs were. The bottom end rebuild was around a grand, plus clutch. Only drama now, after a Mount Cotton hillclimb on sunday, is that the 4spd 200B box went bang as I grabbed second  . very short day all up!
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| Author: | fr3ak [ Tue Dec 07, 2004 8:40 pm ] | |
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if the oil is getting "flicked" off the crank, causing damage... wouldnt that happen to all cranks?
(according to Bob Waar) It's cuz there's too many oil holes in the crank. He suggests 'plugging' the oil holes to make them more suitable for high rpm use. There'd also be a whole lot more needed too...Yet there are plenty that are capable of higher RPM's... maybe look into why they are... different oil? i dunno Personally i know jack-all bout Datsun's and have no experience in racing them. I'll probably be happy to listen to whatever i hear off anyone who drives one every day. And BONDY, I enquired bout the Tighe CAM's. They are $340 and are all custom ground. I was going for a 288' duration with 0.526 lift. What do you guys reckon? I also bought my head, carbies, gearbox etc for $800. Must be the 'magical number'.
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| Author: | Tazholio [ Wed Dec 08, 2004 12:40 am ] |
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I got head, but it didnt cost my anything... |
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| Author: | fr3ak [ Wed Dec 08, 2004 12:55 am ] |
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Yeah, i got a pretty good head job for free too.  The only fault is the shaft doesn't have enough duration and/ or lift to match the good head. Kind of a waste really.... |
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| Author: | fr3ak [ Wed Dec 08, 2004 11:24 pm ] |
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In regards to my above 'wank-off' statement i though i should make some real sense of it. I've bought a Wade 'works copy' 74 degree rally cam. How'd you reckon she'll go in my L18? What are the specs? |
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| Author: | LIndsay [ Thu Dec 09, 2004 12:01 am ] |
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we used to rally the L18 b4 L20's were available - I dont know of any ever breaking a crank in a rally - do know of a lot of L20's that broke cranks tho, mainly early prior to bluebird S2 when they are radius ground as standard. OK first do u require it to be under 1800 cc, if so forget big pistons. If u just need an L18 block - most rally cars have either a l20 crank or z22 crank in an l18 block - this done by tunnel boring the block to take the larger mains of an l20, use Stanza rods if L20 crank. Unless a lot of headwork is done, it wont rev and produce power much after 7000, the 74 cam should be fine, while u have 40mm carbs, to go wilder cam u will need big ports, big valves, bigger carbs and prob in excess of 2 litres - would not spend lots on custom stuff for a crank cuse i dont think that will be the weakest link - would suggest u look at a light flywheel, if u want revs. |
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| Author: | Tazholio [ Thu Dec 09, 2004 11:25 am ] | |
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Yeah, i got a pretty good head job for free too.
So your saying you have a small shaft?
The only fault is the shaft doesn't have enough duration and/ or lift to match the good head. Kind of a waste really.... |
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| Author: | DRracing [ Thu Dec 09, 2004 6:00 pm ] |
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Terry, Terry, Terry, wot are we going to do with you dood?? 
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| Author: | proL18 [ Thu Dec 09, 2004 7:22 pm ] |
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chamfer the oil holes in the crank to keep the bottom end alive above 7000rpm. shotpeen and polish it too, while it's out...and i mean POLISH it. have your mains caps cryo treated and use ARP studs to secure everything. second hand bolts are used to hold your radiator in place, not inside your engine. maybe even make a cradle to keep everything square. shotpeen and polish your rods too. remove all casting marks completely. that's all the datsun racing team in the US did to their 1600 (minus the cryo treatment and ARP stud kit) in 1971 and the same engine lasted all season without coming apart, except for oil and filter changes, with frequent excursions to 7500. |
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| Author: | fr3ak [ Thu Dec 09, 2004 8:50 pm ] |
| Post subject: | |
Thanks Pro! That's some good info. And i'm only keeping the 1.8 capacity to keep it 'original'. And cuz i've decided to not put much more money into it... I still haven't figured out the duration of the works copy Wade 74 degree rally cam. Anyone? Restoration begins tomorrow! |
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| Author: | DAZDA [ Fri Dec 10, 2004 9:19 am ] |
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The 'advertised duration' will probably be about 296 degrees. |
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