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240z SCCA vintage race car, restoration

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On 10/23/2022 at 9:12 PM, clarkspeed said:

I have found the toughest thing on a 5.5 and smaller button clutch is pulling it on a trailer. Many winch just for that reason. I also found the 7.25" dual clutch set up to be much more forgiving. Virtually same durability and heat resistant as a stock based setup. Can work for street or track.

hey thanks Clark! Il have to look into that for the next motor. I’m assuming the 7.25 comes with it’s own dedicated crank mounting surface (not really a “flywheel” I suppose)? Any ideas on what I should run with the 9lb OEM diameter flywheel? I was just going to default to an Exedy OEM clutch unless someone had a suggestion. This is for the interim period before the car is competitive. Ideally I’d get an unsprung disk, but I don’t really need anymore torque capacity than what OEM offered. Saving the 5.5 for the meantime. 

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My take on stock clutches is to use a stockish disk and a heavy duty PP. The puck clutches tend to chew up flywheels, and I had a friend with at CA18DET that chewed a groove in the flywheel and that took out the thrust bearings on the crank. My ACT pp and their "street" disk held up to my L28 with cam, 44s, etc.


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1 hour ago, JMortensen said:

My take on stock clutches is to use a stockish disk and a heavy duty PP.

I agree.  I'm also using an ACT heavy duty PP and street disk. It's holding up to 300+ HP with no issues, but I'm also not dumping it on slicks either. So YMMV depending on your setup and how you dive it.


Edited by rossman
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Thanks guys! I had the same experience Jon. I’m glad it wasn’t just me. I had a 6-puck on the 300ft-Lb L28et, and it started losing grip from all the material removed on the flywheel. Not from the actual pucks themselves wearing. You are the first person who I ran across that had the same experience. Clearly the hardness of the flywheel’s friction surface was inappropriate for the aggressive disk material. I also switched to what the clutch shop called a “double” PP, and an unsprung “street” disk material. 

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21 hours ago, clarkspeed said:

Never had a problem with grooves, but I still prefer disks with spring combined with HD pressure plate and lightweight Flywheel for street apps and racing "on the cheap". Feels so much better and can handle anything a NA L6 puts out.


100% agree on the dual or heavy duty PP being more than enough for any NA L-series. 


I'm surprised to hear you like the sprung disk. Maybe I could give it a try and see how it goes. It just always felt "squishy" to me when I was shifting quickly, especially at lower speeds. It was really evident when the car had a change in momentum as well, for instance going from downshifting to getting back on the throttle. Maybe the heavy spring rate and suspension had more to do with it, and the sprung clutch was just adding to an already "squishy" chassis/suspension. 

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Alright folks, I went ahead and purchased the OEM exedy clutch. I really evaluated what I needed this for, and realized I was tying myself in knots. This clutch is for me to get the car around town while I tune the suspension and motor, so clearly I was over thinking it. I have the 5.5” for competitive racing, and should keep that in mind. I looked into the ACT HD and XD Pressure plates and they were twice the price of the whole OEM kit including disk etc. 


I will likely purchase the HD PP for the 3.1L which will be a good compromise until I consider a 7.25” unit for that motor. 

Not much as far as updates. Been two months of travel, COVID, and work so looking forward to getting back in gear. Finishing the rear lower valence filler work at the moment. Still have the drivers side lower quarter, both doors, and both fenders left. Then can finally spray and start reassembly. 


I was planning to be in Daytona for Greg’s HRS race this Friday but had an important client request that day. Taking the red-eye to spend the weekend with him for the 24hr historics instead. 




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8 hours ago, clarkspeed said:

Umm the red eye.  Believe it or not, depending on which road you take, I am on the way to Daytona.  My shop is maybe 3 miles off the 417 Toll Road in Oviedo. My weekend is fairly open except for plans Saturday night.   When are you driving back?

I will send you a message!

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Hello friends! I will start with the question first: What are you using for main and rod bearings for your L-series race engines? Should I just source OEM Nissan bearings? Kameari sells bearings too. 

Now for some show-and-tell. My rods came in, so I wanted to share with you the parts going into the 3.1L race motor. Sourced from Kameari direct from Mori-San.


Rods are 137.5mm, or 4.5mm longer than the usual L24 rods used. Will yield a higher rod-ratio than sourcing OEM rod length and piston deck being. They are 490g, which are lighter than anyone else’s published (pre-engineered) rods I could find. 

Racing pistons are forged w/ 3.2cc valve pocket volume. Deck height matches with rod length for a near flush deck. 88.5mm


also going to try out the infamous chain sprocket to replace the tensioner. 


N42 is with Yoes doing his magic. 11.5:1 so I can get fuel from my local 100 octane pump. 







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@AydinZ71 I went through something similar, the dims my crank was done to from one builder ended up being NLA so the entire crank had to be welded and reground which cost maybe 1k overall so fairly reasonable. The knife edging and a bunch of other work was already done, and I got the crank in a deal so it made sense to keep it. Depending on how far you want to go with it, choosing your bearing types are still on the table if you're willing to do that. 

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10 hours ago, Dat73z said:

@AydinZ71 I went through something similar, the dims my crank was done to from one builder ended up being NLA so the entire crank had to be welded and reground which cost maybe 1k overall so fairly reasonable. The knife edging and a bunch of other work was already done, and I got the crank in a deal so it made sense to keep it. Depending on how far you want to go with it, choosing your bearing types are still on the table if you're willing to do that. 

yeah thankfully not much work left to do on the crank itself. It was off by 5 though (straightness), but they were able to straighten it. Apparently that’s quite common with the V07 cranks. They seem to be quite confident about what bearing material they want to use so I’m going to just let them go after it. Most of their business is race engines so I trust them. 

I’m not planning on knife edging or doing any mods to the crank itself.  I just don’t have enough experience with that and the shop didn’t recommend it unless I was aware of another motor with enough track hours as a comparison. This will be an 11.5:1 CR racing engine so I’m being a little conservative. The pistons and rods will have a significant weight reduction though. I doubt the head will flow enough to make it worthwhile, but the short block should be capable of 8k rpm with the rod and piston selection I have. They will balance the whole rotating assembly, and will likely add some small reliefs to the crank where necessary for balance.


i should have it all ready in Q1 23’, so I will likely run the 2.4L EP motor before this guy has a chance to go in. 

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I'm no expert at all on this. But I can say what works and add remarks from other engine builders. I don't think knife edging is worth it. I've heard a bull nose rounding is preferred for reduced wet sump drag but have no data to back it up. My builder is doing nothing to my V07 crank. And yes they usually require a little straighten.


I also do not have the secret sauce to spin a V07 build beyond 7200 RPM. Lighter weight pistons and rods? I don't know. I don't think super precise balancing is enough. I destroyed one years ago over reving.  You can review the TonyD posts, and I have no reason to doubt him. But he doesn't post the recipe either for others to follow. Nor should he.

So with that said, the devil is always in the details for a good build. Tolerances, gaps, and clearances must be perfect. And most good builders have their own recipe they don't tell you. My personal experience, and I have built many myself, is pay attention to the details or trust a race engine builder who does. Either way, I do not intend to spin mine very high.

As far as bearings, Nismo still sells the "choose your clearance" mix of sizes. I just found that ACR has similar and that is what I ordered for my current build. Maybe I will need to mix a few, maybe not. But with either you have the possibility to control oil cushion to the tenths.

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@clarkspeed Thanks Clark!

Reciprocating weight was definitely my interest on this engine. Since I was considering this for a track motor, I really had no interest in using the V07 crank unless I had some confidence that I could reduce the reciprocating assembly weight by a large margin. Of course I am assuming the weak-point are the rods at high RPM. I mean, I have not seen a stock forged L24 or L28 crank "break" yet (w/ stock internals), but that doesn't mean it cant/wont happen. Zero experience on the V07. I am just running under the impression that the forged crank is as solidly over-built as any other Nissan crank from that time. 


Some data:

- Conventional stroker build utilizing OEM components (weights from various forum posts): 

L24 rod: 711g

KA24E piston: 375g (no wrist pin)


- The Kameari parts I have:

His Drag I-beam rods: 490g

Forged racing pistons: 290g (no wrist pin)

4.5mm longer rod for increased rod ratio


According to Kame, she will rev to 8k no problem but I still don't think the head will flow enough air to make use of it. I'm just guessing I will be shifting somewhere around 7k, but we'll see what she does on the Dyno.


The head is with Mike Yoes at the moment. I think we talked about a .54 lift, 295deg @.05 duration. Most importantly, he is doing his magic on the porting and chamber work. That is not something I trusted the race shop with, since it is hyper specific to the L-series (where and what to remove). He also has my Jenvey manifolds to port-match. Header will be my Stahl unit with the 1-5/8 primaries. 


We will see how she runs! I'm not trying to get every ounce of HP out of it. In fact, the head will only be 11.5:1 for 100 octane. The goal was to have something that would last, and be reliable. I'm fine with having to replace rings, bearings, but the plan is to avoid a catastrophic failure that can otherwise be avoided.  


I will be surprised if she puts out 300hp, but who knows. 


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Oh it will be a powerful engine no doubt. And should be around 300+ no problem. Just something about tertiary harmonic vibration on the V07 crank that likes to eat bearings. Even with a good damper. If you can sent it to 8k regularly, let me know and I will copy your recipe! 

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  • 1 month later...

Hi all! 

Question for the group: Anyone have resources/pictures/ideas on modifying the OEM oil pan? My budget is currently going towards the things I don’t have the tools or skill to perform (engine internals, machining, etc.) but I think I can manage welding up an extension on the oil pan and considering some baffles. Already need to weld-on a bung for the oil temp sensor, so I thought why not have it a go. 


The “racing” oil pans seem to be in the $600-$800+ range, and I have no problem welding sheet metal. Does not seem sufficient enough weight savings to spend that much on an AL unit. 

I already have a 3qt accusump, so I’m more concerned with addressing G’s than adding much capacity. 

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