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1973_240z_

L24 build, I need help!

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I have a spare L24 out of one of my 73 240's I'm looking to build up a bit. I'm currently attending an automotive school and I have access to pretty well equipped machine shop. My idea here is to find out I can do with my E88 and the L24 bottom end, possibly different pistons if they're necessary. I plan on utilizing ARP hardware throughout the engine. I have a 4bbl and azc intake mani laying around, as well as dual downdraft webers...I'm strongly considering ditching both of these setups to fund a set of triples for this engine. I'm pretty much just looking to see what kind of power and rpm I can get out of my L24, drivability is not a big concern at all. I'm just not quite sure where to start with the top end. I'd like to make power as high in the rpm range as this head and bottom end will allow, and I don't know what cam specs would best suit this engine. I don't know a whole lot about milking power out of these engines, but I'm here to learn. Any input would be greatly appreciated.

-Josh

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Search is your friend. I have a set of 86mm pistons on L24 rods available  if you really want to punch it out. You have a sonic tester available ? 

Go big or go home on the cam . Later versions of the E88 aren’t the best combustion chamber , but maybe learn to weld close those chambers ?

Running 490/290 and still very street friendly. 

Youll be limited on rpms with cast pistons , but still get 7k plus. 

Bump compression for sure.

My e88 is shaved .050 to get some more compression . 

 

Lots of of ways to get power, but spend the time and money on that head, or find a different head with a better combustion chamber 

 

 

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I've been lurking on forums recently and have found a lot of info already, I've looked at quite a few of your posts actually! I'm really looking for some more info on cams and what all could be done with the combo I have.

I saw that a shop in VA is using N42 heads and making the combustion chamber into a heart shape, would that be worth attempting with my E88? I was looking at the cam kit on zcarparts.com with the 10-2006 cam but I hesitate to pull the trigger on that after reading, possibly a bit too much, about Schneider cams on multiple forums. I plan on shaving the head as much as possible to bring the compression up. I believe the machinist instructing at the school mentioned being able to weld on and rework combustion chambers.

I've been back and forth on spending the money on forged pistons.

 

BTW I found a list of what all I have access to at the school

  • Hines Legend CrankShaft Balancers
  • Sunnen SV-10 Cylinder Hone
  • Peterson Cylinder Head Center
  • Peterson Milling Machine
  • Kwik-Way Flywheel Grinder
  • Super Clean Front Load Parts Washer
  • Hot Rinse Station
  • Peterson Blast Cabinet
  • Sunnen Rod & Pin Hone
  • Kwik-Way Valve Grinders
  • Kwik-Way Boring Bar
  • Sunnen Cap Grinder
  • Super Flow SF-450 Flowbench
  • Super Flow Powermark Engine Dynamometers
  • Mustang Chassis Dyno

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Welding chambers is for seasoned veterans I think, but doable. You could shop for a maxima cylinder head which already has small heart shaped chambers . They would  also be cheaper to obtain. 

I’d do a budget build first to experienced on these motors . Your not going to get a lot of knowledgeable help easily . 

Do a regrind for your cam. Cheap and reliable. I’d do a drilled cam and ditch the spray bar . 

Bottom ends are about bullet proof, so don’t spend a lot of money there. 

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I already have a very mild rebuilt 12/72 L24 with flat top .040 overbore pistons, with a ported E88 and stock cam in my car, I'm doing this engine since I had it sitting in the back of my garage collecting dust. I'm by no means an expert, but I'd like to have some fun with this build just to take advantage of the machine work being "free". I've heard of doing a maxima head, when I first got bitten by the S30 bug, I'd never given it much thought though. Might be able to find one locally. This is my 3rd time taking an L6 down to bare block and going through the whole thing myself, measurements and all mainly for practice when I was a little younger (I'm only 18 now, bought my first 240 @ 13). This is just the first one I have some more budget, and more importantly, some time to play with. Thanks for the ideas!

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Don't know when your carbs are going to be the limitation but this is how I see it:

 

- over 6500-7000 RPM needs forged pistons for a reliable build. This would require boring and getting new pistons, a bit over >$1000. 

So very high duration cams might not be needed, maybe a 280/290 duration would be enough?

 

- Over .460" lift and you need different springs and seals. So if you want to make life easy you take a cam with a max lift of 0.460". 

If you want to machine your head then this wont' be a problem.

 

- Over .480" lift reground and you typically need to mess around with thicker lash pads and aftermarket retainers. Not rocket science but takes a little time to fiddle it.

 

- High lift cams might need valve pockets cut out from the piston, there is no rule because there are many parameter but typically a 300 duration 0.550" lift cam would probably need it. A 280 duration 0.480" probably doesn't. But again, other factors that determines your piston to valve clearance.

 

- High duration and high lift really needs a good head. Stock head flows badly at these operating points. The required work for a 8000 RPM head is typically more expensive then head work for a 6500 RPM engine. Bottom line is that race cams and stock heads is a waste of money.

 

I would get a Isky L-490, I think over that and that head might be a limitation. Do you have any flow numbers on the ported head?

 

For my first build I got a 280 duration 0.480" cam and cast pistons, it's a nice sweet spot and pretty easy to build.

But seems like you want to be a little more aggressive.

 

Anyhow, there are a lot of factors.....

Edited by turbogrill

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I’d say shoot for the most you can without forged slugs . The most CR with pump gas and the most cam that’s makes sense with cast pistons . 

Im anxious to do these pistons I have , but alas the next engine will be the L28.

Time to move on from the 24, but I do love this motor. I’ve beat on it A LOT,and she keeps giving !

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It’s great to hear someone say more than “just go with an L28” about the L24! Thank both of you guys for the suggestions, I’ll try to remember to keep this updated with what I end up doing to this engine. I think I’m just going to get whatever I can out of this E88 unless I find an MN47 before I get to doing the head work. Datsun parts are hard to come by in my area, which is why I ended up buying two cars to make one.

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car-part.com 

used car part market . I saw a bunch in your area all day for 150$

 

Lots of them around . Cheaper and the Z guys don’t think about them

 

You can’t open the ports as much as the earlier heads, but your just filling L24 bores so ...

Edited by madkaw

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Hey pickup a copy of "how to modify your Nissan/Datsun OHC engine" https://www.ebay.com/itm/How-to-Modify-Your-Nissan-and-Datsun-OHC-Engine-ExLib-by-Frank-Honsowetz/142883149470?epid=102900406&hash=item21447fd69e%3Ag%3AGJMAAOSwbaxbWUHc&_sacat=0&_nkw=how+to+modify+your+nissan&LH_ItemCondition=4&_from=R40&rt=nc

 

there's loads of information about some modifications that you can do, and will give you insight on how to approach stuff. :)

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