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Leon's Other 260Z


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#41 Leon

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Posted 22 April 2013 - 03:48 PM

Just a little bit of progress made last weekend. I've been cleaning out the garage for months now, trying to create some semblance and organization of an actual shop (rather than a storage facility). Finally, this weekend it became clean enough to actually move the Z in and out of the garage!

 

Of course, I had to give it the long delayed "first wash"... :)

 

DSCN1911_zpscb3e4f0d.jpg

 

DSCN1910_zps87de5b99.jpg

 

The paint is in pretty good shape, but needs a good detail. (note: the car is completely dry in these photos)

 

DSCN1912_zps5907a971.jpg

 

DSCN1913_zps14c0d6bd.jpg

 

DSCN1914_zpsc1ad308b.jpg

 

DSCN1918_zps776f59f3.jpg

 

 

At this point, I'm looking for a good core P90 or P90A head to send to the machine shop. Once I have a head, I should have everything needed to finish it up.



#42 Gollum

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Posted 23 April 2013 - 01:53 AM

I have a P90 but it's going to need some minor machine work. It got buggered pretty good on an exhaust stud removal. To be done right it should probably be welded and re-drilled and tapped. It might survive with just an oversized helicoil though. Make me an offer. :-)


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#43 Leon

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Posted 23 April 2013 - 06:07 AM

I have a P90 but it's going to need some minor machine work. It got buggered pretty good on an exhaust stud removal. To be done right it should probably be welded and re-drilled and tapped. It might survive with just an oversized helicoil though. Make me an offer. :-)

 

PM sent! :)



#44 tamo3

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Posted 23 April 2013 - 06:12 AM

Wow, without dust, your deep green 260z looks so great now!



#45 Leon

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Posted 23 April 2013 - 07:28 AM

Wow, without dust, your deep green 260z looks so great now!

 

Thanks Takashi! Good seeing you at the show on Saturday. Get those brakes finished up!



#46 Leon

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Posted 29 April 2013 - 09:51 AM

Looks like I finally have all the parts I need. I bought a P90 and picked it up over the weekend thanks to Ray (and Alex)! Hope you enjoy the pie, Ray. ;)
 
It's complete and looks like a very good candidate for a rebuild. Not bad for $100 (plus gas money and a pie). Sure beats the crap out of those inflated P90 head prices I've been seeing. I'm not one to complain but $600 and it has a chip in the combustion chamber? LOL. Yeah, right...
 
DSCN1959_zps7c627acb.jpg
 

DSCN1960_zps80969bd4.jpg

 

DSCN1961_zps8c0ece14.jpg

 

I'll be stripping it down this week and then sending it to the machine shop (not sure whether I'll be using Baca's or Clark's at this point) along with the block, crank, and rods. It'll feel good to finally make progress on this thing.


Edited by Leon, 29 April 2013 - 09:54 AM.


#47 tamo3

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Posted 29 April 2013 - 10:21 AM

Looks good, $100 for that is great deal!

Are you going to porting intake and Ext?



#48 JCan

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Posted 29 April 2013 - 12:25 PM

Wow!  Great find!

 

Some lessons learned from my rebuild.

 

1)  be sure to grind your rocker arms prior to reassembly.  I did not and had problems with the rocker arms not mating squarely with the lash caps and the cam.     (see pictures)  The old lash pads wore in the middle and not on the sides, the new lash pads do not have the indentation on the sides so an unground rocker arm does not sit properly on the cap.  This caused me a lot of time to find out why my engine had a loud tapping sound.

 

2)  if you are going to purchase an isky cam.  I ended up with the Isky stage II cam 715148 (see picture below).  With my SUs the car is too lopy and too loud.  This summer I am going to swap back to the isky stage 1 cam.  I suggest the stage 1 cam.

 

3)  I used cast flat top pistons on my N42, 2.8L block.  The crank/block combination pushes the pistons above deck by approx 0.025"  (0.65mm).  I purchased a custom copper head gasket which was 0.063" (1.6mm)   which gave me a gap between the piston and head of 0.037".  When I ran the stock head gasket, I believe the piston to head clearance was 0.025" which concerned me.  My resultant compression ratio is 9.83 instead of 10.2 with the Felpro gasket.

 

4)  Please find shims that are 0.040" and use two instead of four of the 0.020" shims.    I had mine custom made.  it was inexpensive.

 

Thats all I have on the head rebuild.

 

Good luck!

 

Jim

 

 

Attached Files



#49 Lazeum

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Posted 29 April 2013 - 02:23 PM

Jim,

do you have more info about the rocker grinding issue (or lack of)? I'd be curious to know more...

 

Leon,

Build is looking good. I'm following up this thread also :)


- Matt -
'72 240 - L28, P79, Rebello cam, 3xDCOE, Megajolt + Edis ign., etc.


#50 Leon

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Posted 29 April 2013 - 02:26 PM

Wow!  Great find!

 

Some lessons learned from my rebuild.

 

1)  be sure to grind your rocker arms prior to reassembly.  I did not and had problems with the rocker arms not mating squarely with the lash caps and the cam.     (see pictures)  The old lash pads wore in the middle and not on the sides, the new lash pads do not have the indentation on the sides so an unground rocker arm does not sit properly on the cap.  This caused me a lot of time to find out why my engine had a loud tapping sound.

 

2)  if you are going to purchase an isky cam.  I ended up with the Isky stage II cam 715148 (see picture below).  With my SUs the car is too lopy and too loud.  This summer I am going to swap back to the isky stage 1 cam.  I suggest the stage 1 cam.

 

3)  I used cast flat top pistons on my N42, 2.8L block.  The crank/block combination pushes the pistons above deck by approx 0.025"  (0.65mm).  I purchased a custom copper head gasket which was 0.063" (1.6mm)   which gave me a gap between the piston and head of 0.037".  When I ran the stock head gasket, I believe the piston to head clearance was 0.025" which concerned me.  My resultant compression ratio is 9.83 instead of 10.2 with the Felpro gasket.

 

4)  Please find shims that are 0.040" and use two instead of four of the 0.020" shims.    I had mine custom made.  it was inexpensive.

 

Thats all I have on the head rebuild.

 

Good luck!

 

Jim

 

Hey Jim, thanks for the great info!

 

1. I'm planning on sending the rockers to be reground when getting the cam reground. I've not talked to Isky yet, so I'm not sure whether they do rockers as well. I know Delta up in WA does it pretty cheap. So your solution was to have the rockers ground to fit the profile of the lash pads, if I understand correctly?

 

2. For cam sizing, I'm planning on running my own calculations to determine necessary lift and duration. I'll speak with Isky regarding it as well, especially regarding lobe separation/overlap. I'll probably have one ground to my specs, unless Isky convinces me otherwise.

 

3. Thanks for the deck height info. I'll see if I run into the same issues (F54 block with flat-tops).

 

4. If Derek (on this forum) still makes shims, I was thinking about purchasing them. I don't remember whether his are one-piece (0.080") or two-piece (0.040" X 2). I can also make my own on the wire EDM at work, if I'm feeling really frisky...

 

Thanks Jim!



#51 Leon

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Posted 29 April 2013 - 02:28 PM

Jim,

do you have more info about the rocker grinding issue (or lack of)? I'd be curious to know more...

 

Leon,

Build is looking good. I'm following up this thread also :)

 

Thanks Matt, progress is picking up! I need this car ready for my wedding in August.   :iospalo:



#52 Leon

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Posted 29 April 2013 - 02:41 PM

Looks good, $100 for that is great deal!

Are you going to porting intake and Ext?

 

Not really planning on porting, maybe just port-matching. My 45mm Webers are already port-matched to the Cannon intake. Ideally, I'd probably dump the Cannon and get a manifold made for 45s.

 

From my PM conversation with gollum: if my power peak is to be 6500rpm, I need to be making 145lb-ft at the wheels in order to make 180whp. At 6000rpm, I need to have 158lb-ft at the wheels to make 180whp. My stock-cammed L24 makes ~140lb-ft at 4000rpm, so with a more aggressive cam and a 2.8, I think that should definitely be realistic.

With that said, I'm not chasing horsepower. I just want something with a little more "umph" than my L24. It'll be mainly a street car so no wild cams and 9000rpm redlines...


Edited by Leon, 29 April 2013 - 02:43 PM.


#53 JCan

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Posted 29 April 2013 - 06:01 PM

Lazeum.

 

This is one of those esoteric things that I learned the hard way!   http://forums.hybrid...e-even-at-idle/

 

If the rocker arm contact point with the valve stem is not parallel with the rocker arm cam shaft contact point (is that a lash pad?) then gapping the valves will be almost impossible.  When the rocker arm is parallel with the cam lobe then it is not parallel with the valve stem.   When the engine runs the rocker arm with twist slightly and the engine will have a loud tapping sound proportional to the RPMs (if you go to the above blog I think I stored a short video clip)

 

This happened on my car.  Referring to the pictures on my previous post, look closely at the wear on the rocker arm on the valve stem side, you can see wear in the middle with no wear on the edges.  When I used the new lash caps that were completely flat, the rocker arm contacted the lash cap on the edges of the cap not the middle.  

 

Long story short, after 2 weeks of removing the head, cam shaft, rocker arms over and over again, I finally found this issue.  simple fix, I just ground the rocker arms so that they would contact the lash cap at only one place and it worked!

 

Car is quiet and runs like it should!

 

If you have questions, please call me - 858 204 9422



#54 JCan

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Posted 29 April 2013 - 06:10 PM

Leon.

 

On the rocker arms, if the wear looks good on the cam side, you may not need to regrind that, although better safe then sorry.  regrinding on the valve side is a must, it is simple to do, just grind away the edges so that the center has a slight crown to it.  This ensures that the rocker arm will be flat with the cam and contact the valve at one point thus as you break in the motor, the rocker arm will self seat against the valve side and there will be no torque on the rocker arm.  

 

Jim

 

PS  We went to the motorsport show in LA this past weekend, car ran great!  Even with all my fancy tricks to limit HP (high gear ratio + SU carbs) once the car hits 30mph, the car pulls really well!



#55 Lazeum

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Posted 30 April 2013 - 02:04 AM

Jim, I remember your post. Your explanation is clear to me. I'll keep it in mind while I'll check my head. Thanks for your anwer :)

I've read again the post (I was part of it - shame on me!) and it makes much more sense to me today!


Edited by Lazeum, 30 April 2013 - 02:14 AM.

- Matt -
'72 240 - L28, P79, Rebello cam, 3xDCOE, Megajolt + Edis ign., etc.


#56 Leon

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Posted 30 April 2013 - 06:41 AM

Fantastic info Jim, thanks!

 

I'm hoping to finally make the MSA show next year, although I'm likely to go to JCCS again this year if the Z is ready.


Edited by Leon, 30 April 2013 - 06:43 AM.


#57 Gollum

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Posted 02 May 2013 - 12:06 PM

JCan, how sure are you that the clearance on an OEM gasket was going to be .025"? And do you think your deck was resurfaced at all? If you had a stock 2.8 crank, stock L28 rods, and stock flat tops then an OEM gasket would make for a 100% OEM clearance deck. The pistons are SUPPOSED to pop out a bit but what you saw is quite large. You mention the block as though maybe it was the factor causing the excess deck clearance but I've never seen ANYTHING showing an variation in deck height in the L block from 240Z up through 280ZX L engines.

 

But if all measurements were correct, .025" clearance is certainly getting to the limit of what I'd feel comfortable with. If I knew my bearing clearances were spot on and I was running hyper-cast pistons I'd maybe take the gamble and run that, but I think you might have done the right thing in your case. I'm just curious of the root cause.


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#58 tamo3

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Posted 02 May 2013 - 12:51 PM

I didn't know there is intake manifold design for 45.

 

I read article that porting int & ext is to us nismo gasket as template. I was wondering my cannon intake manifold is smaller hole than gasket and need to port cannon intake manifold too. 

Not really planning on porting, maybe just port-matching. My 45mm Webers are already port-matched to the Cannon intake. Ideally, I'd probably dump the Cannon and get a manifold made for 45s.



#59 Leon

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Posted 02 May 2013 - 01:46 PM

I didn't know there is intake manifold design for 45.

 

I read article that porting int & ext is to us nismo gasket as template. I was wondering my cannon intake manifold is smaller hole than gasket and need to port cannon intake manifold too. 

 

Yeah, I believe the Nissan Comp (and its copies) were designed for 45s. Maybe some Mikuni manis too. At least I remember reading that...

 

The Cannon definitely has a lot of extra material.

 

I enjoy incremental builds, iterating and seeing the improvements. At this point, I'd like to put the engine together keeping the P90 unported. I can always pick up another head and play with it, while having the car on the road at the same time. :)



#60 Leon

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Posted 02 June 2013 - 01:43 AM

Block, crank, rods, and head are in the machinist's hands as of Saturday!

 

The block may need to be bored because of rust in the cylinders but otherwise nothing special. Crank will be polished and balanced. Rods, pistons, flywheel and clutch will be balanced as well.

 

Head will be the "typical" modified P90: shaved 2mm, longer valves, yadda-yadda...

 

I just ordered some ARP hardware for the rods and mains. The to-do list, posting so I don't forget something (always happens): send out the rockers to get reground, sourcing 2mm/0.080" cam tower shims, sourcing longer valves, low profile valve stem seals, and figuring out my cam and springs. We'll see what happens with the lash pads. I will need to finalize fuel lines and routing as well. Can't wait to start putting this thing together!


Edited by Leon, 02 June 2013 - 02:11 AM.





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