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Leon

Leon's Other 260Z

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Leon    35

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:

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Leon    35

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

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JCan    1

Lazeum.

 

This is one of those esoteric things that I learned the hard way!   http://forums.hybridz.org/topic/110671-newly-rebuilt-engine-with-loud-tapping-noise-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

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JCan    1

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!

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Lazeum    12

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

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Leon    35

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

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Gollum    23

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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tamo3    0

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.

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Leon    35

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. :)

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Leon    35

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

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JCan    1

Leon.  

 

Are you going to adjust the valve to cam lash yourself or have the machine shop do it?  If you have the machine shop do it, that means you have your custom cam?    Im really excited to learn what you did and how it works!

 

On another topic, I believe you are using tripple webbers right?  Are you going to use the stock fuel rail?  if so, pay close attention to the return line.  I learned (from steve at ztherapy) that the return outlet tends to get clogged (the tube diameter is reduced at the output to set pressure in stock cars).    I believe that having gas continuously flowing from the gas tank to the carbs and back helps keep the gasoline cool and helps eliminate vapor locking.

 

Lastly, I am very interested in learning what head gasket you end up using and what you expect your head to piston gap is.

 

Good luck!

 

Jim

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Leon    35

Thanks Jim!

 

I'll be assembling the head myself, so no custom cam yet. If I run into an issue of a custom grind being way too expensive, I'll have to settle for Isky's Stage 3 as I think it'll be close to what I'm looking for. Either way, I'd like to experiment with a custom grind at some point, even if it doesn't happen this time. I'm still working on my cam sizing spreadsheet. Still need to figure out minimum lift and overlap numbers...

 

The triple Webers on my orange car use the stock fuel rail, with the feed coming in at the front carb, daisy-chained to the rear, and back into the fuel rail. I plugged the return almost 2 years ago when chasing a fueling issue (turned out to be the filter) and never unplugged it, although I probably should. I've not had vapor locking issues though, even in 100deg+ heat at Long Beach last year. On this Z, I'm doing away with the stock rail altogether and will be using AN lines, with a return.

 

Good thoughts on the head gasket and piston-to-head clearance, I'll report when I find out.

Edited by Leon

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Leon    35

Current to-do/buy list:

 

- Regrind rockers (I know Delta Cams does it for a good price)

- sourcing 2mm/0.080" cam tower shims (considering making these myself or buying from Derek)

- sourcing longer valves (Rockauto or SI)

- low profile valve stem seals (FEL-PRO SS72686, thanks for the tip Leo!)

- figuring out my cam and springs, lash pads may need replacement (Isky)

- Head gasket (unsure...)

- Manifold studs and gasket (MSA/Rockauto/local)

- Valve spring shims (not yet found)

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JCan    1

Leon.  

 

Stage 3 [email protected][email protected]   WOW!  Will you have to notch the pistons to accomodate the valves with this 0.490 lift cam?  it has a 72 degree valve overlap but should provide excellent torque out through 7kRPM  right?  meaning that you should be able to race through 8krpm?!   Now my question.  You have balanced the crank, pistons, flywheel, pressure plate.  Are you going to lighten the flywheel/clutch assy? What pulley will you put on the front of the motor?  If you look at the stock pulley  you will notice that it is drilled (I believe to  balance the motor used in initial production).  I left mine alone, do you plan to balance this pulley with the crank?  It is something I overlooked when I balanced my motor.

 

In my build, I did not use valve spring shims, but purchased new springs from isky.  I believe all you have to do is tell him that you have increased the resting spring distance 2mm and he can either tell you that the spring is okay by itself of change out either the inner or outer spring.  Note:  I used the springs as provided and found no issues (though I have only run the car for 300 miles).

 

I have two felpro head gaskets that I purchased new and used to measure piston to head clearance so therefore they have been torqued down once but have not been run in the car for any length of time.  I am happy to mail them to you if you want to use them for piston to head measurements.  I also have valve springs (inner outer) spring caps and lash caps from the p90 head i used if you need them.

 

Fun stuff!

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Leon    35

Fun stuff indeed! :)

 

It should spin freely past 7k RPM but retain decent mid-range grunt. I wish I could race through 8k RPM but I don't think the pistons would like that very much. I'll be using a 10lb Tilton flywheel but undecided on clutch so far. I have a brand new stock clutch that I can use but unsure of how much stress it will take.

 

Great info on the springs, thanks! I was going to do just that, talk to Isky and see what they think. I think I'll end up being OK without any spring spacers, it was just a note I wanted in there so I keep it in mind.

I'll take you up on that generous offer! I'll take the head gaskets. Just let me know how much and where to send monies to cover postage. :)

Edited by Leon

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Leon    35

Strike a few things off the list...

 

- Regrind rockers (shipping off to Delta in next couple of days)

- sourcing 2mm/0.080" cam tower shims (considering making these myself or buying from Derek)

- sourcing longer valves (SI has great prices)

- low profile valve stem seals (FEL-PRO SS72686 bought on ebay)

- figuring out my cam and springs, lash pads may need replacement (Isky)

- Head gasket (will probably get Fel-Pro)

- Manifold studs (MSA)

- Manifold gasket (Rockauto)

- Valve spring shims (TBD)

 

In the meantime, Jim sent me some head gaskets to use for piston-to-head and valve clearance checks (thanks again Jim!).

 

Also, the machinist called yesterday to inform me that the crank needs turning, as the journals have rust on them. I'm now on the lookout for a stock L28 crank in good shape (posted a WTB ad here). I've got some local guys on the lookout as well. If I can't find one soon, I'll have to get mine turned and balanced. We'll see what happens... :)

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Leon    35

Already got a possible source for a crank thanks to the local network (thanks Leo and Kyle!).
 
The parts are beginning to trickle in... :D

DSCN2052_zps37971a03.jpg
 
DSCN2058_zpsfe3be92c.jpg
 

DSCN2059_zpsb615cecf.jpg

Edited by Leon

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Leon    35

Keep us updated on how the valve stem install goes. Even braap says he tends to rip them from time to time.

 

Will do. I did read his thread on how he installs them so I'll be extra careful (don't forget those valve stem condoms!). :D

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Leon    35

Got a polished and balanced crank yesterday (thanks to stravi757)! It'll go into the shop for a quick re-polish (specs of surface rust on some journals) and probably check the balance just to be sure.

 

DSCN2062_zps46a55c2e.jpg

Edited by Leon

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Leon    35

Quick update from machinist: P90 chambers are 44cc. Now I don't know how accurately he cc'd them, but I was expecting closer to 46cc. Thus, my compression ratio will be just about 10:1 depending on compressed head gasket thickness. This is a bit more than I was anticipating but I think it'll be alright given the nice chambers of the P90 plus the hotter cam.

 

He's shooting to have the machine work and balancing done by early next week. :)

Edited by Leon

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