How high do you rev your Z? My 260 is ill.......

Ouch!

To answer your original question, I usually shift at 6700 - 6800, with the MSD 'pill' at 7K.

Hope mine doesn't look that bad, but I have different symptoms than you. Got all the external stuff off last night, all that remains is to unbolt the transmission and motor mounts.

I'm thinking of saving the oil drain pan full of metal chunks to remind me not to let someone else work on my car...
 
Sorry to hear that Ty. I didn't realize you lost a motor as well?

We took Ron's apart last night. Big chunks out of the 2 and 4 pistons, valve contact marks on all pistons.

Other than that everything looked great!

I assume the valve marks on the pistons are from an overev?
 
Sorry to hear that Ty. I didn't realize you lost a motor as well?

We took Ron's apart last night. Big chunks out of the 2 and 4 pistons, valve contact marks on all pistons.

Other than that everything looked great!

I assume the valve marks on the pistons are from an overev?
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Yep but most under downshift over revs. More photos will help and Ron you can Email them directly over to me if you like. Measure the bore and check for scratching int he walls. I may have some pistons around here that would help to get you by.
 
Got it, thanks Joe. I think Ron is going to take a bunch of pictures of the pistons, valves and the mystery header for Keith.

I assume valves smacking into pistons means we need to take a hard look at the valve train as well?
 
Bought that book Joe, thanks!!! And thanks for the offer on the help with pistons too. Haven't got any of that apart yet and the pistons you see that are out of the car were in the pile of bits that came with the car. That half moon piece out of the ones you can see in the bore looks a lot like the one I'm holding in my hand there....

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Stahl race header or a knockoff.

Detonation sucks....What are you runing for timing and fuel? The amount of oil on the piston tops is an issue also. Hard to tell int he photos but the vertical scratches in the bores look pretty deep.

Joe
 
It needs a rebore. The scratches can be easily felt with a fingernail. Deep in several places. Block has been bored once, the pistons in it are +10.

We think it ran rich until about 5,000 rpm. after that, we thought it was ok. Plugs did not show a lean condition, but it sure looks like detonation in the chambers, I agree with you there.

We are told by a local engine builder with Z experience that the #2 cylinder on L24/26s run hot due to the intake manifold design.
 
I would say the fuel pump problems at CMP did more damage than you thought. Sorry to hear you need a rebuild.
 
It is a bummer, but as Jeff says do the vice and pay the price. Some comments:

*The header isn't optimal, but it'll do for now I think.

*Head has excellent IT legal max port work and matching, very nice.

*Block has good attention to detail with some safety wired bits and ARP harware throughout.

*Fueling is done with two electric pumps, back flow valves, and external regulator. Never had problems before, it has always run well. BUT - at CMP I had a voltage regulator go bad and we were having problems keeping fuel pressure where it should be as well as the car running. 18V at the pumps can cause the regulator to be over powered etc. - to make a long story short Steve is right, it might have run a race with fuel pressure less than optimal but I'm not sure. It did run the CMP race well, but on the last couple of laps it behaved a bit odd. I attributed it to the car having to run on battery only, but I imagine that wasn't just it.

*It'll need a re-bore, new pistons, all new bearings, and we're going to have the head gone through and new springs installed. I'll need a source for some 0.010" or 0.020" pistons and good rings. Also need new valves, I can't imagine them not needed to be replaced, as Joe says, after leaving that smilely mark on there.

So, to recap on the revving thing:

*If I like to replace springs every race, or close to it, then I can run to 7400 RPM (providing my fueling is good and I'm not running into trouble there)?

*If I don't wish to replace springs that often I need to stick to 6800 RPM or so?

I'll need suggestions on good bearings, good rings, pistons, springs, etc. I've not talked with my Nismo man yet, so I'm not looking for cheater stuff, I'm just new to Z's and don't know what you folks do for parts sourcing. Remember, I'm just off the Jensen bandwagon and I'm used to sourcing my own and scrounging from an old dude that lives in a bus - this being able to pick up a phone and call a Z Parts place is cool! JensenWorld went out of business long ago because their last racer was cut in half.

R
 
Shit man, we need to race. I wouldn't shift that thing past 6800 for a year or two if that.
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I agree. That CMP race was my second ITS race since my rookie X. And I had intentions of keeping it below 6.5k. But then I got out there (after Steve E's wife graciously brought me a tool to get the car running on the grid!!! Thanks to both of you!!!!) , the green flag dropped, and I got around a couple of people with torque on the start and said "whoa, this is fun, I gotta get more of that!!!!!". And more of that meant some 7k+ shifts......and look where that got me. You know the story, you warned me it would happen.

7k pill for a bit.

R
 
OK now lets look at this whole deal.

6800 is fine on tracks that are 3rd and 4th gear stuff. The the split will keep you in the powerband just fine. on tracks that you see second gear you need to run the motor to 7200..NO big deal . You do not need to change springs every race even at 7200 rpm every shift. 7400 makes no power so I really don't get why anyone would be up there other than maybe pullng a low gear down hill and over running. As as far as the rebuild goes. the only ARP stuff needed in these engines is the rodbolts. I believe all of the L26 rods are 9mm bolts anyway so your not going to save any real big end weight on them. Mainstuds and headstuds are not needed on these engines and I actually had more failures with headstuds on GT motors than just using the good factory bolts. As far as pistons go off the shelf OE if they are sill around our even some of the best buildlers in the country have been seen putting repco pistons in these things. I believe the L26 uses the same piston as the late L24 which I have only been able to find in .020 over. The early piston displaces 3cc less if I remember correctly again. Deaves or hastings or sealed power gold rings. all are good I have a mixture of rings that I use in these engines. Factory bearings are the way to go here especially on the mainline. OE timing sets are also of the best quaility. I have a ITS 240 customer with 4 seasons on the sme engine. We have taken the head off every year and freshened it. DYno numbers indicate there shouldn't be a 5th year on the bottom end but it's not by very much. The header you have there looks like a Stahl header and I have 2 cars with them and 3 others with the Nissan part. bottom line the header is not hurting you at this point. The real deal is you need to get this car back on the track so worse case is find a good running used engine freshen the head and get back out there while you do this one back up. Good luck if I can help let me know.
 
Joe,

At least for this motor and my experience with it I agree with your rev limits. It made good power to like 6.8k or a bit more, but signed off after that. However, at this CMP track we drive there is a four turn complex that is all in-between 3-4 and one doesn't want to shift to fourth, so, one holds third and ends up with some over rev. At least the way my car is geared.

I don't have any OEM bolts etc. so I'll use what is in the motor. L26 is the same piston as the L24, so that should be no problem. I like those Sealed Power rings but didn't know if they had them for Z's, should be possible to find them if you've used them. I swear I saw some 0.030 and 0.040 over sets but that might have been for a 280Z, which it seems easy to get forged sets for.

I'll give Riley Curtis, Lynchburg Nissan (1-800-443-2117) a call. He's the guy that Katman suggested and set me up with the Nimso clutch etc. I assume he could source pistons, bearings, and a timing kit per Nimso? Anyone have other suggestions for good Z suppliers?

R
 
On the piston size, the markings on the top are in mm. so if you have a 1.0, it is .040" already. I don't remember if Nissan made anything but .5 and 1.0mm over.

A few weeks ago, David Spillman had a wrecked 260 that has been behind his shop for a few years loaded up on a trailer looking like it was going to the metal yard. I looked longingly at it, but I have a good engine in the car and a good spare L26 block and two others that are usable. If he still has it, it may be something to get you back on track until you get your primary back up.

I have some stock head bolts and some aftermarket equivalent to the diesel main cap bolts I can hook you up with cheap. I also have a torque plate you can borrow to get it back right. Really makes a difference.

Mike
 
At least for this motor and my experience with it I agree with your rev limits. It made good power to like 6.8k or a bit more, but signed off after that. [/b]
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That's pretty much what mine does too. There's only one track around here that requres second gear, and it seems like sometime every race somebody will get me there.

I'll give Riley Curtis, Lynchburg Nissan (1-800-443-2117) a call. He's the guy that Katman suggested and set me up with the Nimso clutch etc. I assume he could source pistons, bearings, and a timing kit per Nimso? Anyone have other suggestions for good Z suppliers?[/b]
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Around here most of us use Courtesy Nissan out of Richardson, Texas. Finding a dealership that still has some parts guys from the old days isn't easy anymore. If you tell them you're a member of the IZCC they give you, I think, an extra 10% off.

Don't have their number handy, but their web site is: http://www.courtesyparts.com/

Sorry to hear that Ty. I didn't realize you lost a motor as well?
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I've been pretty backed up the last few months. Kid stuff and travel for work (I'm off to Europe tomorrow for 10 days) mostly. Since I never could find the time I had a local prep shop install a new oil cooler and accusump for me just before our first double of the season last weekend. When he installed the oil lines he reversed the pressure and return off the filter adapter, meaning the oil pump was pumping against the check valve. Surprisingly, the (brand new) valve leaked enough to give me about 40 lb/in2, at least until the oil warmed up some, then it sealed tight.

The engine is out but I haven't done a full disassembly yet, just pulled the oil pan. The rod bearings look fine, but I've never seen a crank bearing that particular color. Not sure why one would overheat and not the other.

Next race Memorial day weekend. I already tell it's going to be a thrash getting ready.
 
Nyet on the Stahl header- its a Interpart/BRE header sold as part of the "Whisperpower" system many moons ago. If you collect the 2-1 in the right way in the right place it's actually a pretty damn fine header for IT. I didn't think there were any of them around any more...

Where you need 7400 rpm is with a 3.90 gear at Road Atlanta to win the ARRC. A 3.90 rear and 3rd gear is the fastest way out of turn 7 and 10b, but it means you're twisting it down the hill to 10a. Otherwise Mr. Harlan is correct.

If you're shifting at 7k or below you can run a set of valve springs all season, unless of course your cheating on your cam. :018:

Even going to 7400 at RA the earliest I might have changed springs is..... beginning of the next season. Of course it helps to cam doctor about a jillion stock camshafts to find one which A) has all the same lobes at all the same timing (harder than you think), and B) has worn enough over the nose to to be a little smoother on the valvetrain harmonics.
 
Thanks Keith, when I saw that header, it looked like a Motorsports Auto header to me. I ran one for several years. Everyone was so confident that it saw a Stahl, and it does look kind of like his header that I didn't comment. I think it is a Motorsports Auto header.

Mike
 
"I think it is a Motorsports Auto header."

Nope, I'm right. :D I got a picture of it that will convince you. Monday I'll see if I can get it posted somewhere.
 
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