"K" Marked Camshaft in L28 -- Specifications?

[jpc3006]

I am currently disassembling an L28 engine (F54 block, P79 head) from a 280ZX that I bought from a guy several years ago as a potential spare engine. When I removed the camshaft I checked the marking on the firewall end and it is clearly marked with a "K" and nothing else. It is a Nissan cam with E30 and Japan cast into it. I tried researching this camshaft but it isn't listed in the typical sources. What I've come up so far is that it may be from a Canadian 280ZX or a Maxima L24e. Does anyone know the specifications for this camshaft?

Thanks,

John

[Zed Head]

I think that they're all about the same as far as performance.  Changes were most likely made for emissions.  What would you do differently if you had the exact specifications?

The lift is the same, the valve openings and closings chnage by just a few degrees.

Here's 1982.

[jpc3006]

Zed,

I just wanted to know if it was the original cam in the 280ZX L28. I looked at the 1982 FSM but couldn't find a reference to the code on the end of the cam. The AtlanticZ Club cam index shows a "F" code for the NA 280ZX, it doesn't list a "K" code. I have read that the "K" cam was a L24e cam which has very different specs. I haven't decided what to do with this engine but if I can find some flat-top pistons for the F54 the plan is to mill the P79 head 0.080" and build a higher compression L28. At that point the cam will either be reground or simply replaced with a more aggressive one.

Thanks,

John

[Zed Head]

I'd look for signs that the cam has been changed.  Witness marks on the bolt heads, does the cam rotate easily, is the timing chain and sprocket original, etc.

Are you sure the L24 E specs are different?  It's really just a 2.4 size 280ZX engine.  No reason for significantly different specs., except for better fuel mileage maybe.  Can you link a source for the different L24E specs?

Whatever you find out it's probably a good core for grinding.  Good luck.

[AK260]

If I had my time again on my L28 I would have ignored the sensible voices of the detractors and bought the Kameari roved pistons and max speeding rods to have an even faster revving engine ;)

Having been in a friend’s 240 with that set up on an L28, I was surprised how the reduction in weight didn’t affect low speed drivability. It was very reminiscent of my old S2000.

Something to consider if you can’t find cast flat tops.

[jpc3006]

Zed, 

I finished stripping the head yesterday and it appears to be unmolested, no marks on the cam towers, stock rockers and valves, no scratches or anything indicating that someone had been in there and the cam rotates just fine but the timing chain and sprocket are aftermarket. I know that the kid and his mechanic dad that I bought it from rebuilt the bottom end. It has dished aftermarket pistons and the rods are not in their numbered positions. After seeing what they did to the bottom end I was concerned that they had also worked on the head, but it doesn't look like it. 

I'll try to find the thread that mentioned the L24e "K" head. I looked at so many threads here and at HybridZ that I can't remember where it was.

AK260,

Your suggestion is something that I had in the back of my mind, get a set of custom forged pistons to bump up the compression and leave the head alone. The cast piston route is cheaper but probably not better than forged pistons and lightweight rods. At this point I am going through the engine to know exactly what I have. I won't be working on the engine to much in the winter unless the weather stays unusually warm like it has been here the past week so I have time to decide what route to take.

Thank you both for your comments and suggestions

 

[Zed Head]

I wrote a thing yesterday and pasted a link but I guess I didn't hit the submit button.

Here's a link about a K cam in an MN47 head.  The MN47 head is used on the L24E.  Specs would be in a late 70's, early 80's Maxima FSM, I'd guess.

Post #7 if it doesn't go directly there.

 

[Zed Head]

Also interesting is Blue's cam spec's page on AtlanticZ.  He shows the L24E cam as an E.  And notice though that the specs for the early L24 are the same as the early L28.  You can also see that the specs changed as emissions specs got tighter.  Catalytic converters and all that.  Big picture, I don't think a person could tell the difference by the way an engine performs.  Although, the L24E shows as having lower lift.

So, you could follow the bread crumbs - somebody has an MN47 L24E head with a K cam, Blue shows the L24E as an E cam, the L24E used the MN47 head, K is probably very similar to E.

Are you sure it's a P79 head?  Do you actually see the P and the 79 on it?

http://www.atlanticz.ca/zclub/techtips/cam/index.htm

[jpc3006]

Yes, that AtlanticZ page is where I looked first and it doesn't show a "K" cam, that's why I asked the question in the first place. The head has P79 cast into it, plain as day and it has not been cut as it still measures 4.250" thick.

I spent some time cleaning up the parts and found a few curious things. I measured each cam lobe with a dial indicator and while they all are very close to the specs in the FSM for overall lobe height, some of the lobes have a 0.001" to 0.002" shallow depression between the base circle and the lobe ramp. I can't believe it was manufactured this way and it has to be due to wear but it is not on the lobe point where I would expect it. Another thing is that all of rocker arms seem to be new with no wear when compared to the other components on the head. I originally thought the rockers were stock Nissan parts but they don't have the Nissan parallelogram on them, they are marked "Y73" so they are probably aftermarket. The springs, valves and valve seals all seem to be Nissan OEM parts and judging from their condition probably the original parts that came with the head. So my thoughts are the same as yours, that the previous owner swapped out the cam and installed new rockers when he tried to rebuild the engine.