Swapping Nissan L6 Cams?

[Connor280ZX]

Hi.

As some of you may know, i'm trying to squeeze every HP out of my 1982 280ZX as possible without major engine modification, not being too expensive and still being able to pass CA smog.

 

Now, there are Cams. Cams have always come into my mind first when thinking about performance parts, however, aftermarket cams (from what i've heard) require all new valvetrain hardware to work properly, and will most likely cause the car to not pass smog, not to mention all of that is pretty expensive.

 

So i thought to myself; "What about previous Z's valvetrain? EFI S30's made much more power than any NA S130, though they have the same displacements, but have different valvetrains..." Well, I think 75-76 Z's had the N42 head, followed by the N47 head for 77-80? Correct me if im wrong. I made a thread asking if anyone knew the specs for factory Z cams, which thankfully i was promptly given a few answers.

 

Cutting to the chase: I'm thinking about swapping out my P79 F Cam for an N42/47 A, an E31, A, or an E88 C cam. I'm leaning towards the EFI cams, because im not sure how my ECU would react to a cam coming out of a carburated engine.

 

Now a few questions: -In order to swap one of these cams in, would i need to do anything to my valvetrain?

                                   -Are the cam's basically the same lenth/width? Would any of these even fit in my P79? 

                                   -Would i need to time the cam differently?

                                   -How much power can i expect to gain (if any, not expecting a whole bunch, but +10-12HP would be fantastic)?

 

 

Cam specs:http://www.atlanticz.ca/zclub/techtips/cam/

[skirkland1980]

The P90a lash pads are a little thinner. Why not try some with some freshened rockers and maybe a little tighter lash setting? Check wipe pattern and make sure it didn't move too far back on the rocker.

[Connor280ZX]

The P90a lash pads are a little thinner. Why not try some with some freshened rockers and maybe a little tighter lash setting? Check wipe pattern and make sure it didn't move too far back on the rocker.

 

Had a valve adjustment done a few months back. I didnt do it myself, because i couldnt find that special Nissan valve adjustment tool that is needed to do so. I sent it in, and told the Datsun guy that i'd like a "performance" valve adjustment. I didnt feel much of a performance difference after that, though i did ask him how the valvetrain looks, and he said everything looks very good, with minimal wear on the pads, rockers, lobes, etc.

[mattb3562]

Here ya go...

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

[Connor280ZX]

Here ya go...

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

Thanks, but i attached this same link in my original post, haha.

[skirkland1980]

I was referring to changing your rocker ratio for more lift and duration.

[osirus9]

I'm going to be doing this exact same thing in the motor I'm building, and I'm wondering which cam to use with the stock valve train as well. I've got a P79 with a "B" cam and an N42 with what I assume is the stock "A" cam, but I forgot to check when the valve cover was off. Now the N42 is running in good condition, and the P79 is unknown, assumed running condition. Now I have a p90 with nothing on it that will be the base for my turbo motor.

 

So really, we both have the same question: Are the valve trains interchangeable? And which stock cam is best for more pwer?

 

Also, could I use the valve train from the n42 in the p90? Or would I have to buy all new stuff? I've heard people running turbo motors use "A" cams, but why is that? Is a "B" cam really that different?

 

I see the link to the cam profiles, but I must admit, those cam numbers don't really make sense to me. I came from rotary engines and all this head and cam stuff is greek to me so far, but I'm trying to understand it. Thanks guys.

[johnc]

Please search guys.  Stock cams have bene discussed here many mnay times over the last 14 years.

[Connor280ZX]

I was referring to changing your rocker ratio for more lift and duration.

Oh, ok I see what you mean. Though the P90A head is hydraulic, the rockers/pads are still compatible with solid lifters? If I were to, where would I find P90A lash pads?

Edited November 12, 2013 by Connor280ZX

[Xnke]

The P90A hydraulic head needs the hydraulic cam to operate properly. Stock non-hydraulic cams may produce undesired operation. Use at your own risk. No warranty implied, expressed, or given. No returns on opened items. Do not take internally.

 

Stock cam profiles are not worth the work to swap over.

[Tony D]

I got 147 out of a 1980 ZX, with 225,000 miles on it. Stock everything. Just tune it up correctly. Skip the gimmicks and garbage and concentrate on the basics.

[osirus9]

ok, so after more research it seems to me that all the parts in the L6 valve train are identical between 70-83 except the rocker arms on the 81-83 turbo. I've read a few threads about that as well and there was no real conclusion as to if they are actually different in any way except for part number. 

 

So I suppose I would be safe just re-using all of the valve train from the p79 in the p90 as well as using whichever stock cam I fancy. Now I just have to find a shop around Chicago that actually knows anything about this engine to assemble it all and check the clearances...

 

Also, just by looking at the atlantic z numbers.. and I know very little about all the factors behind cams, but is the reason people like the "A" cam because it has an intake/exhaust duration of 248/248 as opposed to the 240/240 of the J cam that comes in most p90s? By that logic is the E88 C cam the "best" with its duration of 256/256? Or is that too much duration for a turbo motor?

Edited November 14, 2013 by osirus9

[Xnke]

Rocker arms are functionally identical, but p79 and p90 valves are different from all other years and cylinder head castings. Measure carefully if you plan to mix and match.

[osirus9]

Thanks for the info, I didn't notice the different valves, but I also didn't check. I should have been more specific, the p90 has all the valves and most of the springs and retainers, so really I would just be stealing a few valve springs and retainers from the p79, as well as rocker arms and lash pads (keeping them matched up) and using either the B or A cam I've got.

 

I have read about the great success of people just running junkyard motors, so I want to save money on any engine work for now and concentrate on buying a quality intake/exhaust/turbo/EMS while leaving the motor as a hybrid of stock parts. I feel that from what I've read it should be able to get my goal of 325 RWHP just fine with all stock engine parts.

[Xnke]

Use the rocker arms that match the cam, the las pads don't matter as long as they are the correct thickness

[Tony D]

Thanks for the info, I didn't notice the different valves, but I also didn't check. I should have been more specific, the p90 has all the valves and most of the springs and retainers, so really I would just be stealing a few valve springs and retainers from the p79, as well as rocker arms and lash pads (keeping them matched up) and using either the B or A cam I've got.

 

I have read about the great success of people just running junkyard motors, so I want to save money on any engine work for now and concentrate on buying a quality intake/exhaust/turbo/EMS while leaving the motor as a hybrid of stock parts. I feel that from what I've read it should be able to get my goal of 325 RWHP just fine with all stock engine parts.

Boosted? Drunk, on crack, hanging upside down being flailed by a dominatrix! 325 with stock externals isn't that difficult.

 

Your path is the one I have advocated for over 20 years now: with a turbo concentrate on your externals, and most importantly the tuning aspects of your EMS. once you have at engine properly tuned to its limits, THEN adding durability boy upgraded internals is always a progressive step option.

 

Frankly, JeffP is happy with 450 in his car on a stock bottom end...but laments not being able to pull past 7400 knowing it has cast pistons...

 

Adding forged stuff at the start just makes the inevitable tuning oopsies more expensive!

 

After goals are known, appropriate head work will make sizing of the rest of the system easier, but it's something you should handily compensate for later if you do it, and have competence on the EMS.

[osirus9]

Thanks Tony. So essentially, if I'm not doing any headwork any stock cam is basically the same.

 

I was following the other thread on here about which turbo to use with the senza intake as well, so I'm thinking a GT3071R would be a good turbo for my goals as well. It looks like it will support that power easily and stay away from the surge line unlike the 3076.

[deuce8ernerozero]

Efi s30's hp were measured in a different way than s130s. That's why it seems like they had more power. The 77 that was suppose to have 170hp actually was like 135.

[Tony D]

Efi s30's hp were measured in a different way than s130s. That's why it seems like they had more power. The 77 that was suppose to have 170hp actually was like 135.

That's way oversimplifying it, and mixing up a change in how performance was delivered through the years.

 

The L28 camshaft profile power peaks at 53-5500 rpms due to displacement increases resulting inherently in more torque.

 

Most people refer to this lower peak power (but increased over prior years due to displacement) as "the L28 doesn't't like to rev" and like most uneducated shade tree mechanics attribute it to the "longer stroke" of the L28.

 

I assure you, putting in the earlier camshaft profiles returns an L28 that has the exact same characteristics as an L24. In fact, people who don't know it's an L28 in the car will state "man, this is a strong engine!" Thinking because it spins to a power peak closer to 6500 that it's an L24.

 

Without the gearing to maximise it, and the constitution to let the engine run at 3,500 rpms at highway speed, it's all wasted effort.

 

If I'm going to change a cam, it will NOT be for another stock grind! For the effort you MUST expend to set it up right...and the previous statements regarding no perceived gain on a performance valve adjustment (if the guy even knew what that meant, or how to do one) I would say you will be disappointed in the results.

 

Other than the L28 now feels like a strong L24 and revs exactly the same.

[osirus9]

arg... Tony, you really know how to get people to spend money don't you?

 

So would it be worthwhile to have, say Isky, regrind a stock cam to get better performance out of the engine? I don't want to replace the valvetrain though, so that limits my lift, but I shouldn't need crazy lift with a turbo cam correct? Not like the N/A guys.

 

I suppose if I gave them a call they could probably explain it to me, but I'd rather get an unbiased opinion.

 

All I really want is a good power curve starting at about 3000 out to 6500 with a stock cam. But If I'm getting a re-ground cam I'd want to spin to at least 7000. Is that possible on an otherwise stock engine with just a cam?

 

In some other threads I was seeing dyno charts where power came on from basically nothing at 3k to nearly peak power at 4500 and then the power drops off around 6500. Kinda looking to make a more linear progression where I can punch it at 2500 and actually move.