Swapping cams one engine to another

[HuD 91gt]

Hello all.

I just put in a F54/N47 combo into my 240z. The cam/rockers have some burn/wear marks on them. My original plan was to run this for the time being, and send in the old L24 cam off to rebello for their cam kit, and the rockers off to delta for a refresh.

I'm now thinking a smarter idea would be to send the N47 cam/rockers away for a refresh since they are not in the best shape.

Not having done any head work before, can I swap the cam, rockers, springs retainers and lash pads from the l24 head onto the l28 without any drama? I assume I'd have to check the wipe pattern no matter what as the seats may be different heights?

The bonus side to this, is the l24 has a much lumpier idle, I think it may be an aftermarket unit. Is there anyway to check this?

Cheers guys

Edited July 13, 2015 by HuD 91gt

[Zed Head]

The aftermarket guys tend to mark their cams.  Check the back of the last cam tower.  Also, if it's a regrind the base circle will be smaller.  The part of the cam lobe that has no lift will be thinner, compared to a stock cam lobe.

 

It is said that you can swap the complete assembly of cam towers, cam and rocker arms from head to head, by carefully adjusting the cam towers before torquing them down.  It's not a factory recommended procedure though, just something that has worked in the past.

 

Are you sure the cam is worn and burned.  The base circle of each lobe sees essentially no pressure.  Only the force of the anti-rattle springs.  Post a picture.

[siteunseen]

Datsun cams have B and F maybe a C stamped on the end at the rear I believe. Not the end with the dowel for the cam sprocket. After market and regrinds engrave their name and profile number on theirs. Go to atlanticz's tech tip page and under ENGINE it has a cam chart. I'm thinking the C from a 260 is the better one and very rare. Fuel injection requires a different profile from what all I've read. Your N47 is a B stamped cam I'm pretty sure. A mirror and a flashlight will tell for sure.

[HuD 91gt]

Thanks guys, I'll pull the valve cover and take a look. I bolting the whole assbly and just swapping over sounds brilliant! I'll take some photos as well.

Edited July 13, 2015 by HuD 91gt

[siteunseen]

Original datsun cam will have the word JAPAN in raised lettering too. Also E30 or something like that. Sorry for the guesses but I'm sitting in my doctors waiting room now on my phone.

[Chickenman]

One other thing to check. Datsun used two methods of oiling cams. L24' s and L26's used oil spray bars and un-drilled cam lobes as did early L28's ( up to PD 02/77 ). Later L28's got rid of the spray bar and used a cam shaft with drilled cam lobes for oiling. N47 heads usually do not come with spray bars, so the Cam has to have drilled Cam Lobes or you have to swap out Cam Towers.

 

However, you " may get lucky. It sounds like you may have a reground cam shaft in the L24. Have a look at the Lobes and see if they are drilled for oiling. If they are, you can swap the L24 cam direct into the N47 head without switching towers. No holes in the cam lobes and of course you have to run a Spray bar.

 

BTW, you can run an Oil Spray bar and a drilled cam no problem. Some people say you can't, but It's done all the time on Race cars. All L4 engines have drilled cam lobes only. Race engine builders often add an auxilary spray bar to aid cam oiling. The oil pump has more than enough volume and pressure to handle the extra oiling. Especially if you run the Turbo pump.

 

Picture of L 4 valve cover with externally fed oil spray bar:

 

[siteunseen]

Well of course I was wrong, N47 shows to be an A cam.

 

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

[HuD 91gt]

I pulled the valve cover on the old L24 (the one I think may have a different cam), and it is indeed an A cam, that is internally oil (holes in the bottom of the lobes). Here are the pictures. I guess my only way of seeing if it is a regrind is to somehow measure the bottom of the lob. I'll get pictures of what my other cam looks like shortly.

[siteunseen]

I've taken a look at three 2.4 heads I have, they don't have drilled cams, two E88s and an E31.  The N47 had the first drilled cam in my experiences.  If it's been reground it should have some information engraved in the end like who reground it and their profile number.

 

I bet the previous owner took the spray bar off and installed a drilled A cam in your 2.4.  Those spray bars scare me, they get loose where they're are brazed together and lose their "aim" to the lobes.  Leak at the cam towers too if you don't keep the bolts tight and the gasket in between is just a thin piece of paper that falls loose.  My opinion only.  I'm running both the drilled cam and spray bar with a high flow turbo oil pump, if it ever gets put together.   

[HuD 91gt]

Yeah, after looking at both cams, they look very similar to the naked eye. I don't see any other markings in the L24 cam to say it's a regrind. Maybe I'm just imaging things.

Here are the pictures of the wear on my L28 cam.

[Zed Head]

My stock engine sounded cammy when it was running rich.  

 

Numbers-wise, the 280Z A grind, is the same as the early 240Z L24 grind.  Made a picture of 72 and 76 numbers.

 

And I don't know that I would worry about the marks on the cam.  Looks like it may have had some rust on it that wore off, but hard to tell if it's going bad.  Don't see anything significant.  Cam changes can be a whole giant can of worms.

 

The cam numbers are shown in site's atlanticz link also.  I like to go to the source when I can.

Edited July 14, 2015 by Zed Head

[Chickenman]

You've got some galling starting on the L28 Cam lobes. You might be able to micro-polish it out. I'd also check your rocker arms for wear. Once that type of wear starts it escalates rapidly.

 

What are you using for engine oil? You absolutely should not be using an Energy Star or SM/SN rated oils in these cars. They simply do not have enough ZDDP in them these days. Stay away from all 0w-XX oils. These are all Energy Star rated oils with reduced ZDDP for longer Catalytic convertor life. 

 

Run a specialty high ZDDP content oils made for older cars or " Hot Rod " cars. Something like Brad Penn, Pennzoil 25w-50 ( very good oil. 1980's level of ZDDP ) or a synthetic like Amsoil 10w-40 ( High Zinc ) or Joe Gibbs/Driven 10w-40 Hot Rod Synthetic. Also, " 4x4 Truck " brands do not have to be Energy Star rated. these are usually in thicker blends and carry more ZDDP.