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Tomzern

Issues swapping E88 head with N47 head? (L24 bottom)

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Hi!

 

I have an L24 with the original E88 head on it now. This head makes bad noises and needs work, but I have an N47 head that I took from an L24e engine. Can I mount the N47 head on my early L24 block with SU's and stock head gasket without any issues? Will this give a CR bump?

 

Only concern I can come to think of is that the L24E had dishtop pistons, and I am pretty sure that the E88 L24 has flattop?

 

Just trying to find the cheapest way to get rid of the bad noises as this is just a temporary engine :)

 

 

 

Regards,

 

Tomzern

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That head is from a Datsun 810 or something?

Bolt on, but you would need the exhaust manifold because its round port. Also need to relieve the bore for the larger exhaust valve to clear if you are at stock bore.

In the end, you should have a better running motor than the stock. Should put you 10+ to 1 and detonation resistant. Getting ready to put that head on a L28.

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Sounds like you have a Maxima head. You can tell them apart by the extra sensor between number 5 & 6 spark plugs. It is not the same as the L28 N47 head. In fact its considered to be a far superior head with "closed" combustion chambers. In the Datsun world its often refered to as a MN47, the M being Maxima.

 

The MN47 had 39cc chambers where the N47 and the E88 have 44.6 or 44.7cc chambers.

It will raise your compression ratio to about 10:1 with a 1mm head gasket and a 2mm head gasket will give you about 9:1

 

Its a bolt on replacement except for the exhaust manifold has round ports with emmision liners. You will need another exhaust manifold from a L28 280Z. The 280ZX non turbo exhaust manifold will fit, but its routing for the pipe is differant to the S30 model.

 

What is the noise. Could it just be tappet adjustment? That would be the easiest way out.

 

Chas

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The head is actually from a Nissan Laurel C32 found here in Europe:)

Ahh, those relieves are an issue:/ I am standing here looking at the L24e block just to know what you mean and I understand. How can I add those relieves to my old L24 block?

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Here's where the valves just barely hit the bore.
post-23570-0-87165900-1424309771_thumb.j

 

 

Here's how to fix the problem.

post-23570-0-60292400-1427061269_thumb.j

 

 

But I'm rebuilding so if you want the cheapest way out I'd take the E88 to a machine shop and see how bad it is.  Maybe cheaper to fix the E88?  Probably needs new valve seats.

Edited by siteunseen

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You will need to relieve the bore for the exhaust valve. Its the same size as the E88 on the L26 260Z @35mm diameter. The inlet valves on the MN47 are 42mm, Not 44mm like the N47 on the L28 and shouldn't be any problem.

If you do this with the engine bottom end intact and still in the car, Move the piston half way down the cylinder and tape the groove section so no grit will get into the top ring area.

You could use something like cardboard to make disc a couple mm smaller than the bore. Lay that on top of the piston and tape it to the cylinder wall. That would seal better than a dirty piston crown. Just an idea.

Cover over the other cylinders and oil passages to prevent grit entering.

Chas

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Aren't we getting diverted here?  He has an L24E head for an L24 bore.  When he's done it will be like putting flat-top pistons in the L24E.  Shouldn't need any notches.  As madkaw says it should be a bolt-on.

 

Using the 39cc numbers I get 9.8 CR for the combo.

 

 

post-19298-0-24674400-1431108648_thumb.p

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N47 or MN47 will slightly hit the cylinder wall.

The "M"N47 head is from an L24 engine.  Same bore and stroke as the 240Z L24.  It's not the same as the N47 head from the L28.  

 

Nissan screwed up when they named the head used on the L24E engine.

 

Unless we're saying that the Nissan Maxima and Laurel C32 L24E blocks were relieved for valve clearance.

Edited by Zed Head

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The "M"N47 head is from an L24 engine.  Same bore and stroke as the 240Z L24.  It's not the same as the N47 head from the L28.  

 

Nissan screwed up when they named the head used on the L24E engine.

 

Unless we're saying that the Nissan Maxima and Laurel C32 L24E blocks were relieved for valve clearance.

 

I have the L24e block that the N47 head came from, and it has relieves for the valves. 

 

I don't know if my N47 and the Maxima N47 heads are the same. Will check for the sensor between plug 5&6 tomorrow.

 

As for the exhaust manifold, I have already mounted the manifold from the L24e on my car. It was a direct replacement to the original smog manifold, except I had to cut a little in the collector pipe to make it fit the outlet flange on the L24e manifold.

 

Post #3 here shows how I did it:

http://forums.hybridz.org/topic/121668-w48-diamond-exhaust-manifold-on-240z/

 

So the exhaust is already in place and will not be an issue.

 

The relieves on the L24e block are milled out about 2mm into the deck. Im thinking it would be better to use som sort of milling bit on an air die grinder to make it as close to the original relieves as possible, since I have the L24e block for reference. What do you think?

 

I was planning to use a stock L24 head gasket. Are there headgaskets with relieves also, or is that not an issue?

 

The noise probably comes from worn out valve seats/guides, Have tried adjusting a dozen times, even tighter than oem specs but no difference.

 

 

Thanks,

 

Tomzern

Edited by Tomzern

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I have the L24e block that the N47 head came from, and it has relieves for the valves. 

 

That's interesting.  I've never seen that mentioned for the factory stock Maxima L24E.  I may have missed it though.

 

I didn't think that Nissan did any valve relief on their blocks.  There's rumor about the 260Z but many people think the "reliefs" are actually from the valves nicking the bore edge.  

 

From a manufacturing perspective, it's a lot of work for not much benefit.  Best to just design the head so that it works right, and the Maxima head was only used on the L24E.  I can't imagine being the engineer that has to explain that every block needs extra machining because the valves will hit otherwise.  Just doesn't make sense.

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Here's a side-by-side of the MN47 from that Hybridz link and my N42, which has the same "open" chamber shape as the L28 N47.  You can see the "quench' area on the MN47.

 

 

post-19298-0-22531900-1431128917_thumb.p

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That's interesting.  I've never seen that mentioned for the factory stock Maxima L24E.  I may have missed it though.

 

I didn't think that Nissan did any valve relief on their blocks.  There's rumor about the 260Z but many people think the "reliefs" are actually from the valves nicking the bore edge.  

 

From a manufacturing perspective, it's a lot of work for not much benefit.  Best to just design the head so that it works right, and the Maxima head was only used on the L24E.  I can't imagine being the engineer that has to explain that every block needs extra machining because the valves will hit otherwise.  Just doesn't make sense.

 

It's a bit more realistic that the relieves are there from factory, than that they have been nicked out by the valves over time. I will post pictures of the relieves on my L24E block tomorrow. They definitely look machined.

 

Another thing. My L24E comes from a laurel that was produced from 1984 to 1989. The maxima L24E was used from 1981 to 1984, so there may be a few differences on those two engines as well.

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It's a bit more realistic that the relieves are there from factory, than that they have been nicked out by the valves over time. 

Have to disagree.  The nicks seen could be from worn valve guides with a close tolerance.  Machining the block is actual money spent by the company that could be avoided.  Potential money savings in high production automotive factories is one of the most powerful force you'll ever find.  Pennies matter.

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I don't doubt that, and I am no engine machinist or engineer, but the way those relieves look tells me that they are not knocked out by the valves. Especially since they are looking exactly the same on all 6 cylinders. :)

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The question remains though as to what you have.  You might have an L28 N47 head on an L24 block, that somebody notched to make it work.  There's a whole other recent thread on this forum about that.  It's fairly common, to get the bigger valves.

 

We'll know more when you figure out what head you have.

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My guess (and hope) is that I have a newer european version of the US "MN47" head (ref 84-89 build year for the Laurel L24e)

 

I'll be back with pictures tomorrow! :) 2:17AM here now, so might consider calling it a day :P

 

 

Oh, and thanks for all your help so far! 

Edited by Tomzern

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Zed,

Not sure that Nissan  would be the only ones that actually relieved bores on factory engines -at least from my research.

 

You could be careful and notch the bore without dismantling the engine. Shaving cream and a drum sander would make quick work of it. A 2" drum sander with 80 grit and a couple of hours of prep and done. 

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I'm basically playing devil's advocate I guess.  I would like to see an actual factory block with factory-notched bores.  I just haven't seen it in all of the 5+ years I've been on the forums, and all of the old posts I've read from way back in that time.  I get that an L28 head on an L24 bore would need it.  Can't see that a Maxima L24E head on a Maxima L24 block would.  

 

The valves are the same size as 260Z valves (looked them all up on OReilly auto Parts).  Only the exhaust valve, the smaller valve, is bigger in the Maxima head than in L24 heads.  So, it's not a valve size thing, it would have to be a combustion chamber shape and valve seat placement issue.  But I think that is determined by the cam, and rocker arms, which are the same.

 

My logic center just can't find a reason that the Maxima N47 head isn't a straight bolt-on, and there doesn't seem to be any evidence, despite all of those Maxima engines out there.  Maybe Tomzern has the first one.

 

Considering the bigger valve (one) and the slight bump in CR, it's surprising that more people haven't just swapped the complete L24E engine in to their 240Z's. Looks like it has the carb manifold mounting holes.

 

Anyway, let's see how this plays out.  Tomzern, where's your camera?

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I was talking to my Dad last night and he said they used to run the piston down 2 or 3 inches then pack the rest of the cylinder with axle grease before tapping out broken head bolts.  Same as shaving cream.

 

Here's some good pictures of a factory notch from a Skyline.  Post #22 http://forums.hybridz.org/topic/70734-notchingbevelingbutterfly-l24-block-for-valve-clearance/page-2

 

 

Here's where Blue used an MN47 on an L24, post #2 http://www.classiczcars.com/topic/50973-24-valve-reliefs/

Edited by siteunseen

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