# CAM QUESTION



## westex39 (May 30, 2006)

On the 2006 4.0L VQ40DE engine it has a dual overhead cam configuration. Question: Is this considered to be a flat tappet cam setup?

thanks


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## BTF/PTM (Oct 19, 2006)

Most likely it is a bucket and shim setup, where the camshafts act directly on the valves without having any kind of lifter in between. Anyone got the service manual to verify?


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## westex39 (May 30, 2006)

BTF/PTM

That's exactly what it is. Would this be considered a flat tappet type setup?


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## avenger (Oct 7, 2005)

yes, i doubt we have a roller cam setup...

just use redline synthetic oil and stop worrying about the exact oil to use


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## ChuckFrontier06 (Jul 25, 2006)

_*The service manual shows lifters between the cam lobes and the valves.*_


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## BTF/PTM (Oct 19, 2006)

Chuck, I don't suppose you'd be able to scan that page and put a photo up for us? I'm curious.

The term "lifter" is very generic. In a chevy 350V8, the lifter is a little cylinder of metal the operates a push rod. In a Honda SOHC 4-cylinder, the lifter is actually a rocker arm that swivels at the center and pushes the valve open and closed. In a bucket/shim engine, the lifter is usually the term they use for the bucket itself. It doesn't actually lift the valve, but that's what they call it.

Westex, I would probably say yes. Again, the term "flat tappet" is a generic term, it usually defines a valve system that does not automatically adjust itself. It's just a metal link of some form that operates the valve and the clearance between the parts has to be checked and adjusted at some interval. The two other general options are "hydraulic lifter" and "roller lifter". Hydraulic lifters do not need adjustment, they are pressurized by engine oil and thus keep proper clearance between cam and lifter automatically. Roller lifters have metal rollers that, instead of sliding against the camshaft, roll against it and thus help to reduce friction. Roller systems are typically very expensive compared to the other two. Flat tappets are the cheapest, but the trade-off is that you have adjust the system periodically.

Avenger, is that what this is in reference to? Are there special oils listed for certain valve trains?


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## westex39 (May 30, 2006)

This is what the nissan DOHC looks like.

dual overhead cam schematics - Google Search

Click on the wikipedia.org. First one on the list.


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## BTF/PTM (Oct 19, 2006)

Thanks West! That's what I figured these engines used. For the record, the picture shown in that link uses hydraulic lifters, you can tell by the oil groove and tiny oil hole at the center of the buckets.


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## westex39 (May 30, 2006)

BTF/PTM said:


> Thanks West! That's what I figured these engines used. For the record, the picture shown in that link uses hydraulic lifters, you can tell by the oil groove and tiny oil hole at the center of the buckets.



I didn't know there were hydraulic lifters inside the buckets. I went back and took another look. Makes sense to me.
Do you think synthetic oil is a must with this type valve system? 
I plan to use Pennzoil Platinum 5W-30.

Thanks


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## BTF/PTM (Oct 19, 2006)

westex39 said:


> I didn't know there were hydraulic lifters inside the buckets. I went back and took another look. Makes sense to me.
> Do you think synthetic oil is a must with this type valve system?
> I plan to use Pennzoil Platinum 5W-30.
> 
> Thanks


There aren't "lifters" inside the buckets; the buckets themselves are the valve lifters, think of it as a "lifting bucket". What I mean is, the term "lifter" is the term for the part that actually pushes the engine valve open. The hydraulic mechanism inside the lifting bucket eliminates the metal shims that, in the case of the "flat tappet" system, would be there to set proper clearance between the cam lobes and the buckets (lifters). 

With the hydraulic setup, the pressurized oil that gets forced into that tiny oiling hole goes into a chamber inside the lifting bucket. The bottom part of the lifting bucket pushes downward on the engine valve, and the top part of the lifting bucket pushes upward on the camshaft lobe. Those two parts are connected by a spring and the two parts basically slide upward/downward a small amount. The chamber I referred to is the space between the top and bottom parts of the lifting bucket. When pressurized oil is forced into that chamber and pushes outward on the two parts, the upper part of the bucket moves upward to contact the camshaft lobe so there is constant contact when the engine is heated up to operating temperature. When there is too little oil pressure being fed to that lifting bucket, the spring inside the bucket pulls the two parts of the lifting bucket together and then there is too large a gap between the camshaft lobe and the lifting bucket. This causes the loud tapping you hear when a lifter is out of adjustment because the camshaft is slapping against that lifting bucket as it rotates. It will also eventually destroy the lifting bucket, and possibly damage the camshaft and valve. 

All this stuff is designed around what the operating oil pressure of the engine is, how much force the camshaft exerts on the bucket when it is pushing the valve open,the optimum sizes of the oiling passages and pressurizing chambers, how much all the engine parts expand when they're heated up, and a few other things. I could show you the math, but I don't think yall are quite as nerdy as me :loser: 

To answer your question, you don't need any special oil to ensure proper valve lifter function. Whatever Nissan recommends as a minimum, that's all you have to worry about.


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## nissanmadness (Sep 18, 2006)

Just to clear the air, Nissan calls them valve lifters. There are 26 different thicknesses of the valve lifters for the QR25, and 27 different thicknesses of valve lifters for the QR40. There are no mechanical adjustments. You measure between the cam lobe and lifter and install the appropriate thickness lifter to bring you back to specs, should you need to.


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## nissanmadness (Sep 18, 2006)

OOPS, my mistake, there are 27 different thickness valve lifters for the intake and 25 different on the exhaust side. This is for the VQ40 engine. The lifters are not hydraulic. They are kind of bucket shaped if you hold them upside down. The thickness is stamped underneath. So if you remove them for any reason or service, make sure you put them back where they came from.


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## westex39 (May 30, 2006)

Man, I'm lovin' this. I'm really getting an education. I'm real familiar with the old O/H valve engines. But I have no experience at all with the OHC engines.
Thank you all very much for all the good info.

Regards,

Westex


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## avenger (Oct 7, 2005)

westex39 said:


> This is what the nissan DOHC looks like.
> 
> dual overhead cam schematics - Google Search
> 
> Click on the wikipedia.org. First one on the list.


i don't see a nissan DOHC valvetrain.


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## avenger (Oct 7, 2005)

BTF/PTM said:


> Chuck, I don't suppose you'd be able to scan that page and put a photo up for us? I'm curious.
> 
> The term "lifter" is very generic. In a chevy 350V8, the lifter is a little cylinder of metal the operates a push rod. In a Honda SOHC 4-cylinder, the lifter is actually a rocker arm that swivels at the center and pushes the valve open and closed. In a bucket/shim engine, the lifter is usually the term they use for the bucket itself. It doesn't actually lift the valve, but that's what they call it.
> 
> ...


no, there are really only two types of cams. "flat tappet" and roller. flat tappet cams can run mechanical or hydraulic lifters, and thus be self adjusting or not... same for a roller cam

(besides knife edge and other variations)

my 2nd comment to him was about a post he made before


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## westex39 (May 30, 2006)

avenger said:


> i don't see a nissan DOHC valvetrain.


Click on the first website listed. It's a wikipedia. org site.


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## BTF/PTM (Oct 19, 2006)

Thanks for the added info, NissanMadness! I was wondering if my VQ had self-adjusting lifters or not...I guess not. Hopefully the adjustment interval is covered under warranty at least the first couple times they need adjusting.

I'm learnin new stuff to, Westex! That's why I love forums like these, peopel chime in with extra info and by the time you're done you have a thorough explanation of how stuff works.


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## avenger (Oct 7, 2005)

westex39 said:


> Click on the first website listed. It's a wikipedia. org site.


i clicked the link, nowhere did i see it say that picture was of a Nissan DOHC valvetrain


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## nissanmadness (Sep 18, 2006)

BTF/PTM said:


> Thanks for the added info, NissanMadness! I was wondering if my VQ had self-adjusting lifters or not...I guess not. Hopefully the adjustment interval is covered under warranty at least the first couple times they need adjusting.
> 
> I'm learnin new stuff to, Westex! That's why I love forums like these, peopel chime in with extra info and by the time you're done you have a thorough explanation of how stuff works.


Glad to help out when I can. On the plus side I hope none of us needs a valve adjustment for a long time. Hope you all had a Good Thanksgiving. See ya!


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## westex39 (May 30, 2006)

avenger said:


> i clicked the link, nowhere did i see it say that picture was of a Nissan DOHC valvetrain


Try this website.
Overhead camshaft - Wikipedia, the free encyclopedia

I never did find a Nissan cam shaft. This is a good likeness of what I can see of the cam shaft in the engine I have. 
a VQ40DE

I just got of the phone with my Nissan dealership. He told me there were no valve adjustments required on the VQ40DE engines. So, I am assuming that the bucket assembly does have a oil reservoir that acts something like a hydraulic lifter.


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## westex39 (May 30, 2006)

BTF/PTM said:


> There aren't "lifters" inside the buckets; the buckets themselves are the valve lifters, think of it as a "lifting bucket". What I mean is, the term "lifter" is the term for the part that actually pushes the engine valve open. The hydraulic mechanism inside the lifting bucket eliminates the metal shims that, in the case of the "flat tappet" system, would be there to set proper clearance between the cam lobes and the buckets (lifters).
> 
> With the hydraulic setup, the pressurized oil that gets forced into that tiny oiling hole goes into a chamber inside the lifting bucket. The bottom part of the lifting bucket pushes downward on the engine valve, and the top part of the lifting bucket pushes upward on the camshaft lobe. Those two parts are connected by a spring and the two parts basically slide upward/downward a small amount. The chamber I referred to is the space between the top and bottom parts of the lifting bucket. When pressurized oil is forced into that chamber and pushes outward on the two parts, the upper part of the bucket moves upward to contact the camshaft lobe so there is constant contact when the engine is heated up to operating temperature. When there is too little oil pressure being fed to that lifting bucket, the spring inside the bucket pulls the two parts of the lifting bucket together and then there is too large a gap between the camshaft lobe and the lifting bucket. This causes the loud tapping you hear when a lifter is out of adjustment because the camshaft is slapping against that lifting bucket as it rotates. It will also eventually destroy the lifting bucket, and possibly damage the camshaft and valve.
> 
> ...


This is what my Nissan dealership confirmed.


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## BTF/PTM (Oct 19, 2006)

westex39 said:


> This is what my Nissan dealership confirmed.


damn I'm good


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## d3l0n6 (Feb 10, 2006)

BTF/PTM said:


> This causes the loud tapping you hear when a lifter is out of adjustment because the camshaft is slapping against that lifting bucket as it rotates. It will also eventually destroy the lifting bucket, and possibly damage the camshaft and valve.



Is this the noise I hear when I start my truck up everyday? Just no oil pressure in the lifting bucket? Interesting.


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## BTF/PTM (Oct 19, 2006)

d3l0n6 said:


> Is this the noise I hear when I start my truck up everyday? Just no oil pressure in the lifting bucket? Interesting.


That might be what you're hearing. I've noticed that my VQ makes a crapload of noise for that split second before oil pressure has built up inside the engine too. It might be the lifter, it could be a bearing too. It's nothing to be alarmed about as long as it goes away after a second or so.


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