Cam Damage

[JMortensen]

The oil that lubes the cam lobes isn't pressurized like a bearing journal. It's just oil sitting on the lobe. The spray bar puts oil on the lobe continuously. The internally drilled cam oils only one part of the lobe, where the hole is. Yes, the hole is strategically placed, but the distribution of oil is not even. Nissan comp offered spray bar kits to add the spray bar to the L4, and How to Modify specifically states that the spray bar is better lubrication system.

 

When you take into account which is more likely to fail over the course of 200,000 miles, I think you might come to the conclusion that the internally oiled cam is better, but comparing correctly functioning system to correctly functioning system I think it's clear that the spray bar is the better of the two.

 

When in doubt, run both.

[Tony D]

Ahhhh, so it still does exist...

 

My point was that previously every manufacturer of oil products made the claim---especially on Television Adverts. I don't see that claim being made public like that any more. I see galloping oil horses, but nothing about paying for the engine from an oil related failure.

 

I think Arco Graphite's Ford Debacle started the decline in that claim.

 

It's good to know Mobil still warrants against oil-related failure, but I see a $50K piece of litigation to get your $3K engine replaced.

[sonomaz]

I have now had a couple of conversations with Mike at Crane Cams and the ZDDP issue is a concern. Mike also raises the concern of using aftermarket versus OEM rockers. He claims the OEM uses "chilled cast" pads that are higher quality and more consistant on the hardness. Any thoughts?

 

I also brought up the subject of coatings. I was thinking about having an anti-friction coating applied to the cam similar to what they put on piston skirts but I have not found any direct information of using this on a cam lobe. Mike said he had heard of this and even knew of a several people who are doing this but did not have specifics.

 

http://www.embeeperformance.com/coatings/antifriction.html

 

Crane has a surface treatment called Micronite and Mike apperantly is the contact for this at Crane. He stated it is not a coating but is a treatment simillar to shot peening except the media used is microscopic and it is not directed from a hand held gun. He said it works very well for gears but they do not have a lot of experience with cams.

 

It turns out my cam can be reground and the the question is what grind to run. Below is the two choiices I am considering. The first is what I had and the second is the next more aggresive grind. I liked the one I had but who doesn't want more power. My engine set up is in my signature.

 

 

The lift numbers are the same, the only difference is the duration. I like to get this on order early next week so what do you suggest?

[Phred]

Whats wrong with these people. Why they can't have a standard height for checking cams? FWIW 25.4 is the constant for converting mm to in. and vise-versa. Either multiply or divide.

My choice would be the "bigger" cam. The advertised duration is not that much more. If it were me, I would install the cam 2 degrees advanced for street use. This will help pick up the bottom end performance a bit, and help offset the slight loss you'll get by going to a bigger cam. My 2 cents.

Also, the springs at 180 open will be good for a street racer.

Phred

[Poindexter]

Forgive my ignorance- I'm trying to learn more about the impact of cam changes- but do I see a true "lowering" of redline of almost 400 rpm from the first cam grind to the second-starting point? Or is that simply a downward "offset" moving the entire power band lower?

 

These sharper grinds appear to be so aggressive that they can cause valve float much lower in the rev cycle. Just trying to make sense of the trade-offs, and placement of the power curve inside the rev range.

[Phred]

Cam cards give an engine builder a good idea how a cam might perform, but don't draw any hard conclusions by them. There are a lot of other engine component factors that can upset the apple cart. Generally, a "bigger" cam will produce more power higher in the rpm band, with a corresponding loss in the lower rpm range. Having said this, any cam can be made to change it's characteristics by changing the cam timing. Example: a stock L24 cam in an SCCA ITS car set at 1.375 degrees retarded will make power all the way up to 6500rpm. But it doesn't do very well under 3000rpm. Take the same cam and advance it a few degrees, and it will now respond well at lower rpm levels through the mid range. But, the engine will probably fall flat from 6000 and up. I have degreed and dynoed till I was blue in the face, and after all these years I have a good idea what to expect, but I won't throw a cam under the bus just because of what the cam card says. It's very hard for a home builder to pick the perfect cam for his engine. Just remember how important cam timing is, and how it can change an engines attitude.

Oh, and to make this thread relevant, use a good break=in oil additive when you first fire it up.

Phred

[sonomaz]

Poindexter,

 

If you look a little closer you will notice their is no number for valve float on Cam 2. Max RPM for cam 1 is 5600 and cam 2 is 6000. I think max and min RPM on the cam card is where the grinder thinks the sweet spot will be. So cam 2 is 400 RPM higher than cam 1.

 

Any one else want to suggest which one I sohould get?

 

Paul

[JMortensen]

A bigger one...

[sonomaz]

A bigger one...

 

Ha ha ha.... so many things to say to that, nothing related to Z's!!!

[sonomaz]

So the personal budget opened enough to regrind my cam and buy rocker arms. I picked up a set of rockers from Motorsport Auto for ~$250. The issue is they are not manufactured by Nissan. When I spoke to Crane Cams they were very specific about using Nissan rockers to minimize scarf (is this a real word?) issues. So two questions: 1) how important do you thnk it is to have Nissan manufactured rocker arms; 2) where can I get them for a reasonable price?

 

I got my cam back. I'll get some pictures posted soon.

[2eighTZ4me]

Wow - they really prong you for rocker arms. Do you have any factory rockers off that head or another head? I sent mine to Delta Camshaft out west and they do a fabulous job of resurfacing rocker arms. I got a set of 12 done for just over $50 with shipping and they look like brand new. If you have a set lying around, I'd go that route and send the MSA ones back. You'll at least know that they are geniune Nissan and from the correct metallurgy. My humble $0.02 worth.

[Pyro]

So the personal budget opened enough to regrind my cam and buy rocker arms. I picked up a set of rockers from Motorsport Auto for ~$250. The issue is they are not manufactured by Nissan. When I spoke to Crane Cams they were very specific about using Nissan rockers to minimize scarf (is this a real word?) issues. So two questions: 1) how important do you thnk it is to have Nissan manufactured rocker arms; 2) where can I get them for a reasonable price?

 

I got my cam back. I'll get some pictures posted soon.

 

deltacam will resurface stock rocker arms for 4.00/each. They also do cam regrinds for 60.00.

 

I use a zddp oil additive. cost 10.00 extra for each oil change.

[Guest Widebodys30]

I was in contact with Kevin from Schneider Cams.

He is aware of the new aftermarket and regrind Datsun cams losing lobes recent years,

and in his opinion, it's due to the loss of zinc in our modern oils.

[Pyro]

if you have a performance cam then get a case if this.

 

http://www.zddplus.com/

[Tony D]

I remember when NEW Nissan OEM rockers were only $12 each, and people balked at the exorbitant pricing of $144 for a set of 12!

[josh817]

So what if we went with the Chevron Delo and some ZDDP. Such think as TOO MUCH zinc? I'm all worried now as I have the same mileage and a Schneider .495" 290º cam and last time the valve cover was off I was paranoid but when I ran a feeler gauge over the lobe it didn't catch on any nooks or crannies.. Still, a good oil change would be great for my baby.

 

Also if I were in your situation and the rockers were ok I would just get them cleaned up and buy a new cam/have one reground. Only because cams by themselves are what? under $200 I think? If you already have the hot springs and such there is no point on buying the entire cam kit unless you buy from MSA. They won't guarantee anything unless you buy the kit so everything is properly setup for that particular cam as far as spring rates go and such.

[2eighTZ4me]

 

They won't guarantee anything unless you buy the kit so everything is properly setup for that particular cam as far as spring rates go and such.

 

Well - either I got a bum deal, or MSA doesn't really "check" their kits. I got stock lash pads with my cam kit. .120". Lash pads for the Schneider kits are supposed to contain .150" lash pads. Hence, I didn't check wipe pattern thinking that the kit was "matched". What a mistake. 8k mi. later, I've got a rounded off lobe on the cam. Ate it up. So just a word to the wise - even though you buy the kit - double check your wipe pattern and measure your components before firing that bad boy up.

[z-ya]

I'm sorry I'm chiming in a little late here, but the problem is not the cam, or oil, but a combination of aftermarket rockers and the wrong thickness lash pads (wipe pattern way off). An alternative to new rockers is having some Nissan ones reground by Delta Camshaft. I think they charge around $3 each, and the come back looking like new. I've been running reground rockers with a Comp Cams camshaft and the correct lash pads for over 5 racing seasons without any issues.

 

Stay away from aftermarket rockers, and always check the wipe pattern on EVERY rocker arm.

 

Pete

[2eighTZ4me]

All the research I've done on this site and others suggests it is a lack of ZDDP in the oil and "cheap" metallurgy of new billet camshafts. I can't attest to the aftermarket rocker theory, but it would stand to reason as well that the metals today are just not as refined and hardened as they were back then - rockers or cams. So much so, that Schneider sends you a big yellow notice that falls out of the cam box as you unroll your new cam stating that you MUST use one of the following oils due to the presence of zinc. THEY know something is wrong (whether it having to do with the oil or not - they're just covering their butts).

 

My situation was perhaps a combination of both. My cam kit came with the wrong lash pads and I (spelled DUMBA$$) didn't check wipe pattern, as well as used an oil without ZDDP.

 

Regardless, I am using Delta regrind rockers with an old Racer Brown cam, and running Valvoline VR1 with a bottle of ZDDP Plus added. I'm just not taking any chances. Wipe patterns have all been checked and are spot on.

 

I've read many theories on this and don't exactly know what to make of it, but there are those on this forum whose opinions I respect highly who have made a point that ZDDP is indeed a factor.

[Tony D]

The oil IS an issue. EVERYBODY is experiencing it both import and domestics.

 

To the question of 'is there such a thing as 'too much zinc'?

 

Absolutely. Hence the change in formulation for MODERN cars. The zinc poisioned catalysts. The Mobil Blackstar had a lot of Zing and Phosphorous.

 

For a car with no catalyst on it...no MODERN catalyst (the older catalysts were working on different things and didn't 'have' to last 100K miles, though many do well more than that) then the point where spark plug deposits become an issue is a point where 'there is too much additive'...

 

Those of us old enough to remember working on engines run forever on Leaded Gasoline will remember religiously cleaning spark plugs from deposits in the oil and gasoline. Lead Fouling on the plug would bridge the gap and misfire the cylinder. Bad ring seal caused oil deposits from unburned leftovers...

 

Unless you dope to that high a level (and have bad ring seal to boot) I doubt you will run into a 'too much' situation.

 

Frankly, the more relevant question to me would be 'how much do I need'---to the point, what level of expensive aftermarket additive to I need to add to modern oils to provide the same level of protection that was provided by the previous generation of non-zinc-depleted oils.

 

To batch the oil to that level, AND NOT FURTHER is likely the most economical way to do it. I doubt MORE will increase your protection, likely it will just cause other problems. The key is to add 'just enough and not any more' so you get the protection you need.