Pulling Cams Longevity

[James1911]

Hello, Please know up front I know nothing about Grinding Cams, followers or any aspect of it. I do not have any ax to grind. I am just curious if there are a lot of camshaft failures with tractor pullers as there are with street Hot Rodder's. I am an older Tractor Lover having used them until I retired. I am a interested reader of most things mechanical. Reading online I have read of so many nightmare situations of engines ruined by dropped valves etc. from new camshafts and lifters in newly reworked engines. What got me thinking about the failures is the fact that new vehicles are mostly exempt from valve train disasters. I have read of many reasons given to why this occurs and so far have not found many provable reasons for the problem. So today my question is how common among pulling Tractors are those valve train failures and what is the life expectancy of reworked cams and lifters for pulling? On farm tractors I expected 10,000 working hours on them without big engine problems and had several that made it a lot longer. I thank you for your time and ideas.

 

[MSD]

The thing with the JD's is everyone is trying too squeeze the biggest crank in as possible. Doing this means to get the rods to clear the cam you need to grind a flat spot on them. Some rods require less grind than others. We have worked with our rod builder and are getting about the maximum clearance from his. To help make the cam live longer we also put a support bracket on the cam to keep it from flexing. This has also helped. Lifters for the G's have not been a problem but with A's we have seen some of them crack. They are a different design and it might just be age fatigue on those. I personally experienced a cam breaking while driving. I sensed something was happening while pulling and stopped. I did drive it off the track before it completely broke in 2. Luckily I was at an idle when it happened. Bigger valve springs, higher lift rockers and more rpm's do take a toll on some though. Some weeks we can't keep up grinding new ones.

 

[James1911]

Thanks, do you make new cams or just regrind old ones?

 

[MSD]

Thanks, do you make new cams or just regrind old ones?

We regrind them. We have the blanks to make new billet ones for JD's but haven't been able to get someone that can cut the gear in the center on the JD one's

 

[James1911]

We regrind them. We have the blanks to make new billet ones for JD's but haven't been able to get someone that can cut the gear in the center on the JD one's

Thanks You for replying

 

[atex57]

We regrind them. We have the blanks to make new billet ones for JD's but haven't been able to get someone that can cut the gear in the center on the JD one'

I have done the gear for a 70 cam.

 

[MSD]

I have done the gear for a 70 cam.

Are you talking the gear in the center of the cam? Would be interested in getting in better contact with you if that is what you can do.

 

[atex57]

Are you talking the gear in the center of the cam? Would be interested in getting in better contact with you if that is what you can do.

Only made a couple of 2 cyl blanks and cut the gear. 13 teeth and LH helix. Make a lot of blanks for newer engines, mostly from S7 tool steel. Make studs also if you need some. PM if interested.

Ed.

 

[showcrop]

Hello, Please know up front I know nothing about Grinding Cams, followers or any aspect of it. I do not have any ax to grind. I am just curious if there are a lot of camshaft failures with tractor pullers as there are with street Hot Rodder's. I am an older Tractor Lover having used them until I retired. I am a interested reader of most things mechanical. Reading online I have read of so many nightmare situations of engines ruined by dropped valves etc. from new camshafts and lifters in newly reworked engines. What got me thinking about the failures is the fact that new vehicles are mostly exempt from valve train disasters. I have read of many reasons given to why this occurs and so far have not found many provable reasons for the problem. So today my question is how common among pulling Tractors are those valve train failures and what is the life expectancy of reworked cams and lifters for pulling? On farm tractors I expected 10,000 working hours on them without big engine problems and had several that made it a lot longer. I thank you for your time and ideas.

In addition to my tractors I have a 1967 roadster that I have done a lot of overhaul work on. In rebuilding the motor I found the original cam to be badly damaged. When I showed it to the machine shop and asked what would have caused it to have so much material blasted away from the surface of the lobes, he responded that it looked to him like it had been seriously over-reved. I am sure you know that at RPMs over what an engine is designed for the valves can "float" so that the lifters or the push rods can be alternately going air born from the cam lobe, and then getting hit by the lobe when it comes around again. The "hot farm" pullers usually have their compression reduced so that RPMs can be increased. I bet that this process results in plenty of damaged cams during the quest for longer hooks through higher RPMs.

 

[Longknife]

Do you guys use a high zinc racing oil or a zinc additive? I have two built engines in a couple of hot rods I drive on the street and always add Zinc to every oil change.

 

[VicS]

Do you guys use a high zinc racing oil or a zinc additive? I have two built engines in a couple of hot rods I drive on the street and always add Zinc to every oil change.

I use Racing 20x50 Valvoline. Has Zink. No other additives.

 

[James1911]

Do you guys use a high zinc racing oil or a zinc additive? I have two built engines in a couple of hot rods I drive on the street and always add Zinc to every oil change.

Hello, I would appreciate you sharing qualified testing on adding zinc for camshaft protection. Main reason I am asking because millions of production cars trucks and heavy equipment are produced annually and none require any special break in oil I am aware of. I have never known of any camshaft failures on factory vehicles. Thanks

 

[atex57]

Hello, I would appreciate you sharing qualified testing on adding zinc for camshaft protection. Main reason I am asking because millions of production cars trucks and heavy equipment are produced annually and none require any special break in oil I am aware of. I have never known of any camshaft failures on factory vehicles. Thanks

Older engines use flat tappet cams and need oil with additives such as zinc to keep from ruining the cam. An older gas tractor we have was given regular auto oil and almost ruined it. Switched to diesel 15w40 and saved it.

Ed.

 

[James1911]

Older engines use flat tappet cams and need oil with additives such as zinc to keep from ruining the cam. An older gas tractor we have was given regular auto oil and almost ruined it. Switched to diesel 15w40 and saved it.

Ed.

Thanks for your reply. You are entitled to your opinion and I respect that. I am not a young fella and I ran old machinery making a living before Diesel Oil was considered main stream. I ran old style 71 series Detroit diesels as well as old style gas engines and had problems but none from a bad cam and used regular motor oil of the day. I used regular motor oil even in the old style D7 Cats on regular 30 weight oil. Same oil I used in all machinery. I know after market cams have had a bad experience lately with cams but the evidence so far does not have anything to do with zinc in oil. I suspect most cam problems are caused by poor oiling and too high valve spring pressure for the component's used. However that is just an opinion. I will wait for some hard evidence produced by quantitative engineering testing to know the real reason.

 

[chucksoliver77]

Thanks for your reply. You are entitled to your opinion and I respect that. I am not a young fella and I ran old machinery making a living before Diesel Oil was considered main stream. I ran old style 71 series Detroit diesels as well as old style gas engines and had problems but none from a bad cam and used regular motor oil of the day. I used regular motor oil even in the old style D7 Cats on regular 30 weight oil. Same oil I used in all machinery. I know after market cams have had a bad experience lately with cams but the evidence so far does not have anything to do with zinc in oil. I suspect most cam problems are caused by poor oiling and too high valve spring pressure for the component's used. However that is just an opinion. I will wait for some hard evidence produced by quantitative engineering testing to know the real reason.

I think you hit on it with the valve springs, many guys are using spring for 6 or 7000 rpms on a 3000 rpm engine. My 77 turns 4000 with the stock springs and the cam is 30+ years old since Comp. Cams reground it.

 

[cumminstinkerer]

One issue that may be getting overlooked here is that in the last I'll say 5 years, not certain, automotive oil formulations were changed to meet emissions standards, most, if not all of the Zinc was removed! Many flat tappet cams have had issues due to this, among other mentioned items I am sure, however for the small cost of Zinc additive or oil with it in already (Valvoline VR1 for example) why chance a cam failure. Certain diesel oils of today still have the Zinc, Rotella T4 (not T6), Mobil Delvac (their conventional), and Northland Conventional all still do. Even the SAE30 for older engines no longer has the zinc.

 

[James1911]

I think you hit on it with the valve springs, many guys are using spring for 6 or 7000 rpms on a 3000 rpm engine. My 77 turns 4000 with the stock springs and the cam is 30+ years old since Comp. Cams reground it.

Yes springs, cam journal size, cam followers, material strengths weakness and compatibility, RPM's, oils, heat, lubricity of oils used, amount of oil to help keep parts cool, all contribute to any engine problems with hard parts failing plus factors not mentioned here. Zinc, moly, phosphorus, sulphur and many other wear additives have a role but when a majority of parts fail in a particular application should test them in different ways than has been done I think. In diesel engines ash in oil causes a major problem stopping up filters preventing pollution. That is being addressed by Mobil oil and others. Cam after market manufactures will come up with a solution if they work on solutions besides blaming one part of the equation instead of all the parts to it I believe. It is a subject that has many opinions but few solutions so far in my opinion. I have no horse in the race and respect everyone's ideas and opinions. Just need facts and solutions to be convinced the final solution has been found. Back in the 1950's I had engines run for as much as 11,000 hours running regular motor oil of the time and never a cam problem. The highest RPM any ran were Detroit's at 2200 RPM and Ford Gas engines at 2100 RPM's. If want to see what an engine is made of put it pumping water running around the clock and find one's you like and one' not so much.
,

 

[James1911]

One issue that may be getting overlooked here is that in the last I'll say 5 years, not certain, automotive oil formulations were changed to meet emissions standards, most, if not all of the Zinc was removed! Many flat tappet cams have had issues due to this, among other mentioned items I am sure, however for the small cost of Zinc additive or oil with it in already (Valvoline VR1 for example) why chance a cam failure. Certain diesel oils of today still have the Zinc, Rotella T4 (not T6), Mobil Delvac (their conventional), and Northland Conventional all still do. Even the SAE30 for older engines no longer has the zinc.

I agree but other factors have come into play also. Higher RPMS by engines really not designed for the stress and machining problems. If expect 7000 + RPMS it better be designed for it. A good example are Motor cycle engines that turn 11,000 or so and were designed and tested at that rpm and as far as I know they have no cam problems and the oil they use is off the shelf. Just something to think about. Even when extra additives are used the failures continue. It sure is something to test our minds on. I have no solutions, just ideas sorry to say,