What goes into making a flat tappet camshaft?

[Garwood]

I have some ideas for an engine camshaft design that could solve a current problem, but I need some help with the materials and processes part of manufacturing it. What I lack in education I try to make up in creativity and determination, please bear with my ignorance.
Why are flat tappet camshafts and tappets are made from cast iron as opposed to turned or milled from steel?
Are the cam and tappets made from the same material or different- Precisely which materials are they typically made from?
Do the cam and tappets undergoe heat treating before grinding?

Thanks for any help with these questions.

[motion guru]

Give these guys a call . . . http://www.deltacam.com/

And not all cams are made of cast iron - I have a steel cam in a hopped up vintage performance engine I built a few years ago - 10,000+ miles on it now and no problems. Not only do you need to consider materials for lifters but also distributor gear if your cam serves this duty.

[Phil Burman]

Start here:

http://www.newman-cams.com/pdf/camshaftselection.pdf

Cast iron is used in mass produced engines because it works (very well if it is chilled cast iron) and it's cheap to do. How clever you need to get depends on what kind of performance you are looking for and what kind of processes you have available for making a one off.

Phil

Originally Posted by Garwood

I have some ideas for an engine camshaft design that could solve a current problem, but I need some help with the materials and processes part of manufacturing it. What I lack in education I try to make up in creativity and determination, please bear with my ignorance.
Why are flat tappet camshafts and tappets are made from cast iron as opposed to turned or milled from steel?
Are the cam and tappets made from the same material or different- Precisely which materials are they typically made from?
Do the cam and tappets undergoe heat treating before grinding?

Thanks for any help with these questions.

[mobile_bob]

flat tappets are not truely flat but rather crowned or convexed on the face, and yes they are hardened and then finish ground for the proper profile

the cam lobes have a matching profile in that they are not flat across
the peak either, but have a high side that compliments the lifter.

they work together to make the lifter rotate in its bore, without rotation they don't last very long at all.

there are many cam grinders out there that will grind a cam blank to your spec's, just tell them what you want and let them do it. i can't imagine doing it at home for the price they will regrind a core for.

same for lifters, unless you have some really wierd appication i would suggest using off the shelf units, they are only about 5 or 6bucks each, hard to imagine you can produce them for anywhere near that price.

good luck

bob g

[Garwood]

I will have some phone calls to make Monday!

My idea would be easier to make if steel camshaft lobes could be used with flat tappets. This cam design would see a maximum of 2000 camshaft RPM and doesn't have a distributor gear.

If I follow correctly, cast camshafts are used with flat tappets for cost reasons?

[Garwood]

Originally Posted by mobile_bob

flat tappets are not truely flat but rather crowned or convexed on the face, and yes they are hardened and then finish ground for the proper profile

the cam lobes have a matching profile in that they are not flat across
the peak either, but have a high side that compliments the lifter.

they work together to make the lifter rotate in its bore, without rotation they don't last very long at all.

there are many cam grinders out there that will grind a cam blank to your spec's, just tell them what you want and let them do it. i can't imagine doing it at home for the price they will regrind a core for.

same for lifters, unless you have some really wierd appication i would suggest using off the shelf units, they are only about 5 or 6bucks each, hard to imagine you can produce them for anywhere near that price.

good luck

bob g

Bob, I'm familiar with how a flat tappet cam works.

I cannot give much information on this project, but lets just say it's a very unique camshaft system that cannot be cast in one piece.

The situation I've run into is that manufacturing this idea for a roller tappet application is stupid simple because steel lobes can be used. To make this thing work with a flat tappet camshaft system (which I must do for a big application of it) it would be simpler if I could use steel lobes with the existing iron tappets. Manufacturing the cam with iron lobes would be extrmely difficult compared to using steel.

[moonlight machine]

maybe things are different now...... the only time I've seen a steel cam used is with roller lifters. I don't know why you don't use roller lifters if at all possible..... most production engines use them now, it cuts friction a lot.

[Garwood]

I have torn down 3000 RPM diesel engines with over 600,000 miles on them with flat tappet cams and found the cam and lifters in as-new condition.

I think flat and roller tappets each have thier applications. Both have well proven reliablity designed correctly. Both are current production in new automobiles.

[Garwood]

Originally Posted by Phil Burman

Start here:

http://www.newman-cams.com/pdf/camshaftselection.pdf

Cast iron is used in mass produced engines because it works (very well if it is chilled cast iron) and it's cheap to do. How clever you need to get depends on what kind of performance you are looking for and what kind of processes you have available for making a one off.

Phil

Phil, I missed the link you posted at first. It helped me out a lot, thank you very much for that.

[Sidebite]

NASCAR Sprint Cup engines use flat tappet cams per the rules. They used to use steel or iron cams with welded in hardface overlays, but they have changed to a nitrided steel in the past 10 years. I don't recall what the steel spec is, but I could find out.
Current production Ford "modular motor" overhead cams are made by placing pre-ground powder metal lobes with an internal spline feature on a tubular shaft and then drawing a mandrel through to expand the tube and lock them in place.

Davis

[Dave A]

The longevity of a steel camshaft and lifters of some other metal would greatly depend on the rpm's involved, the severity of the lobe profiles, the lubricant and the spring pressures needed. Others have posted on the fact that the cam lobes and lifter bases are not truly flat.

[Michael Moore]

You need to make sure that the lobe and lifter materials will work with each other. Get that wrong and they'll eat themselves up in no time.

FWIW, I recently talked to WebCam in L.A.

http://www.webcamshafts.com

about a cam project. I'd make steel billets and they'd put one cataloged hardweld-lobe on each one for about $300-330 the pair (single cylinder 2v DOHC engine). They said they've had people make the blanks out of 4140 or 8620 and it didn't make any difference to them which one I picked, they'd weld it up and grind it down.

They're pretty amenable to one-off stuff and it sounds like they do a fair amount of it. Another place you could check with is

http://elgincams.com/

cheers,
Michael

[DaveE907]

"Precisely which materials are they typically made from?"

You have to be kidding. "Precisely" and "typically" are jarring in the same sentence.

To begin to answer: the ones that work.

[Garwood]

Originally Posted by DaveE907

"Precisely which materials are they typically made from?"

You have to be kidding. "Precisely" and "typically" are jarring in the same sentence.

To begin to answer: the ones that work.

I want to know precisely which materials your typical automotive camshafts are made from. I'm not asking for one answer, rather a breakdown of the materials and processes used across the board for making camshafts. Pros and cons of different materials.
I'm not trying to build a one-off camshaft, I'm building something that works with any camshaft in a compression ignition engine. My concern is with building the "something", and in order to make it I needed to know what materials to use.

[DaveE907]

You may find this glossary helpful for starters. There are a number of different materials used for flat tappet camshafts (both cast irons and steels) and there are a number of different heat treatments and surface treatments applied to them. The specific material and processing are selected to meet cost and performance requirements. These considerations include velocity, load and lubrication.

One constant is that the tappet face is harder the cam surface. A difference of about 10 points on the Rockwell C scale is common.

All cam manufacturers I've worked with consider their material and treatment specifics proprietary.

http://www.elgincams.com/glossary.html

[fpworks]

I know for a fact that some NASCAR teams use carburized 8620 for the cams.

[bugman53]

To me it sounds like you are trying to invent a product probably to retrofit to an existing motor design. That is why you can’t tell us what you are trying to do. There is not much at all that has not been done with a flat lifter cam. and there are reasons that there are roller bearing lifters used is probably %90 of motors(not counting shim over bucket OHC setups).

Pretty much what i am saying is there is a %99 what you are trying to do someone else has already done and there is a reason that it is not around now or you are not aware of it. Not trying to be a butt hole just making a simple observation to maybe save you some time and money.

also there many companies that will make you whatever you won’t for pretty cheap. Web cams are a great example they have made me custom cams in the past and are great.

Now if you have a cam that makes great power that you designed that web will make that cam for you and not sell it to anyone else but you haft to have a good sized order.

I build motorcycle engines for a living and if there is anything I can help you with I will be happy to help.
Also the cams that I run in my bike are billet 4140 thin wall hollow cams that weigh about a pound each and are hard coated and hold up GREAT. This is a twin overhead cam, cam over bucket setup that rides directly on the top of the valve with a “bucket” between the cam and valve stem with a shim to adjust clearance. The bucket does rotate very very slow so it wears even. I’m not sure what material there made from but they are hard way harder than the cam.

[Garwood]

You've got it. Giving me a dose of reality is not going to offend me. I'm not going to claim you're wrong about someone already coming up with this, but there's strong indication nobodies thought of doing it. If someone has, they haven't patented it, it sure as hell is not in use and while there are similiar devices patented in function they are not remotely intended for the same use. (This is rather outside the box for anything engine camshaft related, it's an improvement in simplification and function on an existing non-camshaft related engine technology. It has absolutely nothing to do with altering or improving the lobe profile or function or increasing engine efficiency).

From the generous help you guys have given I think my next step is to investigate the tappet material and hardness used in the flat tappet engines I need to work with (since I need to use the existing tappets) then I can narrow down compatible lobe materials.

Where I'm really at in the overall scope is there is one tiny itty bitty detail that my little brain can't work out because I can't actually spin a camshaft 2000 RPM in my head and inspect how moving pieces actually interract under such conditions. This detail must be worked out before the scope of patent(s) can be figured. It might be really simple (what my brain says is going to happen) or some unforseen event can make the whole thing non-viable or necessitate a minor or major design change. The real-world application of something like this says some jackass just might park his manual transmission vehicle in high gear on asphalt, chain a large dozer to the rear and pull it backwards spinning the engine the wrong way. Very, very bad things would transpire if that situation existed and certain safeties weren't in place. The thing works in my head, the few trusted, much smarter than I friends that I've bounced the ideas off can't find an obvious fault and the odds of the general interested masses actually forking the dough to buy this "something" as opposed the "something" already on the market is likely good given the improvement in function. Back to the point- I need to build basic, testable, functioning model and abuse it.

[Perry Harrington]

Garwood, you can PM me for my number/email, I can answer a variety of questions for you and point you at others which specifically deal with your needs.

[DaveE907]

Electric motor driven test rigs are common in the camshaft and valve train industry. They range from complete engine valve trains in full production blocks to just a speciic fixture to examine operation of a specific portion of valve train. A well known manufacturer's name is Spintron, however it's become an almost generic term in the industry. Google the word and you'll see setups from full on very expensive purchased machines to custom fixtures setup to be driven by a drill press.

Operation is tested on a wide range of speeds. Instrumentation can range from a simple stroboscope to view the operation up to very elaborate data collection setups.