Cam bushings

joefarmer said:
I'll PM you my research.
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I could see possibly a little bit, I mean a light film of oil has no drag, but this is also assuming that your not dealing with the downpressure of springs pushing on the cam. That is one of the big advantages of the roller cam bearings.
That and also I am wanting to see you spin that cummins 8000rpm!:stab:
 
Some steel cams have issues with eating into the block because of metalurgy, although I have tested a few alloys lately that have tested great with no issues even without bushings.

On some of our big cast cams we are seeing them eat into the block due to High spring pressure and big duration lobes. More pressure for more time per lobe times 12 and there is the issue. In this instance cam bushings are still needed. Until recently I overlooked the journal width, On our next order we are using a wider journal and making the last jounal .060" wider to distribute the load better. this will reduce the need for bushings with large cast cams.

Another thing to consider is bushings when using larger diameter cores, there are going to be some on the market soon.

I have been in some meetings with some engineers lately and have heard a lot of issues with rollers in different scenarios. A few engine builders I was talking to were talking about oil temps going up quite a bit on roller cams over flat tappets. Depending on a different factors there can be a lot of side loading of the lifter in the bore.

What factors in your build are making you think of bushings?

Zach
 
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Mostly looking at them because I'm eyeing your 200 and 207 offerings. And I'm on the fence on my need for them as I'm limited to 4500 at best. More like 3500
 
thats the 1st i have ever heard of roller cam bearing having drag. . . . i have used them in racing gasser motors in a 436 chevy round track motor. just my 2 cents
 
Most people can't swallow the cost of putting in bushings. It is about $650 to have the cam journals line bored and the bushings installed.
 
Our induction-hardened cam doesn't need journal bushings in the block or special tappet coatings.
 
roachie said:
Cummins calls it a bushing, everyone else calls it a bushing. Its a bushing.


Roller cam bearings are something I will never consider.
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I don't think he was stating its not a bushing, but bringing up a whole different subject about roller bearings, why wouldn't you ever consider them? I've thought about it and I could see some issuse for a "street" motor that sees various rpm daily vs, race motor that runs a more consitent rpm for short period of time?
 
I didn't see any harm in it so i plan on having mine bored and installing bushings.
 
matty169 said:
That is what Nascar/cup engines use and they turn about 10k rpm for 500 miles plus qualifying and practice.. Please explain.
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NASCAR is a bunch of toothless rednecks, not unlike sledpullers. The theory of turn-em loose jimbo boogity booogity boogity applies.
 
Cup teams & their efforts have generated a significant portion of our current knowledge base - and I know many of them who can speak the king's English.
 
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