Roller Cams, the other aluminum head thread

Joshua Skinner · Post subject: (Fri Dec 30, 2011 10:30 am)

My understanding is that roller lifters were first used for fuel economy reasons. Actually, that's not right. Packard and Buick among others used roller followers well before WWII. I think it got to the point that CAFE numbers were important enough to justify the additional cost of roller lifters. The zinc and phosphorous were taken out of oil later because it was poisoning catalytic converters and manufacturers were mandated to provide very long emissions warranties. It's not a problem to have those compounds in the oil if the engine isn't burning oil, but too many people are too lax on maintenance.

If we want a billet timing cover, actually a casting is fine, with the gerotor oil pump and a cam stop. Let's also have a removable section over the cam gear so we can change the installed centerline easily.

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USAJon · Post subject: (Fri Dec 30, 2011 7:28 pm)

DD ran a re-grind roller cam back in the day that was nitrated. he removed it when he found it flaking, on his cuda.

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USAJon · Post subject: Fyi (Fri Dec 30, 2011 7:41 pm)

http://www.holley.com/data/TechService/Technical/Understanding%20Camshafts.pdf

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DusterIdiot · Post subject: The ramp... (Fri Dec 30, 2011 8:13 pm)

That's a good article, although I would add one more trick in the duration section. Most cams now have an .020 and an .050 duration...if you look at both durations between two cams they can "connect the dots" so to speak and help determine which cam has the steeper ramp if worried about the lobe opening profile and how fast you are looking to pop the valve off the seat and get it open.

-D.Idiot

CNC-Dude · Post subject: (Sun Jan 01, 2012 10:50 pm)

Well I guess I will buy a stick of material this week and get started roughing out some blanks. One question, I am seeing a lot of what appears to be confusion on whether the rear cam journal should be drilled or grooved from another post regarding cam bearing interchange. I have a Purple Shaft cam as a model to work from and it is drilled thru the rear journal(don't know if its hydraulic or solid or if it really matters). So I guess the question is: Drill, not drill, or groove the rear journal.

Thanks.

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There's no such thing as too much cam....only not enough engine!

Fopar · Post subject: (Mon Jan 02, 2012 12:31 am)

My understanding the grooved cams are for hydraulic and the drilled are for solid.

Richard

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Charrlie_S · Post subject: (Mon Jan 02, 2012 4:44 am)

I would recommend groove. Groove allows more oil the the upper valve train, and is easier to do. With drilling, the two holes have to be exactly right, so they line up with the holes in the cam bearing. I groove all my cams, and several new replacement cams I have seen are also grooved.

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DusterIdiot · Post subject: X2!!! (Mon Jan 02, 2012 9:42 am)

CNC-Dude · Post subject: (Mon Jan 02, 2012 10:59 am)

Ok guys thanks. I agree, grooving will be much easier than drilling.

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There's no such thing as too much cam....only not enough engine!

Exner Geek · Post subject: (Mon Jan 02, 2012 11:28 am)

Although the full groove is required with hydraulic lifters I believe you are better off with the metering holes with solids. The metering holes deliver more than enough oil to the rockers if the holes are drilled at the proper angle. Tom Drake and others had issues with the holes not lining up with the holes in the cam bearing but all the extra oil provided by the full groove just overloads the valve seals and increases windage losses when it drips back down. If you are going to invest $3000 in a valve train why not do it right? It is true than many billets now have the full groove just to simplify things but you can still find properly drilled blanks.

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Doctor Dodge · Post subject: (Mon Jan 02, 2012 12:42 pm)

slantzilla · Post subject: (Mon Jan 02, 2012 12:45 pm)

Groove the journal and put a restrictor in the passage to the head?

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CNC-Dude · Post subject: (Mon Jan 02, 2012 2:01 pm)

The restrictor is a good solution, many 440's are done that way also.

_________________
There's no such thing as too much cam....only not enough engine!

CNC-Dude · Post subject: (Mon Jan 02, 2012 2:04 pm)

Charrlie_S · Post subject: (Mon Jan 02, 2012 2:49 pm)

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