Crow cam grind

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pman92
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Crow cam grind

Post by pman92 »

Hey guys
Helping my brother assemble his 355 Holden stroker he is building.
Put the cam in, put the timing set on at standard position, setup the degree wheel. Found TDC by bolting a stoping thing I made up over cyl 1 (heads are still off, stops piston around 10mm from top of deck). Wound it over clockwise from flywheel end not to disturb degree wheel, marked position and went all the way around opposite and marked again. Removed the stop and found position half way between two marks, marked it as TDC. Found oppsoite 180 degree position and marked as BDC.
Put a pair of lifters in cyl 1 and setup dial indicator.
Checked inlet first. It was open .050" at 5 degrees BTDC, 1 degree retarted off spec sheet. Thought "beauty, adjustable crank gear goes in 2 degree increments, so if I moved it would end up 1 degree advanced, so it's pretty spot on"
So then went to check exhaust lobe, open .050" 31 degrees BBDC, thats a bit weird spec sheet says 49 degrees.
Dial indicator must of moved? Made sure it was secure, rechecked, still the same.
Must of bumped degree wheel or pointer? Rechecked and no all good, TDC is still TDC.
Rechecked inlet, still within 1 degree of spec.
Rechecked exhaust, still 18 degrees error.
Checked .050" closing position, inlet and exhaust BOTH close within 1 degree of what is written on the sheet.
Ok maybe the sheet is wrong, maybe the exhaust profile is different?
Checked cylinder 4 (same TDC position). Both inlet and exhaust, open and close within 1-2 degrees as specified. Rechecked to make sure.

Haven't bothered checking other cylinders yet.
Essentially my brother has a brand new hydraulic roller crow cam which cost him a decent sum of money, with 219 degrees .050" exhaust duration on cylinder 1, and 237 degrees on cylinder 4.
It seems the exhaust lobe has been machined incorrectly on cyl 1 exhaust.

Has anyone ran into problems like this before?
I'll admit I'm not an expert, but 18 degrees sounds like a lot?

He is going back to the machine shop that supplied the cam tomorrow to see what they want to do
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Gareth
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Re: Crow cam grind

Post by Gareth »

Yes, but only with the brand you mentioned...
According to chemistry, alcohol is a solution...
OZ38
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Re: Crow cam grind

Post by OZ38 »

Now think how you would go if the number one did dial in right & number 4 was actually out the 18 degrees. You would probably not pick it up as most only check off number 1.
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vlad01
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Re: Crow cam grind

Post by vlad01 »

Crow cams for ya.

They make excellent springs and pushrods and other hardware, but ironically useless cams.
I'm the director of VSH (Vlad's Spec Holden), because HSV were doing it ass about.
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