Measuring lift and duration of stock and perf cams

[LGAFF]

9 or 10 years ago I stumbled upon an advertisement in Classic Car magazine for someone that did rare and vintage cams and repairs, the business was called Cam Techniques. I called on the off chance I might be able to get some performance cams made. The owner answered, an older Gentleman, I told him I had an LT-5 engine and wondered if he could make cams. He laughed and said there's an engine I havent heard about for awhile. He went on to explain that he, Dave Generous, used to have his business in CT(now in FL), and that he did work for Callaway, including the infamous Sledgehammer.

He in fact had made LT-5 cams for Callaway and although the project had hit target for HP, etc... it was scraped due to EPA regulations that callaway would need to meet with the cam swap. I asked if he could make me a set and he did.... 236 .425 intake, and 222 .415 exhaust. Dave also put the 222.415 on the primary intake lobe. I put a set in my 90 and it made 441 RWHP. A few years later Dave told me he had cancer and was retiring. He asked if I wanted to buy the cam masters and I did, he also made a copy of the Sledgehammer cam for me... he also offered to make a few more sets of cams for me... but using the 236 .425 on both lobes. Years later I had someone else making the cams for me, and I sold the old pairs... and later found out that the primaries were not 236 on the old cams..... so that lead me to believe that maybe the more recent work I had done were also not 236 on both lobes(they had his notes and copies of old cams, along with the masters).

So recently I had another set of cams made and noticed that they weren't any different in measurement than the set of intakes in my basement. So I went about putting together a home made cam duration/lift device to measure them(patent pending) and it was interesting.. video is below.. I welcome feedback. One of my findings was that these cams are not measured at .05..( and yes the indicator is a Bic Pen Cartridge held on by painters tape)

https://youtu.be/kxLuGWYe4PA

[LGAFF]

original thread with pics of masters for a Berco cam machine, etc

https://www.zr1.net/forum/showthread.php?t=21455

[LGAFF]

Would be curious what others have found... I bought two separate dial gauges trying to confirm duration specs ... this is what I came up with...

[LGAFF]

One of the possibilities is that the size of the dial gauge contact point might be changing point at which the duration reads ...@.020 vs .050


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[grahambehan]

Lee, the flat area needs to be larger than the tip of your indicator, at least equivalent to the dia of the wear marks on a used lifter, for you to measure duration accurately.

Graham

[Great White]

Your indicator needs to be over the centerline of the camshaft. It also needs to be perpendicular to the axis of the cam lobe, and to the radius of the cam lobe. Also keep in mind that any dial indicator is a comparator, not a measuring tool. Unless it has been certified, it can not be trusted for a precise measurement. A $15 harbor freight indicator may not give you a good reading if its calibration hasn't been verified.

[LGAFF]

For this purpose i am trying to verify duration on my primary lobe using known values of other cams so i am trying to verify this lobe is 236 vs 222 on the exhaust I think I accomplished that?


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[Jagdpanzer]

I've had good results checking lift and duration by setting the camshaft up in a cylinder head using a modified lifter with the hydraulic element replaced with a solid insert and valve and retainer assembled with a check spring.
IMG_0153.JPG


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[Great White]

Originally Posted by Jagdpanzer

I've had good results checking lift and duration by setting the camshaft up in a cylinder head using a modified lifter with the hydraulic element replaced with a solid insert and valve and retainer assembled with a check spring.
Attachment 14766


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That looks like a very nice setup.

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[LGAFF]

Phil I dont see that on the harbor freight sale ad whats the product number LOL....