How do you know if your engine has an aftermarket CAM? - Pontiac GTO Forum
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post #1 of 6 (permalink) Old 02-04-2016, 12:24 PM Thread Starter
 
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How do you know if your engine has an aftermarket CAM?

I think my 1969 GTO 400 has an aftermarket CAM but is there any way to know without taking apart the engine? I'd assume I could measure lift with the valve cover off and I have read a lot about being able to hear the difference. I'm just wondering if anyone has any really good methods or tricks.
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post #2 of 6 (permalink) Old 02-05-2016, 09:43 AM
 
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Good question..I would like to know too. Mine sounds like an aftermarket cam but could be one of Pontiac's "hot" cams. Th people bought the car from just wanted a collector car and were not gearheads. They knew nothing much about the mechanicals a and I'm glad I rescued the old goat.

I suppose with a dial indicator on the rocker arm and a cam-degree wheel on the crank pulley, you could figure out some lift and duration numbers but I'm not entirely sure that this is the best method.

Here is a video that may partially help:
https://www.youtube.com/watch?v=-py64gw89IE

Luck!
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post #3 of 6 (permalink) Old 02-06-2016, 08:31 PM
 
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If it sounds pretty lumpy, I can almost assure you it's aftermarket. The only Pontiac cam that would really cut up in a 400 is a RAIV. The 744 stick cam, had a slight lope. But even if you have one of these, it will most likely be an aftermarket clone of some type. Several cam grinders have their version of both cams. Even the Summit 2802 looks sorta similar to a high lift 744.

It's been a long time since '69. Not likely you have a Pontiac cam, unless it was an NOS somebody had saved, or you have a real low mileage, original RA engine.
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post #4 of 6 (permalink) Old 02-10-2016, 05:51 PM Thread Starter
 
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Thanks 1968gto421. Looks like it isn't something that I can verify without taking the engine apart to some degree.
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post #5 of 6 (permalink) Old 02-23-2016, 01:03 PM Thread Starter
 
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Strangely enough, one of the previous owners contacted me and let me know that it does have an aftermarket CAM in it. So, that's one way of finding out.

It has a Speed Pro 1175. Now I just have to figure out how to get the best timing for it...

Last edited by Mainlin; 03-17-2016 at 10:12 AM. Reason: had a little more information.
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post #6 of 6 (permalink) Old 03-18-2016, 10:02 AM Thread Starter
 
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Oh, and I want to send a shout-out to Dave Bisschop with SD Performance in Vancouver British Columbia, SD Performance- Pontiac Performance Specialists, who was a tremendous help in finding out what CAM I have in my engine. He saved me hours of time.
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  Pontiac GTO Forum > The 1964-1974 Pontiac Tempest, Lemans & GTO > 1964-1974 Tempest, LeMans & GTO Engine Tuning and High Performance

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