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Type I, Type II and Group 19 camshaft

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ccowx View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote ccowx Quote  Post ReplyReply Direct Link To This Post Topic: Type I, Type II and Group 19 camshaft
    Posted: Jul/29/2020 at 12:24pm
Hi! This should be a quick one. I am trying to settle a debate on camshafts for 1970 V8's. The type 1 camshaft was installed in all 360's and 390's (up to sept 26th, 1969) had 266 duration and .457 valve lift. After that, the 390's got a type II cam, with a bit more duration and lift, but the 360's stayed with the type I, correct?

Someone has some incorrect information that the type II cam was the Group 19 unit with 302 duration and .477 lift. I am positive that this cam was not installed at the factory in anything. Does anyone have the specs for the type II camshaft in later 1970 390's?

Thanks!
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Post Options Post Options   Thanks (0) Thanks(0)   Quote purple72Gremlin Quote  Post ReplyReply Direct Link To This Post Posted: Jul/29/2020 at 12:40pm
Just a guess, and from reading on this stuff, but Im thinking that when AMC came out with the Machine, that had the 340 HP 390, and the bigger cam was for that 
The 302 cam wasnt factory.  
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Post Options Post Options   Thanks (0) Thanks(0)   Quote ccowx Quote  Post ReplyReply Direct Link To This Post Posted: Jul/29/2020 at 12:50pm
This is a fact check for an article going in a magazine, and much as I enjoy the many AMC myths, I am trying to set it straight. Somehow they got the Group 19 specs in there as the Type II cam. I am hoping to get the right specs for that one. I agree, the Group 19 was never in anything from the factory.

The new cam was introduced in September ,69, I thought the Machine was a bit later than that? Either way, that cam was desperately needed because the Type I was a total pussycat in a 390!

I am hoping to provide the correct specs for the type II for this article.

Thanks!

Chris
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Trader Quote  Post ReplyReply Direct Link To This Post Posted: Jul/29/2020 at 2:35pm
I am assuming you want paper documentation and not a camshaft. There are several grinds of 3180259, an AMC blank as far as I know. The one I have sitting on the bench has other paint markings and 0.496" lift.
It is the largest lift from a factory cam blank I have ever come across. 
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Post Options Post Options   Thanks (0) Thanks(0)   Quote SC397 Quote  Post ReplyReply Direct Link To This Post Posted: Jul/29/2020 at 2:53pm
Originally posted by ccowx ccowx wrote:

Hi! This should be a quick one. I am trying to settle a debate on camshafts for 1970 V8's. The type 1 camshaft was installed in all 360's and 390's (up to sept 26th, 1969) had 266 duration and .457 valve lift. After that, the 390's got a type II cam, with a bit more duration and lift, but the 360's stayed with the type I, correct?

Someone has some incorrect information that the type II cam was the Group 19 unit with 302 duration and .477 lift. I am positive that this cam was not installed at the factory in anything. Does anyone have the specs for the type II camshaft in later 1970 390's?

Thanks!

I think that you are correct.
AMCcamList1 by Rick Jones, on Flickr
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Sonic Silver Quote  Post ReplyReply Direct Link To This Post Posted: Jul/29/2020 at 3:16pm
Originally posted by ccowx ccowx wrote:

Hi! This should be a quick one. I am trying to settle a debate on camshafts for 1970 V8's. The type 1 camshaft was installed in all 360's and 390's (up to sept 26th, 1969) had 266 duration and .457 valve lift. After that, the 390's got a type II cam, with a bit more duration and lift, but the 360's stayed with the type I, correct?

Someone has some incorrect information that the type II cam was the Group 19 unit with 302 duration and .477 lift. I am positive that this cam was not installed at the factory in anything. Does anyone have the specs for the type II camshaft in later 1970 390's?

Thanks!
The Type 1 cam was used throughout 1970 in the 360 engine with 266 advertised duration and .425 lift. The Type 2 was advertised as the same 266 duration with .457 lift, and was in the 1970 390 engines after the date you listed. You are correct about the Group 19 not being installed in engines from the factory. I have seen that 196 duration at .050 listed for the Type 1 (266 duration) cam forever. 

   One thing that I will say about the factory 401 camshaft. I sent an NOS one to Cam Motion about 40 years ago to be read by their Cam Doctor machine. They sent me a printout that showed 207/208 duration at .050 and .456-.458 lift on 114 degree lobe centers, with 4 degrees ground in advance (110 and 118 centerlines). I have no direct information on the Type 2 cam, but have always wondered if it wasn't the 401 cam, since it had the same lift. I have never seen a cam with only 196 degrees at .050  have .457 lift with 1.6 rockers.
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Post Options Post Options   Thanks (0) Thanks(0)   Quote SC397 Quote  Post ReplyReply Direct Link To This Post Posted: Jul/29/2020 at 4:09pm
Here is some fun stuff from one of the cam drawings.
 IMG_3751 by Rick Jones, on Flickr
IMG_3752 by Rick Jones, on Flickr
IMG_3753 by Rick Jones, on Flickr
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Post Options Post Options   Thanks (0) Thanks(0)   Quote mramc Quote  Post ReplyReply Direct Link To This Post Posted: Jul/29/2020 at 4:45pm
OK, The group 19 cam was a period crane fireball cam shaft. It has 302 duration listed and I'm not sure of the duration. The type II camshaft your talking about is the white stripe or Rebel Machine camshaft . Off the top of my head it I recall correctly the cam was listed as a 296 /302 duration. Note back in the day they only used base circle on camshafts , there was no at 50 thousands measurement. So it a lot like comparing apples to oranges , one camshaft cam with 302 degrees would be radical, and anothers would be mild as milk. that is why they started the @ .50 thing. The stock cams of the late 60s and early 70's were the very mild 266, and into the emissions era a lot of stock cams were 262 or 264 degree cams. Really milk toast cams. There is a whole section on this topic some here on this forum including the SAE report from AMC on the Rebel Machine and the Camshaft posted in it's entirety.  It listed in the SAE document BUT AMC used the Rebel Machine camshaft in the last 2 quarters of 1970 and the first quarter of 1971. AMC listed no change in horsepower but desktop dyno  puts it at an extra 25 Horsepower. LRDaum  
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Post Options Post Options   Thanks (1) Thanks(1)   Quote WesternRed Quote  Post ReplyReply Direct Link To This Post Posted: Jul/29/2020 at 4:58pm
Since I am on a bit of a manual quest at the moment, I can post the following excerpt from the 67-71 parts manual:



As you can see, the Group 19 camshaft has a different part number to any of the standard production camshafts. Type 1 to type 2 is a production change based on engine sequence number, so it would appear that all 390's built after that got the type 2 camshaft and it is not specific to the Machine. Also note that the 1970 390 type 2 camshaft is the same as the 71 401 camshaft. The 71 TSM lists the lift at 0.286", intake duration as 296.25 deg and exhaust duration as 303.5 deg. Note that the 71 304 and 360 camshafts are also dual pattern and differ from the earlier camshafts. 

I've finally given up drinking for good...........now I only drink for evil.
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Post Options Post Options   Thanks (0) Thanks(0)   Quote ccowx Quote  Post ReplyReply Direct Link To This Post Posted: Jul/29/2020 at 6:16pm
Thanks guys, we can all take a bow for helping to dispel the many myths of AMC! I will pass this along!

As for the milk toast camshafts, you are correct. I drove my car for a few months with the stock cam, but a Group 19 version certainly woke it up.

Thanks again!

Chris
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