Mopar "Purple Shaft" Mystery Cam

General engine tech -- Drag Racing to Circle Track

Moderator: Team

PRH
New Member
New Member
Posts: 35
Joined: Fri Sep 08, 2017 4:16 pm
Location: S. Burlington, Vt.

Re: Mopar "Purple Shaft" Mystery Cam

Post by PRH » Wed Sep 13, 2017 11:07 am

For .006 I've got 294 and for .200 I've got 145.
Thanks.

Kinda makes you wonder at what arbitrary checking lift they used to come up with the "284".

Those old purple cams did work pretty well overall for what they were.
Pretty quiet operation, relatively easy on parts, good rpm stability, "decent" power.
Somewhat handy with a die grinder.

DaveMcLain
Guru
Guru
Posts: 2685
Joined: Thu Jan 06, 2011 8:57 am

Re: Mopar "Purple Shaft" Mystery Cam

Post by DaveMcLain » Wed Sep 13, 2017 11:14 am

PRH wrote:
For .006 I've got 294 and for .200 I've got 145.
Thanks.

Kinda makes you wonder at what arbitrary checking lift they used to come up with the "284".

Those old purple cams did work pretty well overall for what they were.
Pretty quiet operation, relatively easy on parts, good rpm stability, "decent" power.
It seems to be pretty darn close to 284 degrees at .010 cam lift. Most of the people that I know that have used these cams were happy with the performance even with a mostly stock engine they ran well.

I also have a plot from a brand new "284" cam from a big block engine where that also works out to be true.

PRH
New Member
New Member
Posts: 35
Joined: Fri Sep 08, 2017 4:16 pm
Location: S. Burlington, Vt.

Re: Mopar "Purple Shaft" Mystery Cam

Post by PRH » Wed Sep 13, 2017 11:44 am

Would you happen to have any .006, .050, .200 numbers for the .480 and .509 cams?

Have you ever checked any of the solid lifter grinds?
Somewhat handy with a die grinder.

DaveMcLain
Guru
Guru
Posts: 2685
Joined: Thu Jan 06, 2011 8:57 am

Re: Mopar "Purple Shaft" Mystery Cam

Post by DaveMcLain » Thu Sep 14, 2017 9:48 am

PRH wrote:Would you happen to have any .006, .050, .200 numbers for the .480 and .509 cams?

Have you ever checked any of the solid lifter grinds?
No those two are the only ones I've got on file. A friend of mine has a few of those Mopar Performance cams and I should get him to bring them by so that I can measure them just to have the data. I think he has a .509.

Keith Morganstein
Guru
Guru
Posts: 5032
Joined: Sun Feb 19, 2006 10:19 am
Location: MA

Re: Mopar "Purple Shaft" Mystery Cam

Post by Keith Morganstein » Thu Sep 14, 2017 12:26 pm

PRH wrote:
Those old purple cams did work pretty well overall for what they were.
Pretty quiet operation, relatively easy on parts, good rpm stability, "decent" power.
I've read that "Racer Brown" designed those for Mopar

PRH
New Member
New Member
Posts: 35
Joined: Fri Sep 08, 2017 4:16 pm
Location: S. Burlington, Vt.

Re: Mopar "Purple Shaft" Mystery Cam

Post by PRH » Thu Sep 14, 2017 12:34 pm

The original purple shaft cams were indeed Racer Brown grinds.
Sometime around the early 80's the factory came up with new grinds to replace them.

So the story goes according to the old MP engine book.
Somewhat handy with a die grinder.

ZEOHSIX
Pro
Pro
Posts: 375
Joined: Sun Aug 19, 2012 2:25 am

Re: Mopar "Purple Shaft" Mystery Cam

Post by ZEOHSIX » Fri Sep 15, 2017 2:28 am

Jeff Lee wrote:If that is the .484" Purple Shaft, it was the first cam above the .474” street hemi grind cam which was relatively mild. The .484" cam was a pretty good cam in the day. That’s just my opinion, no dyno #’s but I used it in 340’s and even one 440-6. My fellow Mopar buddies at the time agreed that for a hydraulic cam, it ran just about as good as the .509” PS cam which could have PV clearance issues that the .484 PS cam did not have.
.484” was good for 7,000 RPM all day long with Isky adjustable rockers with slight pre-load. Loved my 340’s!
Took the "Purple Shaft" out of my 340 Duster and put in 273 rocker arms and a Crower solid flat tappet/new springs....went from mid 13's to low 12's with pretty much no other changes.....with the added rev range.....I was quickly indoctrinated into the oiling deficiencies of the Mopar A series motor.....I worked at a NAPA parts store at the time and quickly depleted the inventory of 340 re-ground crankshafts in the Western region over the next year before I smartened up and sold that ride for a 440 6BBL ride. I coined the phrase you got the PURPLE SHAFTED when that familiar idle lope was heard at various late night cruising joints in various Mopars......when my buddy went to rebuild his 383 four speed Challenger I talked him into a Isky 270 or 280......that Challenger made some serious passes down the Drag Strip with far better numbers than any D.C. equipped 383....we used to tell people it had a Purple Shaft in it...... :D

Post Reply