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Replacement for Mopar Purple Camshaft

philcollins

philcollins

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The cam currently in my 360 is an old mopar Purple shaft cam.
https://www.summitracing.com/parts/dcc-p4452992ae

That engine has ported X cylinder heads, 9.75 -1 compression ratio. headers, stock intake manifold and thermoquad. (Air grabber). 3.55 rear gear, 4 speeds.

what would be a nice modern grind to remplace that cam.
Ps. One lifter just quit so might be better to change cam at the same time.
 
I'm running a hyd roller. 224@
050. .560/.570 w/ 1.6 rockers. Ported factory heads, LD340. 650 Holley, TTI headers and exhaust. True 9.0-1. 3.55 4 speed. Drives excellent. Runs on 87 octane. Been 12.70s@109 with sticky tires.
Doug
 
Do you have head flows? or can approximate?
with ported heads you can use more lift than with stock heads if your guides have been cut for viton seals???
stock spring heights?
start with Lunati Voodoo and Howard with 15 in the comments column for shelf cams
Comp really has nothing smaller than the xe275hl for Mopars
If you do want to have a more old school replacement use Engle or go over to fabo and pm dart19666 - shaun at Crower
MP and Hughes are pricy and customer service issues reported for like forever
what's your compression and all the details if you need anything else
if you have real 9.7 compression think 264 degree @.006 for a street cam
268 with light car and low gears and converter, good exhaust- in your case 3.55 and 4 speed should work but me I'd stick to 262-264 so good power after a shift and driveability at part throttle
more than that and your low end starts to go away
howard and lunati have different lca afik - so watch the tradeoffs
 
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How is the car used? Are you happy/unhappy with the performance now? If your happy with it, personally I'd just replace the lifters, do the required break-in cycle and carry on. That stock intake would be the first thing I'd be considering changing out if I was looking for more power. You've got a decent amount of duration for a street small-block already..there are cams with more lift at the same or less duration than you have, and they can add a few HP but they will come with trade-offs...more valvetrain noise and wear, new springs, retainers, maybe rocker arms, etc and possibly head machining..There's been a lot of threads around lately by folks that started making changes and didn't realize what a can of worms a 'simple' parts swap can be. I apologize if you're already aware and prepared for that stuff, just throwing it out there..
 
My car is street driven and the performance was ok. The engine was built 22 years ago by the previous owner but as he’s deceased, can’t ask him any questionS. What I know is the compression ratio is a real 9,75 to 1, head ported to max(pushrod tubes, exhaust port max etc). Il will have to check about the valves seal and clearances etc. Piston are 4,04”, rotating assy balanced, block decked. Old school but built with was available 22 years ago. Right now with the purple cam, compression is around 180 psi. Running gm module with 20 degree initial, 32 total.

Replacing the intake manifold is a no-no as I want to keep the Airgrabber functional.
 
180 is good
duplicate the intake close point with more lift/ area
110 lca is fine
your ported heads could more lift /area at the same durations
MP is measured @.008
so for starters start with Engle who also uses .008
 
Time for a thorough cleaning and bearing exam, too....
Be careful going with a smaller (duration) cam. If you're already cranking 180 psi you could run into detonation trouble if you push the cylinder pressure up much more. The purple cam you had closes the intake at 66 ABDC but I 'm not sure what lift that number was figured at. The Comp 274 closes at 63 ABDC @ .006" lift. It doesn't seem like much, but could put you into expensive high-octane fuel territory, or having to do things like reduce timing or retarding the cam, etc.
 
Sure looks like a good candidate for the Comp PP280H(20-670-4).

Which is also available in a nitrided version.....20-670-20.
 
280 comp is shorter than a 280 MP by maybe 8 degrees converted to .006
and as said your cranking compression is ok
so BVVC
the 280 pp is a good, conservative mopar lobe but will be like advancing your cam by 4 degrees
you can make it work with some tuning or install it straight up
 
I'd just go Comp XE275HL, if you have the springs for it and adjustable rockers/pushrods, and valve reliefs. Back in 2003 we did a '72 340 (then 318) Duster for a customer, based on a 360 MoPar shortblock (they had SpeedPro H116 hyper FT pistons with valve reliefs) and Edelbrock OOTB heads. The shortblock came with the .508 Purple Shaft cam, which we threw in the garbage and put the 275HL in. We reused his LD340 intake and 650 Holley DP. With a 2400rpm converter and 3.23 gears it was a BEAST and still is. Plenty of off-idle power and neverending pull to 6500. I like that cam, and it won't overwork the iron head ports. We used 1.6 roller rockers to utilize some of the airflow in the Eddys.
 
hl is ok if heads can handel the lift- not for stock heads without a lot of work
use that purple shaft
 
Engine is running. Checked the main and rod bearing, Everything was fine. Installed comp cam CL20-224-4, engine run much better, a bit more vacuum at idle(15 lbs) better throttle response, no pigning on acceleration. Vert pleased with the result.

Cam break-in was done out of the car Used Lucas break-in oil.

BF9AF014-6826-441A-A984-1A3BC53F949E.jpeg
 
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Nothing sweeter than an incident-free cam run-in.
And thanks for the follow up!
 
wtf is that cam- why make us look it up?
how's it work for you?Its much shorter than the cam you had
Why not PRH choice of the purple plus-much better for a mopar
ony thin I can say about the 274H is that the Summit cam is cheaper
 
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