Mopar Purple shaft cam info needed P4120662

[Mstone68440RR]

In the processing of upgrading to aluminum heads, I have to 440 out of my car and have removed the 906 heads and camshaft to ID the cam for proper springs on the new heads. I sent the cam to a local recommended builder who was able to spin it and produce the following information, as no part number was stamped onto the cam. Full print out attached for all info. Solid lifters and 3/8” pushrods.

Int: Dur 271 .578 lift (1.5 ratio)
Ex: Dur 269.7 .583 lift

He believes it to be a P4120662 based on the lift and duration and reference to older catalogs. This number fits right between a P4120661 and P4120663 which I have some info online with specs, nut nothing for my cam ( possibly discontinued)


Curious as to the operating range of this cam as it has much more lift than I expected. The builder told me the cam lobes are I excellent shape, no signs of wear and tear. He believes some better breathing heads should work well with the cam.

Some motor combo info

1968 440 block .030 over
TRW L2355F30 pistons
Previous heads 906 w/ Harland Sharp 1.5 roller rockers - unknown if any port work was performed.

727 full reverse manual valve body, torque converter unknown specs, probably close to stock?
742 3.91 sure grip


Car has been 8.21 @ 86.88 mph in the 1/8th mile, I believe it was capable of dipping into 7.9 range if I had it tuned perfectly. Goal with new heads would be to get down to 12.0 in the 1/4 mile area and still drive comfortably on the street.

Builder likes the Edelbrock easy streets, price is right. He is leaning towards the 75cc models to boost compression up a tad with Aluminum heads. Pistons are slightly in the hole ( .028 in the hole) with -7cc valve reliefs and old heads used the steel head gasket. Also have read about and spoke to Todd Marsh briefly about his Sidewinder heads. I like the idea of being able to reuse my current rockers and pushrods and even the cam and lifters if it works well with everything else.

Will this cam and AL heads ( with minor work, bowl blend) work well together? Motor did not make much power past 54-5500 rpms at the track. In fact, I had the car dyno’ed at Westech prior to purchase almost 6 years ago and it was right @ 300 hp 300 TQ to the rear wheels using an older torker manifold and a Holley 700 cfm carb ( which I soon found out had non - functioning secondaries). I don’t have access to the Dyno sheet right now, but will find it when I get home

Thanks,

Mark

 

[PRHeads]

Looks like the 590 cam to me.

It’s a good cam but not really what I’d recommend at all for that combo and performance goal.

 

[69a100]

A reverse split duration cam in a RB? Sounds like something a /6 would like! Better flowing heads would help, but I think you could do with a better cam then that one to get what you want. Good Luck

 

[wyrmrider]

don't know that number
but the data you have is better than any published
run it
what stall
what compression does it generate
how does it drive
you can go from there
how far down the hole with your 6 pack pistons?
you will need a .028 gasket to have any quench unless block cut
measure deck clearance
what compression do you want with what fuel?
gear?
same thing with the converter- do some tests

 

[Mstone68440RR]

Thanks for the replies, still curious to see if any one has any real info regarding this specific cam, if it in fact is the part number mentioned?


Where can I look for more info on it, already been to a Google.

Also, just measured the pistons and they look to be right around .028 in the hole. Still need to dig up the Dyno sheets as they should shed some light on the power and torque curves this setup produced.

Car seemed to behave very well on the street once it warmed up, always ran cool with a 160 T-stat. It is the only big block I have owned. Seemed to pull hard from 3,000 rpm to 5,200 or so. Not unhappy with how it performed but I know it has more to offer with heads and possibly a cam more suited to my needs.

 

[wyrmrider]

so what are your needs
what do you want different?

 

[Mstone68440RR]

Would like to maintain street ability while having a decent amount of added power. I know from reading other posts here that a 12 second B with a 440 is pretty easily accomplished without breaking the bank.
I bought the car from an owner who was not involved with build so until now I never knew exactly what I had. Seems like the best path is by adding better breathing heads ( saving 40+ lbs) possibly upgrading the cam and matching that with a decent converter.


I am all ears to those with experience. I am all for low end grunt as I have no desire to take it past 6,000 rpm. Majority of driving will be cruises with a couple trips to the strip every year.

 

[BSB67]

......Seemed to pull hard from 3,000 rpm to 5,200 or so.....

Considering the cam, something is not right here.

 

[wyrmrider]

you are close
pm dart19666 at crower and go see him, take your cam
mopar guy
or run that cam and tune to find out why it,s not running better
degreed in?
what's your compression pressure?
maybe do that and if still not happy try advancing or retarding (depending if you want more bottom or top end}
that will give you a clue on how a 4 degree smaller or larger cam will work





0 and retest

 

[PRHeads]

You’re looking for more specific info?

You had the cam measured, and have the print out.
There is no more specific info than that.

That cam is too big for the rest of the combo.
If it won’t rev above the low 5000’s, the problem isn’t the cam itself.
With the correct valve springs set up at the correct height, that cam will easily rev to over 7k.
It’s still not the right choice for your goals, but the cam profile is not the reason the motor is flat at 5k.

P4120663 is the part number for the MP 590 cam and lifter package.
P4120662 is the part number for the cam that comes in that package...... although it was never sold separately.

For the usage you’re describing, I’d be looking at cams about 20 degrees less @.050 than the cam you have.

Seems like the best path is by adding better breathing heads ( saving 40+ lbs) possibly upgrading the cam and matching that with a decent converter.

That’s what I’d do.

 

[wyrmrider]

What PRH said
I knew that duh
would be a good core for a regrind
or keep the lifters as a marked to the cam lobes set and sell
btw could be springs- have you checked them
I'd still pm crower
been there done that with reverse rotation corvair builds

 

[Mstone68440RR]

Thank you, you just helped me a lot by making me understand the cam is part of a kit. Now I know the cam is designed for 3400-6900rpm range, which is definitely not what I am looking for.

Reading through some old threads it is evident that this is a powerful cam needing good compression, tall gears and a higher stall converter.

Might explain why I always got such horrible mpg with this combo. I need to start looking for a cam with power range much lower in the rpm range.

Thanks for the replies

 

[Mstone68440RR]

What PRH said
I knew that duh
would be a good core for a regrind
or keep the lifters as a marked to the cam lobes set and sell
btw could be springs- have you checked them
I'd still pm crower
been there done that with reverse rotation corvair builds

Springs are part of the reason I have the heads off, lost a valve stem guide and then found a broken damper spring when I first removed the heads. Not knowing what setup I had, I never knew to check for valve lash, which may have led to the failure.

 

[Bighead440]

I too believe it's a .590" cam, and it's too big, AKA: mismatch. Ironically, we ran the same exact 1/8mi numbers with a '71 stock Imperial (dished pistons) engine with St.Hemi springs and a 280*/.474" hydraulic Purpleshaft, in a '67 Coronet with 3.91 gears and a 11" D-250 torque converter. No other aftermarket parts besides a DP4B intake/750 Eddy AFB and Hedman 1 3/4" headers. 5400rpm shift point. If you are going to aluminum heads, run a XE/HL Comp Cams .545" or a similar Hughes or Howards hydraulic and hello 7-second 1/8mi times.

 

[biomedtechguy]

could be springs- have you checked them

THIS!!
Weak springs and lifters that needed to be replaced were choking my 440+6bbl w/.509/292° cam. Right when it was really starting to "ramp up" poof! it would fall on its face. Replaced lifters, pushrods, and springs, locks, and retainers...
WOW!! Now my setup DEMANDS that I let it pull to 6100/6200 RPMs. I'm going to chassis dyno it, and if I see that the HP/torque would be better utilized by shifting sooner, I will.
My point is I suspected worn springs and was right, changed them and it was a GONZO improvement in performance!