Anyone know much about the mopar purpleshaft p4120243 cam i i am looking for the best low rpm torque or would a stock one be best.

Do a search on the board for Erson reverse pattern or Erson RDP cam.

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Casually looking for a Clifford hyperpak intake for cheap.

Are you trying to move something exceptionally heavy?

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Joshua

IIRC, the 243 MP was a little above a stock cam. Somewhere around .440" lift.

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Official Cookie and Mater Tormentor.

That will make a little more power and torque than stock. It is just a small step up from stock. 244 advertised duration and 0.436" lift.

What are you trying to accomplish?

Lou

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Home of Slant6-powered fun machines since 1988

Imdoing a stock rebuild for my truck 1979 w150 not towing often it has 3.55 gears i just found that cam newfor sale its half the price of a new stock cam.

If you have a good stock cam and oil pump I highly recommend getting it reground and keeping the matched gears together. Oregon can grinders, about $75.

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2 Mopars come with Spark plug tubes. One is a world class, racing machine. The other is a 426 CI. boat anchor!

12.70 @ 104.6

Is there a specific low rpm torque grind you guys use or should i just get a stock grind. My other truck has a hydraulic cam and it is a bit less peppy but has better low rpm torque i was wi dering get that grind on a mechanical cam.

here is a link to a post with the specifications for the p4120243 cam


http://victorylibrary.com/mopar/mpcam-tech-c.htm


hydraulic cam and it is a bit less peppy but has better low rpm torque

the oe cam in my 83 D150 hydraulic lifter slant six, had decent low end torque at low RPM's , was a dog above 2000 rpm
I can dig out the specification for you and will post them. I could not imagine going back to that cam.

I am thinking that a small mechanical cam like the p4120243 like you posted would do what you want.
if you can get it at a really good price that is even better
Advancing the cam will help low end response. The specification lists a 106 installed intake Centerline, most folks here run the installed Intake centerline as low as 100,
I would install it at a 102.

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Doo Ron Ron and the Duke of Earl are friends of mine.....
https://www.youtube.com/watch?v=uX8Nj8ABEI8

The Reverse Dual Pattern (RDP) cam noted above would be the next step up from the 244 MP cam.
The ones I grind use the 244 MP cam's exhaust lobe and a slightly larger (252) intake lobe.
Usually ground on a 108 lobe separation angle (lobe centers) but a 110 L/C builds even more low end power and manifold vacuum. (and less RPM)
DD

Thanks for all the help. I got the cam and lifters for $50 so and its new just sat around for ever. So will likely use it. Un less the reverse pattern cam will give better torque. I think i should plane the head or block .100 too. I have a few heads around and i have read here they are all about the same. I have a new hydraulic head but it look weaker since there are big open passages on the deck surface. Do tiu guys know if its any weaker?

and this is where the wheels come off trying to help someone,,

You are just going to just cut the block or head deck, with out doing any measurements to understand where the piston recession is now,
without doing any calculations to understand where that will put your static compression ratio?
Without any concern over the relationship of cam duration to compression ratio and the effect on where that combination puts the torque curve.

Early on your intent seemed to be a daily driver, low RPM torque in a heavy vehicle. Cutting the deck .100 and I believe you are out of that arena.
That will raise the compression enough that you will need a cam with more duration and that will raise the RPM where useable torque starts and where peak torque occurs.
Probably a mild cut of .040 to .060 to get a good solid 8.5 compression ratio then you can run a small cam and have good low end performance.
To get a motor that meets your expectations, plan to stay true to what you want and spend some time with the easily available and free engine build calculators.

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Doo Ron Ron and the Duke of Earl are friends of mine.....
https://www.youtube.com/watch?v=uX8Nj8ABEI8

The hydro head is not much weaker, if at all.

If I wanted to do things quickly and easily, I would probably just plop that cam in you have and cut the head 0.060". That much cut will not get you into trouble if your ignition timing is set right, or you may have to slightly retard it to run on 87 octane. I would degree the cam and I would make sure you have a working oil light (and maybe gauge too) in case you shred the oil pump gear. I would reuse your original oil pump and put a 0.060" or so thick washer under the oil pressure relief spring.

Lou

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Home of Slant6-powered fun machines since 1988

Take Lou's advice. Lou gives good advice. While you are at it re-curve your distributor so that you can run a lot of initial advance and not go over 28 or so total. That really woke up a stock motor I had.

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“Buy the ticket, take the ride.”
― Hunter S. Thompson

but why do a hack, when it is easy and cheap to do it right.

to mill the head, it is off anyway,
* cc the chambers with a $6.99 syringe from Tractor Supply
https://www.tractorsupply.com/tsc/produ ... _vc=-10005
* buy a 49.99 depth micrometer from Amazon and get the piston recession.
* use an online tool like this one to zero in on exactly the compression ratio that you want,
https://www.rbracing-rsr.com/compstaticcalc.html


get the compression ratio right for the octane of your choice then you can run a decent advance curve without leaving performance on the table.
Knowing the exact static compression ratio of an engine that you build is about as basic as it gets.
Having the skills and basic tools to calculate static compression gets you in position to build a better engine
IIRC to remove 1 cc from the combustion chamber .0069 is milled from the head.
for 87 octane in a heavy vehicle I would target 8.5 static.

if you need help on cc'ing a head, checking piston recession or calculating static compression, or determining realistic static compression targets, those are all fair questions.

Of the hours spent in removing a head, removing the front cover and timing chain to get to the cam, time spent running parts to the machine shop and getting them back then reinstalling everything,
the time spent measuring and doing the calculations is a very small percentage of the total time.

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Doo Ron Ron and the Duke of Earl are friends of mine.....
https://www.youtube.com/watch?v=uX8Nj8ABEI8