Mopar Purple Cam 340

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SGlez10

SGlez10

68 Barracuda
Joined
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Carson, Ca
Context: Hi guys I recently purchased a 340 short block (2780930-340-1), based on seller the engine wad rebuilt and bored over to .030 years ago and was never put in a car after it was rebuilt. I was thinking of having it hot tanked just to clean out water passages, etc.

Question: We removed the cam and it seems to be a "purple cam" and it doesn't have any other numbers on it other than the ones you see in the image below. Can anyone tell me more about this cam? Is the pruple cam considered stock? mild? better than stock but not mild? Im not sure where it stands...

I'm not looking to build a racer, just a cruiser that can show off a little when the moment calls for it :)

Thanks in advance

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Google how to use a caliper to measure cam lobes and you'll be able to determine the lift on intake and exhaust and then probably which PN it is and thus the timing events. Solid or hydraulic lifter will make a difference.
 
Did you ask the person you bought the engine from if they had any paperwork about the rebuild? You might also ask them who rebuilt the engine & contact them for any information. If you can't get any of that information, I would pull the pan, check the clearances & then the torque on all of the bolts on the bottom end & the tope end. It's better to check, than to fire it up & it starts eating itself.
 
Demonracer said:
Did you ask the person you bought the engine from if they had any paperwork about the rebuild? You might also ask them who rebuilt the engine & contact them for any information. If you can't get any of that information, I would pull the pan, check the clearances & then the torque on all of the bolts on the bottom end & the tope end. It's better to check, than to fire it up & it starts eating itself.
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I didnt ask for paperwork, but I'll check back in with the guy on the paperwork for the rebuild. Might just have to start measuring to see where we stand.
 
SGlez10 said:
... Question: We removed the cam and it seems to be a "purple cam" and it doesn't have any other numbers on it other than the ones you see in the image below. Can anyone tell me more about this cam? Is the pruple cam considered stock? mild? better than stock but not mild? Im not sure where it stands...
Click to expand...

It can be all of the above, from stock to absolutely wild. See post #2 to get an idea.
 
The old purple shaft hydraulic cam came in lots of flavors, I believe at one time they 8 different lifts. Gonna have to measure it!
 
Keith Mopar said:
The old purple shaft hydraulic cam came in lots of flavors, I believe at one time they 8 different lifts. Gonna have to measure it!
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8? Ahhhh, no, a good bit more. I just counted 12. There are also 16 different Hyd. cams. 4 have the .508 lift. Then there are 14 more solid lifter cams. They used to sell several roller cams for the big circle tracks and pro stock and other pro racing category.
 
Quick look at the lifters will determine the style of Cam, just do as suggested get calipers measure the base circle and measure the load lift then I believe you subtract the base circle from the lobe lift times 1.5 that should give you the cam lift. But Google it as suggested to make sure pretty easy stuff.
 
SGlez10 said:
I'm not looking to build a racer, just a cruiser that can show off a little when the moment calls for it
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Well in that case you will need to know your exact compression ratio. If your compression ratio was set up for a long period cam, then it is not always easy to successfully install a cam of lessor duration, because of the possibility of hitting the detonation wall.
A nice street cam is a 218 to 223 intake duration, with a complementing compression ratio. Tons of low rpm torque to run 3.23s and less. And the bonus is it will get better fuel mileage in steady state cruising.
With good heads, you can make in the range of 300/325hp with a 223 FTH cam. That will spin tires all thru first gear; Any street 14/15 tire you can fit into the factory tubs, with 3.23s or more.
And with an overdrive geared for 65=1680, I made one trip getting phenomenal fuel mileage. Mind you I had a longer stroke,namely 3.58.

Happy HotRodding
 
lemondana said:
Hot tanking will destroy the cam bearings, I believe.
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Yes I’d have them removed before it gets tanked. The block was rebuilt years ago, and sat for a long period. So I wanna make sure it’s cleaned out properly and cylinders honed before reassembly.
 
AJ/FormS said:
Well in that case you will need to know your exact compression ratio. If your compression ratio was set up for a long period cam, then it is not always easy to successfully install a cam of lessor duration, because of the possibility of hitting the detonation wall.
A nice street cam is a 218 to 223 intake duration, with a complementing compression ratio. Tons of low rpm torque to run 3.23s and less. And the bonus is it will get better fuel mileage in steady state cruising.
With good heads, you can make in the range of 300/325hp with a 223 FTH cam. That will spin tires all thru first gear; Any street 14/15 tire you can fit into the factory tubs, with 3.23s or more.
And with an overdrive geared for 65=1680, I made one trip getting phenomenal fuel mileage. Mind you I had a longer stroke,namely 3.58.

Happy HotRodding
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Thanks for the information
 
Get a pair of dial calipers. Ok, here we go.

1) Measure the width of the lobe at the base circle. This is the "sides" of the lobes around the cam core. Take the measurements from both sides of the base circle, where the lifter rides. Write that number down.

2) Now measure the total lift of the lobe, from the base circle to the peak of the lobe. Write that number down.

3) Now divide the number you got in step 1 by 2. Write that number down.

4) Now subtract the number you got in step 3 from the number you got in step 2. That is your total lobe lift.

5) Since the purple cams were designed for a 1.5 rocker ratio, multiply the number you got in step 4 by 1.5. This will be your total lift at the valve. When you get that final number, report back here and we can very likely tell you which cam you have.
 
RustyRatRod said:
Get a pair of dial calipers. Ok, here we go.

1) Measure the width of the lobe at the base circle. This is the "sides" of the lobes around the cam core. Take the measurements from both sides of the base circle, where the lifter rides. Write that number down.

2) Now measure the total lift of the lobe, from the base circle to the peak of the lobe. Write that number down.

3) Now divide the number you got in step 1 by 2. Write that number down.

4) Now subtract the number you got in step 3 from the number you got in step 2. That is your total lobe lift.

5) Since the purple cams were designed for a 1.5 rocker ratio, multiply the number you got in step 4 by 1.5. This will be your total lift at the valve. When you get that final number, report back here and we can very likely tell you which cam you have.
Click to expand...
Thank you for the step by step, much appreciated
 
SGlez10 said:
Yes I’d have them removed before it gets tanked. The block was rebuilt years ago, and sat for a long period. So I wanna make sure it’s cleaned out properly and cylinders honed before reassembly.
Click to expand...
The bearings are a 1 shot, 1 time fit item. Once removed they will need to be replaced. Hot tanked or not.
 
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