Cam identification how-to??

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mopowers

mopowers

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What's the easiest way to identify a camshaft with the engine installed and the intake off??

I was told the cam in my 340 was a MP one. I know it's a hydraulic flat tappet. I'm guessing either the 280* or 284*.

I'm going to install a new intake this weekend. Can I losen up one of the rocker shafts and put a dial indicator on one of the lifters to measure the lift, or will the lifter bleed out enough to screw up the reading?

Thanks for your help.
 
That will probably work but you need a degree wheel as well.
 
I always use a solid lifter and adjustable rocker arm to degree a cam.


I also think that it would be better to put the dial indicator on the valve spring retainer to measure. That way you have all numbers "after the rocker arm ratio" and the numbers will be easier to use.


I would not trust a hydraulic lifter not to bleed down.
 
Thanks for the input guys! I really appreciate it. Unfortunately, I don't have a solid lifter at my disposal. I do have a degree wheel though. If I know it's a MP purple shaft cam though, can't I just get the lift # to figure out which one it is? I'm not interested in after rocker lifts. I just want to know what cam is in it.

Is there enough room to put the dial indicator directly through the holes in the lifter valley onto the cam lobe? Would this damage the cam?

Thanks again guys!
 
Just flip a lifter upside down. Instant solid lifter. Use that with the dial indicator along with the degree wheel and you should be able to map it.
 
RustyRatRod said:
Just flip a lifter upside down. Instant solid lifter. Use that with the dial indicator along with the degree wheel and you should be able to map it.
Click to expand...

That's I great idea! Does that damage the cam, lifter or bore? Obviously, there won't be any pressure on it.

Thanks for the idea, sir
 
Finally got around to ID'ing the cam (I think).

0417141851_zps6f59dda2.jpg


I put a dial indicator on the cam lobe and measured .3155" on lobe lift. The shaft was purple as well. Am I correct in assuming I've got a 280/474 MP cam???

Are these decent cams? I like the way it sounds, but I can't get it to produce any more than about 10.5" of vacuum at idle. I'm hoping it'll run better after swapping the old Torker 340 for an Air-gap.
 
That is most likely what it is, to know for sure you can map it out with degree wheel. I just did the same as you did with my old cam, I was sure mine was a stocker in my 340 and it measured out to .444 on the exhaust
 
Good camshaft for the old grinds. Where it's installed, intake center line, makes a big difference. Advancing them a little more than the recommended ICL generally helps with lower end power.

It may pick up some vacuum with an air gap.
 
Thanks guys. The pins have already been pulled right after I measured the cam when I cleaned off the old gasket.

Rob- do you think it'd be worth my while to pull the timing cover and advance the cam? I'm not even sure exactly how one goes about advancing the cam. I've degreed a few before, but have never had to adjust anything. I'm half tempted to slap it back together and enjoy it while the weather's nice.
 
mopowers said:
Finally got around to ID'ing the cam (I think).


I put a dial indicator on the cam lobe and measured .3155" on lobe lift. The shaft was purple as well. Am I correct in assuming I've got a 280/474 MP cam???

Are these decent cams? I like the way it sounds, but I can't get it to produce any more than about 10.5" of vacuum at idle. I'm hoping it'll run better after swapping the old Torker 340 for an Air-gap.
Click to expand...



Take .3155 x 1.5 = .47325

Or round it to .473"


You really need a degree wheel on the crankshaft to measure how much duration it is off of it's seat.


Direct Connection used to have a nice .474/274 cam back in the old days, it may be one of those.

You need to put a degree wheel on the crankshaft and record duration that the lifter is just coming off of it's seat (measured with a dial indicator on the lifter), and also try to get the duration @ .050".

To do that you will need to divide .050" by the rocker arm ratio (1.5):

.050"/1.5 = .0333"

So you will need to measure the duration off of the lobe (without going through the rocker arm) at .033" on the dial indicator at each angle on the up stroke and down stroke.

Then with lift AND duration we can better guess your cam. If you can measure the lobe centers for the intake and exhaust lobes also since you are mostly there anyway, we can have an even better guess.

Every .033" on the dial indicator directly off the cam lobe will equal .050" lift at the rocker arm, which is how cams are spec'ed.


Are you sure that it is even a Mopar purple shaft cam?
 
mopowers said:
Thanks guys. The pins have already been pulled right after I measured the cam when I cleaned off the old gasket.

Rob- do you think it'd be worth my while to pull the timing cover and advance the cam? I'm not even sure exactly how one goes about advancing the cam. I've degreed a few before, but have never had to adjust anything. I'm half tempted to slap it back together and enjoy it while the weather's nice.
Click to expand...


If you degree it, then you can advance it.

Once you have it degreed, then make sure that it is installed at spec (0° advance from your degree info).

Then decide if you want to advance or retard it and use one of the offset keys for the cam to bump it a degree or two where you want it to go.

Then degree it again to verify that it went where you intended it to go (and not in the opposite direction).
 
krazykuda said:
Take .3155 x 1.5 = .47325

Or round it to .473"


You really need a degree wheel on the crankshaft to measure how much duration it is off of it's seat.


Direct Connection used to have a nice .474/274 cam back in the old days, it may be one of those.

You need to put a degree wheel on the crankshaft and record duration that the lifter is just coming off of it's seat (measured with a dial indicator on the lifter), and also try to get the duration @ .050".

To do that you will need to divide .050" by the rocker arm ratio (1.5):

.050"/1.5 = .0333"

So you will need to measure the duration off of the lobe (without going through the rocker arm) at .033" on the dial indicator at each angle on the up stroke and down stroke.

Then with lift AND duration we can better guess your cam. If you can measure the lobe centers for the intake and exhaust lobes also since you are mostly there anyway, we can have an even better guess.

Every .033" on the dial indicator directly off the cam lobe will equal .050" lift at the rocker arm, which is how cams are spec'ed.


Are you sure that it is even a Mopar purple shaft cam?
Click to expand...

The guy I bought the car from said he used a MP purple shaft and he thought it was either the 280 or 284 one, but couldn't recall exactly which one. The engine is fresh and was built not that long ago. The physical color of the cam's shaft is purple as well. All these things lead me to believe it's the 289/474. I'll pull the lower pulley and bolt my degree wheel to the dampner to verify though.
 
krazykuda said:
If you degree it, then you can advance it.

Once you have it degreed, then make sure that it is installed at spec (0° advance from your degree info).

Then decide if you want to advance or retard it and use one of the offset keys for the cam to bump it a degree or two where you want it to go.

Then degree it again to verify that it went where you intended it to go (and not in the opposite direction).
Click to expand...

Thanks for the info.
 
If you have it this far apart, you might as well see where it's installed if you didn't do it.

I'd put it in at 104 ICL, IIRC, spec is 106 ICL on that cam.

I'm done in about 20 minutes working in the garage for the day, give me a call if you want to talk about a gameplan.
 
Thanks for the reply Rob. Just saw it. Been in and out of the hospital. When I'm able to get back to messing around in the garage, I'll give you a hollar.

Thanks,
Evan
 
as hinted above there are several generations of Direct Connection- Mopar Performance cams
also this may be one available with alternate lobe center angles- usually 108 and 112
cylinder pressure is the same if installed on the same ICL however 108 gives more low end cylinder pressure if installed say 4 degrees advanced from the timing split
since degreeing the cam is a separate job from what you are doing I'd drive it and see what you would like to improve.
post up your cranking compression
and work on your tune- distributor curve- B4 making changes
 
Wyrmrider said:
as hinted above there are several generations of Direct Connection- Mopar Performance cams
also this may be one available with alternate lobe center angles- usually 108 and 112
cylinder pressure is the same if installed on the same ICL however 108 gives more low end cylinder pressure if installed say 4 degrees advanced from the timing split
since degreeing the cam is a separate job from what you are doing I'd drive it and see what you would like to improve.
post up your cranking compression
and work on your tune- distributor curve- B4 making changes[/QUOte do any of them numbers tell any thing about the loft
Click to expand...
 
My engine guided tried to get me to buy another can he said they was no way to from and out what I had I told him it was a new can that he put in there he said if I didn't have the I'd card I was out of luck
 
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