Old Camshaft spec help

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Michael Siple

Michael Siple

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After (7) years of running the 340 that came in our Duster we had to remove for a rebuild due to blow by - finally found out about it's internals. Come to find out this cam is a mechanical Mopar Performance 557. This 340 was built in 1997 & ran until removed 18 months ago - that's a long time for one to stay together. I've searched but have not been able to find out much of anything else numbers wise. Stumbled onto a few threads where duration was anywhere from 252 to 284. What I'm trying to do is to find out the rest of the specs but have found nothing after searching myself. Stamped # comes up with zip. Help & direction is appreciated. -Mike

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Not hard to find at all.

Duration Intake Nominal​

296°​

Duration Exhaust Nominal​

296°​

Duration Intake @ .050”​

252°​

Duration Exhaust @ .050”​

252°​

Intake Lobe Centerline​

108° ATDC​

Exhaust Lobe Centerline​

112° BTDC​

Lobe Separation Angle​

110°​

Overlap​

76°​

Intake Opens​

40° BTDC​

Exhaust Opens​

80° BBDC​

Intake Closes​

76° ABDC​

Exhaust Closes​

36° ATDC​

Intake Lift​

.557"​

Exhaust Lift​

.557"​

 
Michael Siple said:
After (7) years of running the 340 that came in our Duster we had to remove for a rebuild due to blow by - finally found out about it's internals. Come to find out this cam is a mechanical Mopar Performance 557. This 340 was built in 1997 & ran until removed 18 months ago - that's a long time for one to stay together. I've searched but have not been able to find out much of anything else numbers wise. Stumbled onto a few threads where duration was anywhere from 252 to 284. What I'm trying to do is to find out the rest of the specs but have found nothing after searching myself. Stamped # comes up with zip. Help & direction is appreciated. -Mike

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Part# P4120655 DURATION 296 OVERLAP 76 LIFT .557 REC. INSTALL CENTERLINE 108
LASH .028 in. / .032 ex
 
Yes I've never heard of the stamp helping.. weird. I believe that cam has been ground on a couple different center lines over the years but according to my Mopar performance camshaft list it comes in at.252@50
 
I really like that Cam's numbers and wish I would have put that in my current build. How did it work for you and what were some of the supporting cast.
 
Dart Frog said:
I really like that Cam's numbers and wish I would have put that in my current build. How did it work for you and what were some of the supporting cast.
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old article in Mopar Collectors Guide April 1999 gave up some info how it was built. 040 over , ported 2.02 J heads , stock stroke, headers , 727 with 8'' 3500 converter, 391 rear - 323 gear when we got it. It had a 6 pack with nitrous. Air cleaner lid just did touch hood causing minute rub under hood. Removed the plates because we never used any nitrous. Taking it apart we found the info was correct - it matched what they said. Ran well for us for 7-8 years until it started fogging things up waiting at lights the end of 2022. Had to do something - it was a little embarrassing. Broken rings in every cylinder. Then & now pics . Too much party for # 5 - he was sleeved.

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Wow that ring condition is something. I thought mine was bad when I pulled it down last winter and had two Pistons with the rings it came out in pieces. But our builds are similar I am now running mechanical cam 284 advertised on a 106 centerline one step below yours. I went to a top steel ring when I put mine back together.
 
Looks like the rings expanded and butted together.
 
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