Stock Mopar Valve Spring 'Load-Rates'

[69 Cuda 440]

Factory listed {Mopar A-Body} Valve Spring Pressure

273/180 HP
* Closed...... 83 lbs.
* Open...... 177 lbs.

273/235 HP
* Closed...... 98 lbs.
* Open....... 210 lbs.

273/275 HP 'D-Dart'
* Closed..... 150 lbs.
* Open....... 313 lbs.

340/275 HP
* Closed....... 82 lbs.
* Open........ 247 lbs.

383/280 HP {1967} and 300 HP {1968}
* Closed...... 134 lbs.
* Open........ 208 lbs.

383/330 HP {1969}
* Closed...... 129 lbs.
* Open....... 280 lbs.

440/375 HP {1969}
* Closed..... 129 lbs.
* Open....... 280 lbs.

 

[69 Cuda 440]

'More' Mopar Literature


273/180 HP {2-Barrel} ~ {1964 thru 1967}
* Closed..... #83 lbs. @ 1.69"
* Open..... #177 lbs. @ 1.31"

273/235 HP ~ {1965 thru 1967}
* Closed..... #98 lbs. @ 1.69"
* Open...... #210 lbs. @ 1.295"

273/275 HP ~ {'1966 D-Dart'}
* Closed..... #150 lbs. @ 1.55"
* Open....... #313 lbs. @ 1.05"

318/230 HP {2-Barrel} ~ {1968 and 1969}
* Closed..... #103 lbs. @ 1.69"
* Open....... #142 lbs. @ 1.30"

318/230 HP ~ {1970}
* Closed..... #92 lbs. @ 1.65"
* Open..... #189 lbs. @ 1.28"

340/275 HP ~ {1968 and 1969}
* Closed.... #114 lbs. @ 1.65"
* Open...... #245 lbs. @ 1.20"

340/275 HP ~ {1969 thru 1973}
* Closed..... #96 lbs. @ 1.65"
* Open..... #242 lbs. @ 1.21"

383/343 HP ~ {1962}
* Closed.... #100 lbs. @ 1.86"
* Open...... #248 lbs. @ 1.415"

383/330 HP ~ {1963 thru 1965}
* Closed...... #98 lbs. @ 1.86"
* Open...... #208 lbs. @ 1.43"

426/365 HP ~ {1964 and 1965}
* Closed...... #98 lbs. @ 1.86"
* Open...... #208 lbs. @ 1.43"

383/325 HP ~ {1966 and 1967}
* Closed...... #134 lbs. @ 1.86"
* Open........ #208 lbs. @ 1.43"

383/280 HP ~ {1967}
* Closed..... #134 lbs. @ 1.86"
* Open....... #208 lbs. @ 1.43"

383/300 HP ~ 383/330 HP {1968}
* Closed.... #128 lbs. @ 1.86"
* Open...... #240 lbs. @ 1.43"

383/335 HP ~ {1968 and 1969}
* Closed..... #129 lbs. @ 1.86"
* Open....... #258 lbs. @ 1.40"

383/335 HP {1970} ~ 383/300 HP {1971}
* Closed.... #105 lbs. @ 1.86"
* Open...... #234 lbs. @ 1.40"

383/290 HP ~ {1970}
* Closed... #125 lbs. @ 1.86"
* Open.... #200 lbs. @ 1.42"

440/350 HP ~ {1966 thru 1969}
* Closed... #105 lbs. @ 1.86"
* Open..... #234 lbs. @ 1.40

440/350 HP ~ {1970}
* Closed... #125 lbs. @ 1.86"
* Open..... #200 lbs. @ 1.42"

440/375 HP ~ {1967 thru 1970}
* Closed.... #129 lbs. @ 1.86"
* Open...... #258 lbs. @ 1.40"

440/390 HP ~ {Six-Pack and Six-Barrel}
* Closed... #115 lbs. @ 1.86"
* Open..... #310 lbs. @ 1.37"

 

[4spdragtop]

Found this while looking for stock spring size for 67 273 commando.
Paul was a wealth of knowledge and willing to share it.
RIP Paul.

 

[Outsder]

I'd say those spring pressures probably ideal engineer specs, but by the time they made it off the off the assembly line the numbers were less. I changed cams and springs, and pulled some pretty low milage performance era motor stock springs and checked them with maybe like 30k orig miles and they were considerably less on big block Magnum and small block 340 motors. Looking at my old notes, no closed 129# springs for BB Magnum red springs w/damper, more like a 105#s.

 

[RustyRatRod]

I'd say those spring pressures probably ideal engineer specs, but by the time they made it off the off the assembly line the numbers were less. I changed cams and springs, and pulled some pretty low milage performance era motor stock springs and checked them with maybe like 30k orig miles and they were considerably less on big block Magnum and small block 340 motors. Looking at my old notes, no closed 129# springs for BB Magnum red springs w/damper, more like a 105#s.

Just like any spring, once broken in loses about 10%. That's why I choose about 10% more seat pressure than needed.