66-70 vs 71 Hemi Valve Cover Studs/Nuts, What's the Diff?

[RSI700VIPER]

I'm doing some engine detailing on my '71 426 Hemi and I'm noticing lots of venders are carrying a separate set of valve cover fasteners for a 1971 Hemi.  The pictures of the parts look the same but the cost is 50 percent higher.  Anyone know what's the difference?

[anlauto]

That's a good question, other then the higher price I can't tell the difference either Maybe the nuts are taller ?

[Cuda_mark]

That's a good question, other then the higher price I can't tell the difference either Maybe the nuts are taller ?

It looks to me like the flanges on the nuts are much larger and free floating on the 71. A captured flange instead of a smaller cast in flange?

[GCragtop]

https://www.moparaction.com/2020/01/15/1971-hemi-engine-detailing/

[anlauto]

From that article: '71 nuts that hold the valve covers are unique to '71 Hemis only. They are taller and have a smaller washer than '70. The nuts are 1/4-28, 7/16" hex approx  .35"  thick and the washer OD is .54"

[RSI700VIPER]

Guess that answers it.  Wonder why mother Mopar change to taller nuts with smaller washers after 5 years?  I would think a larger washer would be better to spread the load out.  Maybe they changed vendors and that's what they had. 

[anlauto]

Be interesting to know if every 1971 Hemi used the different nuts, or they just happened to use whatever they had one day, and it just so happens that the expert that "documented" the difference found the one or two samples with different nuts....LoL