Mazda MX-6 Forum banner
1 - 1 of 1 Posts

·
Registered
Joined
·
2,694 Posts
Discussion Starter · #1 ·
Just finished porting and polishing another F2T head, I always install 0.060" vale spring shims on any head I run.
I was out of shims and had to look them up all over again.
The size that fits the F2 head is I.D. 24.5mm /1" O.D. 34.544mm/1.36"
Sealed power part number 259102 abbreviations are A, B, C. A= 0.060" B=0.030" C=0.015", HP after is case hardened steel.
It appears 102 is the number that represents size (id/od).

I was curious as to the pressure increase the shims add to the springs.
Spring resistance over travel isn't linear but I use simple math to calculate spring rates, making the resulting numbers minimum potential increases. I did however use maximum factory workshop manual spring rates because of course 30+ year old spring perform at peak level or I'm optimistic and lazy.
Because I decided only seating pressure matters due to infinite wisdom or too much weed and beer or delusional reasoning which is the fact any opened valve float could be considered free extra cam duration but the valves always end up having cylinder pressure pushing them shut as the piston rises.

Free length:
iN- 1.949" 49.5mm
EX- 1.984" 50.4mm

Seated load/ height:
IN- 1.614" 41mm - 51.5lb
EX-1.614" 41mm - 60.9lb

Seated preload travel:
IN- 0.335" 8.5mm
EX- 0.370" 9.4mm

Seated pressure with 0.060" shims:
IN- 51.5 / 335 X 60 = 9.22lb + 51.5 = 60.72lb (17.9% pressure increase)
EX- 60.9 / 370 x 60 = 9.87lb = 60.9 = 70.77lb (16.2% pressure increase)

Shim cost- 6$-10$ for 12.
 
  • Like
Reactions: juanpac_tupac
1 - 1 of 1 Posts
This is an older thread, you may not receive a response, and could be reviving an old thread. Please consider creating a new thread.
Top