FF
1. #11246 (Arthur E. Smith) Formula F Wrist/Piston Pin Update Needed
Thank you for your request. The CRB has no plans to change this rule since this kind of change will create issues with the piston
what are the current rules for wrist pins for Kent engines and what should they be to keep everything above boards?? while there are periodicly rumors to the contrary, there is only one Ford Motor Company.
b. Formula F is a Restricted class. Therefore, any allowable modifications,
changes, or additions are as stated herein. There are no
exceptions. IF IN DOUBT, DON’T. Homologation is required for all
cars registered after January 1, 1983.
the current GCR authorizes use of non-standard pistons and NOT pins. the current GCR is silent on pins other than the long standing weight requirement. therefore, without authority to do otherwise, Ford pins are currently required and how many competitors are running Ford pins??
e. Pistons
1. Standard or 0.005 inch oversize pistons shall be used.
2. Standard size AE pistons P/N 18649, casting P/N 18634, standard
size CP piston, part # 81-2 FF1600, or CP oversize piston,
part # 81-2- FF1600+5 may be used.
3. Alternate piston identified as follows is allowed: P/N AE-M717D,
casting number 711 M 6110. AE Hepolite P/N 20552, Casting
# 20548A. Note: Mahle pistons are not allowed.
4. Dimensions and Weights
Maximum diameter:
Standard: 3.187”
0.005” o/s: 3.192”
Depth of bowl: 0.470” (minimum)
Maximum diameter of bowl: 2.44” AE Hepolite,
2.50” CP Piston
Centerline of wrist pin to crown: 1.737 +/- .002”
Overall height: 3.30” AE Hepolite
2.80” CP Piston
Minimum weight 515 grams (w/ clips, pins and rings)
Weight of pin: 115 +/- 2 grams
Ring Groove Widths: Top Groove: 0.064”
2nd Groove : 0.0795”
Oil Groove: 0.159”
5. Piston rings are unrestricted provided that:
A. One oil control and two compression rings are used.
B. No modification is made to the piston for the installation of
rings.
C. Pocketing of the piston valve reliefs is allowed up to a
maximum of .050” to obtain the maximum combustion
chamber volume.
the recommended change was simple and did not support any changes to the piston:
6. Wrist pins are unrestricted given no modification is made to the piston for the installation of the pin.
pistons and pins are clearly different parts, made from different materials, and sold seperately in the marketplace............... competitors should be authorized in black & white to buy 115 +/- 2 gram pins that require no modification of the pistons from the supplier of their choice
Art
artesmith@earthlink.net