wrist pins - compliance with the rules as written

[Art Smith]

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

[John LaRue]

Art,

Your letter #11246 requested that pins be "unrestricted"; not that alternative manufacture pins of same dimension/weight be permitted. It also appeared to eliminate them from the overall weight of assembly.

Class: FF
Submitted: 2013-04-24 18:38:58
Details:
CRB:
this letter is written to recommend the rule for Formula F Ford Kent wrist pins (piston pin) be updated as written, competitors have NO authority to used anything other than Ford wrist pins (ie: c. Formula F and Formula Continental are restricted classes. Therefore,any allowable modifications, changes, or additions are as stated herein. There are no exceptions. IF IN DOUBT, DON?T).

GCR as of May 2012

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: 1.702” /- .002”
Overall height: 3.30” AE Hepolite
2.80” CP Piston
Minimum weight 515 grams (w/ clips, pin (s - delete s) 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.
suggested update
6. Wrist pins are unrestricted provided that NO modification is made to the piston

[Purple Frog]

Compared to modern engines the Kent piston is very top-heavy. There is a lot of material under the top of the piston. It was determined that to allow an "unrestricted" wristpin would allow competitors to remove a lot of weight from the underside of the top of the piston, and make up for it by using a heavier wristpin. Thus the total assembly would meet the weight requirement, but the piston assembly would be better "balanced" than one that had to use the required weight pin. This proposed change would be beneficial enough in performance gain that any who desired to be competitive would be forced to alter their engine accordingly. The FSRAC did not want to pass a change that would in effect force folks to change current engines.

[Daryl DeArman]

.

[Daryl DeArman]

Weight of pin: 115 +/- 2 grams

Weight of pin: 115 /- 2 grams

Which spec is correct? In either case, "unrestricted" while leaving in the minimum/maximum weight requirement is contradictory.

Why not resubmit the letter with "Piston pin manufacturer, material and dimensions are unrestricted provided its weight is 115grams +/-2grams and that no modification to the approved piston is required for installation"?

Seems like there should be plenty support for some similar wording if there is a problem with sourcing FoMoCo wrist pins.

[Art Smith]

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”

the form of the submitted recommendation was in keeping with the convoluted nature of the current form of the rules and used language from the ring rule (5.) to that end. no change was recommended to the existing wrist pin weight requirement found in 4. Dimensions and weights. a more wordy version would fix the compliance problem and hopefully eliminate the imagineering.

6. Wrist pins, given compliance with the 115 +/- 2 gram weight requirement found above in 4. Dimensions and weights, are unrestricted given no modification is made to the piston for the installation of the pin.

Art
artesmith@earthlink.net

[Art Smith]

maybe someone else will have better luck with the application at the CRB webpage..........



IS condition:

9.1.1. B.12.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: 1.702” +/- .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”

Recommended Update:

9.1.1. B.12.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: 1.702” +/- .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. Wrist Pins are unrestricted provided that:
A. weight is 115 +/- 2 grams.
B. No modification is made to the piston for the installation of the wrist pins

Ditto recommended change for 9.1.1.B.13.e


Art
artesmith@earthlink.net