FF intake manifold fasteners ??

[Art Smith]

madam and sirs:

it's my feeling that a number of FF engine rules were changed under the umbrella
of a "rewrite and reorganization for clarity" promulgated in the February 2008
Fastrack (see FF p.9, http://scca.org/documents/Fastrack/08-fastrack-feb.pdf)
(ie: not sumitted to the membership for review and comment) . while not as
troubling as the continuing lack of objectively verifiable definitions for key
aerodynamic related terms, with the RunOffs just around the corner the change
to the fastener language is probably worthy of your review and consideration.
as promulgated, D.1.s.1.A now states:
"Fasteners - nuts, bolts, screws, studs,
etc. Intake manifold fasteners may be of either a socket head or hex head
configuration, and must be 5/16” diameter."
the prior equivalent language stated:
"Fasteners (nuts, bolts, screws, studs, etc.) except intake manifold fasteners.
Intake manifold fasteners may be of either a socket head or hex head
configuration."

ignoring for the moment the continuing promulgation of rules that are not objectively
verifiable, the addition of the phrase "and must be 5/16" diameter" is a serious
concern. all of my cast iron and aluminum FF heads (Ford stock and prepared) are
tapped 5/16-18 for attachment/location of the intake manifold and all of my intake
manifolds (Ford stock and prepared) have 5/16" OD fastener clearance holes as
machined at the factory. have I missed for more than thirty years the potential for
approval of an "innovative" rationale that enables re-drilling and re-tapping of
the FF cylinder heads and/or FF intake manifolds just like I missed the rationale
that permits the now public compliance of drilling and tapping of both the 2-liter
Pinto head and cylinder block?? since no tolerance or extent is included in the
"clarifiaction", I wonder about the intent (only curiousity) and worry about the
potential variance in compliance verification given the importance of the RunOffs to
the memebership and the Club.

absolutely nothing is known about the origins and review of the change:
1.) the member's name suggesting or requesting the change is unknown
2.) the objective(s) and benefit(s) of the change are unknown
3.) alternatives considered (if any) and the rationale for their rejection are unknown
4.) the financial impact to the membership is unknown
5.) the nature of the test data (objectively verifiable or not) and/or analysis submitted to those reviewing the draft change is unknown
6.) the process used and the name(s) of those who reviewed the draft change are unknown

assuming, for discussion purposes, the objective of the change was to preclude use
of reduced shank fasteners like shown in the attached photograph, I'd recommend
consideration of:
intake manifold fasteners shall be of either socket head or hex head configuration. with the exception of either the socket or hex head and the first 0.060" beneath the head, the outside diameter (OD) of the fastener shall be 0.3125" ± 0.010" or 5/16-18 thread.
the language is objectively verifiable, precludes the assumed stepped-shank objective of the change prompting this correspondance, AND preserves compliance at no cost for
members who have made the time to procure intake manifold fasteners with the correct
grip length so their aluminum intake manifold aren't supported on sharp steel 5/16-18
coarse threads.

the fasteners shown in the photograph, like lots of other experimental bits and pieces tested from time to time, are not part of my baseline FF engine configuration. the fasteners were made four to five years ago from 180+KSI fasteners purchased from ARP. like so many simple ideas, the real cleverness was in fixturing the fasteners so they could be ground to get both the required corner radius and surface finish
(fatigue life) at the reduced shank diameter (the tooling guy I work with has approaching 40 years of aerospace tooling experience and routinely saves unusual cartoons from the
waste basket). testing of the reduced shank fasteners in that same timeframe on a
National/National plus class engine with a state-of-the-art tuned exhaust showed 1HPc
could be moved from the bottom of the powerband to the power peak OR from the
power peak to the bottom of the powerband (ie:a zero sum game just like seen with tuned exhausts). while the fasteners didn't perform as well as expected, their testing provided invaluable insight into the complex gas dynamics and fluid mechanics of the intake side of a FF engine, the frequency (rpm) characteristics of the mechanical flow filter we know as the intake manifold, and the GCR compliant path forward/upward.

as always, your time and consideration are greatly appreciated.

Arthur E. Smith
artesmtih@earthlink.net

[Greg Mercurio]

Is there a point here? If the point is to tie up the CRB for a year writing "objectively verifiable" to mke you happy then go for it. I suspect there will be a lot of "adequate as written" comments in Fastrack.

Or, if it's really important to you, why not re-write the thing yourself and present it to the membership?

This is not aerospace, man-rated spaceflight. It's club racing.

[Daryl DeArman]

This is not aerospace, man-rated spaceflight. It's club racing.

That it is. When someone asks for clarification on a rule, I tend to view the "adequate as written" responses as a green light should I see some grey in the subjective language. If exploiting that grey area results in some finished product that is beyond what the rule writers had envisioned, then correct/clarify the language, obviously it wasn't adequate.

Kind of like that facial illusion titled "my mother in law". Whatever face your mind sees first (the old lady or the young lady) is the image that is dominate, you have a hard time seeing it any other way. the "rules writers" seem to view the GCR in the same manner--it is only natural. Though it doesn't make it right.

[Steve Demeter]

Bolts are bolts.

I say the silly rules about what kind of bolts can be used to hold your manifold are silly.

As long as they are steel, have threads and a means to drive them, who cares.

the size and shape of the openings in the manifold, head and gaskets are controlled so what does it matter what kind of bolts are used to hold the whole mess together.

[R. Pare]

Art:

The rules on the intake manifold bolts were not changed at all from what they were supposed to be - this is nothing more than an "oversight" correction - most likely brought up by an engine builder who knew the history of that rule, but had just recently noticed that the current rule really wasn't written correctly.

The original wording was that the bolts had to be "stock" (meaning "as supplied from the Ford factory", which precluded reducing the shanks), but sometime just a few years ago (sometime just post '98 - I'm missing a few years GCRs just after then), it became obvious that "stock" bolts were near impossible to find, and that to still insist on their use was unenforcable. They then changed the wording to allow other-than-factory-stock bolts, but somehow forgot the implications when not specifying the diameter.

Unfortunately, the new wording forgot to include that 5/16" diameter specification - the original reason behind the "stock" requirement that was instituted umpteen years ago when some motor builders were shaving the bolt diameter to allow shifting the manifold around to get the best performance.

No big deal at all here. Much ado about nothing.

[rickb99]

.....the original reason behind the "stock" requirement that was instituted umpteen years ago when some motor builders were shaving the bolt diameter to allow shifting the manifold around to get the best performance.

Thanks for stating that R.P. I've been sitting here pondering why the bolt diameter would even be an issue. Thinking of all kinds of 'secret' passages to get extra air into the engine etc. Now it makes sense.

I guess Pan Head bolts were left off the list of acceptable because of possible aerodynamic improvements??

[R. Pare]

Nothing to do with secret passages, just intake runner to head port alignment.

[scorp997]

I didn't see anything in the rulebook that restricted the enlarging of the holes in the intake manifold - which would allow the 'movement' described above. I suppose this falls under the clause "if it doesn't say you can do it, you can't".....

[scorp997]

and saw the line "[FONT=Univers][SIZE=1]The engine shall not be altered, modified, or changed in any respect
unless specifically authorized herein."
[/SIZE][/FONT]

I didn't see anything in the rulebook that restricted the enlarging of the holes in the intake manifold - which would allow the 'movement' described above. I suppose this falls under the clause "if it doesn't say you can do it, you can't".....