153 replies to this topic

[Brandon]

I'll respectfully disagree that 1/4" of material modification on one side of the valve's flow path should be called "porting".

 

IT permits "porting" within 1" of openings to facilitate 'port matching' between manifolds & head.  LTR, STR, bowl, throat - off limits.  Exhibit tooling marks beyond that 1" threshold and you're non-compliant.

STU permits "porting" fully - no dimensional restriction or limitation.  Hog it out and make as much modification to the turns/angles/shapes as you'd like.  All areas of the intake & exhaust tract are viable candidates to see tooling/polishing.

SM - the proposal permits blending of the plunge-cut within 1/4"

 

What we're attempting to facilitate here is an attempt to ensure folks who may have more than a 'deburr/knock-down' yet less than 'hog out the port' (hyperbole there) won't have to rebuild their head because their machinist did a bit of blending "as part of their normal machining procedures".  Now, I'm not going to get into what's considered a 'normal machining procedure' however the idea is we're permitting the appearance of tool marks within 1/4" of the ferrous material.

 

The petition's goal was to firmly establish a techable threshold for where tooling marks can be observed within the throat while attempting to ensure a maximum number of participants wouldn't have to replace their heads.  Again, IMHO, this is not "porting" as I understand it nor as to how the SCCA has designated it within the GCR.

 

Once more, if you don't like the "stock head rule" state it as such to the CRB in your letter.  

Similarly, if you feel some number does need to be specified to accommodate "standard machining procedures", be sure to spell that out in your letter as well.

I'm not an engine builder so I left that specific piece open to their knowledge and experience however I did attempt to clarify what I wished to see in the overall context of the rule: define, delimit, & delineate.

[Caveman-kwebb99]

I'll respectfully disagree that 1/4" of material modification on one side of the valve's flow path should be called "porting".

 

IT permits "porting" within 1" of openings to facilitate 'port matching' between manifolds & head.  LTR, STR, bowl, throat - off limits.  Exhibit tooling marks beyond that 1" threshold and you're non-compliant.

STU permits "porting" fully - no dimensional restriction or limitation.  Hog it out and make as much modification to the turns/angles/shapes as you'd like.  All areas of the intake & exhaust tract are viable candidates to see tooling/polishing.

SM - the proposal permits blending of the plunge-cut within 1/4"

 

What we're attempting to facilitate here is an attempt to ensure folks who may have more than a 'deburr/knock-down' yet less than 'hog out the port' (hyperbole there) won't have to rebuild their head because their machinist did a bit of blending "as part of their normal machining procedures".  Now, I'm not going to get into what's considered a 'normal machining procedure' however the idea is we're permitting the appearance of tool marks within 1/4" of the ferrous material.

 

The petition's goal was to firmly establish a techable threshold for where tooling marks can be observed within the throat while attempting to ensure a maximum number of participants wouldn't have to replace their heads.  Again, IMHO, this is not "porting" as I understand it nor as to how the SCCA has designated it within the GCR.

 

Once more, if you don't like the "stock head rule" state it as such to the CRB in your letter.  

Similarly, if you feel some number does need to be specified to accommodate "standard machining procedures", be sure to spell that out in your letter as well.

I'm not an engine builder so I left that specific piece open to their knowledge and experience however I did attempt to clarify what I wished to see in the overall context of the rule: define, delimit, & delineate.

 

Holy shit, I never even  met you Brandon but finally someone with a brain!  I have looked at Powers pics several times now and if that is porting hell my niece and nephews should open an engine shop and take SM racers money.  

[FTodaro]

People are confusing .250" as the width of the deburr/blend, as compaired with a maximum depth measurement from the ferris seat, where no tooling can NOT exceed.

So all of you who have complained that .250" is not a deburr, it's porting or blending. You are right, but that is not what the petition is proposing

We are specing the max measurement from seat not the size of the deburr.

I admit, I may have added to the confusion, but that is what we have proposed.

So please review this with your motor builders if you do not understand this.

[Bench Racer]

I'll respectfully disagree that 1/4" of material modification on one side of the valve's flow path should be called "porting".

 

Again, IMHO, this is not "porting" as I understand it nor as to how the SCCA has designated it within the GCR.

 

GCR Glossary:

Inlet Port - The cylinder head duct leading to the intake valve.

Nuff said about what a port is. Even Kyle's niece and nephews could figure out what porting is. I'll help the kids, adding, subtracting or massaging port material is porting. 

 

People are confusing .250" as the width of the deburr/blend, as compaired with a maximum depth measurement from the ferris seat, where no tooling can NOT exceed.

So all of you who have complained that .250" is not a deburr, it's porting or blending. You are right, but that is not what the petition is proposing

We are specing the max measurement from seat not the size of the deburr.

I admit, I may have added to the confusion, but that is what we have proposed.

So please review this with your motor builders if you do not understand this.

Please take this info from a person that has spent his entire career working with written specifications (not razzel Dazzel blowing smoke) and drawings. Written specifications and drawings have one purpose, communication. The word specification and single drawing within the petition communicate that massaging the aluminum any place within the .250 inch is accecptable. Petitioners, it can not be stated any clearer, your petition does not communicate what you believe it does when it comes to your .250 inch de-burr information.

 

David Dewhurst  

[RWP80000]

Brandon, 

 

"Similarly, if you feel some number does need to be specified to accommodate "standard machining procedures", be sure to spell that out in your letter as well.

I'm not an engine builder so I left that specific piece open to their knowledge and experience however I did attempt to clarify what I wished to see in the overall context of the rule: define, delimit, & delineate."

 

 Based on your comment (above in quotes), here is a revision to the entire SCCA GCR's section "9.1.7.f. Cylinder Head" for Spec Miata.  This was done with the intent of clearing up some ambiguities along with organizing the flow of the section to make it easier to follow (keep from jumping back and for when reading while trying to comprehend what was being communicated) as well as develop better wording relative to the Plunge Cut machining transition line which also makes a specific dimensional proposal considered to be reasonable and quantify'able ( and all above is open for debate).

 

f. Cylinder Head

1.            The original casting must not be machined, welded, ported, polished or modified in any way except as authorized /specified below.

2.            The gasket face of the cylinder head may be resurfaced provided the maximum compression ratio is not exceeded and the minimum height of the cylinder head is

maintained.  The minimum allowed heights of the cylinder heads as measured in the factory service manual are shown in the following table.

 

(Use Existing  GCR Table w/o change)

 

 

3.            The “throat area” of the port is defined here as being the inside diameter beginning in the lower portion of the cast steel valve seat that is at a 90 degree angle to the flat plane of the valve seat and which also extends/transitions  down into the aluminum casting below the seat.

 

4.            It is permitted to plunge cut the “throat area” in order to correct core shift that is commonly found in many cylinder heads.  This cut must be concentric with the valve guide axial centerline and cannot extend further than the specified number (shown below) as measured from the bottom of the ferrous valve seat.  There can be no tooling or machine marks in the head below this specified number.   The “throat area” as defined in “3.” above will be measured with a gauge and must conform to the maximum diameters and depths listed in the table below.

 

(Use Existing  GCR Table w/o change)

               

5.            No aluminum in the bowl area and/or port (other than that specified for the plunge cut) may be removed, added or manipulated for any reason other than as described here.  It is understood that the head may look slightly different from bowl to bowl due to casting irregularities.  The area under the valve seat where the plunge cut ends and the casting resumes cannot be blended by hand, machined or chemically/electrically processed to create a smooth transition. No material may be removed or added from the short term radius in the port. The plunge cut to valve bowl, port walls “transition machining line” may be hand processed only for the purpose of removing “machining flash”. This is to be done using a flexible abrasive medium such as a Scotch-Bright pad, steel wool or paper/cloth.  There can be no tooling or machine marks created along the “transition machining line” with this" permitted" process as could result from the use of a hand scraper/file tool or a rotating power tool. Additionally the flash removal process cannot result in a width (where the machine/casting transition line is smoothed of any visible surface irregularities) greater than 1 mm.  This “transition machining line” hand processing criteria may also be applied to the head combustion chamber after resurfacing per” 2.” above.

 

6.            It is permissible to remove and replace the valve seat inserts for the purpose of repairing a head within OEM valve location tolerances using aftermarket replacement seats meeting OEM dimensions. 

 

7.            Spark Plug threads may be repaired with the use of the various aftermarket available thread inserts as long as the spark plug installed depth position is not altered from OEM.

 

8.            Valve guides may be replaced provided the position of the valve is not changed and the replacement guides are Mazda OEM parts. (Wording to be extracted from current section” h. Valves, paragraph 1.” Shown Highlighted in the full paragraph below for reference.)

 

 

h. Valves

1. OEM valves must be as supplied by Mazda. Valve location

or angle must not be moved. Reshaping of the valves is

strictly prohibited. Valve guides may be replaced provided

the position of the valve is not changed and the replacement

guides are Mazda OEM parts. Valve stem installed

height must be per the Mazda factory service manual:

 

 

Rich Powers

[RWP80000]

Brandon, 

 

"Similarly, if you feel some number does need to be specified to accommodate "standard machining procedures", be sure to spell that out in your letter as well.

I'm not an engine builder so I left that specific piece open to their knowledge and experience however I did attempt to clarify what I wished to see in the overall context of the rule: define, delimit, & delineate."

 

 Based on your comment (above in quotes), here is a revision to the entire SCCA GCR's section "9.1.7.f. Cylinder Head" for Spec Miata.  This was done with the intent of clearing up some ambiguities along with organizing the flow of the section to make it easier to follow (keep from jumping back and for when reading while trying to comprehend what was being communicated) as well as develop better wording relative to the Plunge Cut machining transition line which also makes a specific dimensional proposal considered to be reasonable and quantify'able ( and all above is open for debate).

 

f. Cylinder Head

1.            The original casting must not be machined, welded, ported, polished or modified in any way except as authorized /specified below.

2.            The gasket face of the cylinder head may be resurfaced provided the maximum compression ratio is not exceeded and the minimum height of the cylinder head is

maintained.  The minimum allowed heights of the cylinder heads as measured in the factory service manual are shown in the following table.

 

Existing  GCR Table w/o change

 

 

 

 

 

 

3.            The “throat area” of the port is defined here as being the inside diameter beginning in the lower portion of the cast steel valve seat that is at a 90 degree angle to the flat plane of the valve seat and which also extends/transitions  down into the aluminum casting below the seat.

 

4.            It is permitted to plunge cut the “throat area” in order to correct core shift that is commonly found in many cylinder heads.  This cut must be concentric with the valve guide axial centerline and cannot extend further than the specified number (shown below) as measured from the bottom of the ferrous valve seat.  There can be no tooling or machine

[Brandon]

Rich,

Thank you.  This is nearly what I'd anticipate being defined in the GCR with only two exceptions/alterations/clarifications:

1. How does Tech make a distinction between hand-done vs. powered for the flash removal?
2. If it's expected to be 'by hand' I'm afraid a 1mm allowance may not be enough.

Think about the worst-case scenario: a builder who's done 15 of the 16 valves perfectly but on #16 manages to get 1.5mm of flash removal at some point around the cut.  Trashed head?

 

I think considering #2 above may help clarify how to accomplish #1.  And your wording gives absolute numbers for builders to attain and for verification in tech.

Bravo.

*applause*

 

Thanks again for the rules-smithing.  :-)

Brandon 

[tony senese]

 

6.4 mm pretty big for a deburr if you ask me....

[Caveman-kwebb99]

Wow what an awesime pic of a ruler.. Impressed with the intellect.

[tony senese]

Well, Kyle, you looked at it!

[RWP80000]

Rich,

Thank you.  This is nearly what I'd anticipate being defined in the GCR with only two exceptions/alterations/clarifications:

1. How does Tech make a distinction between hand-done vs. powered for the flash removal?
2. If it's expected to be 'by hand' I'm afraid a 1mm allowance may not be enough.

Think about the worst-case scenario: a builder who's done 15 of the 16 valves perfectly but on #16 manages to get 1.5mm of flash removal at some point around the cut.  Trashed head?

 

I think considering #2 above may help clarify how to accomplish #1.  And your wording gives absolute numbers for builders to attain and for verification in tech.

Bravo.

*applause*

 

Thanks again for the rules-smithing.  :-)

Brandon 

Brandon,

Good catch. I did not intend the absolute requirement for only "hand" processing but rather use of a "flexible" abrasive medium so as not to leave tool marks. Based on your comments this could be corrected if the word "hand" was removed from the last sentence relating to the application of this process to another area of the head.

 

The wording was developed with an intent of allowing some flash removal (which necessarily means smoothing) while inferring a cautionary warning as to the risks of using more aggressive methods as any tool markings left or smoothing exceeding the "1 mm" width specification are not to be tolerated.  As you infer, a quick "slip" or "dwelling" excessively long in one spot could render a head "non compliant". I am sure there will be those who could take this language and spend hours bringing the width of the "machining transition line" to the full width of the 1 mm spec around the full transition line but I am not concerned as all that work will not result in in enough of a performance gain compared to the risk of ruining a head in the process.

 

I agree that we do not want TECH to be trying to discern the process but rather the outcome relative to the specified criteria.  In this case, that would be the absence of tooling marks.  If someone used a flap disc or abrasive cloth on a shaft but stayed within the specification while also avoiding the creation of tool marks, there is not a compliance issue. The purpose of referencing "tool marks" (and undulations that are not consistent with the base casting surface represents the creation of a tool mark) is to prevent the process from becoming "blending" rather than just flash removal. (It might be appropriate to add the "undulation" wording for added clarity and for TECH to be on the lookout for.)

[Richard Witt]

Ohhh, I thought vees were bad  lololo

[Jim Drago]

Ohhh, I thought vees were bad  lololo

They are.. But for some reason not under the same scrutiny as SM..

Just the manifold scenario alone is a joke.  "Very influential people" have had a controlling interest in that class for a long time.   A $50 intake manifold was BLATANTLY cheated for years by expanding with with hydraulics and ball bearings. Once exposed, (these manifolds that could only be described as a snake that just ate a meal that was way too big for its body)they were speced as the standard..  When the CRB tried to step in and spec a manifold for about $250 that would all be the same and have no supply issues. The idea was squashed by some of these same people... Go figure.. Ironically, now the same people have put themselves on some moral pedestal when dealing with SM and SM compliance. 

[chris haldeman]

What a Noble cause