26 replies to this topic

[Duncan]

I noticed reading both the SCCA and NASA rules that neither mention the use of a helicoil to repair a stripped spark plug.  Other SCCA classes, such as Formula V, specifically spell this out as an authorized modification.

 

Is there any other portion of the GCR or CCR that covers this type of repair?  Is this something that might cause an issue in tech? 

Duncan

[Bench Racer]

Duncan, curious, my first question would be, how did the threaded plug hole become stripped. You might look in the Mazda factory shop manual for a proceedure for stripped threads. I always on all my vehicles put a tad of anti seize on the plug threads.

[Caveman-kwebb99]

Dewy just tell the man that the rules don't say you can use heli then you just can't. This is your response 10 out of 10 anytime we talk about anything else

[Steve Scheifler]

Duncan, curious, my first question would be, how did the threaded plug hole become stripped. You might look in the Mazda factory shop manual for a proceedure for stripped threads. I always on all my vehicles put a tad of anti seize on the plug threads.

I don't want anything that might act like an insulator on my plugs. They come out often enough that there should be no risk of seizing.

[Duncan]

Duncan, curious, my first question would be, how did the threaded plug hole become stripped. You might look in the Mazda factory shop manual for a proceedure for stripped threads. I always on all my vehicles put a tad of anti seize on the plug threads.

 

I have no idea how it became stripped.  I didn't put the helicoil in.  The factory shop manual has no procedure for a stripped plug.

 

Duncan

[Steve Scheifler]

Even a complete ninny wouldn't take issue with a thread insert unless you find some way to get an advantsge from it. Just use it.

[Caveman-kwebb99]

Even a complete ninny wouldn't take issue with a thread insert unless you find some way to get an advantsge from it. Just use it.

+2,000,000. Many things like this in life that just make sense even if rules don't make sense.

[Duncan]

Even a complete ninny wouldn't take issue with a thread insert unless you find some way to get an advantsge from it. Just use it.

 

I agree completely, but I did write John Mueller (I mostly race NASA) to try and get an official stance on it.

 

Duncan

[Caveman-kwebb99]

I would be suprised if you didn't get same answer from Mueller. He tends to be common sense on stuff like this.

[RWP80000]

For Reverence (Near the start of the SCCA GCR for SM): 

 

C. AUTHORIZED MODIFICATIONS

The following items represent the only modifications and safety items

permitted and/or required on Spec Miata automobiles other than safety

items as required in Section 9. Permitted components or modifications

must not perform a prohibited function. Updating or backdating is not

allowed for any car, model, specification, or component, except as specifically

authorized in these rules.

 

(Portions of the complete section wording removed for brevity)

 

All engines and internal components used in rebuilding or refurbishment

must have been offered for sale by Mazda in the US for the correct year

and VIN of car, except as otherwise provided for in these rules. This rule

prevents use of aftermarket parts or Mazda parts of incorrect specification

or application.

 

Assembly, rebuild, and refurbishment procedures, and all associated

dimensions must adhere to the published factory service procedures,

except as otherwise stated in these rules. No components may be added

or omitted from those specified by the published factory service procedures.

All components must be standard dimensions.

 

It is permitted to use industry standard procedures to repair damaged non-engine components

(e.g., welding a transmission or differential housing)......

 

Duncan, based on the above wording and review of all of my Mazda service manual information, I find nothing to support being able to make this "industry standard procedure" as this  is an engine component.  This is why I have added this item in a recent post I made relative to a rewrite of the SM section 9.1.7 f  "Cylinder Head" (which was recently updated per RM-14-20). under the forum topic of "Why the Petition Standard" comment #16.

 

Bench Racer: your question-Duncan, curious, my first question would be, how did the threaded plug hole become stripped. 

Funny you should ask, as it happened we spent the week one "night" in the "Purple" lot of Mazda Raceway performing this exact feat because shortly before the Runoff's I had installed our refreshed engine which had a new "Pro" head and .010 overbore.  We spent the morning sessions of the 9/28 practice day breaking in the engine and scuffing tires.  We completed the rest of the day running at full power but during the last session of the day my son came in complaining of a mis-fire which we attributed to possibly being low of fuel.  We added fuel but he came in after less then a lap only this time the car had a loud noise under the hood that turned out to be coming from the #3 spark plug due to compression pressure escaping.  Turns out this happened through no fault BUT my own as I had installed the spark plugs but not torqued them as they were not the ones intended to be raced. The #3 plug had worked itself loose and in the process aluminium had seized to the plug threads such that when installing a new plug it was found that it wound not hold a torque.  So that is how I know it can happen other than a gorilla installing your plugs. I typically use anti-seize and torque to 15 fr-lbs.

 

Needless to say I then elected to remove the head from the vehicle as I did not want to risk aluminium shavings getting in the cylinder even though there are ways to capture all but the smallest.  Once I head the head off I went to a local NAPA store to procure a tool and also see who they recommended as a machine shop competent to perform this as the car trailer is not the best shop in the world.  I did get a recommendation and elected to let them do the thread repair work.  They said they would not be able to do it that day but leave it and they would do it the next morning.  Sure enough the next morning about 10:30 I get a call the head is ready  and I can come pick it up for the very fair price (for Monterey) of $60.  I immediately make the 20 min trip to town and pick the head up and return to install it.

 

Now for the good part.  As I go to align the cams for purposes of having them properly positions to install the timing belt I find that they are very difficult to turn and upon closer examination I find that there is a sticky coating over everything in the head (cams, lifters and aluminium). I also found a red, rusty watery liquid when I removed the cam bearing caps  It turns out that the Machine Shop had put the fully assembled head (which I had delivered in a sealed plastic container) in a water based parts cleaning tank without asking if I was OK or even bothering to tell me that they had.  As a result, I had to completely disassemble the head needing to use WD-40 to free up the lifters to even get them out  of the bores.

 

This is why I always have concern with respect to the ability of "Independents"/"do it yourself'er's to be able to have explicit/detailed rules related machining processes performed merely by dropping their parts off and requesting want they want done even if they provide a copy of the rules to be followed.  You just never know what you don't know they might do!  Very few have access to shops that allow them in the back room much less oversee the work being done.  It is also why I took a crack at trying to reduce some of the ambiguity in the wording of the Cylinder Head section however it seems everyone has gotten bored with this and is moving on based on the lack of feedback good or bad

 

Rich Powers. 

 

 

 

 

[Duncan]

I would be suprised if you didn't get same answer from Mueller. He tends to be common sense on stuff like this.

 

He told me he had to consult with someone and would get back to me in a few days.  I'll post up any response I get here.

 

Duncan

[Ron Alan]

For what it is worth Duncan...a local racer here recently had a failure on track(sudden loss of power) When we started trouble shooting we removed spark plugs to check compression and found one that was melted. Was a new motor so it went back to the builder. Next month he came back with the motor fixed and the SAME thing happened again! He was losing faith in his builder so he sent the head to another local guy. Turns out the head had a helicoil in one plug hole...the hole which kept failing the spark plug. For cost reasons and the thought this wasn't the issue...the head was fixed and went back out...and failed AGAIN! Needless to say the head went to the scrap pile.

One thing to note...the helicoil did not end in the same spot the stock threads ended. When the plug was installed, about 2/3 threads showed in the combustion chamber. Not sure if combustion heat was causing the problem or maybe the grounding surface area? Needless to say...be cautious if you move forward to insure material ends in the same stock location.

[Duncan]

John Mueller wrote me back and said that after consulting with the head of NASA tech, that a helicoil is a legal repair for NASA SM.

Duncan

[Bench Racer]

Thanks Rich, very interesting.
Ron, your story also.
Kyle, I try different angles attempting to please.

As long as were having FUN, that's all that counts.

[RWP80000]

Ron,

The insert repair done on our head in Calif. prior to the Runoffs was done using a "Time-sert" kit.  It has solid bushing as opposed to a coiled wire(as in a typical Helicoil).  It was a full length bushing than ended at the same point in the chamber as the original threads and the spark plug projection measured identically.

 

You may want to take a look at this as they also have oversize inserts to deal with the more severely damaged situations (like the Ford Triton engine) making the head you are talking about salvageable.

 

Rich

[Protech]

"KD" or "Time Sert" work fine.They are solid over size bushings. redloctited in to stay. Very little grease on the plug threads help a lot.

 MM 

[KW78]

Not sure, but I believe this makes Duncan a cheater.  Clearly the rule book doesn't say you can do this so you can't.  I can't actually see where you are allowed to change the spark plugs at all but I am sure I am missing that.  Furthermore this is not stock machining so is there a weight penalty for it?  I clearly can conceive of how in the first corner that the bushing style insert alters the heat transfer to the plug, so we can run more timing in qualifying and get a competitive advantage for several engine revolutions.  Furthermore, a steel insulator in an aluminum hole has some advantageous affect I am pretty sure with the whistler test, as its vibration frequency is different.  This will cause a lower reading in tech so I think we can put a thicker rod bearing in the cap and a thinner one in the rod side and effectively bump the compression with the stock parts.  Also if we are allowed to do this, then I see no where where it specifies which plug the insert can receive, so I think I would put the b-spec mazda plug in because I hear that tech doesn't have an adapter for that so anything becomes tech shed legal at this point.  I have called my engine builder and we are pretty sure we can find 6 to .8 hp in this area and be tech shed legal in the gray area allowed here.    Sorry for the decimal point typo but you know what I meant.  If this is not allowed than can we at least agree to agree that Duncan should be suspended for a few months for trying to increase his compression by overtightening his spark plugs. 

[Johnny D]

Personally, I think what he's doing is harmless, he's just trying to fix his head, but...

I am thinking WTF, with everything in flux.

I hope the head is completely stock and you're totally not gambling on a rule change with what you have.

Unless it's for IT/PT and then I'll be quite.

J~

[Duncan]

Not sure, but I believe this makes Duncan a cheater.  Clearly the rule book doesn't say you can do this so you can't.  I can't actually see where you are allowed to change the spark plugs at all but I am sure I am missing that.  Furthermore this is not stock machining so is there a weight penalty for it?  I clearly can conceive of how in the first corner that the bushing style insert alters the heat transfer to the plug, so we can run more timing in qualifying and get a competitive advantage for several engine revolutions.  Furthermore, a steel insulator in an aluminum hole has some advantageous affect I am pretty sure with the whistler test, as its vibration frequency is different.  This will cause a lower reading in tech so I think we can put a thicker rod bearing in the cap and a thinner one in the rod side and effectively bump the compression with the stock parts.  Also if we are allowed to do this, then I see no where where it specifies which plug the insert can receive, so I think I would put the b-spec mazda plug in because I hear that tech doesn't have an adapter for that so anything becomes tech shed legal at this point.  I have called my engine builder and we are pretty sure we can find 6 to .8 hp in this area and be tech shed legal in the gray area allowed here.    Sorry for the decimal point typo but you know what I meant.  If this is not allowed than can we at least agree to agree that Duncan should be suspended for a few months for trying to increase his compression by overtightening his spark plugs. 

 

Let's not go overboard.  I'm only a hypothetical cheater, since I haven't actually installed this head on a car yet.   Since it turns out it has a cracked valve seat, it turns out not to matter anyways, at least in my case. 

Duncan

[Caveman-kwebb99]

Lmao... The who KW post is in so many ways what sm is quickly turning into. I know I have kidded about this in the past but I think we should have a special place on the forum and we can hold weekly 12/step meetings where we can all be open about our addition to cheating . we can call is smca...