Rocker Stud Hole Repair in Aluminum Heads

« **on:** June 05, 2012, 11:07:29 PM »

I've been having problems with rocker studs ripping out of my aluminum heads. Back at the race in Long Beach of '09, it happened and Pat repaired the 2 studs with a time sert. it happened again recently and i did a quick fix using a helicoil.

I want to time sert all 16 studs. Should I do it with regular steel inserts or should I spend the extra $$ for stainless?

« **Reply #1 on:** June 05, 2012, 11:38:31 PM »

Quote from: Brad @ SCJB on June 05, 2012, 11:07:29 PM

I've been having problems with rocker studs ripping out of my aluminum heads. Back at the race in Long Beach of '09, it happened and Pat repaired the 2 studs with a time sert. it happened again recently and i did a quick fix using a helicoil.

I want to time sert all 16 studs. Should I do it with regular steel inserts or should I spend the extra $$ for stainless?

I say steel, stainless is not any stronger (quite the opposite) and their in an oily environment, corrosion wont be a factor IMHO

Never had really good luck with stainless in aluminum anyways... $:-\$

Is there something funky about your rocker geometry? Has the pushrod length been verified and reverified?

A threaded stud should not come out/loose if it were torqued and locked properly, the boss should break out first.

« **Reply #2 on:** June 05, 2012, 11:46:04 PM »

cool. i just need to measure my hole depth on the heads. the studs have a 0.772 base thread length and the time serts come in lengths of 0.600 or 0.870 ...so not sure if i should go short or long.

« **Reply #3 on:** June 05, 2012, 11:57:55 PM »

Quote from: Brad @ SCJB on June 05, 2012, 11:46:04 PM

cool. i just need to measure my hole depth on the heads. the studs have a 0.772 base thread length and the time serts come in lengths of 0.600 or 0.870 ...so not sure if i should go short or long.

IMHO the long ones are less than .1" which looks like 1/10". I would imagine there is a wee bit more than that under the end of the studs...But at the same time I am a measure three times then have someone else cut it kind of guy.

GT

« **Reply #4 on:** June 06, 2012, 01:18:18 AM »

Quote from: Brad @ SCJB on June 05, 2012, 11:07:29 PM

I've been having problems with rocker studs ripping out of my aluminum heads. Back at the race in Long Beach of '09, it happened and Pat repaired the 2 studs with a time sert. it happened again recently and i did a quick fix using a helicoil.

I want to time sert all 16 studs. Should I do it with regular steel inserts or should I spend the extra $$ for stainless?

Keep in mind that getting the insert at the proper angle is very critical. The guy I have used for that type of repair in the past sets the head up at the proper angle in the mill.

« **Reply #5 on:** June 06, 2012, 06:52:04 AM »

« **Reply #6 on:** June 06, 2012, 06:54:21 AM »

just a side note (i know hes reading this lol) big thanks to Jim Rich for helpin me out with this one stud by putting a helicoil in there to get me by the weekend of the avi trip last month. Jim, I am pullin the heads off this week and will be sending you the loaner rocker and pushrod this week. thanks again.

« **Reply #7 on:** June 06, 2012, 07:38:05 AM »

I had a similar issue w/ the bb in my car but it was because I somehow had bought some arp studs that were metric instead of standard an pulled 3 out at the fontana drags. I pulled the heads and dropped em off had every threaded hole taken care of and I went longer on the inserts, but the machine shop trimmed em down after they were installed.

Edit:
I went steel, couldn't see spending the extra on stainless, like said above their pretty much sealed in the engine and hopefully getting oil.

Fat fingered from the phone- Corey

« **Reply #8 on:** June 06, 2012, 10:31:30 AM »

Is that an exhaust stud boss? TFS has a new stud that is to be used and which has an incredible 1.300" length at the coarse-thread end. The common studs were designed back in the iron head days and now they are being applied to softer aluminum/hot exhaust/big spring pressures/severe duty marine racing application.

A timesert/helicoil repair to the same thread depth will solve nothing if you don't switch to the newer stud which spreads the load over many more threads. Attached is a picture I took the last time I was at Lem's. Get these studs.

« **Reply #9 on:** June 06, 2012, 10:48:19 AM »

$85 a side....sheesh

« **Reply #10 on:** June 06, 2012, 12:21:19 PM »

Quote from: Brad @ SCJB on June 06, 2012, 10:48:19 AM

$85 a side....sheesh

How much did you pay Jim?

Sounds like $85 per side would be money well spent.

« **Reply #11 on:** June 06, 2012, 12:36:35 PM »

Quote from: GT Jets on June 05, 2012, 11:38:31 PM

I say steel, stainless is not any stronger (quite the opposite) and their in an oily environment, corrosion wont be a factor IMHO

Never had really good luck with stainless in aluminum anyways... $:-\$

Is there something funky about your rocker geometry? Has the pushrod length been verified and reverified?

A threaded stud should not come out/loose if it were torqued and locked properly, the boss should break out first.

im ot as smart as some of these guys but i do use steel versus stainless metals alot and may disagree it depends on the grade of stainless and steel for strength cuz most the time stainless is harder on bits n to machine than most steels so stainless might be stronger in ur case just my opinion hope it helps

« **Reply #12 on:** June 06, 2012, 02:01:00 PM »

Quote from: 80mphpls on June 06, 2012, 12:36:35 PM

im ot as smart as some of these guys but i do use steel versus stainless metals alot and may disagree it depends on the grade of stainless and steel for strength cuz most the time stainless is harder on bits n to machine than most steels so stainless might be stronger in ur case just my opinion hope it helps

I can personally guarantee the stainless steel is NOT stronger...Gotta get some toilet reading for ya.

The ONLY time stainless will be considered stronger than steel is if the fastener in question is installed in an extremely corrosive environment. The only reason I say stronger is because the steel bolt will rust through making it weak.

Quote from: LakesOnly on June 06, 2012, 10:31:30 AM

Is that an exhaust stud boss? TFS has a new stud that is to be used and which has an incredible 1.300" length at the coarse-thread end. The common studs were designed back in the iron head days and now they are being applied to softer aluminum/hot exhaust/big spring pressures/severe duty marine racing application.

A timesert/helicoil repair to the same thread depth will solve nothing if you don't switch to the newer stud which spreads the load over many more threads. Attached is a picture I took the last time I was at Lem's. Get these studs.

I knew there had to be a reasonable explanation.

So Lakes, how would one go about fixing the pulled holes? Is there a 1" long Time Cert? $:-\$

GT

« **Reply #13 on:** June 06, 2012, 02:34:58 PM »

And do the stud bosses need to be drilled deeper for those studs? Would be my next question. Obviously, that is the solution though! I'm assuming this is only for TFS heads? My Edelbrocks came factory with certs in the bosses and I have no idea how long the exhaust rocker studs are, but have never heard of this happening on them. Of course, I never heard of it on TFS heads either......until Brad........

And yes, carbon steels are always much stronger than anything stainless. I have several handguns manufactured in 17-4ph SS such as my Freedom Arms and my Seville (Same material we make water cooled molds and particularly mold manifolds from, no better stainless material out there short of what NASA can get) and I can prove instantly their blued steel counterparts are stronger. They' re just not corrosion resistant, is all. I like mine because they clean easily ( I been known to disassemble them and clean them in the dishwasher) and look pretty. But certainly not stronger.

Ray

« **Reply #14 on:** June 06, 2012, 05:17:22 PM »

Time serts are available in different lengths.....although you may not need to go to the longer studs/time serts.

your 7/16-14 studs have about 7 threads engaged right now. I'm going to use a diameter in the middle of the major and minor diameter for this exercise...because I think that's closest to being relevant. 7/16 is 0.435" or so, while the drill size for 60% thread engagement in a 7/16-14 thread is about 0.381" ... so lets use an effective diameter of .409". The circumfrence of a circle of .409" in diameter is about 1.28", times 7 threads engaged is 8.99 inches of thread length engagement. (if you could uncoil that piece of aluminum stuck to your stud, it would be that long)

If we go to an insert...the tap has a major diameter of .534", the drill is a 29/64"....and we'll use .495" for the effective diameter of this thread....it will have a circumfrence of about 1.55".

This size insert is available in a .400, .600, .870, 1.000, etc...length if we use a .600 insert (at 14TPI), we'll have 8.4 threads engaged, which results in about 13" of total thread engagement in the aluminum. That's 30% stronger...which will probably be just fine....I wouldn't be at all concerned with the 7 threads engaged in the insert by the stud, that'll be just fine too.

If you want a little more security, and you've got the meat in the casting, you can use a BIG SERT...which has a major diameter of .634", and earns you almost 16" of linear thread engagement....almost double what you had in the beginning.

This probably isn't the exact right way to calculate thread strength, but I bet I'm close. Glenn will be by shortly to straighten me out I'm sure

.

Oh, and stainless is pointless in an application that is not gonna rust anyway.

« **Reply #15 on:** June 06, 2012, 07:00:24 PM »

Quote from: lbhsbz on June 06, 2012, 05:17:22 PM

Time serts are available in different lengths.....although you may not need to go to the longer studs/time serts.

your 7/16-14 studs have about 7 threads engaged right now. I'm going to use a diameter in the middle of the major and minor diameter for this exercise...because I think that's closest to being relevant. 7/16 is 0.435" or so, while the drill size for 60% thread engagement in a 7/16-14 thread is about 0.381" ... so lets use an effective diameter of .409". The circumfrence of a circle of .409" in diameter is about 1.28", times 7 threads engaged is 8.99 inches of thread length engagement. (if you could uncoil that piece of aluminum stuck to your stud, it would be that long)

If we go to an insert...the tap has a major diameter of .534", the drill is a 29/64"....and we'll use .495" for the effective diameter of this thread....it will have a circumfrence of about 1.55".

This size insert is available in a .400, .600, .870, 1.000, etc...length if we use a .600 insert (at 14TPI), we'll have 8.4 threads engaged, which results in about 13" of total thread engagement in the aluminum. That's 30% stronger...which will probably be just fine....I wouldn't be at all concerned with the 7 threads engaged in the insert by the stud, that'll be just fine too.

If you want a little more security, and you've got the meat in the casting, you can use a BIG SERT...which has a major diameter of .634", and earns you almost 16" of linear thread engagement....almost double what you had in the beginning.

This probably isn't the exact right way to calculate thread strength, but I bet I'm close. Glenn will be by shortly to straighten me out I'm sure .

Oh, and stainless is pointless in an application that is not gonna rust anyway.

I think the amount of material in the boss would be th deciding factor..

Originally wrote "meat in the boss"

and couldn't let that fly as was, but still cracked me up enough to have to put it in writing.

I would think the longer studs would be the ticket, just not sure how one would repair the pulled holes.

I don't like the idea of the big certs....Not enough metal left to give that warm and fuzzy feeling...Or like the old man says, warm and slippery.

If it were mine, I would go with the longest time cert and the original studs. Then I would install the longer studs in the good holes.

Maybe I'm over thinking things... I do that sometimes.

Also lbhsbz, temperature fluctuations would freak me out the most, the aluminum is going to grow/shrink several times more than the steel. especially on the exhaust side of things. $:-\$

« **Reply #16 on:** June 06, 2012, 07:12:58 PM »

And where the hell is Ralph in all of this??

I thought he would have weighed in already. What's this world coming to? $:-\$

« **Reply #17 on:** June 06, 2012, 07:18:25 PM »

i dont know shit about this metalurgy you guys are talking about

but, what i do know is that these heads were purchased from the same lem evans that paul speaks of.. if it was me i would be calling lem and telling him whats going on and the best way to fix it....

to go one further, these heads should have a full check up since it has never been done, including spring check.. now if it was me, while i had lem evans on the phone i would ask for charlie evans phone # so i could ship the heads to him for all the proper and necessary repairs... yes it will cost a few bucks but the heads will be 100%
http://www.evansracingengines.com/

my .02

« **Reply #18 on:** June 06, 2012, 07:30:01 PM »

Quote from: Ralph Brunt on June 06, 2012, 07:18:25 PM

i dont know shit about this metalurgy you guys are talking about but, what i do know is that these heads were purchased from the same lem evans that paul speaks of.. if it was me i would be calling lem and telling him whats going on and the best way to fix it....

to go one further, these heads should have a full check up since it has never been done, including spring check.. now if it was me, while i had lem evans on the phone i would ask for charlie evans phone # so i could ship the heads to him for all the proper and necessary repairs... yes it will cost a few bucks but the heads will be 100%
http://www.evansracingengines.com/

my .02

See what I mean...Good chit right there. Can't argue with any of it.

Hi Ralph!

« **Reply #19 on:** June 06, 2012, 07:35:37 PM »

hi glenn

on a side note, before you tear it down do a compression and leak down test, the motor is talking to you, let it finish the sentance......

« **Reply #20 on:** June 06, 2012, 08:03:19 PM »

Easy fix put a cheby in it

« **Reply #21 on:** June 06, 2012, 08:25:50 PM »

Quote from: Just Electric on June 06, 2012, 08:03:19 PM

Easy fix put a cheby in it

But Brad never does it the easy way.

« **Reply #22 on:** June 07, 2012, 08:36:56 AM »

Quote from: Brad @ SCJB on June 06, 2012, 10:48:19 AM

$85 a side....sheesh

Not $85 per side but $85 for 8 exhaust studs, install 4 per side, 1 per exhaust stud boss. The intake studs should be fine.

Quote from: GT Jets on June 06, 2012, 02:01:00 PM

I knew there had to be a reasonable explanation.

So Lakes, how would one go about fixing the pulled holes? Is there a 1" long Time Cert? $:-\$

GT

I have not personally seen this problem with the A460 heads but it seems to be asscoiated with the exhaust stud boss only, and only with very high compression engines, or with nitrous, or blowers, etc, where the exhaust area gets very hot and the valve must open against extreme exhaust pressures (which loads the exhaust valve train/rocker stud). The older A460 head versions don't even have a threaded hole deep enough to accomodate these new 1.300" base studs. The new A460 heads do have the proper length exhaust stud boss threaded hole and the new studs with the 1.300" base thread need to be added to heads used in the higher performance applications.

I don't know if Timeserts are available in a 1.25" depth or not. But I do know the thread of a stud that pulled out can be repaired with a Helicoil oriented in such a way that screwing in the long-base stud will thread past the repair and extend into the original thread farther down. Or, two Helicoils can be stacked one atop the other. But if a short-base stud is reinstalled after any repair then the additional threads are not taken advantage of and the same failure can happen.

Paul

« **Reply #23 on:** June 07, 2012, 08:53:08 AM »

Quote from: Just Electric on June 06, 2012, 08:03:19 PM

Easy fix put a cheby in it

My honest-to-God serious reply is that "putting a cheby in it" would result in Brad finishing in lesser positions than he would while running the Ford. This seems to be the case all over the world where the two engine platforms compete on a level playing field....UNTIL (and as racing history has almost always shown us) the Ford is either outlawed by the sanctioning body or the rules are changed to penalize the Ford (in effect) and give the BBC the advantage.

I will confess that I do chuckle when engines we build are protested by the chevy guys, and the Techs are scouring the Ford build for hidden nitrous, etc.

And in some events it's not uncommon to see this exact scenario while the Ford is still using factory iron heads & block and the chevy guys have aluminum heads (actually, little on the competitors' BBC is truly a BBC component at all but is actually aftermarket).

So there's my reply to the above quote; if you want to further this specific topic then let's not hijack Brad's thread. Just start a Ford vs cheby thread and I'll be happy to participate.

LO

« **Reply #24 on:** June 23, 2012, 01:51:31 PM »

Quote from: GT Jets on June 06, 2012, 02:01:00 PM

I can personally guarantee the stainless steel is NOT stronger...Gotta get some toilet reading for ya.

The ONLY time stainless will be considered stronger than steel is if the fastener in question is installed in an extremely corrosive environment. The only reason I say stronger is because the steel bolt will rust through making it weak.

I knew there had to be a reasonable explanation.

So Lakes, how would one go about fixing the pulled holes? Is there a 1" long Time Cert? $:-\$

GT

ok i did alot of reading on this and ur rt steel is stronger because it will give a lil under strain from being a softer metal where as the stainless is a harder metal and under strain may snap or break i mistaked hard for strong hey u learn something every day i make tattoo machine with this stuff not engine parts

Brad @ SCJB

GT Jets

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