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?
If i get some free time tonight at work, ill play with it and post it for everyone to see.
Time to man up and yank it John! Ray
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.
In my best "grandad" voice with a cigarette hanging out of my mouth.... "if a day goes by and you learn nothing, I hope like hell you got a lot of sleep"....
$85 a side....sheesh
I say steel, stainless is not any stronger (quite the opposite) and their in an oily environment, corrosion wont be a factor IMHONever 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
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.
well holy jackpot shit WOO-HOO
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.
They are all fukin tasty. My long time favorite, "Dirty Dicks -beerjet-
Glasscutter, Skip, OC2 Nordie and many more nail me good every time, relentlessly, I love those guys!
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
Easy fix put a cheby in it
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 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