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Tech / General EngineIs your car making a strange sound or won't start? Thinking of adding power with a new combination? Need other technical information or engine specific advice? Don't see another board for your problem? Post it here!
7-16-14 thread, right?
Your pic shows nearly 1 thread worth of stretch (.071'), so about .060".
That's thicker than the head gasket itself, maybe even two of them.
I will pay for ARP after seeing this.
7-16-14 thread, right?
Your pic shows nearly 1 thread worth of stretch (.071'), so about .060".
That's thicker than the head gasket itself, maybe even two of them.
I will pay for ARP after seeing this.
7/16-14 is correct. OEM Gasket is ~0.027-0.028" compressed in the TBI 350, L31 350 and B-car LT1.
You can feel the bolts stretching on the way to X degrees. I Never have liked the TTY feel of putting the correct twist on a TTY bolt. Feels like the head going to spin off at any moment and a few have yeilded before getting there. I had a brand new GM LS head bolt completely yeild before spec.
I am putting ARP studs in my 383 now. The Jegs bolts in it had multiple bolts break. I will not be torquing to 80 ft/lbs though. I am going off their old instruction sheet from the same studs that show 65 ft/lbs. Friend of mine showed me a LT1 block sitting in the floor of his shop that had ARP studs torqued at 80 ft/lbs for 2-3 years. It had nickel to quarter sized stress rises in the deck surface around every stud. This was a NA 12:1 383. A stud pulled on that engine and the block needs to be decked if it is even re-useable. I wish I had taken a picture. At this point, I would throw that block out and find another if it were me. I looked around on various boards and 80 ft/lbs on a stock block is well beyond what the block deck can withstand. To add insult to injry that LT1 also had visible signs of combustion gases getting past the rings up top. It was torque plate honed with bolts at 65 ft/lbs, then assembled with studs at 80 ft/lbs. The block distortion then caused poor ring seal.
Torquing like normal is fine for a lot of things but TTY is used when you want to make damn sure the bolt doesn't come loose.
When was the last time you saw a 5/8" head, head bolt come loose on a SBC? I have had 30+ year old engines and the head bolts and gaskets were not the reason they had to be torn down. GM used those things for close to 40 years without problems then decided to use something new.
Come to think of it, ALL the blown head gaskets I have seen on SBC engines used this type of bolt. Extremely common for them to blow between 3&5 and 4&6 on engines with these bolts and factory MLS composite gaskets. Later TBIs, Vortecs and LT1s all blow gaskets there if even remotely close to overheated. TTY bolts are likely stretching at the hot spot created by the siamesed center exhaust ports.
The head gaskets in my 83 305 failed because they literally rusted away. The coolant ports rotted away completely into the combustion chamber. The 305 had 0.020" compressed steel shims.
You're basing your assumption off of 1 bolt that's longer than a couple of others???
Are they from the same manufacturer? Were they made on the same day? There's a ton of variables here.
For that one bolt you'd got pictured to stretch that much, the shank or the threads would be severely distorted, which by looking at the pic, they're not...
I don't know why you keep beating this drum.
The paperwork from GM says they're NOT TTY.
If you over-torque any bolt, it's going to stretch.
I've got some TTY LS headbolts, new and used, out in the shop and I can torque the new ones and I'll guarantee they don't stretch that much. Something else is going on here and it's not because the bolt stretched that much from being torqued to spec.
Here's straight from the The AERA Technical Committee in black and white...
The AERA Technical Committee offers the following information on cylinder head installation for 1996-99 GM 5.7L VIN R engines. This information is somewhat different than previous engines. GM is now recommending a torque turn method of tightening the cylinder head for this engine.
It does not however, use a torque-to-yield bolt to mount the cylinder heads.
The cylinder head mounting bolts may be reused if they are not damaged in the threads or show neck-down or stretch condition. The bolts should be thoroughly cleaned of sealer before inspection and installation. Cleaned bolts should have a coating of GM sealing compound Part #1052080 applied to the threaded area only. The use of an aftermarket equivalent sealing compound is also acceptable to use on threads.
Follow the steps listed below to correctly install head gaskets for this engine being careful not to get any seal on the head gasket mating surfaces or gasket.
1. Place the head gasket over dowels with the bead up.
2. Carefully guide the cylinder head into position over the dowel pins and
gasket.
3. Coat threads of the head bolts with sealing compound and finger tighten all
bolts.
4. Tighten all bolts in sequence to 22 ft. lbs.
5. Tighten all bolts in sequence an additional turn in degrees, using J 36660 tool.
Short Bolts (3,4,7,8,11,12,15,16) Additional 55° Turn
Medium Bolts (14,17) Additional 65° Turn
Long Bolts (1,2,3,5,6,9,10,13 Additional 75° Turn
The AERA Technical Committee
Last edited by Bills87IROC; 12-18-2022 at 01:57 AM.
It was EVERY bolt that had similar stretch. The long ones were stretched even more. Same GM bolts, obviously made different days. They are even stamped 10.9 TY on the face of them. Regardless of that info, seeing and feeling the bolt stretch when torqued, I am going to throw the bolts away and get new ones every time.
As I have also said its well known that these are torque to yeild in the LT1 community. They even have the narrowed down, stretch section that is an absolute give away for a TTY bolt.
It was EVERY bolt that had similar stretch. The long ones were stretched even more. Same GM bolts, obviously made different days. They are even stamped 10.9 TY on the face of them. Regardless of that info, seeing and feeling the bolt stretch when torqued, I am going to throw the bolts away and get new ones every time.
As I have also said its well known that these are torque to yeild in the LT1 community. They even have the narrowed down, stretch section that is an absolute give away for a TTY bolt.
The only thing "known" is that there's an updated torque sequence and that's where the confusion comes from.
Even Felpro has a whole page dedicated to this subject. People see a Torque To Angle spec and "assume" the bolts are Torque To Yield.
If every one of those bolts was actually stretched, the shanks or the threads would be severely distorted. The extra length has to come from somewhere...
If there's no measurable distortion, they didn't stretch that much.
Also I will take a different picture tomorrow, with more bolts. The bolts are stretched in the yeild zone of the bolt. The used bolts are ALL stretched between the areas I highlighted in red.
The only thing "known" is that there's an updated torque sequence and that's where the confusion comes from.
Even Felpro has a whole page dedicated to this subject. People see a Torque To Angle spec and "assume" the bolts are Torque To Yield.
If every one of those bolts was actually stretched, the shanks or the threads would be severely distorted. The extra length has to come from somewhere...
If there's no measurable distortion, they didn't stretch that much.
Felpro and the major auto parts places have the Vortec bolts listed as one time use throw away as well. That is where I first learned about it.
They "recommend" that for warranty purposes on their head gaskets.
If some shade tree reuses head bolts that actually are stretched and then the head gasket blows, you know what that guy is going to blame and its not the fact that he reused defective bolts.
If the engineers say they're NOT torque to yield and that they're merely torque to angle, then I'll take it as gospel.
Also I will take a different picture tomorrow, with more bolts. The bolts are stretched in the yeild zone of the bolt. The used bolts are ALL stretched between the areas I highlighted in red.
What you need to do is actually mic the shanks and see if they're actually distorted. Even then, that doesn't mean they're torque to yield.
That just means they've been stretched beyond their elastic limit. That could have been due to overheating, over torqueing, etc.
Torque turns is used for joints that don't consistently come together or friction varies a lot. It's a process improvement over a simple torque spec. The initial torque is just enough to bring all the parts together. And then the clamping force is achieved by turn angle. Good technique when dealing with rusty old parts, or sloppy fit parts like the strut mounts. But usually there's an accompanying torque spec for CYA (cover your ***).
Torque to yield has to have clean threads with consistent friction because you actually torque the bolt first and then go past that into yield but not too far.
You can pretty much guess what kind of bolt it is by the torque procedure.
You can pretty much guess what kind of bolt it is by the torque procedure.
This is where the confusion comes from. People assume bolts are TTY when they're actually TTA like the Felpro and Engine Builder articles state.
And yes, the TTA method is a much better way of ensuring proper torque. It's also easier for manufacturing when assembly is automated. A robot can be programmed with a TTA sequence far easier than using some sort of automated torque wrench, if there even is a thing.
This is where the confusion comes from. People assume bolts are TTY when they're actually TTA like the Felpro and Engine Builder articles state.
And yes, the TTA method is a much better way of ensuring proper torque. It's also easier for manufacturing when assembly is automated. A robot can be programmed with a TTA sequence far easier than using some sort of automated torque wrench, if there even is a thing.
Except they are TTY not merely TTA. Its even in the L31 Marine Manual I have to throw the bolts away. Head Bolts, Main Cap Bolts and Connecting Rod Nuts are all throw away. I want to say the oil pump bolt and camshaft sprocket bolts are also single use per the manual. The Marine L31 engines were built to 1999 specs except for the cam and intake.
Except they are TTY not merely TTA. Its even in the L31 Marine Manual I have to throw the bolts away. Head Bolts, Main Cap Bolts and Connecting Rod Nuts are all throw away. I want to say the oil pump bolt and camshaft sprocket bolts are also single use per the manual. The Marine L31 engines were built to 1999 specs except for the cam and intake.
Except they're not, lol
I don't know what part of the AERA Technical Committee's statement you don't understand...
Now you're trying to say the Main bolts are TTY???
here is my uneducated 2 cents... any time you are torqueing a bolt to a certain value and then an additional number of degrees, i was thinking that was basically to add a certain amount of stretch to the bolt. x degrees of rotation on a certain pitch thread = y amount of stretch.
all bolts are designed to be torqued to a certain amount of allowable stretch, but not necessarily as a one time use type deal. stretch is essentially what keeps the bolt tight under varying conditions, kinda like a bungee cord. bolts in the pics above have the same coating and look as the LS tty bolts, and i would assume that is what they are... come to think of it, op said the bolt heads showed 10.9..... are the vortec blocks tapped in metric?
It was EVERY bolt that had similar stretch. The long ones were stretched even more. Same GM bolts, obviously made different days. They are even stamped 10.9 TY on the face of them. .
Also in regard to Cylinder Head Gaskets... 3 things needed to be changed for the Gen-III SBC (for better gasket sealing/ longevity).
1. Coolant Port locations needed to be relocated.
2. Fastener locations needed to be relocated.
3. Gasket material needed to be changed to MLS.
Gen-III/ IV seem to have far better results in regard to Coolant related gasket failure...
But the Fire-Ring failures seem to be a toss-up on a Gen-I with newer aftermarket MLS gaskets vs Gen-III/ IV.
.... that LT1 also had visible signs of combustion gases getting past the rings up top. It was torque plate honed with bolts at 65 ft/lbs, then assembled with studs at 80 ft/lbs. The block distortion then caused poor ring seal.
Yep, that's a no-no. You can't switch fastener type once the cylinders are honed.
Yep, that's a no-no. You can't switch fastener type once the cylinders are honed.
I ended up having too. Torqued the studs to 65 ft/lbs. I have seen guys do it for years on LT and LS engines. I have even seen rod bolts get changed in LS engines without machine work. If the crank spins it goes down the track, lol.
So you going to switch to studs so we can all reboot the argument and I can make another half worthless post with master of the obvious stuff about studs?
There are tons of Engines assembled using less than ideal practices.
Such as the Posts above mentioned...
Replacing the Stock Connecting Rod Bolts with ARP 8740/ ARP 2000 Bolts, which install with a higher Torque-Specification (greater clamping forces) and not resizing/ reshaping.
Sometimes the distortional changes do not impact the operation of Rotating Assembly at lighter loads...
And sometimes it does!
You run the risk of not being successful.
Sometimes the variable tolerances will lean in your (ill-assembled) favor...
Sometimes NOT.
Proper Assembly practices will push the percentages of success further and further in your favor...
Nearly an actual guaranty of success.
So you going to switch to studs so we can all reboot the argument and I can make another half worthless post with master of the obvious stuff about studs?
You tell me...They are installed. Felpro 1003s under the heads.
I also refused to use ARPs newer revised 80 ft/lbs spec. Same studs once had a sane 65 ft/lb spec, so I used that. For some reason they decided they wanted more yeild on the same studs at some point and are destroying perfectly good threads and deck surfaces on OEM blocks. Somewhere around that time period they also decided to ignore the added expansion of aluminum and use the same torque value for all cylinder head materials, further adding to stress on the OEM block.
Before now I thought I did okay. Now the more I learn I'm thinking I'm lucky my engine runs at all after I touched it.
Haha same. ICEs especially performance ones have always been one step removed from a live grenade with the pin pulled anyway.
Jets won out over reciprocating prop driven planes because of more thrust to weight, less complexity, more hours between overhauls, etc. Those big high powered radials loved to grenade.
i have never seen a standard bolt marked as 8.8 or 10.9.
Well the GM Vortec head bolts I have a small bucket near full of, nearly all are. I have been into dozens of these engines and throw the bolts away on every one I pull the heads off. I will take them with some other scrap some day before long.
But the Fire-Ring failures seem to be a toss-up on a Gen-I with newer aftermarket MLS gaskets vs Gen-III/ IV.
it was my understanding the gen 1 had a pretty good leg up over the gen 3 stuff as far as fire ring failures. simply due to having more bolts per cylinder on the gen 1.
I thought all the ISO stuff was metric too but I see there is an ISO standard for inch threads. I don't know what it says though.
gm probably had the same foreign factory that was popping out the LS bolts start making the late model gen 1 head bolts as well. Maybe both bolts share a common core and they made them with whichever thread was needed. (totally a guess, but would explain why the standard bolts are stamped with the 10.9)
I have no idea what is the situation with the Bolts that you came across, but...
There are Bolts that have Metric Threads (Example: 8mm x 1.25), but use a SAE dimension Head (Example: 1/2" or 3/4" Socket)...
These sometimes are marked with the Hardened-Fastener Nomenclature for Conventional Metric Bolts (Example: 8.8 or 10.9).
I have no idea what is the situation with the Bolts that you came across, but...
There are Bolts that have Metric Threads (Example: 8mm x 1.25), but use a SAE dimension Head (Example: 1/2" or 3/4" Socket)...
These sometimes are marked with the Hardened-Fastener Nomenclature for Conventional Metric Bolts (Example: 8.8 or 10.9).
They are late model GM bolts. I say late model but think 2004-2022ish Hecho En Mexico crate engines and GM Performance parts as well as marine engines. Normal SAE thread, 1/2" head and marked 10.9 TY.
I wish I had a picture of the main cap bolts out of one of these later engines as well. They are not even close to the same design as the older bolts. Where the old bolts have a shank that is essentially the same diameter as the threaded portion, these are necked down at the shank right above the threads and then go up to centering dowls under the bolt head and look similar to LS main cap bolts. They have started using the torque angle specification on them as well. I have not attempted to dig out the service manual information, but the cylinder head and main cap removal procedure stated to throw away the bolts. I think it was a ~2010 Mercruiser manual with information written by GM. Late Model 350 as GM is building the current crate engines.
They are late model GM bolts. I say late model but think Hecho En Mexico crate engines and GM Performance parts. Normal SAE thread, 1/2" head and marked 10.9 TY.
I dunno, this whole engine is strangely configured. I bought it as a complete pull-out from a big block repower. Flame arrestor to oil pan, water pump to flywheel. It has a MEFI controller that looks like an E40 PCM, flat response LS3 style knock sensors mounted on studs in the block drains, a 4 bolt drive by wire throttle body on the L31 marine intake, and marine exhaust manifolds with integral water jacketed catalytic converters and 4 oxygen sensors. This engine only had about 150 hours on it. I gave $1200 for it complete with 8" long freeze cracks on both sides of the block. It is a 6.3L, 383 CID, 4.00" bore with a 3.80 stroke (basically a Marine HT383) and a GM 395' marine camshaft. Hecho en Mexico block and 062 Mexican heads. I am going to use the rotating assembly and the intake setup in the clean standard bore 350 block that came out of my Express van to install in my 1980 Camaro. I will probably convert it to a P01 or P59 PCM. At $1,200 I will easily be able to recover most of that selling off the good marine specific parts. Even used many of those Mercruiser bits bring a big chunk of change. The HT383 forged 3.80" stroke crankshaft alone cost more from GM than I bought the whole engine for. I noticed GM seems to be able to put the HT383s together with ZERO clearance grinding to the block. Will soon find out if the rotating assembly drops into my L31 block the same way. Both are 880 castings. With 150 hours on it, I will probably re-use just about everything internally from that engine, minus the throw away stuff. Crank, Rods, Pistons, Oil Pump, Timing set, Lifters, all should be good to go. I heard the engine run before it came out of the boat even. Smooth, no weird mechanical noises, good oil pressure, etc. This engine does have all kinds of extra good stuff on it. 5qt oil pan, extended length windage tray, alternator, water pumps, power steering pump, full serpentine setup and a high pressure fuel pump module that is supplied from a mechanical pump. If I can figure out a way to use the fuel module it will make the Camaro EFI conversion a lot easier not having to route a return line to the tank.
ARP, Manley, Jegs and the old large head GM factory SBC Head bolts(pre-vortec, some I have from the 70's) all have that skinny neck down part before the threads. If you need pictures, I'll take them but you can look on ARP's website, Summit or Goolge to see it.
I just found the email on FEL-PRO ES 72856 and for good measure, I've asked again to see if I get the same answer. This was a response from the FEL-PRO website form. And if you notice the Fel-Pro set has the grey/silver outer bolts with 10.9 TY on the heads. I have two boxes(a set) right here. Now I don't know who makes GM head bolts these days but often the same suppliers parts has many names on their boxes.
ARP, Manley, Jegs and the old large head GM factory SBC Head bolts(pre-vortec, some I have from the 70's) all have that skinny neck down part before the threads. If you need pictures, I'll take them but you can look on ARP's website, Summit or Goolge to see it.
I just found the email on FEL-PRO ES 72856 and for good measure, I've asked again to see if I get the same answer. This was a response from the FEL-PRO website form. And if you notice the Fel-Pro set has the grey/silver outer bolts with 10.9 TY on the heads. I have two boxes(a set) right here. Now I don't know who makes GM head bolts these days but often the same suppliers parts has many names on their boxes.
If they are made by the same supplier as GM, they are TTY PERIOD END of STORY. Even Vortec Iroc who worked for GM and would be in the know said they were too.
I have reused rings, rod bearings and hard faced flat tappet lifters in other engine blocks and gotten away with it when I was flat broke and needed to get a vehicle moving again. Does not mean it was the right thing to do.
I have those bolts fail using the TTY method before reaching the specified angle NEW.
12-17-2022, 03:05 PM
