Heys guys, I bought the FEL-PRO ES 72856 head bolt set not realizing that they were TTY bolts when doing my head gaskets, I chased the threads out on the block, cleaned the sealer on the bolt off and used my own thread sealer and they threaded in with 0 resistance and torqued just fine, I did increments of 25, 45 and 65 ft-lbs for every bolt in the correct sequence. Will these work fine as I have them or do I need to change them out since they're the "wrong" type of bolt. I would hate to have to do this job again solely because I was an idiot and didn't look when buying..

 

It looks like you are fine using them in place of the older style bolts, per the document above.

 

You will want to check and ensure that you actually performed the torque to yield procedure when you install them. They need to be torqued to a certain spec, usually between 50 and 70 ft/lbs, then tightened an additional number of degrees, usually between 90 and 180. If you don't do that final step, the bolts can stretch and induce a head gasket leak.

 

When did you realize it? How did you realize it? Who made you realize it? Why did you realize it? To what extent did you realize it?

Step 1: determine if the shank is equal to, or smaller than the thread minor diameter. If not, it is impossible for thek to actually be torque-to-yield bolts.

You mixed that last part in, but it does not apply.

Rotational directions are not a torque to yield bolt procedure. It's just an updated way of applying a certain measurement of force, equally across a fastened surface.

A 3/8-24 bolt turned 360 degrees is going to attempt to load the bolt head against the surface by pulling the bolt 1/24" longer, in This is a measured tension in addition to the initial torque. Torquing things to a lb-ft value can vary by lubricants, so the angles work more consistently.

Going in a pattern and easing up in steps helps spread the load evenly.

Actual TTY bolts are stretched an amount past plasticity and do not return to the original length. THAT individual reason for "one time use" is not the ONLY reason for suggested one time use.

Measure your boots before. Install them correctly. You probably won't need to measure them for years. But if you do, you'll be able to make an informed decision on whether a bolt failure was involved, and whether they are re-usable. Head bolts are just a "new makes sense" thing. Not a mandated replacement on many engines.

 

According to FEL-PRO themselves, the ES line of head bolts are designed to be TTY. For what it's worth, using the regular torque spec and using TTY seem like two different ways of achiving the same end result with the fastener if I'm understanding correctly except TTY is just more accurate since if you use regular torque spec your subjected to more variables affecting the end result like the health of the threads and whether or not they're dirty, or if you use lubricants.

So in theory if you have clean/good threads eliminating those as variables, the regular torque spec and TTY would theoretically have the same result regardless of the intended design use of the fastener?

I've been driving the car for the past few days, no blowout yet and I'm at 10:1 compression.

 

Use the TTY values. I tried using the standard torque values on a set years ago and one broke requiring head removal, a new head gasket and a new set of bolts. The bolt went from righty tighty to righty loosey. It was before knew that style bolt was TTY and 1 time use.

Remember the SBC has continued to be built by GM far beyond any production vehicle road use that ended in about 2008-2009 for the L31 350 and at some point GM updated the head bolts to be actual TTY units. That FACT is in both the Mercruiser and Industrial engine service manuals written by GM and pertains to GM/Mahle/Felpro OE replacement head bolts being made today for the SBC.

 

Used bolt in the center was out of a ~2017 GM built Mercruiser I pulled apart a few years ago that was freezed cracked. I robbed the HT383 spec rotating assembly out of it. Since the block was junk anyway, I put the head back on it, with the used head gasket and start torquing the used bolts just to see what would happen.. I did one bank TTY and the other to the older specified torque value. The TTY side all tightened up but some became spongey feeling. The 3 step torqued side had 3 or 4 of the shorter bolts and 1 mid length break clean off before they reached the specified torque. My L31 I built recently has a new set of those bolts and even tightening them to the TTY spec was a feeling I do not enjoy. It is not a natural feeling when the bolts stretch and seemingly feel like they are losing torque when you are tightening them. I have run the absolute snot out of that engine for the last year and half or so and no issues so far with an unmilled block, unmilled heads and Felpro 1094R head gaskets.

 

Well it's been a couple of days, I did another coolant compression gas test and it failed, I'm assuming due to the fact that I had to remove and retorque the bolts when I reapplied the thread sealer the clamping force was compromised. Either way everything is coming apart again and I'm going to track the source of the failure before it goes back together. This time I'm going ARP bolts with fel pro gaskets

might be a good idea for me to mag check the block too, ill let you guys know what i find

 

After tearing down the heads I found that all of the head bolts were loose, the short ones took next to no effort with a breaker bar to loosen, I feel like that was causing the issues I was experiencing. Not even sure how the engine was running, looking at the head gasket there's no obvious blowout that I can see, I put a straightedge on the block and the heads, both were perfect. I'm having my machine shop pressure test the heads before I put them back on.