stlbluesbrother

During disassembly of a 455 engine, 2 head bolts (ARP) broke. The previous builder torqued them down 12 yrs ago. Fortunately, I was able to back out the bottom ends without issue.

Should I replace all head bolts or would it be OK just to buy/find 2 replacements that can handle the same psi?

Thanks

380 Racer

Replace 'em all.

Run to Rund

It is very unusual to break ARP bolts unless they were torqued to the yield point. I agree, replace all of them.

gearheads78

Never seen ARP's break.

Like they said trash them all.

Rickman48

X 10 - do them all, and send the remnants to ARP with the question 'what went wrong??'
Might get $$back.
Never heard either of one breaking!!

dkiel358

I agree don't want to take any chances considering they are cheap in the big picture

stlbluesbrother

Thanks guys.

By the way, would a proper replacement be ARP 180-3601? Titan Motorsports is selling them for $81.69 on ebay.

ah64pilot

ARP bolts for an Olds motor should be 180-3700

Also, ARP bolts are torque to yield bolts...they are a one time use design. They are designed to "stretch" when torqued to provide better clamping pressure. I would always replace the bolts. The only ones you can reuse are the stock accessory bracket bolts that have a stud on the end.

gearheads78

Since when? I have always reused them and every engine builder I know does too.

Run to Rund

ARP gives several torque values for different steels they use and sizes, in % of yield value vs. clamp load. I have had leaks with old Fel Pro's, on the shelf too long perhaps, and now use Corteco. I have always selected decent, non-rusty used stock head bolts and have never blown a head gasket. But then, I have never gone over 10.6 to 1 either.

MDchanic

Interesting, ARP, in its instructions for 455 head studs, does not mention torque-plus-#-of-degrees torquing, OR say that they can only be used once.

- Eric

gearheads78

One of the main reasons LSx guys are using ARP head bolts is they can be reused unlike the factory bolts.

ah64pilot

Taken from ARP website:


"Three basic elements that contribute to the friction factor:

1. Most importantly - The fastener assembly lubricant
2. The condition of the receiving threads
3. The surface finish of the fastener

Because of these variables, a phenomenon known as "preload scatter" or preload error occurs. This is basically the difference between the amount of preload achieved on the first installation of the fastener and the amount of preload achieved on subsequent torque/loosen/re-torque cycles. It's not uncommon to see "preload scatter" in the range of 4,000-8,000 pounds between the first and tenth pull on a new fastener depending on the lubricant used."


I guess this is why I have always bit the bullet and bought new bolts...it's not like you replace them every couple years, you might as well put new bolts in a new build.