Head bolts - reuse or always use new?

[ScottH]

So here's the question, can head bolts be reused?

I'm not talking about OEM bolts that have been on engines for 30 years, but can you reuse newer head bolts that have only been installed for a short time, say head has to come off for a gasket, etc.?

Just curious cause my son says once torqued down they shouldn't be reused.

Any opinions?

Thanks

[jhow66]

According to year of engine. Most all newer engine (alum. or alum. head) have replaceable bolts.

[Tx Firefighter]

I've always reused old head bolts unless they are TTY (torque to yield) type.

MOST TTY head bolts don't just torque to a value (ex. 60 ft/lb). They usually torque to a value, then an additional amount. For example, you may torque to 60 ft/lb, then turn an additional 90 degrees.

[SSC's76]

SBC bolts are re-usable unless you can see a defect re-use them and dont worry about it. Of course if your using any sort of power adder that would increase cyl pressure new bolts are cheap insurance.

[jamis]

Tx Firefighter is right

[grayw0lf]

How would you know if the bolts are TTY type? I've never had much faith in my Chilton's manuals. The engine kits / gasket kit instructions often seem to differ on torque specs from what is the Chilton's / Haynes manuals.

[bigvinnie]

I've built a half dozen motors in my day, and always re-used the head bolts cuz I'm either too cheap or too lazy to go get new ones.... I've never had any problems. Disclaimer - your results may vary.

[SSC's76]

Originally Posted by grayw0lf

How would you know if the bolts are TTY type? I've never had much faith in my Chilton's manuals. The engine kits / gasket kit instructions often seem to differ on torque specs from what is the Chilton's / Haynes manuals.

SBC bolts are not TTY bolts. Most manulas will state whether or not your engine requires head bolt replacment. Usually if you need to use a tq angle meter and go a certian * beyond a tq spec then you have TTY bolts. A common TTY bolt engine would be a fNord 3.8L.

[Tom]

#1st thing I do to an engine is ARP head bolts. After that whenever a head comes off the head bolts are numbers from which spot they came out of and re-used.

[LONGHAIR]

I've never heard of that one Tom. I'm not saying that it's a bad thing....just seems overly fussy. There is no wear-to-match thing here, like rocker arms.

Personally I don't see the need to replace them on a mild rebuild, unless of course there is something wrong with them. I also wouldn't try to replace just one.........If one is bad replace them all. Also, if you are talking about a more performance build (especially if you use power adders like nitrous or even think you will later) I prefer studs. The weak link here is not the bolt itself, it is the threads in the block. A stud can apply more clamping force with less stress on the block. Plus you eliminate the "lubricated threads" thing on your torque values. You can put sealer on the threads of the studs and your torque is applied to the nuts, which you can lubricate....both problems solved at once.

[Fred T]

The biggest problem with head bolts is due to over-torquing. When you tighten any bolt, the bolt stretches and is hold in place by the friction against the threads due to the bolt pulling against the threads. Applying too much torque can stretch the bolt beyond it's elastic limit and it will not return to it's normal state when loosened. This becomes a problem when the bolt is tightened again, making it tough to get the bolt with the proper amount of internal tension to hold the bolt in place.

My advice is to clean and inspect the bolts. If there are no visible defects, the finish is intact, and you are certain that they have not be over-torqued, use them again. Otherwise, it's time for a new set.

All of the info on the ARP site is true, but they are writing on the premise of building engines that operate on the edge of engineering limits, such as race engines. From an engineering standpoint, it is good advice, but most of us aren't building engines to be raced. I used to do design work for weapons carry on the B-52, and the advice I gave here is the same as what was used for the weapons attach fittings. And we didn't want any bombs dropping early.

[grayw0lf]

Good info! Thanks Guys! Reuse it is!

[ScottH]

Get info as always from the board.
Many thanks to all who contributed.

Scott

[784X4GUY]

I agree with the said above I have always built just mild engines and have never bought a new set of head bolts. Just looked over the old ones real good and if everything was good just cleaned the threads chased the holes and lubed em and torqued em down. Never once have I ever had a problem, ie blown head gasket or anything like that....Good luck....Mike

[mattfranklin]

I'm tempted to reuse because I'm frugal. However, once on a 1966 Ford F100 with the inline six 240 CID I broke one on retorquing. That was back in the mid-1970s when retorquing was still a thing. I really lucked out, in that i could back it out with a screwdriver and lift out the stub with a bit of gum on a dowel. So, now, when I think about reusing, I get flashbacks and my face starts to twitch.

EDIT: I bought the ARP 134-3601 from our local speed shop (Morgan's Machine and Marine) for about $80. Summit had them for $74, but I like to shop local and Morgan's is great and really cares about quality of parts and machine work. And they were in stock and immediately in my hands. The ARPs are a high quality product. I sleep easier knowing I'm using them.

[cadillac_al]

If Chevy used cheap head bolts like ford then you would have reason to worry. SBC head bolts are pretty hefty. I think it would require a 3 foot cheater bar to break one.

[68gmsee]

Even though it's a 12 year old posting it's still relevant.

As others mentioned above, I've reused head bolts on GM engines and have never had a problem re-torquing to specs using Felpro head gaskets.

[YoungPup1977]

I just have to ask, How much does new head bolts cost ?

How much money did you spend on rebuilding the engine ? Did you put new bearings in it, rings ? new timing chain ? or just changing head gaskets.....

But you don't spend the money for head bolts ? I really don't care which way you choose, I am just wondering the reason behind not buying new head bolts...thats all..... oh, yea do you put new rod bolts in when you "rebuild" your engines, resize your rods with old rod bolts....you do resize your rods right ? thats when the "rebuild" word comes into play.....Have Fun !!!!

[68gmsee]

Originally Posted by YoungPup1977

I just have to ask, How much does new head bolts cost ?

How much money did you spend on rebuilding the engine ? Did you put new bearings in it, rings ? new timing chain ? or just changing head gaskets.....

But you don't spend the money for head bolts ? I really don't care which way you choose, I am just wondering the reason behind not buying new head bolts...thats all..... oh, yea do you put new rod bolts in when you "rebuild" your engines, resize your rods with old rod bolts....you do resize your rods right ? thats when the "rebuild" word comes into play.....Have Fun !!!!

I don't know about other but in my case I've reused head bolts mostly on head gasket replacement and occasional valve jobs on older prior to 1980's sbc engines. This has been on my vehicles only.

[hans2]

On a stock build with stock heads, inspect and reuse is fine. I typically drop the $50-60 bucks in new bolts, however, as cheap insurance for any kind of performance build.

[Tom]

This is the oldest thread I've ever seen brought back from any forum ever. There should be a prize or something.

[YoungPup1977]

Originally Posted by Tom

This is the oldest thread I've ever seen brought back from any forum ever. There should be a prize or something.

Tom, you have been here 6 years longer than this post started, what award do you want ?