XF crossflow head bolts

[SLO247 1,713]

Heres an easy one. Do alloy head crossie head bolts need to be done when the head comes off or can they be re-used?

[adrianphu123 73]

I believe they can be reused

[Stumps 311]

can be reused but really should be replaced as they to stretch and wear etc

[ando76 4,354]

They are torque to yield - therefore they need to be replaced every time.  they retail for around $55 on the net- why would you risk it when a head gasket costs about the same. 

 

Head studs can be bought from US for around $150 so if you plan on pulling the old girl apart several times then they are worth it but for just a freshen up and forget I would be using new head bolts.  Durapro have proven good for me and I just put another set on Brenton's plan B x-flow with 11.9:1 comp and I do not expect any issues.

 

I know of several top engine builders that use bolts over studs on these engines - even in high comp flat tappet motors and if you look at a head bolt as opposed to a head stud you can sort of see where they are coming from.  Me I use studs for high performance stuff but Brenton's engine was the exception to the rule as I want to test this other theory.

 

Sorry for rambling but yes replace those old bolts - they have had their day in the sun.

[351XD_Fairmont 604]

Just wondering what the theory behind using bolts over studs was ando?

Also yes you should replace them SLO247

[ando76 4,354]

Some believe that the studs pull the head down to firm and do not allow expansion like the factory bolts do.  If you look at a head stud they are the same thickness from thread to thread.  A head bolt on the other hand has a taper from thread to head of the bolt.

 

Some engine builders believe that this allows a little bit more flexibility in the head and stops them from warping in high heat conditions and also clamp the head correctly.

 

From an engineering point of view a stud has more clamping force than a bolt so they believe that when you torque a head stud down to factory tolerance you are in fact creating extra force on the head face - in particular in between each stud/bolt and this causes head gasket sealing issues.

 

I've seen both work in high stress situations so I'm not convinced either way.  My theory is that if it is a race motor that is likely to come apart (as race motors do) then use studs cause you will save money in the long run - and they look horn.  If it is an engine that is not likely to come apart again - or a budget build - throw new bolts at it and forget it. 

[ando76 4,354]

Also if you are planning on using bolts or studs it is good practice to have the machine shop mill out the first three threads where the head bolts go into the block.  Both studs and bolts can pull the threads up over the face of the block when torqued and can cause sealing issues around the bolts. Yes it does happen. 

[SLO247 1,713]

Thanks very much, exactly what I was after. I will do them.

[351XD_Fairmont 604]

Cheers for that ando, gives us all something to think about

[Tweaker351 148]

I know new bolts are cheap and all, but ive never bought a new set for a crossflow and have done heaps of crossie heads over the years. Ive never had a failure reusing the head bolts.

If it was an ef-au etc I would buy new ones but not an old crossie, unless it was off its chops. I guess you would buy studs anyway.......

Just my 2 cents, cheers.

[winton 399]

Also if you are planning on using bolts or studs it is good practice to have the machine shop mill out the first three threads where the head bolts go into the block. Both studs and bolts can pull the threads up over the face of the block when torqued and can cause sealing issues around the bolts. Yes it does happen.

Hay Ando76

Any reason why you can't do this at home with a drill then run a tap down it to clean up the thread ?

[TF_250 398]

X-Fow head Bolts ARE NOT torque to yield Bolts and can be used several times. you Dont torque them to specified angles you torque them in a series of steps read below or google it.

 

 

 

http://www.aagaskets.com.au/PDF/AA006%20Torque%20To%20Yield%20Head%20Bolts.pdf

 

 

[Mr Polson 10,214]

I went looking for new xflow head bolts when I had to replace the cam in my Ghia wagon, no where had them, and only Bursons could get them in. I just reused the old ones.

[Tyler06 266]

Im with cyco. Crossy bolts arnt torque to yeild and are not required to be replaced. Thats coming from my mate that owns All Torque Cylinder head engineering. I have also done plenty of head gaskets and have never replaced them. Obviously I run studs in mine though lol. Good point on the thread pulling up ando.

[SLO247 1,713]

Can't argue with that. Thanks.

[ando76 4,354]

Hay Ando76

Any reason why you can't do this at home with a drill then run a tap down it to clean up the thread ?

You can chamfer them at home - no problem - but don't run a normal tap down the thread. See at the bottom of the link so kindly provided by Jason as to why.

 

I just get the machine shop to do it as it costs naff all and is one less thing to do when you get the block back.

 

I just use an old head bolt and run the thin grinding wheel down the threads in four places like a tap to clean up the threads.

[ando76 4,354]

X-Fow head Bolts ARE NOT torque to yield Bolts and can be used several times. you Dont torque them to specified angles you torque them in a series of steps read below or google it.

 

 

 

http://www.aagaskets.com.au/PDF/AA006 Torque To Yield Head Bolts.pdf

Thanks Jason - I have been proved wrong yet again.

 

But hey if you want to re-use a bolt that originally went into your engine in 1980 something and has been torqued to 102nm at least once, that you know of, and been through a million heat cycles, then more power to you.  Especially when a new set is $55. 

 

And yes Tyler most head re-conditioners will tell you to re-use them as they are all use to these things being taxi motors or family hacks and not the way I use them or expect them to be used. 

 

We are not talking $500 here - we are talking $55 odd dollars - really would you chance an old bolt when a head gasket failure will cost you a lot more.

 

Whilst I was wrong on my torque to yield comment - I don't think I am wrong on my reasoning not to re-use old bolts - but hey we are all different.  Me I like doing things once and doing them right. 

[matt_lamb_160 252]

My last crossy ran 12:1 comp for 5 years with used head bolts. So long as the bolts have not been over tightened ever there is no reason for anything to be wrong with them (if steel doesn't yield it does not loose stiffness) unless the threads are shitty. On a nice rebuilt or hipo engine you should swap, but in a re-ringer I would never bother.

 

4.0ltr motors are torque to yield and need to be replaced.

[TF_250 398]

Thanks Jason - I have been proved wrong yet again.

 

But hey if you want to re-use a bolt that originally went into your engine in 1980 something and has been torqued to 102nm at least once, that you know of, and been through a million heat cycles, then more power to you.  Especially when a new set is $55. 

 

And yes Tyler most head re-conditioners will tell you to re-use them as they are all use to these things being taxi motors or family hacks and not the way I use them or expect them to be used. 

 

We are not talking $500 here - we are talking $55 odd dollars - really would you chance an old bolt when a head gasket failure will cost you a lot more.

 

Whilst I was wrong on my torque to yield comment - I don't think I am wrong on my reasoning not to re-use old bolts - but hey we are all different.  Me I like doing things once and doing them right. 

Yep in the OP situation I would reuse them, its no different to reusing the main bolts, flywheel bolts, rocker bolts, cam bolt, crank bolt or any other bolts for that matter. There is doing things once and right but what is right is only your opinion then there is wasting money on things not needed, I guess everyone can decide that for them selves.

[ando76 4,354]

Yes they can Jason and at $55 to replace a 35 year old bolt with unknown history they surely can come to their own decision.  My engine guru, who has forgotten more than most of us will ever know, and built more engines than you and I both Jason, told me to replace them every time - so that is what I do. 

 

Oh and I've built 4 flat tappet x-flows this year and done 2 oil pumps and another 2 sumps this year so far with an order for another one just received today. So yes that is my opinion and I thought that is what this forum is all about - sharing your opinion. 

 

Yes Matt - you have had success in your application and that's great and I'm sure there are others that can point to success BUT people we are talking about $55 here to replace a 35 years old bolt!!!!! Torque to yield or not. 

 

Oh and I never re-use flywheel or flexplate bolts - unless they are ARP as I have found re-using stock bolts leads to them coming loose which transfers metal from the flexplate/flywheel onto the crank and renders it fucked.  Yes it has happened to me. 

 

Right or wrong - you make up your own mind.

 

P.S. I'm not contracted to Durapro or any other company that supplies head bolts or studs. 

[matt_lamb_160 252]

Wow, that's a bit aggressive. We were just offering our opinion just like you did

[Butcha 111]

Eh cost vs consequence. $55 for head bolts vs $55 headbolts+$70 gasket+3 hours..

 

Ive reused the headbolts in me roundy round car 4x without consequence so.. http://

[ando76 4,354]

My apologies Matt. 

 

Sometimes I go a little to far when I believe strongly in something and yeah that reply was a bit over the top. 

 

For me it's all about risk management.  The OP does not state the purpose of this engine but your advice in the second last sentence of post #18 makes good sense. 

 

SLO247 - make up your own mind bud - I'm out. 

[matt_lamb_160 252]

I agree with Ando's point, given that we do not know the exact application it is important to consider the options.

 

The OP should know all he needs now.

[Disavowed 0]

Xflow headbolts are not torque to yield