can you re-use head bolts?

jerry S · Jun 26, 2007

I took the heads off and sent them in for porting. Can I re-use the head bolts when I re-install the heads?

fvike · Jun 26, 2007

Of course! Torque those suckers down!

joesgt281 · Jun 26, 2007

jerry S said:
I took the heads off and sent them in for porting. Can I re-use the head bolts when I re-install the heads?

yes.
some of the 4.6L motors had bolts that stretched when torqued and you couldn't re-use those.
but i'm assuming you're talking about a 289/302/351.

Stanger007 · Jun 26, 2007

The later model 5.0s are supposedly torque to yield bolts that are supposed to be replaced after using.

Total BS if you ask me. ARP must be happy. I'm going with head studs next go around.

Wes

brianj5600 · Jun 26, 2007

I have had them stretch, so be aware. If the snug up, but won't get to torque, pull it out and check the length. They will be noticably longer and narrower at the top of the threads.

rbohm · Jun 26, 2007

i have reused head bolts in the past. one thing i have found is that they tend to stretch over time, and while they can be reused once or twice, but after that i recommend they be replaced. and yes arp is happy because they sell the best replacement bolts on the market today.

unrealmach1 · Jun 26, 2007

On certain engines (mostly late model) they use a "torque to yield" tightening plan. Basically, bolts stretch as they are torqued down and this creates a clamp load. After the bolts are taken off they should return to their original length, but in a "torque to yield" plan they stretch the bolt until it becomes "plastic" and doesn't return to its original length. When the bolt is stretched to this state it is no longer reusable. Any bolt can become a "torque to yield" bolt if it is over torqued. For the $50-60 bucks I'd replace them to be safe.

65ShelbyClone · Jun 26, 2007

The pre-'80s bolts are just normal Grade 8 fasteners AFAIK. They should be good for a couple uses. I went with ARPs after some "grade 8" bolts from Performance Automotive Warehouse actually stretched and broke at ~60 ft/lbs right out of the package. Wasted a pair of headgaskets in the process. I guess it's good that they broke otherwise I would have run the engine and been pulling heads in the car rather than on an engine stand.

HistoricMustang · Jun 26, 2007

jerry S said:
I took the heads off and sent them in for porting. Can I re-use the head bolts when I re-install the heads?

If this is the first time the heads were off the motor you can re-use (as they were torqued at the factory), just be careful not to over torque when you re-apply.

If you are not sure about how many times they have been used then invest in another set and when installed after each use simply make sure they are not over torqued. I would also suggest upgrading to studs if you purchase a new set.

HistoricMustang
www.historicmustang.com

Rusty67 · Jun 26, 2007

ARP has done some interesting studies. Apparently with quality fasteners like ARP bolts and some others you are actually SUPPOSE TO reuse them but the trick is making sure they go into the same hole every time. Apparently the threads will wear into each other. At least thats what ARP has said. I imagine you can old torque them down so many times before they eventually stretch too much.

As long as they are not torque to yield I would say you could provably use them about 3 times total with no worries. As for me, I'm going to get studs for the head.

CraigMBA · Jun 27, 2007

Rusty67 said:
As for me, I'm going to get studs for the head.

So long as you realize that you can't pull a head off an engine with studs installed while the engine is still installed in the bay.

Consider yourself warned.

Rusty67 · Jun 27, 2007

CraigMBA said:
So long as you realize that you can't pull a head off an engine with studs installed while the engine is still installed in the bay.

Consider yourself warned.

This is not necisarily true. It depends on the stud you use.

brianj5600 · Jun 27, 2007

CraigMBA said:
So long as you realize that you can't pull a head off an engine with studs installed while the engine is still installed in the bay.

Consider yourself warned.

I pulled my AFR heads off a 351 with ARP studs in a 67.

CraigMBA · Jun 27, 2007

I used ARP and couldn't get them off on my '65. I wound up going back to bolts.

Rusty67 · Jun 27, 2007

CraigMBA said:
I used ARP and couldn't get them off on my '65. I wound up going back to bolts.

Did you buy the under-cut studs ? They are slightly shorter. Also, I think the 65 engine bay is a littl smaller then the later models.

CraigMBA · Jun 28, 2007

Rusty67 said:
Did you buy the under-cut studs ? They are slightly shorter. Also, I think the 65 engine bay is a littl smaller then the later models.

I don't know and you're right, it is.

blown65 · Jun 28, 2007

I have studs on my 65 also and I highly doubt you would get the heads off of it. The newer stangs have a little more room so its probably possible on them.

Rusty67 · Jun 28, 2007

blown65 said:
I have studs on my 65 also and I highly doubt you would get the heads off of it. The newer stangs have a little more room so its probably possible on them.

What if you jacked one side of the engine up ? Also, Jerry has a 69 I believe so he has more room in the engine bay.

CraigMBA · Jun 28, 2007

Rusty67 said:
What if you jacked one side of the engine up ?

That might of worked. You'd have to do it twice (once on both sides) but if I remember correctly you'd have to get like a 30 degree twist to get the head to slide out. Plus you have to remove the export brace. Either way it's not pretty.

Also, Jerry has a 69 I believe so he has more room in the engine bay.

That is also correct.

can you re-use head bolts?

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