Reusing Head/Main Bolts

[NolimitZ32]

I know it has been covered but the search only brings up invalid topics so:

Has anyone reused their Head and Main bolts during a rebuild and what was the outcome? I remember reading that people would end up with warped heads after reusing head bolts. I need to hear this stuff from the horse's mouth, I'm trying to get my Z running, I wanted to go 16G but that will have to wait, so for now I am trying to finish rebuilding the engine on a budget so i can at least have a running Z.

P.S. expect to see waaaay more posts like this from me.

[bentandbuzzin]

You never reuse the old head bolts. The service manual even tells you that if you need proof of this. When you install head bolts and torque them down they stretch. So if you try to reuse them the heads will not seal. Just spend the money and buy new ones or you will have to reinstall the heads all over again.

[NolimitZ32]

I've read this, this is why I am asking, as we all know the VG30 is an extremely over-engineered engine and I'm trying to figure out if this was one of those over engineered things or if there is truth to this thats why i was seeing if anyone has actually done this. Either way thanks for your input man.

Also how about the main bolts, are those reusable?

[xclusivez32]

i just bought some head bolts from z1 $80, im in the same boat as you i just want to have a running z this year. good luck

[NolimitZ32]

yup, looks like i'm gonna be buying new head bolts, wish i could spring for the ARP kit but damn its like $400 for head and main, thats as much as I am spending on machine work and all of the other parts put together.

So how about the main bolts? do they need to be replaced as well?

[NissanFairladyZ32]

Im pretty sure the mains are torque to yield as well

[bentandbuzzin]

I'm not sure about the main bolts but if they are torque to yield then yes you must replace. If anything i would replace those because if they are stretched and you reuse them...all that money you spent and hard work you put into rebuilding that engine will be wasted. You could severely damage or destroy your bottom end. I would want fresh bolts to hold the components together so i wouldn't have to worry about a failure. ARP studs are expensive but for a reason. If your going to be racing this engine and removing and replacing the heads several times this is where the studs pay you back. They save you from having to buy head bolts each time you remove the heads. So if your not using the car for racing just buy new head bolts. Important things like these bolts are the last thing you want to be cheap with after all that work you performed.

[NolimitZ32]

The reason I want the ARP is because this engine will be getting built later down the road so it feels like i'd be throwing away $160 on head and main bolts if I know that I will be tearing the engine apart in a few years but I guess since I can't afford $400 now i'm just gonna go ahead and waste the $160.

[Nicko500]

I can't find where the service manual say to always replace them.

I am running with used head bolt without problem, but maybe I'm lucky

[raremotive]

Main bolts are alright to reuse, notice how you only torque them once.

Also, you only torque them to 74 in-lbs max

Your heads are 90 ft-lbs or 1080 in-lbs.

That is the difference between a bolt and torque to yield.

[NolimitZ32]

Thank you rare. and thanks for the reassurance nicko but i think for what its worth i'm going to buy a new set for the head.

[budget300zx]

i know im necro-mastering this thread, but can you reuse an arp setup on the head bolts or do you have to replace the studs anytime the head is removed?

i would like to get the main and head kit...but IMO its not worth it if i cant reuse them and have to buy them next time my head is off.

is this the same if i use arp rod bolts in eagle rods?

mains ill deffinatly get though.

[NolimitZ32]

Any bolts/studs that are torque to yield MUST be replaced, I don't remember what the instructions for the ARP stuff was since its been years but the docs that come with the ARP hardware actually tell you how to torque them. Again anything that is torque to yield must be replaced because you are deforming the bolt/stud. Your best bet is to call up ARP and ask them because you can't really go by the FSM when you are installing non-OE components. The second part of all this is whether you need the ARPs or not, I've never heard of a Z lifting a head or popping the girdle under normal conditions (being 500ish bhp) so there really isn't a need for the upgraded hardware. Also you should look around because there are different levels of ARP hardware and if you are planning to ever run ridiculous HP or boost you may not need to spend the money.

[budget300zx]

at a 100% max as in only on the dyno no street drives 800hp but i will run 300-400hp daily tune. and 500-600 on a perfomance tune. Going to have nistune with a dedicated car pc in dash for monitoring and changing tunes.

i will most likely get ARP main, head, and rod stud kit.

{edit}for anyone searching these are the same as 2jz head kits.


From ARP- To Reuse
dry out the stud holes in the block
thoroughly clean studs and remove assembly lube
use a thread chaser to clean the threads
apply arp lube to the bolts
reinstall back into block

to remove the lub/grease use brake clean if anyone is wondering
thread tap size is 12mmx1.25 if you need to know
use compressed air or air compressor to blow it out well

[NolimitZ32]

Boom. 800 is a hell of a number to reach, what setup do you have planned? Also 800 on OEM bolts is asking to break something.