2JZ Head bolts - Stock vs ARP

[DrNick]

Engine is a 2JZ-GE with turbo conversion and slightly lowered (9.2:1) compression ratio.

Just about to replace the head gasket. I am unsure what to do about head bolts.

The manual says the stock ones can be reused if they have not stretched, although I am being advised by friends to not reuse them. What power levels do stock bolts become an issue on these cars? I'm only going for 400rwhp when its complete,

So I have 3 options to reuse , buy new OEM or buy ARP. I'm happy to buy whatever is required for the job, I just want to try and avoid any unnecessary purchases as these are some pricey bolts

[1jz68u]

how would you know if the stock bolts have been stretched?

what is more pricey having them give way on you then have to buy new ones anyway and possibly some more damage or getting new ones now?

i went for ARP when i took the head off my 1JZ, the ARP were basically the same price as the OEM but apparently don't stretch like the stock ones and are stronger.

but that last part could be all bull i guess.

anyway i would at the very least replace them with OEM.

just my 2cents

hope it helps

[Big rob]

Actually you always want to elastically stretch head studs.

[PlacentaJuan]

Actually you always want to elastically stretch head studs.

yes but they are supposed to stay elastic, ie SHRINK back to their iriginal state/size when not in tension.

if they STAY stretched then you need to replace them.

how does the manual say to tell if they are stretched, and by how much? does it have measurements, and minimum allowable strech?

[DrNick]

Thanks for the responses - I'm thinking I will just replace them after all. I will price up the OEM and ARP and see just how much difference there is.

Heres what the manual says about checking the old ones :

INSPECT CYLINDER HEAD BOLTS
Using a vernier caliper, measure the thread outside diameter
of the bolt.
Standard outside diameter:
10.8–11.0 mm (0.425–0.433 in.)
Minimum outside diameter:
10.7 mm (0.421 in.)
If the diameter is less than minimum, replace the bolt

[Big rob]

yes but they are supposed to stay elastic, ie SHRINK back to their iriginal state/size when not in tension.

if they STAY stretched then you need to replace them.

how does the manual say to tell if they are stretched, and by how much? does it have measurements, and minimum allowable strech?

Correct once the studs are plastically deformed, their ability to maintain a clamping force is significantly less.

[PlacentaJuan]

Thanks for the responses - I'm thinking I will just replace them after all. I will price up the OEM and ARP and see just how much difference there is.

Heres what the manual says about checking the old ones :

INSPECT CYLINDER HEAD BOLTS
Using a vernier caliper, measure the thread outside diameter
of the bolt.
Standard outside diameter:
10.8–11.0 mm (0.425–0.433 in.)
Minimum outside diameter:
10.7 mm (0.421 in.)
If the diameter is less than minimum, replace the bolt

yea i wouldnt even bother measuring if all you are looking for is 0.1mm, so replacement would be the best bet.

[wilbo666]

yea i wouldnt even bother measuring if all you are looking for is 0.1mm, so replacement would be the best bet.

0.1mm+ Worst Case, 0.3mm+ best case.

I'd measure and go from there.

There was a chap that reported that it took 20+ (I forget the exact number, but it was a lot) of installs before the bolts started to fall outside the OK range.

I'd look to reuse personally. There are many 2JZGTE with stock head bolts pulling great numbers

Cheers
Wilbo

[PlacentaJuan]

but the brand new bolt will be off buy .02mm from factory.

so a bolt that has streched 0.25mm that started off as a 11.0mm bolt is ok.

but a bolt that streched 0.10mm and started as a 10.8mm thick bolt is a reject.

the tolerances are too close for me; i would go new ones, unless i had bought the originals myself and installed them to the correct torque myself, and knew the entire history of the engine since they were installed then i would consider reusing.

actually i have no idea on the price for new bolts, so that would be a major contributing factor as to weather or not i would consider new or re-use.

anyone got prices yet?


wilbo666 that is interesting information re: 20installs before streching. do you know what brand they were?

mayeb if you were plannign on opening the engine all the time (ie constant rebuilds because you dont have a 2jz) then i would think about getting the expensive ones, but when i finally open up my engine and make him betterers i wont be planning to do it again so ill get standard (or the cheapest) studs.

[wilbo666]

wilbo666 that is interesting information re: 20installs before streching. do you know what brand they were?

Turns out it was a reference to rod bolts, not head bolts.

Stock Toyota Bolts. Rod bolts are Torque to Yield same as the head bolts.

And it also seems that it was 15 times.

Read this post and image:
http://www.toymods.net/forums/showpo...0&postcount=11

From this thread:
http://www.toymods.net/forums/showthread.php?t=7825


Just some more information to go off I've reused 1JZ head bolts in the past after measuring them without issue.

Cheers
Wilbo