After getting my motor rebuilt with a mhg about 2 months ago, my mechanic insisted that he used the stock head bolts to maintain my warranty with him. My question is, will these stock headbolts, torqued at stock pressure (58 lb-ft) be sufficient, or should i void my warranty with my mechanic and install ARP's at a higher torque rating? will the engine handle more boost/supporting mods in its current form? any help would be much appreciated
Mechanic used stock head bolts after rebuild, is that acceptable?
- Thread starter Josh Kushner
- Start date
Well, it is his warranty.
AFAIC I wouldn't install stock hardware on an engine meant for performance. Are these OEM bolt new? Because, I bought a 7M once with new OEM HG and not replaced OEM head bolt. During first prolonged boost, I lifted the head.
What about asking him to retorque (that's not uncommon after some month/miles of driving) and see if OEM bolts have hold?
AFAIC I wouldn't install stock hardware on an engine meant for performance. Are these OEM bolt new? Because, I bought a 7M once with new OEM HG and not replaced OEM head bolt. During first prolonged boost, I lifted the head.
What about asking him to retorque (that's not uncommon after some month/miles of driving) and see if OEM bolts have hold?
Yeah like rollus said using the head bolts that came on the motor isn't good because they've already stretched, you need to get new ones or have him torque it passed 58 because as everyone else in the forums stated, 58 ft lbs was not enough and maybe 76-81 was more sufficient to get the right seal
thank you guys so much for your quick responses, the mechanic i am unfortunately affiliated with at the moment is quite stubborn and in my opinion, not too familiar with high compression, turbocharged, japaneese engines, so i feel like the best decision at this point would be to buy ARP's and install myself/other mechanic. i asked him to retorque to higher and he looked at me, completely confused as to why i would ask such a question. in the mean time, until i can afford the bolts, would it be sufficient to tighten the stock ones? is there a write up on here about the quickest way to access my head bolts?
Quickest way would be take the valve covers off and torque, head studs are a different story when installing after assembly though ( simple way but tedious I think would be to take the cams off and then install), and I wouldn't know for stock bolts, maybe someone else will chime in
OP's mechanic is incompetent. That said it's highly unlikely the old bolts have ever entered their plastic region. Having them at stock torque with a MHG isn't good though.
1. Are you sure he surfaced both the head & block?
----------> follow up do you have any proof or did you see if the finish on both was adequately done for a mhg
2. How confident are you he will uphold his warranty and what is the duration?
- Depending on the answers to number 2 I would either re-torque the stock bolts to 70-75lbs per instructionsHERE and never mention it to him. You will have a better shot at keeping the hg sealed and if it does go he will wont know the difference when he un-torques them to redo it for you.
Or if you dont have confidence he will uphold the warranty or once it is up you can install arp studs torqued to proper spec.
If you are unsure of the answer to question 1 it may all be a wash and there isn't much you can do but wait for him to redo it and be prepared to instruct him on how you want it done the second go.
----------> follow up do you have any proof or did you see if the finish on both was adequately done for a mhg
2. How confident are you he will uphold his warranty and what is the duration?
- Depending on the answers to number 2 I would either re-torque the stock bolts to 70-75lbs per instructionsHERE and never mention it to him. You will have a better shot at keeping the hg sealed and if it does go he will wont know the difference when he un-torques them to redo it for you.
Or if you dont have confidence he will uphold the warranty or once it is up you can install arp studs torqued to proper spec.
If you are unsure of the answer to question 1 it may all be a wash and there isn't much you can do but wait for him to redo it and be prepared to instruct him on how you want it done the second go.
the head was machined and resurfaced and the block was resurfaced manually (inefficient way of ensuring proper RA spec imo) i personally ensured he wasn't pulling some BS. i suppose the best thing to do is to take my car to a more competent mechanic and purchase the ARP's and have them install it. If i were to get the bolts replaced, and the studs were torqued to a much higher amount, could that possibly put more stress on my current setup thus causing it to blow quicker? Unfortunately i was not the one paying for the rebuild so i did not have much of a decision in the choice of mechanic.
^i agree.
i've had great luck with old stock headbolts and felpro hg torqued to 75ftlbs. the stock head bolts aren't torque to yeild....
i've had great luck with old stock headbolts and felpro hg torqued to 75ftlbs. the stock head bolts aren't torque to yeild....
so it looks like my best bet is to retorque the stock bolts until i can afford ARP's. thank you guys for your help! 
Stock headbolts are 100% completely fine. ARPs are cheap insurance and I'd recommend them on every build, even a stock GE. If your engine is already assembled with stock bolts that's perfectly fine. The low torque value is a problem, though. I'm surprised the mechanic was comfortable modifying the car with a MHG, but didn't know about the under torque problem. Find a new mechanic.
For now, open up the valve covers, retorque the existing bolts to 75 ft-lbs and call it a day. Your mechanic doesn't need to know you torqued them to the *correct* value. Toyota is not often wrong, but the head torque spec on the 7M is a bonafide failure and fuck up which they unfortunately never formally corrected on the 7M literature. This leads to your exact situation where an honest mechanic sticks to the books and assembles a ticking time bomb.
For now, open up the valve covers, retorque the existing bolts to 75 ft-lbs and call it a day. Your mechanic doesn't need to know you torqued them to the *correct* value. Toyota is not often wrong, but the head torque spec on the 7M is a bonafide failure and fuck up which they unfortunately never formally corrected on the 7M literature. This leads to your exact situation where an honest mechanic sticks to the books and assembles a ticking time bomb.
You also have to think about it from the mechanics point of view, hes not a supra owner or an enthusiast he dosent know that Toyota messed up the head torque in these cars.
He is just doing his job and rebuilt it to the torque that the manual said. If he put his own opinion on every torque value he saw on any vehicle he would cause all sorts of problems. So he relys on factory specs. Only we know the factory is wrong.
Sure there's no excuse for reusing the stock bolts, but once again for alot of people a bolt is a bolt
I would re-torque it to the higher, mentioned above torque. That will be fine in the meantime and then use this time to learn more and research about the car.
On these old cars the best mechanics for them is the owner, There willing to learn and repair what is required. there personal standards are much higher that your average mechanic that knows nothing about that vehicle.
Goodluck!
He is just doing his job and rebuilt it to the torque that the manual said. If he put his own opinion on every torque value he saw on any vehicle he would cause all sorts of problems. So he relys on factory specs. Only we know the factory is wrong.
Sure there's no excuse for reusing the stock bolts, but once again for alot of people a bolt is a bolt
I would re-torque it to the higher, mentioned above torque. That will be fine in the meantime and then use this time to learn more and research about the car.
On these old cars the best mechanics for them is the owner, There willing to learn and repair what is required. there personal standards are much higher that your average mechanic that knows nothing about that vehicle.
Goodluck!