Theory question: replacing stock bolts with ARP without rebuild?

[Keros]

I've heard that this can be done:

Replacing stock headbolts with ARP head studs (and tourqing to the standard ARP spec) by threading out the stock bolts one by one in the tightening order, and replacing each bolt with a stud and tightening it down (to the same as what the stockers were, then tightening them all to spec once they're all replaced) until all the stock bolts are replaced with ARP's.

I do not have a BHG on my 7M-GTE (I can check the compression numbers, if that will help). I changed the oil last week and it's still clean... coolant is still looking good as well, changed it a month or two ago... But I don't know what's between the head and the block... I don't want to waste money doing a complete rebuild on something that doesn't need rebuilt, but I honestly don't trust the head gasket as far as I could throw the engine... I do not know anything about the history of the engine. It's supposedly a JDM swap with about 20000km on it. My assumption (and what I've been told) was that it came out of a crate, off a pallet, and under the hood, just before I bought the car. Previous engine may have suffered rod-knock.

If it ain't broke, fix it 'till it is, is generally my motto. The motor pulls amazingly strong and solid, runs smooth, has zero hesitation and sounds amazing. It burns a bit of oil on startup (stem seals?), but other than that there's no reason to rebuild. But, I don't dare turn up the boost past a bit more than stock for fear of blasting the head gasket out the side of the block.

So, would swapping out the stocker head bolts for ARP's as discribed above be risking distruction, or would it be a good idea to get some reliability?

 

[figgie]

First off. If it ain't broke. Don't fix it. Regardless of what the current flavor of the BHG is today. BHG is caused by one of two things.

Overheat or upping the power. Period.

Do none and the motor will survive.

225,000 mile motor to prove it on OEM even with a moderate power increase. Cause of death was a spun #2 bearing (or what was left of it).

 

[starscream5000]

Retorque the stock bolts in there and you'll be fine as long as the HG isn't compromised already and you aren't going to be producing enough power or boost to compromise the HG later on. Crack loose the bolts one at a time per the TSRM spec and retorque to the updated value for stock bolts.

 

[ATL88Supra]

Retorque the stock bolts in there and you'll be fine as long as the HG isn't compromised already and you aren't going to be producing enough power or boost to compromise the HG later on. Crack loose the bolts one at a time per the TSRM spec and retorque to the updated value for stock bolts.

indeed !

 

[Keros]

Retorque the stock bolts in there and you'll be fine as long as the HG isn't compromised already and you aren't going to be producing enough power or boost to compromise the HG later on. Crack loose the bolts one at a time per the TSRM spec and retorque to the updated value for stock bolts.

Would this proceedure grant the same results as the ARP swap, but without the $125 bill for studs? And would the pre-stretched nature of the stocker headbolts have any effect on it?

I have an upgraded CT26 (of some magical trim I don't know), intake and 3" turbo back exhaust. I'd like to do the lex AFM/550cc mod to continue building up the engine. So I suppose I should rephrase my question: to continue building horsepower, should I rebuild the engine when there's nothing wrong with it, or can I tighten the stockers or swap to ARP's?

I realize the obvious solution would be to leave it as-is, but my Supra is not my DD, so leaving it as-is makes me bored and my wallet fat :biglaugh:

Yeah, and there's really nothing wrong with my Supra, which makes me worried there is something wrong and I don't know it yet.... I'll probably find out when a piston rockets through my hood. It's a good excuse to buy a carbon fibre hood though :naughty:

 

[SevenMKIII]

"so leaving it as-is makes me bored and my wallet fat"
I'll trade you wallets :naughty:

Just take their advice and crack each loose and retorque it to the proper spec. It will hold for a while until you do something to blow it.

 

[starscream5000]

I would consider buying ARP studs just to retorque with, and not changing out the HG that's on there already, a waste of time and money as you are taking a gamble anyways by squishing the HG a little more with the retorque. If you want to get anal about it, buy new Toyota head bolts since they are torque-to-yeild IIRC.

If you plan on going for more power (350-400 ish?) then you may want to consider the rebuild, but that's up to you depending on your power goals and how much boost you will subject to the stock HG...

 

[Keros]

"so leaving it as-is makes me bored and my wallet fat"
I'll trade you wallets :naughty:

Just take their advice and crack each loose and retorque it to the proper spec. It will hold for a while until you do something to blow it.

haha, sounds good, and cheap. Cheap is good. Never having had a BHG before, I feel inadequate to hand out any advice about the 7M :biglaugh:

Run 'er till she blows :naughty:

SS5K's ninja post:

Valid points, I'm only planning to go about 300hp until it's rebuilt. I'll be doing the lex AFM/550cc mod and an electronic boost controller, then getting it dyno tuned (conservatively) professionally. I assume that's the best way to go, anyway.