Sort of unrelated but has anyone ever heard of a boosted Miata lifting a head? Or blowing out a head gasket under high boost?

Are OEM Head bolts totally sufficient for 99% of the builds on this site but people are using ARPs because....they're ARPs??

Are head studs the answer to a question no one really should be asking?

I understand the benefit of the head studs for ease of cyl head installation and don't doubt that that alone makes them worth the money.

I'll hopefully be installing my head in a few days and I'm trying to decide if I NEED to order ARPs, should buy new OEM bolts, or just reuse the head bolts I have. I know Sav tried to reuse some head bolts with NG results, but others seem to have no problems reusing stock bolts (including lots of SM engines?).

What do you gehs think?

 

From everything I have read we just use ARP head bolts for ease of swapping heads. I have personally done about a half dozen head swaps with reusing stock head bolts and have never had an issue. Braineacks miata ran for 18k miles boosted at 240hp with reused stock head bolts.

 

Yep, that's what I gather too - confirmed re-usability with ARP vs you really shouldn't re-use the stock head bolts, and if you do, the proper way to do it is measure/check for stretching/etc.

Stockers work though. So there's that.

 

It's all based on recommendation. The stock bolt technically have to be measure for stretch after they are torque and taken off and changed. So If you need a new set of stock head bolts, I am sure the price difference is not much if any from ARP. And if you are spending lots of money on the engine, what is extra $100 to make sure you don't have to deal with BS?

 

I don't have a FSM in front of me, does Mazda recommend reusing the head bolts? Is there a published spec for checking the bolts for reuse?

• Rosenthal has head bolts for $12.82/ea so that's $128.20 before shipping and tax. No washers, no lube.
  
• Trackspeed has ARP studs for $129.00 before shipping and tax. With washers, with lube.

Same price? I'm buying the ARPs every time.

 

Probably, but reusing critical fasteners is generally not wise and I'm not interested in being the R&D guinea pig that finds out when stock head studs stretch/break (BTDT with main studs, have the wrecked block/crank/oil pump to show for it). Therefore, I use ARP studs so I never have to worry about it.

 

I've done about 30min of various Miata ARP torque setting searches all over the net. Read your posts about ARP on other MT threads. Got my numbers set from your posts. Read this one just before bed and this cements it. So now I'll sleep fine especially after the way you worded this last answer.

Torquing the bottom end tomorrow. Heads later on when my shims arrive/are set.

Thanks.

 

I had the bolt debate with my fabricator I called Arp they said 80 I called fm I believe they said 60. We split the difference but I would suggest a sticky or someone needs to school Arp on there own products. I'm referring to the nuts. As mentioned studs hand tight.

 

I ran the ARP2000 rod bolts to 60 ftlbs. I ran them to 20 then 40 then 60. I did not have a stretch gauge so I used this method. I'm a bit nervous on this ?

 

ARP has become fully retarded on what they think the B6/BP Miata head can handle.

 

I don't know about ARP rod bolts. ARP specs are fine for that you are not going to yield rods with too much torque the critical thing at that location is what the bolts themselves can handle. Mine for Carrillos specify a stretch length rather than torque but I think it was in the 20's. It's the head studs clamping a soft aluminum head that ARP's current specs are too high for. I think they are calling out what the studs can handle not what is appropriate for a Miata head.

 

My Engine builder is kicking himself as he used the torque setting that came in the ARP box from 949racing.....he used 80 but at the time thought this seems high....

Later on the dyno we had all sorts of weird issues. Seems we didn't crack the head but we did oval the bores....it appears temporarily while under the excessive clamping pressure.

Being a Miata / mx5 specialist supplier, I wish 949 would put a sticker on the box with a warning.

But for the sake of this thread, 80(as per ARP instructions) is way to much. I also think 50 - 60 as mentioned above is more in the proper region.

The problem is no one (or very few) will question ARP suggestions due to the great name in quality products they have....