ARP hear stud question
#41
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?
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?
#42
mkturbo.com
iTrader: (24)
Join Date: May 2006
Location: Charleston SC
Posts: 15,189
Total Cats: 1,685
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.
#44
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?
#45
Elite Member
iTrader: (37)
Join Date: Apr 2010
Location: Very NorCal
Posts: 10,448
Total Cats: 1,900
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?
Same price? I'm buying the ARPs every time.
- 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.
#46
Former Vendor
iTrader: (31)
Join Date: Nov 2006
Location: Sunnyvale, CA
Posts: 15,442
Total Cats: 2,103
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.
#47
Senior Member
iTrader: (2)
Join Date: Sep 2009
Location: Edmonton, AB, Canada
Posts: 1,193
Total Cats: 29
Not as curious as you might think. IIRC it was FM who worked with ARP to get those studs made. Their original torque spec was 49ft.lbs, which matched the factory clamp load. When I bought my first set in 2009, the instructions said 65ft.lbs, so that's what I did. I installed several sets at that setting before looking at a fresh set of instructions somewhere around 2011-2012, and to my surprise they said 80ft.lbs. A little forum reading turned up Bob's experiences with cracked heads at 80ft.lbs. Clearly, the engineer at ARP who said 49 is no longer there, and ARP doesn't care enough to put thought into their specs beyond "X diameter + Y thread pitch = Z torque".
I torque ARP studs to 65ft.lbs.
I torque ARP studs to 65ft.lbs.
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.
#48
Senior Member
iTrader: (12)
Join Date: May 2008
Location: Roselle, Illinois
Posts: 849
Total Cats: -34
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.
#51
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.
Last edited by bbundy; 03-10-2015 at 10:44 PM.
#52
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....
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....
Thread
Thread Starter
Forum
Replies
Last Post
bigmackloud
Miata parts for sale/trade
19
01-08-2021 11:24 AM
JesseTheNoob
DIY Turbo Discussion
15
09-30-2015 02:44 PM