ARP head bolts, Must or Overkill?
 

I'm rebuilding my 1.6L head because oh a head gasket oil leak (leaks on the back to the outside and doesn't mix with the coolant)

I'm doing the work now to be ready to do a track day at Thunderhill on April1. Currently the car is just stock with an intake, header, and exhaust but later this summer I'll be bolting on a Greddy kit and trying out the whole turbo thing.

I was just going to reuse the head bolts as stated in the work book but someone mentioned the possible need to replace them. At over $120 the bolts are going to cost me more than the head and I'm wondering if it is just overkill.

As a side note my Spec Miata friend said he has never heard the other racer's replacing head bolts with ARP.

overkill. Just make sure the threads are clean and lube them correctly on both ends.

What do you like to use to lube them. I have RedLine engine assembly grease for the cams, etc.

ARP says to use their thread prep or thead lube depending if it is a open or blind hole or 30 weight oil but to increase the torque. Is there something similar for the OEM bolts or do you just use oil?

As you can see, I'm going through info overload!

I just used oil for my last couple of engine builds but ARP has a special moly lubricant that is much different than your assembly lube.

Clean everything well and use the 30 weight oil. Torque per the book.

I am doing a low boost (7-9psi) build on my 1.6, would the arp studs also be overkill? Not sure how powerful the "Greddy Kit" is...

Yes overkill. If you are using a greedy kit, why are you evening opening the motor?

Overkill BUT if you need new studs anyway, ARP costs about the same as OE Mazda, so...

Cheap insurance IMHO

Overkill, I used stock head bolts for years at 250 whp with no issues. Just make sure your head surface is true and clean the threads and lube them.

Always follow the lubricant recommendation of whoever is providing the torque specs.

IIRC ~85% of the torque to turn a fastener is lost to friction and 15% goes into the actual bolt load. If you lower the coefficient of friction without changing the torque sequence you can increase bolt load by a huge amount... which sounds good on the surface but you can easily put a bolt in the yield region of the stress/strain curve.

Also, if you are using the ARP head studs (as we did for "insurance") make SURE you use the researched Miata torque and not the specification that comes with them.

Even the 949 supplied ones come with the wrong torque......oval bores result.

Torque specified with the bolts is for iron heads (or something equally not suitable for our motors) and is way to high.

We made this mistake and wondered why we couldn't get the engine to run up properly on the dyno....very frustrating. Silly mistake but VERY easy to do, especially when you are pushing to get the motor built for an event and just follow the directions...:vash:

I had lots of HG problems with the Silver car when I was tracking it (composite HG and OEM bolts). So now I just run MLS gaskets and ARP head studs on all my Miatas (using the Mazda torque value of 60 ft-lbs). No issues since doing that, but it might be overkill. I'm OK with overkill though.

I was referencing cxracer's greddy kit, didnt know if that was above or below my intended power range. But thanks for the advice everyone!

^^ This, if you have to open the motor anyway, the cost of the studs is cheap in comparison of the repairs required should the reuse of OEM bolts fail.