Exhaust manifold studs
- Thread starter BuiltMK3
- Start date
Gotta get em at Toyota...I check w/ ARP and no luck. Tried to see if the Chevy/ford ones would work (with helicoils), but they're not big enough to drill out the hole to remove the 10mm threads.
Soooo, ended up using Toyota ones, but did get ARP stainless 10mm 12 point nuts and washers. Here's the part #:
10mm 12 pt nut AMN12-2-3
10mm washer AMWC630
Be warned...The nuts are $5.50 each!
I went ahead and helicoiled the 10mm studs into the head...much stronger and no more worry about stripping them like this motor is prone to do. Also enable a 45 ft/lb torque vs the stock 29 ft/lb
Soooo, ended up using Toyota ones, but did get ARP stainless 10mm 12 point nuts and washers. Here's the part #:
10mm 12 pt nut AMN12-2-3
10mm washer AMWC630
Be warned...The nuts are $5.50 each!
I went ahead and helicoiled the 10mm studs into the head...much stronger and no more worry about stripping them like this motor is prone to do. Also enable a 45 ft/lb torque vs the stock 29 ft/lb
figgie said:
Very true...hence the helicoils. :biglaugh:
Work out to be 2-3 times stronger than the aluminum itself (that's why they're used in the aircraft industry). One of the problems with this head is the exhaust manifold will work itself loose from the heat cycling...the extra 10-15 ft/lbs of torque enabled by the helicoils go a long way in preventing that. Especially with ARP nuts/washers.
Helicoiling the exhaust studs is really easy when the head is off...and I've had way too many guys tell me how they've stripped an aluminum stud hole. I figure it's good insurance.
i had my head rebuilt recently and most of my stud threads were deteriorating so i knew i should have something done. They installed Time-sert (not helicoils) they are better. then they installed new studs which look to be grade 8 at least. As for the nuts i will probably use stock manifold nuts unless they used different thread on the studs and didn't tell me.
Yea, i removed the exhaust manifold today and 2 of the studs came out of the head with the nut. They are soaking in PB blaster right now in a Zephyr Hills bottle. :biglaugh:
jdub said:
actually
i worked in the aerospace industry. That was not the reason for helicoils and on structual parts they NEVER EVER used helicoils
First of all airplanes on most panels don't use that type of system. They use a riveted in place like thishttp://www.milspecproducts.com/ms-cm1exploded.JPG
no helicoils no mess.
Unlike in the automotive industry where they use cutting tapps. The Aerospace industry actually uses pressure to form the threads. This process is much stronger than cutting as pressure threading moves the aluminum from where it is at to make the thread. No chips, no debris.
figgie said:actually
i worked in the aerospace industry. That was not the reason for helicoils and on structual parts they NEVER EVER used helicoils
http://www.milspecproducts.com/ms-cm1exploded.JPG
no helicoils no mess.
Unlike in the automotive industry where they use cutting tapps. The Aerospace industry actually uses pressure to form the threads. This process is much stronger than cutting as pressure threading moves the aluminum from where it is at to make the thread. No chips, no debris.
Thanks for the correction...I based my statement on research I did when I concluded there was a problem with the studs stripping on the exhaust side of the head. Here's a couple of articles where they mention helicoils are used in aerospace:
http://www.manufacturingtalk.com/news/hec/hec103.html
http://www.casa.gov.au/airworth/aac/PART-6/6-058.HTM
http://avstop.com/AC/apgeneral/REPAIROFDAMAGEDINTERNALTHREADS.html
Do a Google search on helicoils and you'll have plenty to keep ya amused for a while. Seems that helicoils are used in certain applications in addition to rivets, etc...didn't know they didn't use them on structural components.
Seems helicoils are used in both Continental and Lycoming aircraft engines for spark plugs...read several FAA Airworthiness Advisorys on the subject. There are also specific FAA Advisories forbidding their use (propellers for example). I've seen them used on aircraft engines per FAA specifications (both turbine & recip), but I'm not an AME...I just fly the equipment :sonic:
The conclusion I came to (especially after reading a Stanford Univ. mechanical engineering research paper) is helicoils are very strong, especially when used in softer material like aluminum. They can be used in applications that have a very high psi specification (exceeding 200,000 psi) for the bolt/stud...the paper addressed larger diameter fasteners, but combined with what else I found out, helicoils are a very good way to go.
In addition, applications in aluminum and magnesium where galvanic corrosion between dissimilar metals is a concern, holes can be coated with primer or helicoils purchased with an epoxy coating to prevent seizing. One other problem with steel to aluminum threads is galling...that can really ruin your day when the bolt/stud "locks up".
There's no doubt in my mind that helicoiling the 7M exhaust studs is, granted not the cheapest, but one of the best options to prevent stud failure and help keep the exhaust manifold nice & tight against the ports.
Just my humble opinion...for what it worth :icon_wink
