The Stovebolt Site Forums The Shop Area The HiPo Shop Metric fastners in a Chevy v8

I live in a land where plastic rusts. Doing the valve seals debacle I had to pull the headers off. I noticed the bolts were rusted. Okay go to jungle store and order SS header bolts. Go to install headers and new bolts.
Grab 3/8 socket... what the ?? Does not fit. Try other sockets/wrenches, Nope. Grab 10mm socket and a perfe ct fit. Why machine a 3/8 thread and use a 10mm head?
Bet you can guess where the bolts were manufactured.

ARP does the opposite. They put american sized heads on metric threaded bolts.

ARP and others have the combo Fibonachu mentions because folks that are stuck with metric threads want to use their SAE tools. An accommodation for USA customers. I don't know who is accommodated with the combo you have. I hope you did not use a cordless or electric or pneumatic driver in case the whole fastener was metric. A SS bolt will be hard like a tap. Anyway if that was not spelled out by vendor, I would have sent them back. What vendor was this? Part number? Don't know what "jungle store" means.

My extra strange thoughts. Sense the internet and AI does not show any SAE thread/Metric head bolts..........Header bolts are usually 12 point, maybe you tried a 3/8 6 point socket on a 12 pt head, then used a 10mm. 3/8= .375, (10mm= .393) and the 10mm 6 pt slipped over the 12 pt, jammed up, torqued and voila.... or as I said, the whole bolt is metric and you "rethreaded" the head.... or the whole bolt is metric and you have a motor with metric threads. I asked for vendor and PN so we can please see this weird bolt.
The 3/8 SAE and a 10mm thread have near the same pitch. So this adds to some concerning possibilities.

Jungle store = Amazon. No 12 pts. I specifically looked for regulator bolt heads. Reason is, I can't get a socket on several of the bolts. Header tube is very close to the bolts hole, had to use open ended wrench. After finding 10mm head, I checked threads with thread a sizer.
They are 3/8 threads.

SS fastners are brittle, hence never sneeze, and tighten frequently

Vender is JBKE
part no. Is LYH-AD224EX

On Amazon it states 3/8 Thread, nothing about 10mm head. The bolts went in just using fingers and hand holding socket where I could.

I see what you mean, very deceptive. The vendor failed to tell amazon it is a metric head, Just says 6 pt head. A search comes up as available at Amazon, Sierra Leone and Jamaica. That's why the internet does not know about this bad choice. You did the right things, you didn't ever suspect this kind of bolt. All is well.
Thanks for the info. I wrote to Amazon to tell them there is missing info purposely left off by their vendor who is dumping a manufacturing mistake bolt on them. Once Amazon terminates them, folks will have to buy from Sierra Leone or Jamaica

Just little things like can...well just shake your head.
I wrote this down in my truck notebook. At least I tested sockets first.

They do look better with ceramic coated headers.
Typical stuff from chinaco.

That’s why I order fasteners most of the time from McMaster
Unless it’s for a special purpose like rod, main or head bolts

We have a vendor here, Automotive Fasteners, who typically have exactly what I need in stock. There are some cheaper made fasteners available, you just need to be careful when ordering.