241 Heads

[Fu Manchu]

Does anyone know why this thread is not M10 x 1.5 thread?

The two top threaded holes are M10 x 1.5. One of which is one of the harness earths. This has my interest.

 

[Fu Manchu]

It’s threaded as either of these two. I can’t thread them in to check though.

I’m also unsure how to read the pitch.
Hole size is 7/16ths.
20 threads per inch? 14 threads per inch?
A UNC size?

The bolt in there is M10 x 1.5
It threads in and then catches at that depth.

 

[Deuce]

Yes, 14 & 20 are the thread tooth count per inch.
I think metric is the distance between each tooth (metric is weird. It'll never catch on)
14 tpi is kind of close to 1.5 metric count.
I don't see why they would change systems for 1 hole. Are you sure it's not just a little burr in the hole stopping you?

 

[Fu Manchu]

Well I tried to thread the bolt in. It caught. So I went to chase it out with a M10 x 1.5 tap but it too caught so I didn’t force it through. Left it.

Yeah it seems odd that the heads would be threaded like that.

 

[losh1971]

Being a US engine I would have thought the whole engine would have imperial threads, Buick was. I've had other US engines and always been imperial on the engine, yet all the rest of the bolts were metric.

 

[Fu Manchu]

Right. It is M10. I got my hand in to thread using the other hole hidden away and it too was M10.

I was reluctant to force the M10 in more than finger tight until I check it out.

Got a spanner onto it and it went in and out the thread ok. Took it very gentle. I’m not fkin about with bolts on the heads. Gently chased out the thread with a tap. It’s never been used so had darker oxidised alloy coming out. All good now.

So now I can use that for the earth from the harness. Then the bracket for the catch can will go on fine.

 

[07GTS]

some of those threads are just for a cable zip tie with the bit poking out to stick into, not all for actual threads

 

[Immortality]

Being a US engine I would have thought the whole engine would have imperial threads, Buick was. I've had other US engines and always been imperial on the engine, yet all the rest of the bolts were metric.

For some reason GM started using metric threads on the LS motors. Yanks are hard to understand.

 

[Fu Manchu]

For some reason GM started using metric threads on the LS motors. Yanks are hard to understand.

I read that in a New Zealand Accent.

 

[hademall]

Are you sure it's not just a little burr in the hole stopping you?

That’s what she said.