I am getting near(ish) to the end of my LQ1/F23 swap. I don't have any starter bolts and will need to source some. I know they're M10 but I need to know the thread pitch and also the correct length for both. If anyone could me help me out I'd be grateful.

DF

Do the standard ones not work? I've always simply used the ones from the fix-it section of any auto store.

Oh, I didn't realize these were an off the shelf item. Called my local Car Quest and by golly they have em. Thanks.

GM starters w/ 2 vertical bolts need special bolts made for this job. Do Not substitute.
Bolts have "self locking" features to prevent bolts and starter from dropping on highway.

3 different length. Many use 1 short and 1 long. Other use 2 medium or 2 long, etc.
Example: https://www.dormanproducts.com/p-15719-45640.aspx
Click picture to "zoom" to see way different bolt.
Other bolts may say are "starter bolts" aren't for most GM cars.

Hardware and holes must be clean and dry and proper torque.
If engine is aluminum block look up torque table for that engine, not Fiero engines.

Likely need starter shims too.
See my Cave, Starter
If use a ½ shim... file or hammer cut end to thin that area so parts doesn't have point stress.

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Dr. Ian Malcolm: Yeah, but your scientists were so preoccupied with whether or not they could, they didn't stop to think if they should.
(Jurassic Park)

The Ogre's Fiero Cave