I have been buying ARP bolts the past couple of mods and have been messing up the measurements by just single pitch numbers (ARP bolts are not cheap when doing this over and over). So I wanted to start this to let everyone know what every bolt size is for our cars, as far as engine bay for now. I will edit the list of sizes as more come in. Thanks guys for the help. List how many for the part (headers, intake, TBI unit etc), underhead length (threads only), bolt head size, bolt thread width Also please specify which engine the bolt came off of, I know our motors are roughly the same but you never know. I hope to soon have a complete engine bay nut and bolt ARP reference thread, with your help. To start off. I need these below. I will also be adding my collector bolt sizes for the 2055's as well as many others once I have time (working on car right now, needing this information) Starter Bolts (LO3 TBI) (Stock) xx Total Bolts 3/8-16, 4-5/8" (MSD APS Mini) xx Total Bolts Ignition Coil Bracket Bolts (LO3 TBI) (LO3 TBI) 2 Total Bolts 1 bolt is 1" with 3/4" under-head, unknown pitch and head size 1 bolt is 3/4" with 1/2" under-head, unknown pitch and head size EGR Valve Bolts (LO3 TBI) 2 Total Bolts Hooker 2055 Header Flange Bolts 16 Total Bolts 3/8-16, 3/4" or 3/8-16, 1" (I verified 1" will work with Fel-Pro 1444 gaskets) Hooker 2055 Header Collector Bolts 4 Total Bolts 7/16-14, 2" Magnaflow 16829 Cat-Back Exhaust Bolts 1 Total Bolt 3/8-16, 1-1/4" (Please verify, have a hard time tracking threads but this is what I got) TH-700R4 Transmission Pan Bolts 14 Total Bolts Edelbrock 3 point Strut Tower Brace 6 Total Bolts? Thanks guys, this will be a great thread in the coming months. Also a great reference page for needing a bolt that isn't there anymore. P.S. I will re-organize this once it starts to fill up, I'll do it in alphabetical order.

Hey WWD.

Starter bolts use a special alignment groove thing on the shank of the bolt to make sure the bolts are aligned just right. Keep in mind, if the starter is a few thought off, it'll grind. Shims will take it up or down (in relation to the ground), but with the right bolts, the starter will be lined up right WRT to the flywheel/flexplate.

The bolts are 3/8" NC, and around 3" or so. As my block was cracked in the outer hole, I did use a GR8 piece of ready-rod, and a nut. Of course this is a no-no, but I was very careful to make sure I lined it up right before tightening down the nut (ie I did this assembly with the engine on a stand, up-side-down, and the starter bendix kicked out into the flywheel.). If you are careful, you can do this method.

Anyone have any idea what size the bolts are to the dust cover on a T56?

Educated guess would tell me 1/4" coarse, but its probably metric on the T56.

This is what is listed for ARP Starter bolts. 2 sizes of 3.7" (about what sonix said) and 4.45 (said to be used on mini and large style starters).
Compare

Went to ARP's site and they recommend 430-3504 starter bolts which are for high torque mini starters (I'm getting the MSD APS mini starter), still would like this verified.

Still need some answers guys. Thanks

Header Bolts (Small-block Chevy V8)
3/8"-16, 3/4" or 1" long.
12 total

Most manufacturers say 3/4" length. And that's fine, if you don't want them to stay in.

I've paid too much money for just about every maker's special header bolts. Stainless steel with flat washers. Key locks. Expansion locks with set screws. You name it. Either they're impossible to assemble on all the holes because of the tube bends. Or they won't stay in. Either way, you get exhaust leaks. ARP claims you don't need locks, but even ARP bolts wouldn't stay tight on mine. Yes, tightened to ARP's specs.

The only header bolt lock system that WORKS is to use old-fashioned split-ring lock washers.

So get stainless steel bolts with 3/8" 6-point or 12-point heads, or Allen or Torx heads, brand of your choice. Then run down to your local hardware store and get 12 stainless steel lock washers for them. Problem solved.