350 flex plate/torque converter bolts?

[STLRegal]

What the hell kind of bolts/nuts do I need for this setup? Neither the flexplate nor the TC is threaded and the bolts from oriellys are even too big to slide through.

Engine is a Chevy performance 330hp crate engine
TC is an unknown high stall.

I'll update with pictures in a bit

 

[STLRegal]

Pictures

 

[pagrunt]

Should be 3/8" bolt, if not try 5/16". Worse case try M8 or M6. What size was the bolts you grabbed?

 

[Texas82GP]

Go with all grade 8 hardware on that. Use threadlocker. I'm guessing that takes a 3/8" bolt.

 

[STLRegal]

Not sure. I just asked for 84 Monte Carlo SS flex plate bolts. I measured the bolts and look to be 3/8, but they are marked with an M so could it be metric? I'm more confused by the lack of threads on either. Is it common for FP/TC bolts to require nuts as well?


When I pulled the 3.8 and 200 the bolts threaded right into the TC.

 

[Injectedcutty]

Not sure. I just asked for 84 Monte Carlo SS flex plate bolts. I measured the bolts and look to be 3/8, but they are marked with an M so could it be metric? I'm more confused by the lack of threads on either. Is it common for FP/TC bolts to require nuts as well?


When I pulled the 3.8 and 200 the bolts threaded right into the TC.

You need grade 8 (6 dash marks on the head of bolt) 3/8-24×3/4" long with matching high strength nuts and some blue loctite. I always use ARP bolts for these critical areas as you don't want them backing out, and use the torque spec they suggest for the bolts. Some Oreillys carry them, i usually get them from summit racing. Part #ARP-230-7301... $17. Hope this helps.

 

[Injectedcutty]

What the hell kind of bolts/nuts do I need for this setup? Neither the flexplate nor the TC is threaded and the bolts from oriellys are even too big to slide through.

Engine is a Chevy performance 330hp crate engine
TC is an unknown high stall.

I'll update with pictures in a bit

What's the flexplate from? Just noticed you said the bolts you got won't fit through the hole.

 

[STLRegal]

It came with the engine which is a Chevy 350 HO. Which I bought from jegs.

I couldn't find a part number but it is a 12.75 flex plate

Here's the link on jegs
http://www.jegs.com/p/Chevrolet-Per...O-Turn-Key-350ci-333HP-Engine/819588/10002/-1

 

[Texas82GP]

Not sure. I just asked for 84 Monte Carlo SS flex plate bolts. I measured the bolts and look to be 3/8, but they are marked with an M so could it be metric? I'm more confused by the lack of threads on either. Is it common for FP/TC bolts to require nuts as well?


When I pulled the 3.8 and 200 the bolts threaded right into the TC.

Usually the backup is welded to the torque converter, at least with stock stuff. You will be allright as long as the hole size in the flex plate is the same as the torque converter. The "M" stamped on the bolts they sold you for the stock setup indicates those are Metric bolts.
http://blog.chiltondiy.com/2013/12/how-to-recognize-metric-and-sae-bolts-2/
It would be best to measure each hole with a digital caliper micrometer to compare them. You can get one inexpensively at Harbor Freight or even the Home Depot if you don't have one. They are a great tool to have in the box. If you don't want to do that try a 3/8 bolt and see how it fits on each side, and if it's not 3/8 try the next logical size. Just be sure in the end you use Grade 8 hardware if they are standard thread bolts (USS Course or SAE fine) or that they are 10.9 tensile strength if they are metric. Use the blue locktight as previously recommended. My gut says Scott gave you the part number you need above for ARP brand hardware which is great stuff.

 

[STLRegal]

well I test fit the bolts that came off the original TC and flex plate and they fit well. i think I was just over thinking it. It just didn't seem right to have the flex plate resting directly on the threads of the bolt.

Should I use lock washers on top of blue loctite?