What size are the TB Plate Bolts?

[IsaacHayes]

I'm not sure the 2.8 TB plate bolts will work on the 3x00. The torx they use is very very small I'll have to get my torx that I use for taking apart my cell phone to take them off.

Crazy that GM halved the throttle shaft from the factory on the old motors. That means at WOT it has more flow than my 3100 did stock! LOL Too bad those gen2's didn't really need it. hahah

I will find out tomorrow if it works in the 3x00 ones.

[IsaacHayes]

Well in case anyone is wondering, the flat head 2.8l TB bolts do NOT fit the 3x00 TB's. Damn. Weird that the 2.8's had the shaft halved stock...

[3400-95-Modified]

What are you trying to accomplish and what do you mean by halved?

[IsaacHayes]

The shaft that the butterfly plate bolts to, well on performance TB's and on stock 2.8's, they cut the front half of it off, so that only the back side of the shaft is left, and the bolts just hold the plate down to the back half of the shaft and do not go through the front of the shaft. So it gives you more CFM when WOT as you have half the thickness of the shaft blocking air flow.

The stock 3100 plate bolts are tapered head, and won't lay flat on the butterfly plate. So I was gonna use 2.8 TB bolts since they are flat as the shaft is halved, and halve the shaft on the 3x00 TB. But the thread size is way too small on the 2.8 plate bolts. It takes like a T9 torx IIRC to take them off too.

http://www.holley.com/data/products/pictures/large112-558.jpg

Take a look at that and a stock 3400 TB and that should explain it.