Up until a cpl months ago, I would have assumed that the 426 was no different than any other BB Mopar. Pick a converter, 727 and bolt it together.

But wait, the Hemi has 8 bolt crank flange and larger crank bolts. So non of my flex plates fit. So now get an 8 bolt flex plate, then bolt a converter on and go.

But wait, 7/16 converter bolts.

This is where I am now. is there anything else to this that I'm still missing and am going to find out bit by bit lol

I've searched and read that Hemi converters are "dimpled" to clear crank bolt heads, but all my converters are dimpled in that area to some extent.

Bottom line;

I have a 727 that was built with stage 2 shift kit some years ago and 3500 stall converter. (10 x 5/16). Had this behind a 450hp 383 and worked well even with 3.54 gears.

1. Can you use any BB 727 behind a 426 Hemi? (or is there more info I'm missing, like the 3 different ring gear sizes I read which made no sense for 68-71 anyways)

2. Did the Hemi come with both 10 and 11" converter bolt patterns or only 1? (I've only read they were 10x 7/16 so far)

3. Can I assume with 8bolt Hemi flex plate, all I need do is drill and tap 3500 stall converter for 7/16 bolts and go? Also keeping in mind crank bolt head clearances.

I do have a Saturday Night special new in box as well, but it's much lower stall and 11 x 5/16 pattern.

Help!

most aftermarket convertors have 7/16 bolts, I don't thing there is enough depth to run a tap? at one time mopar performance had a 8 bolt flexplate with 5/16 convertor bolts
gary

All 727 converters have a 130-tooth starter ring gear.

The B&M #10231 flexplate is for 8-bolt cranks and has both 5/16" and 7/16" drive bolt holes on a 10" circle.

Some great info already, and really appreciate the responses.

Hate being rushed, but car is supposed to be together and in a show by a week Thursday, so any snags or surprises are what scares me.

Should I be concerned about 5/16 torque converter bolts vs 7/16?

My gut says no, but that's coming from a punk that did 3000rpm neutral drops 30 years ago before ever owning a high stall. (never an issue with the 5/16 bolts, can't say the same for one of my 8 3/4" yokes though! lol)

All the stock and race Hemi cranks use a 1/2 fine thread size bolt, not 7/16 like all the other Mopar crankshafts

cab is right. i found out the hard way, trying to use crank bolts i had lying around. went to bolt on the flexplate, and my bolts were too small. had to wait a couple days to get the right ones [1/2x20].

And, the bolt torque between the flex plate and the crank is significantly higher. Those well-tuned Hemi's are nearly 2-stroke like in their power delivery. It takes a smart converter builder to hook on to that at the right place in the torque band.

Well ordered everything, so we will see how it all goes.

thanks!