A seemingly simple question I should already know the answer to.... I am going to swap my 904 to a 727 this weekend. I am running the original 318 block that I grew into a 340 six-pack in my 69 ragtop Fury. I am finally putting a 727 from a 340 Dart behind it. I have the original 340 Dart's torque converter as well. I have a drive shaft from a 727 2-door Fury, so I am ok there...The question is, Do I have to change the flex plate
Joined: Sat Dec 10 2005, 04:28PM
Location: United States
Posts: 4954
Hey Rag top
It looks like the answer to that question might be yes you do
I looked it up in the trusty ol Mopar parts catalog for 70 and 71 years. It shows the drive plate part number #2400 885 for standard automatic trans for 318, 340 and 360. Standard trans is the 904. But for the "heavy Duty 727" it shows one part number across the board #2204 768.
Joined: Fri Oct 07 2005, 12:03PM
Location: Central Ky.
Posts: 1575
Well, it's more of a "might" have to. All 6-bolt cranks use the same pattern there but the 904 most likely has a lo-stall stocker converter ( 12") & the stock 340 converter should be the smaller 11"( 10 3/4 actual ) & that's where the pattern would be different. Should both be the 5/16" bolts for converter to plate on both.
Joined: Wed Oct 12 2005, 08:03AM
Location: utah
Posts: 40
Both are right, all 6 bolt v-8 and later sl6's the flexplates all supersede to 2 different ones, one has an 11" bolt pattern (and has round holes) and a 10" pattern (and has triangle shape holes). Measure the pattern on the converter you are putting in , it will be 10" or 11", and look at your old flexplate, I am betting the 904 has the big pattern, if you need a small one, they are still available, part# 4058429 (if I remember right). It fits all the way up to 92, and should be easy to find.
Well my trans is in!!! As it turns out the original 904 t-converter and the 340 unit are the same bolt pattern so I did not have to change the flex plate. I have a minor problem with the kick-down linkage not reaching, I'll fracticate that tomorrow. The real problem now is, in all my parts lying araound, I do not have a dipstick/tube for a small block 727. I'll figure something out on that too....Cut the tab off and re-tack it probably.