This is my first post in awhile. I looked through some older posts to try and find answers to my questions and couldn't so here I am posting.....

Now that that's over with here's my dilema:
I have a 65 Valiant with a 170 & 3 speed on the tree and I'm looking at a 225 out of a 75 Valiant with an auto. I'm hoping to keep the 3 speed that I have but I read somewhere that there are some potential problems between the 67 and older and 68 and newer slant 6's... Does anyone have any advice? It looks like I might need a new flywheel for the newer engine.... Any advice/helpful hints would be awesome!

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65 Valiant 4 door 3 on the tree 225 /6
65 Valiant 2 door Auto 225 /6

You will need the appropriate flywheel, clutch should be the same. You will also have to use the oil pan and pickup off the 170 as well as the motor mounts. Also you will either have to use a 225 exhaust pipe or splice in a section on the 170 pipe to make it longer.

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Official Cookie and Mater Tormentor.

There are a couple of important issues you will have to address. First, make sure the newer engine has the pilot hole drilled for the manual trans input shaft. Not all automatic trans cranks are. Should be about 3/4 in diameter and about 1 in deep. If it is not drilled, all is not lost as long as it is a non-perf application. I have successfully drilled the back of the crank for a pilot hole with a 11/16 ,3/4, 13/16, or 7/8 masonary bit, (I do not remember the size.) Start with a smaller pilot bit to center the hole as much as you can. I used middle of the road masonry bits, no China bits, and they cut the forged steel quite effectively. It was down and dirty but for a non-perf engine, it was successful and used for over 25k miles or so. The truck died about three yrs or so later and no problem ever surfaced during its operation. Small note here, I would not do this in a performance application.

Second, if you decide to use an early automatic trans, you will need to make a bushing approx 1.75 o.d. and 1.5 in i.d.. These are only approximate numbers, you'll want to measure the converter hub hole at the back of the crank and the converter hub. Leave a little slop, maybe .030 or so, shouldn't be too tight. The early engines have the smaller hub hole for the converter. I think it changes in 67 or 68. It is important to have the spacer sleeve because a stock 1969 318, driven mildly aggressive, will destroy the flexplate in about 10 months. Speaking from my own error here. Using a later trans solves the converter issue but creates shifter issue. Not rocket science but too important to ignore. dan...

The pilot issue is easy to solve. Just get a roller pilot for a V-6 Dakota truck and trim the end of the input if needed.

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Official Cookie and Mater Tormentor.

slantzilla is absolutely right. Best solution for manual trans application. You often see Chrysler 3 or 4 speeds with 1" shortened input shafts. No harm is done to trans.

Heres additional info specifically towards using newer engine w/pre 68 automatic transmissions. SB's have same issue, don't know about BB's. Probably a 904 spec issue.

http://www.225.ca/tech/s6rn05.htm gives this info: "...the increase in the rear flange's locating hub/torque converter pilot hole size. Chrysler did this in 1968 to allow the use of a larger automatic transmission input shaft spline. (60-67 is 3/4" diameter with 18 splines, 68-87 is 7/8" with 28 splines). The early converter nose pilot hole is 1.565" diameter, the late one is 1.815"