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Old 03-02-2014, 11:57 AM   #1
calirubi's Avatar
Join Date: Feb 2013
Location: Chula Vista, ca
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1970 cj5 enging swap help

Have a great 1970 cj5 that needs an engine upgrade. It had the Buick odd fire 225 v6 and a three speed. I wanted some opinions on what engines will fit best sense the engine bays on these years are about four inches shorter than other years. The transfer case just got fully rebuilt with Tera flex low gears and a twin stick conversion and I have a newer wrangler five speed tranny too. Thanks for any input guys

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Old 03-02-2014, 12:09 PM   #2
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in my opinion the 5 speed is not an upgrade to the 3 speed..yes,it has overdrive but I don't think they are as heavy duty..the 225 is a good engine to me..if you are wanting a lot more power,go with a v8..it will fit,I have run small block chevys in willys jeeps..if you go that route a gm truck 4 speed is a good upgrade

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Old 03-02-2014, 06:21 PM   #3
Join Date: Mar 2014
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This might be out of the box.

Mercrusier 470 224ci Alloy block 188hp

You can stroke it and get 253ci well over 200hp

Technical The elusive 224/3.7 MerCruiser banger - THE H.A.M.B.
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Old 03-04-2014, 06:05 PM   #4
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I might have to find a sm420 four speed due to the length of the five speed if I don't stretch the wheel base. The chevy 350 sounds nice. Easy to find and pretty cheap too. From the measurements I had it look tight. That merc motor is interesting.
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Old 03-05-2014, 08:19 AM   #5
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If you want a bolt-in, the 340/350 Buicks will. The existing transmission should be a T14 which were some of the better Jeep 3 speeds.

If the future use plans include trail riding, a 4 speed would be the best option and for those, the SM465 will be the shortest adapted length. While the Buicks bolt in, the parts selection isn't that great and the prices will be more than a Chevy.

As for the merc, it may weigh a bit less but power wise you would be better off keeping the 225. With a cam, headers and a small 4bbl, pretty easy to pull 200 hp from one.

What would I do? There would be the ubiquitous Chevy 350 in it with the SM465 and I would be keeping the D18 and add an overdrive. Best of all possible worlds. I like D18's. They can easily handle V8 power, give you the best rear driveshaft angle, have the option for a bolt-in overdrive, and keep both diffs in-line which, at least for me, makes picking lines a lot easier.

Being a 70, does it have flanged axles or 2 piece? The flanged version appeared about mid year and is the best factory rear axle ever put in a CJ.
1947 CJ 2A, 1949 CJ 3A, 1955 CJ 3B, 1968 CJ 5, 2012 JKUR
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Old 06-14-2014, 11:31 AM   #6
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Location: Jacksonville, NC
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When you take out the 225, what will you do with the T14 Tranny?
1970 Kaiser Jeep CJ-5
1997 Jeep TJ (Right Side Steer)
2013 Jeep JKU Technology Demonstrator
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Old 06-22-2014, 08:48 PM   #7
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I had a 71 CJ5 with the oddfire V6 I dropped in a evenfire 231 Buick V6
and rebalenced the flywheel. bolted right up.

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