360 Swap For 273

 

Tech Question

 

Nathan Cook, Yakima, WA, 1969 Dodge Dart 4dr, 360

You know that feeling when you get excited about doing a motor swap and hope everything will interchange. Well that’s what I thought when I decided to build a 1971 360 for my 1969 Dodge Dart. I am replacing the stock 273 and thought that the brackets would match until I almost finished the 360 and ran into a problem with the power steering pump. The water pump for the 273 has a mountable hole on the side and the 360 water pump doesn’t. I was wanting to know what you recommend. Should I find a more up dated power steering pump or try to change the bracket. Another thing is the lower pulley that mounts to the harmonic balancer didn’t line up so I am going to try the pulley from the 273. Any help you can provide would be greatly appreciated. Thank You.

 

Nathan-

Your real problem isn’t so much “engine” related as it is “year” related.

Small blocks changed quite a bit from 1969 to 1970. ALL small blocks. Your 1971 360 is just a “post 1969” small block. The primary change was to the water pump setup, which changed from cast iron to aluminum. Along with the material change, the radiator hose nipple changed to the opposite side. This, in turn, required that the timing indicator move 90-degrees clockwise – to the driver’s side. This, in a classic domino effect, required a different vibration damper TDC “line” location.

Somewhere around 1972, the damper bolt pattren was changed from nonsymmetrical (one hole offset) to symmetrical. This, however, is easily fixed by ovaling out one hole (in the pulley), as needed.

If you try and use components, pulleys, brackets, etc. designed for pre-’70 SB engines, on a 1970-up water pump, you’ll be in a heap o’ trouble – hassle city. This is why, for 14 years, we’ve been recommending that you use all components, such as water pumps, alternator brackets, pullies, hoses, etc. from the same year engine, be it 273 or 440. Pick a year – almost any will work. But when you start the Chinese restaurant method of mixing one from column A, and two from column B, you’d better have plenty of Excedrin handy – or a great fabrication shop at your disposal.

If it makes you feel better, the big-block situation is even worse – there were at least 5 distinct “families” of brackets and pulleys.

Rick

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