250 differences HELP

[65andonly18]

Ok so ive been trying to find a 250 to put in my 65, and when i looked at the casting numbers on Fordsix.com they grouped 69 thru 74 as the same but when i looked into those years after 71 the horsepower went way down. So how to i make sure that i get a 69-71 engine if the casting numbers are the same? Help please.

 

[wallaka]

They changed the way they measured horsepower in 72, from a gross measurement (no air filter or accessories and open exhaust) to a net measurement (with all of the running equipment, stock manifold and air cleaner). The later numbers are more accurate.

Don't worry about it.

 

[MustangSix]

They switched to a cast iron rod in 1978. Otherwise all the rotating assemblies are the same.

The only other major change was the cam timing in 73-74. Same cam, but the later cam gear retards the cam by several degrees. That pulls the power down, but reduces NOx emissions.

But most of the "power loss" can be attributed to the change from measuring SAE Gross HP to SAE Net HP. The engines are otherwise the same.

 

[69sixstang]

Make sure you do some measurements before , getting to far into this 250 swap. I have both motors and there is a ton of differences. 1. taller deck height 2. timing chain differnt 3. Oil pan is differnt (whole bottom of engine is wider. 4. aftermarket headers are differnt. 5 bell housing is differnt(unless you have a late 66 motor) 6. water pump is 4 bolt instead of 3 There is even a differnce between your 65 and a late 66. I learned all this from triaL and error. Hope this helps you out.

Mark