i know alittle about the old 472 and 500 motors from years ago, but i don't know nothing about the 425. i was given one that i was thinking about using in my 27 t roadster, so i need some info about the little motor. do the intakes from the bigger motors fit the 425? if so how well does the older (69 - 70 472) heads work on the 425? thanks
10-31-04, 05:59 PM
You might want to read the "cheap improvements to the 425" thread in this forum. The 472/500 intakes will fit.
Why would you want to use the 69-70 heads? All 68-73 472 and 500s have the 76cc heads. Maybe you already have the heads... They do have bigger ports than the 425 heads. And since when is 7 liters little? :)
10-31-04, 08:03 PM
yeah, there is alot of good info in my thread about cheap power improvements...
the stock 425 has a lackluster 8.2:1 compression.... I know that the heads form a 472/500 (not sure which years though) will go right on the 425, and give you a smooth 10.5:1 compression, and make really nice low end torque.. but by 4k RPM, the engine would be out of it's power band... which in the DeVille's these engines came in, is already redline....
thanks for the info on the other thread i found it. the reason on the heads is to get the bigger ports, a little cam and you can move the power where you want it at. i have run some 455 olds in the past that may be why i called it the little motor sorry.