Thread: converting 429 to 460

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ive got a 4 barrel 429 with d3ve a2a heads. i would say that this motor is all original. if i were to convert it to a 460 by fitting a 460 crank and standard style 460 pistons what would my new compression ratio be. i have read that dove heads have a 77cc combustion chamber where as d3ve heads have a 97cc combustion chamber. is there an automatic increase in the compression ratio by going from a 429 to a 460 while still using the original d3ve heads. if so can you tell me what i might expect my original 429 compression ratio might be and what it will be if i do the conversion to a 460. how is the 460 motor compared to the 429 in regards to its feel, performance, drivability, fuel economy, revs, or any other factors you can give me. this motor is in a ford galaxie 1970 ltd. it was australian delivered rhd with a 390. someone else did the conversion to the 429 and i suspect the motor was out of a thunderbird, just an educated guess. is converting to the 460 worth it or just a waste of time and money. thanks, paul.

You don't mention whether your 429 has flat top pistons, or if the 460 pistons will be. With both having the same top configuration, the compression ratio will of course be increased in direct ratio to the displacement, or approx. 8%.
An 8.6 ratio would increase to 9.2.

OK, found some specs. All '73-76 429's and 460's were 8:1 except the '74 275 horse 460, at 8.8:1. The earlier performance 429's had from 10.5 to 11.7.
With both having the same ratio, the 460 must have dished pistons, so would end up with the same ratio as your 429 has now.
If you are going to rebuild it anyway, the 460 conversion might pay off. I wouldn't tear down a perfectly good engine for a 30 cube gain, though.
That 8.8 comp. version in '74 probably had flat-tops, those might be worth looking for.

Not sure I would put the 460 crank in. As the Pope said, it's only a 30 cube gain.... With the shorter stroke, the 429's rev up a lot quicker then the 460's... If it were mine, I would use the best pistons I could and optimize the compression at about 9.5, do a bit of porting on the heads and use it as is....

hi there guys thanks for your responses, i think i will invest in a good 429 rather than converting to a 460, and compression i can sort out with the correct pistons to suit application.

Sounds like a heck of a good plan to me.... Always liked them 429's. With the right cam and good compression they will run stronger then a lot of the 460's, especially the one's with the "lazy" timing chain and gears set.... Have fun with the build.

Originally Posted by gal429460

ive got a 4 barrel 429 with d3ve a2a heads. i would say that this motor is all original. if i were to convert it to a 460 by fitting a 460 crank and standard style 460 pistons what would my new compression ratio be? is there an automatic increase in the compression ratio by going from a 429 to a 460 while still using the original d3ve heads? how is the 460 motor compared to the 429 in regards to its feel, performance, drivability, fuel economy, revs, or any other factors you can give me. thanks, paul.

The 1973 429 is the slowest, laziest 429 ever produced. Although all the individual parts you have in the engine can be massaged into fine perofmance engine parts for the street, the actual combination of those parts together (as in your engine) is a bad as the oem cobination can be.

Assuming that it IS a bone stock oem 1973 429 (and it sounds like it based on the heads, carb and the car from which it originated), you have a wimpy 7.6:1 compression ratio. Switching to the early-style heads (D0VE, C9VE or C8VE) will bump compression ratio to about 8.6:1 in this particular case. Doing this and also adding a timing chain set to pre-1972 specs will help measurably. So would porting the early-style heads prior to installing them. If you think you have a decent engine now, you are in for a big surpise once the changeover is made, as it is curretnly the doggiest of 429 motors.

Generally speaking, the 429 is a very smooth running engine and can last a long time. But the 1973 cobination is the worst offered of the 429s. My advice is to continue to run the engine if it is running fine, and in the meanwhile start learning about these engines and collecting the parts needed to give it some oomph or use when you rebuild.

Paul