question about the differences in 404 motors

Background - i have an opportunity to buy a 7020, motor got hot, a rebuild may be an option, but im not sure yet, but if a different motor is required then so be it. That is where the questions come in. The 7020 got a 404, the 7520 got the 531. But when looking at different models that carried the 404, i see a few differences such as a turbo, but for example, the 4020 is listed at around 85 hp, the 4620 is listed at around 135 hp, the 7020 is listed around 127 hp. I am not including combines, even though that could be an option.

So the question(s) now becomes, the 4020 to 4620 is a big jump in hp, the 4620 and 7020 were built at the same time, 10 hp difference, are these differences due mainly to injectors, or pump, or were there more differences? I know the compression ratios vary a little, but were cylinder heads modified as well? A friend of mine has a 404 out of a 4010 that i could get, but a 7020 with 85 horse, another option could be a 531 from a scraper, but i dont know if that would be an easy transition, even though the 7520 got them.

Help with the differences in the 404 would be great, i have searched, but havent really found anything concrete and i see a lot of knowledgeable new generation guys on here, hoping they can help.

Thanks.

Yes they are the same and different??? I know in can be confusing. The 4010 404 is not a good thought, they don't have as many engine side frame holes as the newer ones, as the progressed they got better, the 4620 blocks are the same bolt patterns as your 7020, they have a bit different shape near the lower left side to allow for 4620 steering lines to pass through, the higher HP engines have bigger injection systems, inter-coolers and turbos., the newer 466 engines will work good too, with the exception of the latter style engines (50 sereis0 they have a larger side frame bolt and pattern. for your application a 7720 combine engine would be a good choice, 466 cid,turbo, and will deliver 175 HP all day long.

Tim S,
Thanks for the insight. That does answer a LOT of questions for me. I was kind of surprised to see the 7020 only listed as 125 hp tractor. I actually never thought of the 7720/8820 motors. I figured there was to much different in the 466s to put one in, but i like that idea a lot more. My 8820 almost has power to spare, so a 7720 motor would be pretty cool, plus there is a combine salvage yard close to me that has plenty of 466 motors and he is a nice guy.

If this deal does happen, ill probably have more questions for you hah

Again, thanks a bunch for the help.

I will be glad to help guide you through the swap. There are a few minor things to work out..I think a little bracket to mount the air cleaner on and a couple other things that will work out good as you go....

Forget all that and go with the 466 that fits your bolt pattern.

Find a 466 or 7.6 . More displacement and much better flowing cylinder heads. The 404's were choked with small ports and a modest cam profile.

Tim gave the best choice, a 7720 combine engine. We put one in a late 4430 and a 4320. Lots of snort, BUT they like to heat up if worked too long. Not enough cooling capacity on the tractors end of the deal. Yours may be fine though.