lol true.....

 

2V heads and a mild torque / RV cam and the 429 will be OK, at least almost as good as a 400 on gas. Both are gonna really like gas.

The CJ heads and such aren't for gas misers, they are for getting more through there each cycle.

I'm one that argues for using a 400 in place of a 351M or 400 for many reasons, but most people have to go look for a 429 / 460. If I had a 429 laying there that was salvageable, and if my 351M or 400 was blowed up and needed serious work, and if I didn't have to source too many brackets like "AC", and if I liked "headers" (I grew tired of the leaks many many years ago) .... I might use the 429.

 

I have a 429 in my 78. Good motor. I got no problems with her, but i dont drive it everyday. I got my 800$$ two wheel drive truck for that.
429/460 pretty much same engine. same block anyways. 385 series. 429 different stroke. I say run it!! its a good motor.

 

My motor will sure light up my 39.5 swampers like no bodys business too.

 

Yeah, I'm not looking for big power, just reliability. Both the 429 and the 400 I have out of their respective vehicles. Whichever's going in a 77 F-150 4x4 sclb with a 4" lift and 33's (probably going to get 16" wheels and 235-85r16's, though). Truck weighs roughly 5600lbs, so torque is more of a need than hp. If anything, I'm looking at another 77 F-150 4x4 this weekend that has a 400 in it already and I may just swap that one out for the 429 because it's already got a c6 in it.

If the 429 can get me 9+mpg, than I may drop that one into the DD. Do you guys think the 71 400 will get better? It already has a straight up timing set and flat top pistons. If the 429 gets the same mileage, I'll just drop that in and be done with it. Any real world (honest) numbers?

 

Depends how you build the 429. I get around 6 with my 250 with a 70 429 in it but it is built. My 400 in the Bronco gets close to 10 and it is a mild build. I wouldn't be looking at either motor for being a fuel saver.

 

2x I get closer to 10mpg but Mine, has a mild cam @9.3:1 compression and a C6 4:10 w/33's . As stated before it's easy to get less... Just takes a heavy foot. I de-stroked a 460 added heads and decked to my requirements; I can still run regular if I want.

 

Quick item for you, I had a '71 Colony Park that came with the 429 2V engine. I researched all the PNs and found that the only difference was the intake and carburetor. Check the casting number on your heads to be sure. The change to a 4V setup was amazing.

 

The BOSS 429, I believe was factory rated at 375 HP but i'll bet it was closer to 500. Anyone know for sure?? Popa John

 

460 started life out in the 60s as a lincoln powerplant. 10.5:1 compression and rated at 500 ft/lbs but still a car motor.

 

What is meant by 429 2V heads is the 2V in the casting number, many 429 4bbl engines had the same 2V heads. They are better for low RPM grunt and gas mileage than the Cobra Jet and SCJ heads with big holes.

I'ld say if it was a Mobile Economy Run that you were going to compete in, the winner would be a 400 (or even 351M) with stock heads, some of those good aftermarket flat top pistons with 9.5-9.8 CR, a torque making cam, and a good ignition setup. The 351M and 400 both suffered mostly from retarded cams and low low compression, and there's easy fixes for both.

 

The compression on the 429 is unknown, but the 400 has 9.1:1 compression with straight up timing (it's the 71 year 400). Factory rated at 260hp at the flywheel (so roughly 190-200 at the rear wheels). The 429 2v was rated at 310 at the flywheel (around 250-260 at rear wheels). I don't want a 460 because everyone has a 460 and I'm building this truck to be something a little different from the usual. Working on a budget, so don't mention a diesel as an option. Looking more for torque than hp, although hp is fun every once in a while. Not building a high performer, just a DD for when winter rolls around (truck will be por15'd and what not). Both motors have enough power me and enough power for the truck. Just, will be cheaper in the long run?