I'm thinking about updating the drive train in my 79 crew. Now I have a 200 hp/300lb 400, with a nv4500 and a 3.55 d60. I'm interested in a 300 ford for a lot of reasons. Light, good mileage, good torque, reliable, easy to build. First off, I'm wanting to get about 200 hp and 400 lbs of torque out of this, is that doable? I'm ok with a cam swap and a little head or block work. Clean heads/block up, maybe bore it and maybe new valves, stuff like that.I'm not looking for a race car and I can accept being a little slow. I'm slow now. Just read about the 15 mpg and super reliability these engines are known for. Is what I'm wanting easily obtainable? Or should I just build the 400?

 

In a large truck like a crew cab I would stay with the 400 V8. For best mileage get an Edelbrock SP2P small runner intake and a small 4V carb, and an RV or towing cam and a low restriction exhaust. To get 400 lb ft out of a 300 six will require a turbo or an engine built for lots of revs. You are better off keeping the 400 and refine it.

 

Dang, thats a downer, I really like the idea of a high performing 300. Your help is greatly appreciated though.

 

You definitely can get some great performance out of a 300. Just drop the numbers you're looking for a bit.

With some work, a 300 six could easily put out around what your 400 is putting down now. 200hp/300tq is reasonable with a good intake/exhaust, a new cam, larger valves, and a port and polish on the head, etc.
However, after that the head becomes a major bottleneck, which is why you either need to get into some serious headwork or turbo/supercharge it.

 

Where abouts would the powerband be with that 300 build? What about mileage? My 5 speed has granny and overdrive, plus I don't spend a lot of time hauling anything. The 400 does ok now but I'd like a little more power. But if I could get the same power level now but at a much lower rpm and better mileage I could think about it. I can't even get the 400 to rev over 4000 anyway so I'm probably not even making 200 hp. What else is in the aforementioned "etc", not trying to start anything. What about raising static comp ratio?

 

From figures I've read, that would put you around the 190 - 210 hp mark and around 290 - 320 tq, depending. Certainly nothing to complain about, and a good strong torque curve. Just not big V8-like numbers.
But, it's all very usable power.

If you want big power, I'd stick with your 400. Another thing to consider is the different bolt patterns. The 300 and 400 don't use the same bolt pattern, so you'd need to get a different adapter plate (one for a 300/302/351) for that NV4500.


With my engine, I have a Bronco (probably no as heavy as your crew cab, but maybe). 3.00 gearing and an NP435 transmission (no overdrive). I haven't done headwork or cam and just have a high flowing exhaust, high performance ignition, and a 4bbl, and my Bronco hauls. I'd estimate about 175hp/300tq. Again, that's just an estimate from figures I've read on line and researched. I don't have any hard numbers.
My last fillup was 13mpg with 100% around town driving and about 17 on the open road. It also revs so freely I've accidentally hit 5000 RPMs a few times without meaning too (a little high for this engine). I do 4000 - 4500 regularly.

An overdrive would put you at a bit lower RPMs than I am on the freeway, so I imagine that would help with gas mileage too. Of course, big heavy tires, and a heavier truck are going to factor into that as well.

 

Think of it this way - a 300 is your 400 minus two cylinder and with a U-Turn head.

A 460 has the same transmission bell pattern as your 400. If you're going to swap engines that's the direction to go. There's so much more aftermarket support for a 460 vs. the 400 or 300.

 

Ok, found a bellhousing adapter for $230 so they won't be a problem. My question is, how much is reuseable from the 400 to the 300? Will I need to switch radiators, fans, of course engine mounts, any other mounts, any problems with headers and exhaust? Wanting to know about any unforeseen problems I might come across. I'd have to find another engine no matter what as the truck is my dd so time sitting in the garage should be a short as possible. I get around 9mpg right now. The 400 also seems to have to be around 3000 to make any real torque. Even just climbing hills bobtailed. I highly doubt I make 200 hp now, as I've said I can't get it to rev into the 4000's and the old thing is pretty worn out.

 

Do you all think this would be a good idea? I just don't want to go through all this work and money just to have another dog thats the slowest thing on the road. I'm not looking for a racer but a little bit of moving would be good. I'm sick of having to hold the 400 wide open to pass anybody or climb a hill.

 

You may want to pick F250-restorer's brain on this. He had a 390 V8 in his and swapped it out for a 300. Not to mention it's in front of a C6, which isn't exactly kind on power.

It's going to be the whole deal. You'll need to change everything like the radiator, mounts, exhaust, etc. You'll probably be able to tie into your current exhaust somewhere depending on how it's currently routed, but you certainly won't be able to reuse much up near the engine. However, it's all a direct swap as it was made by Ford, and came as an option in your truck, so it's not like you're reinventing the wheel or something.

The call is ultimately yours. No one can tell you if you're going to be pleased with it compared to what you have. However, when built up, it certainly is NO slouch, especially with proper gearing, which it sounds like you have with your 3.55 and the 5 speed. But is it going to be enough for you? Dunno. I know it's plenty of engine for me.

Just be realistic about what it is though. It's a BIG six cylinder, but its' still smaller than most V8s that were offered in the trucks. It's a great engine, and it's a real truck engine, but it's not a performer without some dedication and work.

That said, there are probably still plenty of trucks your year and model that are still driving around with 300s in them from the factory with the anemic exhaust and little 1bbl carb.

 

I might be considered crazy for this, but I think he should keep the 400. The money he doesn't spend on all the parts needed for a engine swap, he can spend on a rebuild of his current motor. Look in the 352/400 engine section and I believe you'll find that you can build a powerhouse for under 5 grand pretty easily.

 

Clifford 6=8 boasts a setup that gets 330 hp and 413 foot lbs of torque. Both nbers reached in the 3300 to4300 rpm range.

 

I do not believe those numbers. I'll even say at that RPM those numbers are not possible, regardless of the build level.

 

I do not consider your idea crazy. See my first post (#2) above - I gave essentially the same advice.

 

Sorry, totally forgot about your previous post. I guess I was just trying to add emphasis by saying it a second time lol. I've always thought it'd be cool to have a v8 with a longer stroke than my six (4 inches vs. 3.98 inches)