I have been contemplating whether to build the 4.9L with some extra's, or swap in a 351W mildly built. I would like to have a nice motor with good performance and decent fuel economy while not busting the bank. What are your opinions on which way to go? With the 4.9L I would want to do a complete rebuild and add a cam, dual plane intake, 4bbl and likely EFI manifolds with dual exhaust. With a 351W I would likely do about the same.
Which would be the most reliable, cost effective, and economical?

 

Well, since you have the 4.9 in there already, and those motors are notoriously reliable, you might want to just build on that platform. Swapping in a 5.8 will require new engine perches in addition to motor mounts, new radiator, exhaust system, etc, so keeping the 4.9 would also be most cost effective. As far as economical - well, that's up to you.

 

Both will be reliable if properly built, but the 4.9 would be the most economical solution. Like the previous poster stated, you will have to purchase things like motor mounts and perches, radiator, accessory brackets etc.

That being said, the 4.9 won't make near the same amount of power as a 351w with the same amount of money thrown at it. If it was my truck, the 351w would be getting stuffed in

 

My .02 worth..

If you have a 351W or access to one..I would stuff it in..
It will provide you with the higher revs and it is a VERY reliable motor..

If it is a 2bbl engine, you can put the stock HO cam in it (reasonable price) and a good 4bbl intake and carb and have a 351HO..

Of course, I'm biased somewhat as my 85 has 124K miles on it and still runs great...

The 300 I6 is a Very strong and dependable engine...Torque is great..The only drawback is lower rpms...

You can check the prices out on building either engines....

Whatever meets your needs/budget....

Whichever way you go, you will have a RELIABLE set-up....

Just throwing that out there.....Trav..

 

I agree with what the others have said, but would add that a lot of it depends on what you want to do with the truck and your plans for the transmission and gearing. The six is happiest at lower rev's, so if you plan to put the truck on the highway you would benefit by adding an overdrive tranny or higher axle ratios. The big six can turn in some impressive MPG figures if you keep the rev's low - as well as the overall speed of the truck for that matter. The 351W doesn't mind rev'ing and will be fine with your current tranny and gears, although it would provide better MPG at lower rev's.

But, if your plans are more toward offroading then I'd suggest staying with the six as well as the tranny and gears. That's 'cause the six has lots of low-end grunt. A built 351W can have plenty of torque, but needs to spin more to get it and might like lower gears for offroading.

 

I plan to use it as an occasional driver to work which is 50 miles roundtrip, and for hunting, and occasional towing (bass boat, hay trailer, small trailer with two quads). I know either engine would do the job, just can't decide if I want the conveneince of already having the 4.9L and everything that works with it, or the nice rumble of the 351 and the extra ponies. I also plan to gear it with 4:10's or 4:56's and run 35" tires.
Thanks for the replies so far. I was unsure if building the 351 would be cheaper in the long run since parts are more readily available and cheaper from what I can tell.
I do have lots of time to think it over before I will be at that stage though, just have a lead on a running 351w complete with all accessories for 300.00.
Will the wiring for the 4.9l duraspark II swap work on the 351, or will I have to find another engine harness?

 

If you are going to 4:10's or 4:56 gears I think you'll need overdrive to put it on the highway - even with 35" tires.

 

I rarely get on the freeway, and usually drive in the 55/60mph range. With the 3:54 gears and 31's it is pretty close to perfect for my driving style. I figured with the 4.9L that I would need at least 4:10's with 35" tires. I live in the mountains with lots of steep winding roads so being on the lower end works good for me.

 

Ok, sounds like you know what you are doing. Good job.

 

Haha, no I real don't know. I am just guessing at this point. I have had several jeeps with oversized tires and know what works on those, but with the truck I am unsure which combination would be best. The jeeps have all had overdrive transmissions, so if you think higher gearing would be better I would be open for any insight. I want it to pull good in the mountains with a load, but to get the best in town mileage possible. That is why I am unsure on whether the 6cyl, or V8 would be better as well. I know the 4.9L has good low end torque, but not sure if lower gearing and a V8 wouldn't work better for me. Hopefully some others with lifted trucks and larger tires will chime in with their set-up and how they like it.
According to this site http://www.grimmjeeper.com/gears.html which has been reliable to me in the past I would be turning 2750rpms at 70 mph with 4:10 gears and 35" tires. For my jeep with the 4.0L that is a good cruising rpm, not sure it would work well with the ford 6 cyl. though.

 

A few things to keep in mind:

With a 4bbl carb, an Offenhauser C-series intake or a Clifford intake with the water jacket built in, and a set of Hedman headers, the 300 produces 200 horsepower and 300 lbs-ft of torque with the stock cam: right on par with a 351 Windsor while producing better gas mileage figures. And, as soon as the 4bbl carb goes on, the low-revving nature of the 300 changes. It'll still be a low-revving motor, and produce even more torque, but it'll also be happy winding up to 4500-5000 RPM whenever you choose to do so.

That's just with a carb, intake, and exhaust. We haven't even gotten to changing the cam, porting the head, oversize valves, bumping the compression, screw in studs, de-shrouding the valves, forged pistons, port-matching, etc. But, when you get to the point of going past just carb, intake, and exhaust, things get expensive. The only reason a V8 is cheaper is because everybody caters to them.

The next thing to keep in mind is the gearing. Like you've already been talking, if you plan to go to 35'' tires, you'll want different gearing. The thing is, a 300 can be over-geared EASILY, and put right out of it's power band in stock form. If the motor has been modified, then you can run gearing like a V8 because the power band has been modified. Even with the motor being "souped up", unless the cam has changed, you'll want to run slightly taller gears than you would if it was a V8.

With 35'' tires, 4.10 gears (~1770 RPM at 45 MPH) with the 300 would be a perfect setup. I think you're running the New Process 4-speed as well? That would be a great combination. It's also extremely close to your stock setup, 3.55 gears with 31'' tires (~1730 RPM at 45 MPH). You might only have to change the speedometer gear by going 1 tooth size different to get your speedometer right as well.

Also think about this: It's just as cheap to put in a 4bbl carb and headers on your 300 as it is to swap in a 351 Windsor.

I'd keep the six. I'm biased too though. Everybody here has heard my soap box sermons on the 300.

 

After watching lots of youtube video's I have decided to stick with the 300 for now. I am planning to rebuild it with a comp cams 260 extreme cam, lifters, valve springs etc. an offy or clifford intake, EFI manifolds, 390 holley carb, and a mild port and polish job on the heads. The bore will depend on the condition of the bottom end, I will keep it standard if it is okay. Hopefully this set-up will get me the power and fuel effeciency I am looking for. This will be later along in the build though. For now I am planning the interior makeover. Also collecting body panels to keep bodywork at a minimum.

 

Sounds like a good plan. Everything I've read about the 300 says it makes a great engine with a bit of massaging.