Engine questions

[Thunderherd]

Couple of questions here. First, fuel mileage questions. I'm currently getting between 10 and 12 mpg. Depending on where and how I drive of course. Seems I have a 390 engine. Big, aggressive cam (really sounds like a big block race engine). Edelbrock carb. Original 352 heads looks like. I put a Petronics distributer in(boy did that ever make a big difference for the better). 3 speed transmission with 3:70 ratio rear end gears. Now what kind of mileage are you guys getting, with what kind of set up? This is just to much gas usage for me. I was thinking of puttin in an RV cam. And changing whatever rear ratio I can get close o a 2:80.
Second option would be a different engine. Possibly a 351, mildly built. Or, I've got a wrecked '98 Lincoln Town Car sitting out back. Anybody tried the 4.6 engine in our Square Birds? Would that big, wide engine fit. The FE engine already comes real close to the steering box of course, but I think one of my winter projects will be to put in a rack and pinion steering. I've got a bad shoulder and it gets hard to park this thing sometimes with the manual steering I have now. If somebody has done either the 351 swap, or the 4.6 modular engine, what kind of mileage are you getting with these engines, and how did the swap go?In other words, will it really be worth it, gas mileage wise, to do either of these swaps. And really, if somebody has done this modular engine swap, I would really like to know and to talk to you about it. Thank you guys lots. Looking forward to your thoughts.

[simplyconnected]

Of course you have terrible gas mileage with nearly 400 cubes and a racing cam. That choice is typical of a restorer with little experience. The HP and torque numbers look good but the engine is useless for daily low-rpm street driving.

Given the choices, I'm comfy with a 351W/AOD combination. All the parts are very accessible and at reasonable prices. You can keep your RE gear and let the overdrive do it's job.

351Windsor engines were used in F-150 Lightning trucks and in Mustang Cobra-R's. They are stump pullers but they also use much of the same parts as the 5.0 SBF (like pistons and rings). The difference is, 1/2" longer stroke times eight cylinders. This will tame down your gas mileage, tame down your RPMs and still give you great torque. Your suggestion for changing RE gears is way too radical. I like a 3.55 or a 3.7:1 for all-around high speed and around town driving in a grocery getter. My Mustang 351W had a 4:30 gear w/AOD and a stall converter. 95% of my driving was Interstate commute with 'rush hour' thrown in on occasion.

The Lincoln engine is another good choice IF you keep it with the EFI setup. Remember that the Lincoln is small, 100 cubic inches smaller than your 390. Again, a drastic change. The 351W with Edelbrock aluminum heads is the way to go. Look for a Lightning cam grind because it's made for a hauling truck. Good gas mileage comes with EFI because the gas is atomized. Carbs kinds dribble gas in under negative pressure so much of it never gets burned. - Dave

[pbf777]

I often advise individuals that the references within forums are for general thoughts & ideas, but be cautious, as it is improbable that all the information needed for a logical decision rests there. One should find and develop a relationship with a respectable local service of such nature which can advise you, "one on one", taking in the many considerations (both vehicle & owner) that will constitute a proper decision regarding an engine swap scenario.

With that, first I would pass on the 4.6 engine, as it will involve a fairly complicated process of converting the wiring harness and associated E.F.I. components for proper function to your chassis. And you would not want to convert the 4.6 to carburetor function as it would lose low and mid-range torque, which their not notorious for as delivered, and that Thunderbird ain't no light-weight that's for sure.

The 351W conversion could have a possibly good outcome, again with proper considerations. (way to many considerations for this thread) Keep in mind, this would be an engine from a different family (S.B. vs. FE), so nothing currently attached to the FE will simply "bolt-up", not-a-thing!

The FE was never known for outstanding fuel mileage, but I'm not sure that the 351W, in the same state of tune, would be significantly better; nor would I label them as "stump-pullers" by comparison, but that may have had as much to due with vehicles/chassis it was installed in, as the engine itself.

I think one should review the current engine (FE) installed in your vehicle and determine if it's just to "racy", for your tastes, and maybe only needs to be "detuned" some. This should be far less costly than your other approaches. And appear proper also.

One possible "conversion", coupled to the FE for improving the mileage, may be to consider an overdrive transmission option and keeping the 3.70 : 1 ratio rear gear. I believe the best process, in this application, is utilizing the Ford C6 (stronger!) transmission which bolts directly to the FE, with a Gear Vendors O.D. unit & tail shaft housing adapter. But, it also can be accomplished using the A.O.D. (weaker!) transmission with a bellhousing to block adapter (cheaper!).

Just some thoughts. Scott.

[Thunderherd]

https://www.flickr.com/photos/148640157@N06/30503229951/in/dateposted-public/

https://www.flickr.com/photos/148640157@N06/30591295775/in/dateposted-public/

Heres a couple of pics of my bird. Including one of my mastercylinder/proportioning valve setup.

[scumdog]

Apart from anything else a stroker kit fitted to a Windsor would give you more than 390 cubic inches, just a thought...
Me? I would stick with the 390 and adapt a AOD behind it.

[Thunderherd]

One thing I guess I neglected to mention here, although I said I have a 3 speed transmission, it's a standard transmission. Three on the tree. Standard transmission, no power accessories whatsoever. All manual. So if I keep the 390 in her, I'll keep the standard transmission, just change the rearend gears, or, look for a T-5 transmission. If anybody has a T-5, let me know. I kind of like Daves' idea of the 351 W, and if I went that route, I might go with the AOD. Decisions decisions.

[Yadkin]

You'll get ten different opinions from ten different folks here.

From the limited view of your engine bay it looks very clean- congratulations.

Consider keeping your current engine and changing to an RV cam. Replace the manifold and carburetor with a multi-port EFI system. That will maximize your fuel mileage, minimize your warm-up time, and drive more like a modern car.

[simplyconnected]

Apart from anything else a stroker kit fitted to a Windsor would give you more than 390 cubic inches, just a thought...
Me? I would stick with the 390 and adapt a AOD behind it.

Yep, Ford's lowest HP 351-based crate engine is a 427 that delivers over 450-HP and over 500-ft/lbs of torque, burning unleaded premium fuel.

A typical 351W has a 4" bore (using common Mustang pistons) and a 3.51" stroke.

Ford Racing's 427 dimensions are, 4.125" bore x 4.00" stroke (using a SCAT Forged Steel Crankshaft).

Believe me, a production circa 1990 or later 351W will more than satisfy your needs if you add aluminum heads, mild roller cam and fuel injection. - Dave