What flex plate. And balancer can be used?

[mike1157]

Thinking about going with a traditional Harmonic balancer, finding a single serpentine crank pulley, and converting the engine away from the stock piece.

I'm guessing I' m gonna run out of room in front real quick between the front of the engine and the radiator, but the stock, integral piece just seems like its not up to the task of doing what it's supposed to do. What potential balancer would fit a 250? Or is the stock piece better than I think it is? I only plan to spin the engine to 5500 RPM, w/ 6k being redline.

Also when using a 4R70w, what stock application has the correct flex plate that will fit the 250 crank, and have the 164 tooth ring that I think I need?

 

[bubba22349]

You might look at the 300 / 4.9 serpentine belt system parts to adapt to your 250, I don't know all the details of how it fits but its what I plan to use. About the only problem I see for using the serpentine system on a 250 is that the water pump impeller blade angles would need to be moded or swapped out to be able turn backwards. A few months back I had to replace the water pump on my 94 F150 and noticed that on these water pumps the impeller has straight 90 degree blades, they can turn in either direction without a problem so that impeller might also be good for the swap. For flex plate the one for a 300 / 4.9 should be an easy swap look for the flex plate used on a F150 with an AOD 1987 and other years. Good luck

 

[xctasy]

I've seen how you engineer, and I know you'll balance info with craftmanship to come up with the ultimate solution.

1. I'm withbubba22349 on flexplate. The F150 164T truck FMX or AOD 4.9flexplate is the straight drop in, and has no Detroit Unbalance. Your lovely US 250 block has the right flange, and everything lines up. Use the F150 separator plate and bolts, and find a small starter. We use the later One wire Aussie V8 Falcon starter which is the same pitch as all the 164 teeth starters.

2. Since the US 250 has the strongest, largest front spigot you'll see on a 4 liter I6 ...with the US 250, for some very important reason, the powertrain engineers at Dearborn changed to the 240/300 six spigot for some reason, while our Aussie 4.0's to this day still use the ages old 144 1.25" spigot. Because of that you've got any number of neutral balance options. I'll shot gun blast you with what I know, and then you can decide. I'm pretty sure you know exactly where your gonna go.

Like a lot of engineering executive decisions, there must have been some data for the big block 1.375 crank snout to have been added to the US 250. So I'd personally use the Ford 4.9 serp balancer, and then decide on the way you want to array your ancillary drive. That then sets the balancer you use.

I personally love the way Ford redid the later non cross flow 75-80 US 250 ancillary drive in Granadas, Versallies, Monarchs and Mavericks. They swapped the alternator, a/c and air pump positions totally re-engineered it from the ages old 200 Ford set up , but the F150 truck 4.9 serp drive is a next step up from that. Somewhere in between the 1975-1980 X shell L and C code 250, and the later F150 truck Serp set up, you'll find the parts to link your turboed Fox body X-flow accessory drive, and that governs which balancer you'll end up using. Ford never did a sepr drive 200 or 250, but if they did, it would have looked like either the HSC/HSO 2300/2500 ohv engine, or the F150 Truck EFI.

Lots of owners of individual 351 W and 351C Fox Ford conversions just take one of the Crown Vicky 302 serp drive, and superimpose it on the early Windsor or Cleveland 351 blocks, and then elect to remove the air pump and air con.

With your I6, you can use the whole of a F150 sep drive, and cut it down to suit, even removing the stock water pump drive if you want to.