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The Need For 460 Water Pump Backing Plates

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Gary Lewis

The Need For 460 Water Pump Backing Plates

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This is to document an unusual reason why the backing plate is needed on 460's with the poly-groove belts. (The backing plate is a necessity for proper cooling as well.)

When I got Huck, the 1990 half-truck, I noticed that the AC/PS bracket was broken at the bottom. Bill quickly suggested that there might not be a backing plate behind the water pump, and sure enough there wasn't one.

So, why does a missing backing plate cause the bracket to break? In the pic below, circled in red you can see the four 7/16" bolts that very securely bolt the bracket to the block and the head. But circled in yellow you can see the one little 3/8" bolt that secures the bottom tab of the bracket to the water pump.

In this pic you can see how that tab on the bracket is supposed to hit the water pump. The top four bolts are snug and the bracket hits the water pump perfectly. But without the backing plate there is a 3/16" gap between the bracket and the water pump.

And the pic below shows what happens if you don't put the backing plate in and tighten the bolts down. The bracket on the left has been broken but fixed while the bracket on the right, which is the one off Huck, is still broken. Why do the brackets break? Because the bracket is pretty solid up top, and when those four bolts are tightened down it is going nowhere. And that little tab isn't nearly strong enough to flex that cast aluminum. So it breaks instead of bends.

Gary, AKA "Gary fellow": Profile

Dad's: '81 F150 Ranger XLT 4x4: Down for restomod: Full-roller "stroked 351M" w/Trick Flow heads & intake, EEC-V SEFI/E4OD/3.50 gears w/Kevlar clutches
Blue: 2015 F150 Platinum 4x4 SuperCrew wearing Blue Jeans & sporting a 3.5L EB & Max Tow
Big Blue: 1985 F250HD 4x4: 460/ZF5/3.55's, D60 w/Ox locker & 10.25 Sterling/Trutrac, Blue Top & Borgeson, & EEC-V MAF/SEFI

ArdWrknTrk

Re: The Need For 460 Water Pump Backing Plates

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So wait...

You had TWO broken accessory brackets?

I was pretty darn sure it was intact. 🤨

Jim,
Lil'Red is a '87 F250 HD, 4.10's, 1356 4x4, Zf-5, 3G, PMGR, Saginaw PS, desmogged with a Holley 80508 and Performer intake.
Too much other stuff to mention.

Gary Lewis

Re: The Need For 460 Water Pump Backing Plates

Administrator

I have three AC/PS brackets: The one you sent from the F450 and it has not been broken; The one from Huck and it is broken; and one from I don't know where and it has been broken but is repaired.

Bill - Did you send me one? Was I supposed to send it back after PC'ing it?

Gary, AKA "Gary fellow": Profile

85lebaront2

Re: The Need For 460 Water Pump Backing Plates

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No you I didn't, I was going to offer the good one from the new engine in return for a PC'd set, even the repaired one if you needed it. BTW, what water pump are you using? I have never had a fit problem on mine.

Bill AKA "LOBO" Profile

"Getting old is inevitable, growing up is optional" Darth Vader 1986 F350 460 converted to MAF/SEFI, E4OD 12X3 1/2 rear brakes, traction loc 3:55 gear, 160 amp 3G alternator Wife's 2011 Flex Limited Daily Driver 2009 Flex Limited with factory tow package Project car 1986 Chrysler LeBaron convertible 2.2L Turbo II, modified A413

CountryBumkin

Re: The Need For 460 Water Pump Backing Plates

That's a good point about the backing plate adding the additional thickness needed for that bottom bracket bolt. But I'm not so sure that bottom bolt is even needed. The water pump sure doesn't need it and the bracket itself is very well secured to the cyl head by the four 7/16 bolts.

-Mike
1982 F250 4x4 XLT Lariat, 460cid, 9.5:1, TFS 290 Street Port heads, Crane Hyd. Roller cam (278/286 adv.,216/224 @.050, .560"/.586" lift), Edelbrock Performer 460 intake, MSD Atomic TBI fuel injection, MSD 6AL ignition, MSD Billet distrib., Hedman headers, NOS Cheater system, 4" Suspension lift, 3" body lift, 4.56 gearing, 17x12.5Rx37 tires MT Baja ATZ-P3.

ArdWrknTrk

Re: The Need For 460 Water Pump Backing Plates

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In reply to this post by 85lebaront2

85lebaront2 wrote

BTW, what water pump are you using? I have never had a fit problem on mine.

Y'all EFI guys are using the later pump, with the different inlet???

Jim,
Lil'Red is a '87 F250 HD, 4.10's, 1356 4x4, Zf-5, 3G, PMGR, Saginaw PS, desmogged with a Holley 80508 and Performer intake.
Too much other stuff to mention.

Gary Lewis

Re: The Need For 460 Water Pump Backing Plates

Administrator

I'd agree that the bracket probably doesn't need the lower bolt. But I want it there as Ford designed it that way.

As for water pump, it is the later EFI pump, although I don't know the brand. Came from Scotty, so I'm sure I have the brand in the paperwork. But it does have the larger shaft and flange as Huck's pulley won't fit. Only the one Jim sent from the F450.

Gary, AKA "Gary fellow": Profile

85lebaront2

Re: The Need For 460 Water Pump Backing Plates

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In reply to this post by CountryBumkin

It is probably more of an anti-vibration stabilizer.

Bill AKA "LOBO" Profile

85lebaront2

Re: The Need For 460 Water Pump Backing Plates

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In reply to this post by ArdWrknTrk

I have an early pump on Darth, but the new engine has the later pump. on neither one is there any interference with the alternator tensioning bracket. I am using AutoZone new Duralast pumps.

Bill AKA "LOBO" Profile