Changing an XE262H for an XE284H

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Changing an XE262H for an XE284H

Post  F350 Strait on July 26th 2012, 1:02 am

I have a 545 stroked 460 that I built in 06. My original build used Comp Cam’s XE262H cam as I was using my 79 F350 for some towing and fun. I will shortly start a rebuild of the engine and am planning on replacing the XE262H with a XE284H cam. I’d go to a hydraulic roller but can’t afford it at this time.
The build used Scat’s 545 rotating assembly with H rods, JE forged aluminum pistons with a 33cc dish – 30 over and Scat’s stroked crank – 10:1 static compression. The block was torque plate bored 30 over, line honed for the crank & cam and zero decked. The heads are Jon Kasse’s aluminum Super Cobra Jet heads with stainless steel valves, 7/16” rocker studs, and with push rod guide plates. With the new cam, I will also get Comp Cams recommended dual valve springs and their Magnum hydraulic lifters. I’m using Edlebrock’s RPM Air Gap intake with Holley’s Street Avenger 870 vacuum secondary carburetor and Edlebrock’s mechanical 10 gal fuel pump.
Right now my truck has stock type converter with an Art Carr rollerized C6 with a Gear Vendor OD behind that. First, will I need a 2000+ stall converter for this cam/engine set up? Second, with the 33cc dish in the piston and a cut out for the intake already in the piston top will I need to do additional cutting on the pistons to clear the valves? Yes I will check when I rebuild, just curious. Also, eventually I am going to go to 4:56 gears in the rear. The Gear Vendors OD will keep the freeway RPM’s reasonable.
Thanks for any input,
Earl

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Re: Changing an XE262H for an XE284H

Post  rmcomprandy on July 26th 2012, 10:51 am

First, the torque converter will need to be around 3000 RPM stall speed with that big of a camshaft.
Second, if the notch in the piston is in the correct location for an SCJ/P-51 and is .150" deep, then you will be OK.
Third, get a different carburetor unless you're climbing hills.

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Re: Changing an XE262H for an XE284H

Post  F350 Strait on July 26th 2012, 9:48 pm

Thanks for the reply. The people that I've talked to here say that the size of the engine should allow me to run the 2500 stall. Of course it's only 500 rpm to 3000.

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Re: Changing an XE262H for an XE284H

Post  rmcomprandy on July 26th 2012, 11:45 pm

F350 Strait wrote:Thanks for the reply. The people that I've talked to here say that the size of the engine should allow me to run the 2500 stall. Of course it's only 500 rpm to 3000.

Your post says 2,000+ RPM stall speed. You may get away with running a stall speed of 2,400 to 2,600 RPM but, it will be a complete dog off the line with the curb weight of an F350.
I presumed that would be important but, maybe not. In any case, I would recommend a custom ground camshaft for your application.

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Re: Changing an XE262H for an XE284H

Post  F350 Strait on July 28th 2012, 4:00 pm

RM
Thanks for the input. I’ve been comparing the cam I currently have in the truck, XE262H10, to the XE284H10 with an old sym dyno that I have as follows:

XE262H10 w/comp 4* advance XE284H10 w/comp 4* advance
RPM HP Torque HP Torque
1500 160 561 152 561
2000 241 633 224 587
2500 318 669 285 598
3000 378 662 355 621
3500 437 657 428 642
4000 486 638 485 637
4500 501 585 522 610
5000 480 504 536 563
5500 420 501 473 451
6000 353 309 399 349
6500 288 232 314 253

I’m not saying that reflects reality but that the XE262 is close to what the engine dyno’d at when I first built it so by keeping everything the same in the sim dyno it reflects the net difference between the cams, if that makes sense. What I’m looking at is the torque that I will have with the XE284H10. Won’t that keep the engine from bogging say driving around town? Granted I am running a smaller than optimal carb on the truck but right now I’m not looking for all out power. What am I missing? It’s probably experience . . . the more I think about it, I probably won’t be towing with it, just having fun.

Earl

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Re: Changing an XE262H for an XE284H

Post  cletus66 on July 28th 2012, 5:02 pm

I would have Randy get you a custom cam specifically for your combo. You tell him what you want it to do, and he'll get you the correct cam for your application. The cost difference is negligible.
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Re: Changing an XE262H for an XE284H

Post  rmcomprandy on July 28th 2012, 11:46 pm

F350 Strait wrote:RM
Thanks for the input. I’ve been comparing the cam I currently have in the truck, XE262H10, to the XE284H10 with an old sym dyno that I have as follows:

XE262H10 w/comp 4* advance XE284H10 w/comp 4* advance
RPM HP Torque HP Torque
1500 160 561 152 561
2000 241 633 224 587
2500 318 669 285 598
3000 378 662 355 621
3500 437 657 428 642
4000 486 638 485 637
4500 501 585 522 610
5000 480 504 536 563
5500 420 501 473 451
6000 353 309 399 349
6500 288 232 314 253

I’m not saying that reflects reality but that the XE262 is close to what the engine dyno’d at when I first built it so by keeping everything the same in the sim dyno it reflects the net difference between the cams, if that makes sense. What I’m looking at is the torque that I will have with the XE284H10. Won’t that keep the engine from bogging say driving around town? Granted I am running a smaller than optimal carb on the truck but right now I’m not looking for all out power. What am I missing? It’s probably experience . . . the more I think about it, I probably won’t be towing with it, just having fun.

Earl

Dyno numbers, (sim or not), are done at wide open throttle ... I presumed you are intending to drive this truck at other throttle openings and transients.

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