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Ford 351 Boss Engine Build

Ford 351 Boss Engine Build - Late Model Boss, Part Three

Charlie's Automotive Finishes Up Circle Track's Nascar Late Model Stock Race Engine Based On Ford's New Boss Block And N351 Cylinder Heads
From the June, 2010 issue of Circle Track
By Jeff Huneycutt
Photography by Jeff Huneycutt
Ford 351 Boss Engine Build
It's time to go racing!
In the last installment of our NASCAR Late Model Stock engine build, brothers Charlie and Robert Long of Charlie's Automotive completed filling out the Ford 351 Boss block with a Crower crank and rods along with a set of Wiseco pistons. And in case your dog ate the last issue of Circle Track before you got a chance to read it, we courted a little heresy with the build by using Chevrolet-spec LS rods and pistons. Charlie Long has found this works because he likes Wiseco's excellent LS piston forging with its boxed design, and the rods are the maximum 6.250 length and have shown excellent durabil-ity. This works, however, but does require a bit of machine work on the underside of the pistons because Chevrolets use an offset on the rods while Fords do not. This means when you bolt Chevy-spec rods to a Ford-style crankshaft, there may be contact between the small end of the rod and the side of the piston pin boss.

Ford 351 Boss Engine Build
Before installing the heads,... 
   
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Ford 351 Boss Engine Build
Before installing the heads, Robert Long double checks piston clearance to the top of the block. He wants each piston to be between 0.008 and 0.010 below the deck at TDC to maximize squish, which promotes good fuel burn. Also, since most Late Model Stock rulebooks only have a minimum cc rule for the combustion chambers and no compression rule, you can sometimes gain a bit with Fords because the 10-degree valve angle means valve pockets aren't required in the top of the pistons like Chevrolets.
Ford 351 Boss Engine Build
After checking, Charlie Long... 
   
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Ford 351 Boss Engine Build
After checking, Charlie Long found the valve guides to be dead on. The expense of adding bushed guides with Ford's new N351 heads are not necessary, and all that needed to be done was to hit each of the guide bores with a hone to open up the clearance slightly and add a crosshatch pattern which helps keep oil around the valve stems.
Ford 351 Boss Engine Build
Charlie's uses a Drake water... 
   
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Ford 351 Boss Engine Build
Charlie's uses a Drake water pump from Van Dyne Engineering on practically all of its Ford engines because it is efficient and engineered with an integral backing plate. One odd feature, though, is this pump only comes with a 2-inch diameter hose inlet when almost all racing radiators are made for 1.75-inch hoses. To fix this Charlie's has to cut down the o.d. on a mill.
Ford 351 Boss Engine Build
Here's a shot of the water... 
   
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Ford 351 Boss Engine Build
Here's a shot of the water pump mounted up on the block with the modified housing.
Ford 351 Boss Engine Build
After extensive testing, the... 
   
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Ford 351 Boss Engine Build
After extensive testing, the Long brothers have settled on PSI valvesprings distributed through CV Products. These springs are chamfered on the i.d. to keep them from rubbing on the steps of the retainers, which significantly helps with longevity.
Ford 351 Boss Engine Build
The valvesprings will be on... 
   
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Ford 351 Boss Engine Build
The valvesprings will be on the cylinder heads at a 1.810-inch installed height. That will give them 180 pounds of pressure on the seat and 425 open.

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Circle Track Tests Ford's New Boss 351 Block And N351 In A Complete Late Model Stock Build
Charlie's Automotive puts together the short-block on our NASCAR Late Model Stock Ford engine build.

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