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A Ford Modular V8 Engine Primer

Get to know the '96-'09 Mustang's Overhead Cam V-8
From the May, 2009 issue of Mustang Monthly
By Jim Smart
Photography by Jim Smart
Ford Overhead Cam Modular V8
  • 4.6L SOHC Engine introduced in '91 in the Lincoln Town Car
  • '92 Crown Victoria and Grand Marquis 4.6L SOHC
  • '93 Lincoln Mark VIII first to get 4.6L DOHC
  • '94 Thunderbird 4.6L SOHC
  • '96 Mustang GT and Cobra 4.6L SOHC and DOHC
  • '97 Ford F150 and Expedition 4.6L SOHC
  • '98 E-Series Vans 4.6L SOHC
  • '99 6.8L SOHC V-10 introduced in new Super Duty trucks
  • '00 Ford Excursion
  • '02 Ford Explorer and Mercury Mountaineer 4.6L SOHC
  • '03 Lincoln Aviator 4.6L DOHC
  • Romeo was the only Modular engine plant from '91-'95.
  • Windsor came on line for '96 to build 4.6L and 5.4L SOHC engines for trucks and vans
  • Although Romeo is primarily a car engine plant, it has produced Modular engines for trucks
  • Although Windsor is primarily a truck engine plant, it produced Modular engines for '99-'00 Mustang GT
  • Romeo engines employ different blocks, heads, and cranks than Windsor although they look similar
  • Most Romeo blocks are marked with an "R" in the casting
  • Windsor blocks are all marked with a "W" in the casting in two places
  • Romeo heads employ bolt-on cam journal girdles
  • Windsor heads don't have cam journal girdles, just individual journals
  • Because Romeo and Windsor engines have different timing cover/cam cover bolt hole sizing, it is best to use Romeo heads and blocks together and Windsor heads and blocks together
  • Romeo blocks have jackscrew cross-bolted main caps
  • Windsor blocks have dowel pin cross-bolted main caps
  • Romeo engines have primarily six-bolt flywheel/flexplate flanges
  • Windsor engines have eight-bolt flywheel/flexplate flanges
  • Oil filter/cooling neck types vary depending on vehicle type
  • Timing cover depends on vehicle type
  • Romeo cam sprockets are zero-fit and slip right on
  • Windsor cam sprockets are pressed on
  • Romeo cam covers have 11 bolts
  • Windsor cam covers have 13 bolts
  • Difference timing covers for SOHC and DOHC
  • Same basic timing chain/sprocket system for both SOHC and DOHC
  • DOHC engines have secondary timing chains for secondary camshafts
  • SOHC has a standard oil pump and DOHC has high volume
  • Ford Overhead Cam Modular V8
    There are four basic types... 
       
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    Ford Overhead Cam Modular V8
    There are four basic types of Modular crankshafts: nodular iron or steel, six-hole or eight-hole. Eight-hole is suggested if you're building for power. For street engines, you don't have to have a steel crank. Nodular iron is very strong.
    Ford Overhead Cam Modular V8
    These flat spots drive the... 
       
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    Ford Overhead Cam Modular V8
    These flat spots drive the oil pump on the front of the crankshaft.
    Ford Overhead Cam Modular V8
    Dished pistons are at the... 
       
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    Ford Overhead Cam Modular V8
    Dished pistons are at the heart of the Modular engine. Dish size depends on chamber size. PI (Power Improved) heads from '99-up have a small 42cc chamber and large dish. Non PI heads (before '99) have 52cc chambers and a smaller dish. Several piston dish sizes are available. Most Modular pistons are hypereutectic, not forged. Use forged pistons for supercharging and nitrous or when you intend the rev high.
    Ford Overhead Cam Modular V8
    This is a Windsor block, easily... 
       
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    Ford Overhead Cam Modular V8
    This is a Windsor block, easily identified by the "W" in two places along with dowel pin main caps.
    Ford Overhead Cam Modular V8
    An "R" and jackscrew main... 
       
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    Ford Overhead Cam Modular V8
    An "R" and jackscrew main caps identify Romeo blocks.
    Ford Overhead Cam Modular V8
    Bore spacing and sizing are... 
       
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    Ford Overhead Cam Modular V8
    Bore spacing and sizing are modest - 3.550-inch on all Modular engines. You can bore this engine .030-inch oversize. A maximum of .020-inch oversize is suggested. Cooling runs 60/40 -- 60 percent one size, 40 percent the other. We suggest a high-flow Cobra water pump for all Modular engines.

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