Quad 4 Specs PDF Print E-mail

Quad 4 Rods manufacturers bell housings to adapt your Quad 4 engine to a number to different transmissions:

  • GM T5 from S10 Pickups or V6 Cameros
  • GM 200 4R if your choice is an automatic with overdrive
  • Ford C4 if room is an issue

If you are from the old school and not into computers, Quad 4 Rods has an intake manifold, fuel pump, pressure regulator, fittings, and Weber side draft carburetors.

In place of a distributor, we have a simple, rugged, and reliable ignition system to supply spark.

Developed by Oldsmobile and produced from 1987 to 1995, the Quad 4 easily squeezed 180 horse power from only 136 cubic inches, even more, with the 190 HP W41 option and slightly less (160HP) in the standard version.

Quad 4's were all transverse mounted in the Olds Calais, Achievas, Pointiac Grand Am's, Chevrolet Baretta's, Buick's to both 5 speed gearboxes and automatics with unique bolt patterns.

All Quad 4's had the same 92 MM bore, 87 MM stroke, dual overhead cams, and 4 valves per cylinder. The base "D" code engine (see 8th digit on the VIN number) differed from the 180 HP "High Output" code engines by:

 
  • Engine
"D"
"A"
 
  • Compression Ratio
9.5 : 1 10.0 : 1 
 
  • Intake Valve
36 MM 36 MM
 
  • Exhaust Valve
29.8 MM 
31.3 MM
 
  • Camshaft Lift Intake
9.5 MM 10.4 MM
 
  • Exhaust
9.5 MM
10.4 MM

The higher lift HO cams required valve reliefs on the piston for the intake valves. The W41 option had even a higher lift on the exhaust that required valve reliefs on the pistions for the exhaust valves.

  • Caution: Do not install "A" code cams in "D" code engines or W41 cams in a "A" or "D" code engine without changing or modifying the pistons - the voice of experience!!


There were also changes in the calibration for different engines along with electronic speed limits of 107MPH "D" code engine and 142MPH on a "A" code engine.

Externally, there were only a few clues to tell an "A" code from a "D" code engine:

  • "A" code engines were not made before 1989
  • "A" code engines only came in 5 speed cars
  • From 1989 to 1991, the "A" code had a cast iron exhaust header
  • From 1989 to 1991, "A" code motors had smaller front pulleys.
  • "A" code motors read "High Output" on the coil cover.
  • The W41 engines had "W41" cast on the coil cover.