Reher-Morrison's intake manifold end rail spacers are CNC machined from 6061-T6 aluminum. These spacers fill the gap between the bottom of the intake manifold and the top of the lifter valley at the front and rear of the block. (This area of the lifter valley is sometimes referred to as the "china wall".)
This gap can be quite large due to: Installing certain cylinder heads (i.e. Dart or Brodix 20º, etc.), installing a standard manifold on a tall deck block, or milling the block, intake manifold, or cylinder heads.
Filling this gap with large amounts of silicone or other sealers is not advisable, as large gobs of silicone will never completely cure properly. This can result in vacuum leaks at best, and potential damage to the engine at worst.
Reher-Morrison sells various versions of these spacers in different thicknesses for both big and small block Chevrolet cylinder blocks. See the following list to see what best meets your requirements
| Part Number | Engine Block |
Size | Qty | Price |
| 300-251 | Small Block Chevrolet | .420" | 1 Pr. | $43.25 |
| 300-252 | Big Block Chevrolet | 1/8" | 1 Pr. | $43.25 |
| 300-253 | Big Block Chevrolet | 3/16" | 1 Pr. | $43.25 |
| 300-254 | Big Block Chevrolet | 1/4" | 1 Pr. | $43.25 |
| 300-254M | Big Block Chevrolet - 9.850" Deck Height | 1/4" | 1 Pr. | $43.25 |
| 300-255 | Big Block Chevrolet - Tall Deck | 1/8" | 1 Pr. | $43.25 |
| 300-256 | Big Block Chevrolet - Tall Deck | 3/16" | 1 Pr. | $43.25 |
| 300-257 | Big Block Chevrolet - Tall Deck | 1/4" | 1 Pr. | $43.25 |
| 300-258 | Big Block Chevrolet - Tall Deck | 3/8" | 1 Pr. | $43.25 |
| 300-259 | Brodix/Donovan - 11.30" Deck Height | 1/4" | 1 Pr. | $43.25 |
| 300-300 | Big Block Chevrolet - Dart/Brodix 20º Heads (Top Spacer) * | 1/2" | 1 Pr. | $49.95 |
|
300-301 |
Big Block Chevrolet - Dart/Brodix 20º Heads (Bottom Spacer) * | 1/2" | 1 Pr. |
$49.95 |
* Dart/Brodix 20º cylinder head applications required both a top & bottom spacer.