Estes Mini Scale Combo Pak, #0874, Tomahawk & Exocet, Build, Part 6, Installing The Engine Blocks

In the instructions, both of the two models have a slit cut in the upper body tube. The shock cord is fed through the slit. The exposed shock cord gets a paper cover glued over the top.

One model will get the slit tube method, the other will get a Kevlar line tied to the engine block.  

A notch is cut into the outside of the engine block. The Kevlar line is tied and tightened over the notch.

Feed the Kevlar line through the middle and out the bottom.

The original yellow engine spacing tube was missing. I cut a BT-5 coupler to 1 3/4" long.

The fit in the tube was tight so I peeled off the outside layer for a slip fit.

The spacing coupler is pencil marked 1/4" from the bottom.

Slip the Kevlar line through and out the bottom of the spacer coupler. The engine block rest on top of the spacer coupler.

Apply a bead of glue 1 1/4" inside the low end of the BT-5 tube.

Push the engine block in and into the glue up to the pencil line on the spacing  coupler.

For now, leave the Kevlar line out the back of the model.

The second model got an engine block without the Kevlar tie.