We occasionally get inquiries from modelers who are concerned that their engine will not fit on the VMAR engine mounts supplied with VMAR ARF's. Although there is no way to guarantee that the VMAR engine mounts will accomodate every engine on the market we are quite careful to make sure that VMAX and most other popular engines fit on the mounts, provided that the engine is of the recommended size. Discussions with consumers reveals that some modellers occasionally misunderstand the way the engine mount is to be used or do unnecessary work (drilling) when installing their engines.

Resolution:

In Brief: The VMAR clamp style engine mounts do not have to be drilled for most engines. The engine lugs fit between the engine mount beams and the clamping plates. Generally the instruction manuals illustrate how to use the clamping plates.

In Detail: No drilling is normally required to use the VMAR clamp style engine mount. Remove the four black machine bolts and clamping plates from the engine mount beams. Place the engine on the engine mount beams and reinstall the clamping plates and bolts so that the clamping plates are above the engine lugs and the bolts are placed such that one bolt is ahead of each engine lug and one bolt is aft of each engine lug. Align the engine to be pointing straight ahead or slightly to the right and tighten the clamping bolts firmly to hold the engine in place.

Generally the clamping plates have three bolt holts to allow for two different orientations and different fore and aft locating of the engines. Four Stroke engines should be set further foreward if they are too long aft of the engine lugs. In the event that an engine does not fit on the beams with the clamps and bolts in place, the bolts should be removed and the engine mount drilled or drilled and tapped for bolts to pass through the engine and the lugs in the traditional manner.

Some engines such as the OS LA series have narrower cases than others and may be pose difficulties when mounting.  If modelers are determined to install an OS LA they may have to remove the engine mounts and respace them closer together. The engine mounts can be removed by undoing the mounting bolts from the back of the beams i.e. inside the fuel tank compartment slightly aft of the beams or, depending on the model, when blind nuts have been installed behind the firewall the bolts can be loosened from the front.  Alternatively, modellers may wish to leave the engine mounts in place per the factory location and use a plywood adapter plate to accomodate the OS LA. Use 1/8" or thicker plywood. To make a plywood adapter plate, remove the four machine black machine screws and clamping plates from the engine mounts. Make the adapter large enough to completely cover the flat area of engine beams... from left to right and from the beam forward tip to the aft end near the firewall ensuring that the adapter plate is sized to sit flat on the engine beams. Mount the plywood plate to the engine beams with the four screws and washers. Do not reuse the metal engine clamps. Now position your engine on top of the plywood plate, center it and mark the cutout area you will require in the plate center area so that your engine lugs can sit down upon and be supported by the plywood. Cut away the engine clearance area. Center and mount the engine using machine bolts/nuts/washers... the bolts should pass through the engine lug holes and the plywood adapter plate.

Some engines have wider crankcases or in cases where a larger engine is being installed and the beams are not wide enough apart, they beams can be removed and reinstalled with a wider stance OR filing the clamping plates to accomodate the case width may help where only a small additional bit of clearance is required.