Murphy
07-09-2004, 08:31 PM
Installed a set of GLM aluminum manifolds and risers this week and tested today. Here's how it went...
1986 Classic 22, Tempest 300 SBC, performance modified during rebuild two years ago.
Part 1 - Removed the old risers and manifolds. The Tempest uses the four-hose setup with each riser and each manifold getting fed by it's own hose. The riser gaskets have two large holes on the sides and two small holes on the front and back. The small holes were almost completely clogged with rust scale. I can't see how the risers were getting much water during startup before the thermostat opened.
Part 2 - removed the bracket mounting studs from the old risers and manifolds and reinstalled on the new ones. All mounting holes on the GLMs were in proper locations for mounting the shift bracket, ignition module, fuel filter, and circuit breaker.
Part 3 - Installed new manifolds and risers. All gaskets were provided and of good quality. The risers bolt down through the top using 5" bolts whereas the original risers used mounting studs and nuts. The old water hoses fittings were located on the side of the original risers not on the front of the riser like most. This meant the remote oil filter bracket that originally mounted on the front of the port riser had to be relocated. The photo shows how I solved this problem.
Part 4 - The Tempest came with 3" risers. The GLMs are 4". I used a hole saw to cut new holes in the transom, installed new wet hose and 4" Rex Marine exhaust tips with internal flappers. On top of these I mounted IMCO 4.5" x 12" external mufflers to quiet things down. See photo.
Overall, results are very satisfactory. The loss of 150 lbs in the engine compartment has the boat riding 2-3" higher in the water at the stern The hull definitely comes onto plane faster with much less bow lift. The exhaust note is lower and softer at idle but is a good 15-20% quieter at all speeds above idle. Engine temp is reading 10 degrees cooler, probably due to improved water circulation. Handling seems unchanged. My speedo says I picked up 2 mph.
Total time for complete install working alone was about 10 hours with mods, the usual trips to hardware store, and cleanup.
Murph
1986 Classic 22, Tempest 300 SBC, performance modified during rebuild two years ago.
Part 1 - Removed the old risers and manifolds. The Tempest uses the four-hose setup with each riser and each manifold getting fed by it's own hose. The riser gaskets have two large holes on the sides and two small holes on the front and back. The small holes were almost completely clogged with rust scale. I can't see how the risers were getting much water during startup before the thermostat opened.
Part 2 - removed the bracket mounting studs from the old risers and manifolds and reinstalled on the new ones. All mounting holes on the GLMs were in proper locations for mounting the shift bracket, ignition module, fuel filter, and circuit breaker.
Part 3 - Installed new manifolds and risers. All gaskets were provided and of good quality. The risers bolt down through the top using 5" bolts whereas the original risers used mounting studs and nuts. The old water hoses fittings were located on the side of the original risers not on the front of the riser like most. This meant the remote oil filter bracket that originally mounted on the front of the port riser had to be relocated. The photo shows how I solved this problem.
Part 4 - The Tempest came with 3" risers. The GLMs are 4". I used a hole saw to cut new holes in the transom, installed new wet hose and 4" Rex Marine exhaust tips with internal flappers. On top of these I mounted IMCO 4.5" x 12" external mufflers to quiet things down. See photo.
Overall, results are very satisfactory. The loss of 150 lbs in the engine compartment has the boat riding 2-3" higher in the water at the stern The hull definitely comes onto plane faster with much less bow lift. The exhaust note is lower and softer at idle but is a good 15-20% quieter at all speeds above idle. Engine temp is reading 10 degrees cooler, probably due to improved water circulation. Handling seems unchanged. My speedo says I picked up 2 mph.
Total time for complete install working alone was about 10 hours with mods, the usual trips to hardware store, and cleanup.
Murph