As seen in Speedboat Magazine’s
Sept/Oct 2023 Issue.
CORRECT
Distributor Gear
Dear Bob:
I bought a Crane Cam in 2014. It is part number 139021 and has the iron gear. Do I need to use a melonized distributor gear
with this camshaft?
Thanks for your help.
Chad White
Campbell River, British Columbia, Canada
Iron gear on billet camshaft.
Crane Cams is no longer in business as they were absorbed into Comp Cams. The camshaft that you purchased is a high quality 8620 core hydraulic roller with the iron gear. If it did not have an iron gear, you would have to use a bronze distributor gear which is sacrificial which means the gear is designed to wear instead of the cam gear.
Distributor gears (left to right): bronze, automotive, melonized marine.
Regular steel gears supplied on many aftermarket performance distributors including MSD are not reliable in the performance marine environment partially due to the sustained higher RPM. When MSD used the same steel gear on the marine distributors as they used on the automotive distributors, we experienced gear failures on a frequent basis. Sometimes these failures would also damage the camshaft gear resulting in a more extensive repair. Through testing, we discovered that the General Motors melonized distributor gear was a reliable alternative and worked with MSD to make the switch. The stock GM distributor shaft is .490″ diameter and the MSD shaft is .500″ diameter. As a result, the melonized gear that MSD sells is the GM gear that has been reamed to .500″ diameter. The GM melonized gear is easy to identify because it looks rough and unfinished below the location of the gear teeth.
Some of the GM distributors used in production and performance engines have a gear that is silver in color. We have not seen significant failures with that gear.
The answer is yes, you do need to run a melonized distributor gear with your billet camshaft with the iron gear.
350 Mag MPI
OVERHEATING
Dear Bob:
I am the owner of a 2006 Crownline 225 LPX with a 350 Mag. The boat is equipped with Captain’s Call and a Bravo 1 drive. The 2-point quick drain is overheating at idle. I have replaced the thermostat, impeller, engine water pump and finally the whole raw water pump. After the boat starts up, the temperature rises to 180 and all seems fine. After a minute or two, the temp starts to creep up. If I rev it up, the temp comes down to around 150. I have hooked a hose directly to the raw water pump inlet with the same results, so I don’t believe the issue is with the outdrive. It has the power steering cooler, which is clear and there’s no engine oil cooler, so I don’t believe there is blockage. It has been suggested that not enough water is going to the engine, and that some 350 Mags need a restrictor installed to force more water through the block. What do you think about that, and do you have any alternate ideas?
Thank you very much.
Reid Halvorsen
Phoenix, AZ
MerCruiser 350 Mag.
There are a few versions of your engine package. It does sound like the cooling water is not being routed through the engine block properly by the recirculation pump. The raw water pump supplies water to the thermostat housing assembly. When the engine is cold, most of that water is directed straight to the exhaust manifolds and risers. Some assemblies have restrictor balls on a spring-loaded shaft to limit the amount of water going directly to the exhaust at idle. If these balls are worn or the springs are collapsed, less water will be directed to cooling the engine. If the thermostat has been changed, it must be the proper type and in the proper position. It is possible to put it in wrong. Recently, I had a situation similar to yours and discovered that the shaft in the recirculation pump was broken and the impeller was not turning even though the pump looked and felt fine from the exterior. I would inspect the recirculation pump just to be sure.
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