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JBP rail kits , Plug from a customer video

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1970 Weiman

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I have a question for Tom and/or Old Rigger. The guy in the vid touched on it, but there were no specifics.

When 'aligning' the engine to the pump input, should you induce an intended misalignment on the H-bar u-joints, or do you go for zero degrees? I understand that the angle on both joints must be the same in both axis, (ie the pump shaft and crankshaft must be parallel) but should there be an induced angle to reduce u-joint wear and vibration? Ie set the engine higher to get angle at the u-joints?

My 1970 Weiman has an intermittent 'grumble' at idle speeds that has been there since it was new. Two engines (big block, then small block), 2 pump refreshes, and a re-rigging 30 years ago has made no difference. From time to time, it still grumbles at idle speed. When I re-rigged the alignment 30 years ago I wanted 1-2 degrees but ended up with the <1 degree it had before, and it still grumbles.

Thank you for taking the time to answer.

Edit: I see this is my 1st post on RDP, but I've been here awhile. I was on and posted under the same handle on PB for many years. I'm not as "new" as 1-post indicates. I've owned the same boat since 1976.
 
jetboatperformance

jetboatperformance

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1970 Weiman said:
I have a question for Tom and/or Old Rigger. The guy in the vid touched on it, but there were no specifics.

When 'aligning' the engine to the pump input, should you induce an intended misalignment on the H-bar u-joints, or do you go for zero degrees? I understand that the angle on both joints must be the same in both axis, (ie the pump shaft and crankshaft must be parallel) but should there be an induced angle to reduce u-joint wear and vibration? Ie set the engine higher to get angle at the u-joints?

My 1970 Weiman has an intermittent 'grumble' at idle speeds that has been there since it was new. Two engines (big block, then small block), 2 pump refreshes, and a re-rigging 30 years ago has made no difference. From time to time, it still grumbles at idle speed. When I re-rigged the alignment 30 years ago I wanted 1-2 degrees but ended up with the <1 degree it had before, and it still grumbles.

Thank you for taking the time to answer.

Edit: I see this is my 1st post on RDP, but I've been here awhile. I was on and posted under the same handle on PB for many years. I'm not as "new" as 1-post indicates. I've owned the same boat since 1976.
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Great question , So some of what your hearing is what we term "machine noise" its more prominent in jets with solid mounts and a "lumpy cam" typically worse or more pronounced out of the water and at low RPM in the water but also goes away when a load is introduced to the impeller (slight RPM increase) . Some is due to clearance between male and female splines (drive line yoke vs pump shaft ) But yes a tiny difference between the crank center line and pump center line is desirable (see drawing) We sell a ton of rail kits that are end user installed I tell them to "contrast" the two free U joints against each other , The forward cup being a few thousand higher than the rear (about the thickness of a dime to a nickle) All the while keep the internal gap between the pump shaft retainer ring and rear of the female spline around 3/16ths
 

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1970 Weiman

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jetboatperformance said:
So some of what your hearing is what we term "machine noise" its more prominent in jets with solid mounts and a "lumpy cam" typically worse or more pronounced out of the water and at low RPM in the water but also goes away when a load is introduced to the impeller (slight RPM increase) .
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You know what it is. You described the conditions under which the noise occurs (and goes away) exactly.

Thanks again for the reply.
Dave P
 
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jetboatperformance

jetboatperformance

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1970 Weiman said:
You know what it is. You described the conditions under which the noise occurs (and goes away) exactly.

My boat is now only used once a year for an annual outing to Moabi with a core group of 7 boats and families that have been doing this trip for 18 years. It still runs well, I still ski behind it, and enjoy putting around in it. I toy with the idea of doing another cosmetic restoration and complete mechanical re-fit, but it will probably never happen. I'm 70 now, and my big project days (and the income to fund them) are in the rear-view mirror. But I can think about it.

I've been annoyed by the grumble for 45 years, even more so because I made an attempt to correct it when I remounted the engine, but failed.

I have a couple of take-out H-bars and splines from boats that were scrapped. The assembly in my boat is the original, 50+ years and 1200 hours. Perhaps one of my take-outs will fit the splines more tightly than what's in it now, and be an improvement. I'll put some time into determining if I can improve the spline to pump fit when I'm prepping the boat for this year's outing.

Thanks again for the reply.
Dave P
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Anytime Happy to help
 
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