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 Posted: 09-25-2019 02:17 pm
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Esprit2

 

Joined: 05-01-2005
Location: Minneapolis, Minnesota USA
Posts: 460
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Bruce,

Yes, I use the 3G type of seal exclusively for my own work. But the old seal is still out there, so rather than get into a seal by seal discussion, I just tell people to cut the new Turbo impeller to match the old impeller's length. If a hacksaw is used, the cut should at least be 'square', clean and smooth, as in, dress it with a grinder. It will still be spinning in a fluid, and any truly ragged or angled edge can cause a localized turbulent flow that could contribute to cavitation. Keep it smooth.

Early Lotus shaft diameters are the same as Jensen-Healey's... 1//2" Later, Lotus metricated the pump, and the impeller shaft & bore became 12mm. The front shaft/ hub diameter, and the bearing OD/ housing bore were unchanged. So either bearing, 1/2" or 12mm, can be used in your older J-H pumps, as long as you buy an impeller with a matching bore.

The main thing to watch for is impeller shaft length. The bearing isn't a one-size "Lotus" part. It's a fairly common 'type' of bearing, with many shaft length combinations. And it seems that the many different Lotus & J-H parts specialists are buying "close but not quite" bearings where they can get the best deals, and they're not all selling the same bearings. I've seen a variety of bearings sold for 907 pomp applications that have different impeller shaft lengths.

The ones that worry me are, IMHO, too short to have an adequate depth of engagement with the impellor. I heard from one J-H owner who received such an impeller, wondered about engagement, but used it anyway. Later, the impeller fell off the shaft within the pump while he was driving the car. Of course, with zero circulation, the engine quickly over-heated.

Regards,
Tim Engel