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Help Choosing the Correct Prop


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I recently purchased a 1987 Chaparral 198XL that needs restored.

I would like to get it running and on the water this summer and then work in the fall/winter to get it restored.

It came powered with a 5.0L V8 with an Alpha One drive. The prop that is on there is dinged and bent pretty well.

Does anyone have a recommendation for the right prop to put on this boat? I'd like to ski behind it, so pulling from a stop is more important than top end speed to me.

Thanks for the help!!

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Seeing you have an Alpha 1 MR drive, (essentially the same drive, but with some changes ranging from model year 1967 to 1990) you'll want to replace the impeller kit inside the lower unit itself. That style of seawater pump is a high pressure, low volume design, that should really be changed out every 3 years or so for reliable cooling. I typically go with MerCruiser kit 46-96148T8 or Q, and mounting gasket 27-94996T2 or Q2. Also a good time to have the engine alignment checked, and the drive yoke splines greased.

Unless you want a stainless steel prop, I would just go with a 4 blade aluminum, probably need a 20" pitch, right hand rotation for your application.

Just out of curiosity, what is the diameter of the power steering pulley on your engine? The reason I ask is this will help determine what your RPM range should be at wide open throttle. I'm pretty sure your p/s pump pulley diameter should be 5.5" or 7".

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Thanks Shepherd, I'll have to check on the diameter of the power steering pulley.

I definitely plan on replacing the impeller before getting out on the water. Yesterday, I put a new battery in it and it wouldn't crank. Checked the slave solenoid and it was good, so I popped off the starter and it's bad. Also, I found out that the old owner snapped 3 of the 4 screws holding the distributor cap to the distributor, so that will also need replaced.

I've got some work to do before she is lake worthy for sure.

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Before you buy ANYTHING.

Remove ALL the sparkplugs. Draw a diagram & label the plug wires to later put them back correctly.

See IF IF you can turn the pulley over by hand. If yes ? maybe the engine is O K. If you can not. STOP all spending.

Shepherd1

Can that supposed year be shifted into FOWARD & still have the engine be hand turned over ?

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Before you buy ANYTHING.

Remove ALL the sparkplugs. Draw a diagram & label the plug wires to later put them back correctly.

See IF IF you can turn the pulley over by hand. If yes ? maybe the engine is O K. If you can not. STOP all spending.

Shepherd1

Can that supposed year be shifted into FOWARD & still have the engine be hand turned over ?

Good advice. I first checked to make sure it was winterized, there was anti-freeze in the j-hose. So that was a good sign.

I will check to see if the engine is free.

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