a few questions from a newbie

[rsc179]

I've done a little boating in the past (rented or borrowed) but now I own one. It's a Larson SEi 190 w/3.0L inline Mercruiser Alpha 1 Gen 2 in what looks to be very good condition (opinions?).

There are a few things I'm, curious about.
Where is the tube for the speedometer, it seems to be reading low and I want to make sure it?s not obstructed. I've already checked the hose from the gauge back to the drive. And yes I know it?s not a very accurate meter.

The WOT is 4300rpm but the specs say 4400-4800 and I'd like to get that little extra out of it (I'm thinking of swapping it out for a 4.3 in the fall). So I thought I'd tune it up and clean/adjust the carb. Back around the mid 80s I was a Chevy Certified Technician so I know a bit about this engine and carb. But frankly I've forgotten what, if anything, I have to do to the HEI when I set the timing. Could someone remind me?

Could a drop of 500rpm be caused by the prop alone? It's a 14.5x19, stock for this boat, and it has some corrosion and nicks. I'm getting a new one anyway but was wondering.

What would happen if I went with a 21 prop? It has plenty of off the line power now, I'm just looking for a little more speed.

Does aluminum or stainless really make any difference?

And one final question for when I swap the engine in the fall. I'll be able to see this after I pull the 4cyl, but I'd like to know in advance. What kind of fastener is used in the hull for the engine mount? The mounting boss is there for the 6cyl but no imbedded hardware, what kind of nut is used?

Thanks in advance
RC

 

[tmh]

Re: a few questions from a newbie

Check you speed with a gps at WOT to help with prop selection.

You're under the rec. WOT rpm now so going UP in prop pitch won't be good. Do the tune up and whatever else to get the engine putting out the most it can THEN check WOT rpm and speed. If you're on the high end of rec WOT rpm with a 19" prop, then a 21" may give you more top end.

SS helps a few mph maybe. More with a higher hp engine and heavy boat from what I've read. If you have a beat up prop then you may see more improvement. Again do the bst you can with the engine then post new test #'s in the prop forum.

 

[jerryjerry05]

Re: a few questions from a newbie

Changing to a 17p would bring up the rpm.21p would lower them.
Alum or stainless,Depends on your style of boating.If you plan on hitting sandbars and stumps and running aground: Go aluminum
If you run in deep water and don't expect to find the bottom:Then stainless is the way to go.A 15p stainless would run the rpm you need.
And when you change motors you will need to change the gear ratio in the top of your drive. Going to a V-6 would make a lot of work.Jerry

 

[chiefalen]

Re: a few questions from a newbie

first make sure of the speed with a gps.than full tune up i don't know what year boat. rent a good 19 pitch prop.checks speed again and rpms if they didn't come up. if you keep your boat in the water than you'll have to check the bottom.hopefully u wont have to check the foam thats latter.post back what happens.

 

[Fireman431]

Re: a few questions from a newbie

Going up to a 21 pitch will lower your WOT RPM's by approximately 400. Try a 15 x 19 and then a 15 x 17. Clearance may or may not be a problem (it shouldn't be). Tune up first and calibrate the speed with a GPS and a good tach to make sure the original tach is reading correctly.

 

[rsc179]

Re: a few questions from a newbie

Greate information, one question left.
On the 2002 3.0L (w/ the electronic ignition). What I've found on setting the timing is to connect the two white wires comming from the distributor together and disconnect the shift interupt switch.
The white wires are easy enough to find but where is the "shift interupt switch"