Here We Go: My 383 Stroker Winter Project

[Scott Danforth]

Re: Here We Go: My 383 Stroker Winter Project

amazing what happens when the engine breaths.

 

[joewithaboat]

Re: Here We Go: My 383 Stroker Winter Project

Folks repeat all kinds of garb that isn't true, mostly because they have never tried it or seen it with there own eyes .......LOL...

 

[Tail_Gunner]

Re: Here We Go: My 383 Stroker Winter Project

I just got back from a few hours of messing around with the boat. I got myself a timing light with an advance dial and checked the total timing, which ended up being only 26 degrees.. I bumped the total timing up to 32 right away and gave it a go. I hit 60-61 (mostly 60, hit 61 for a fraction of a second) mph at somewhere between 45-4600 rpm. Then I bumped it up to 34 degrees and I got a constant 61 mph and quickly hit 62 on two of the runs. Everything ran great. Then I decided I would throw on the 1" open spacer that I bought and I jumped up to 63 mph at about 4600 rpm. So the spacer helped, and advancing the timing helped too.

Hey that is great if you picked up some performance buy opening up the exhasut actually youve bypassed the y pipe and outdrive the real bottleneck Volvo actually makes a high performance transom sheild....you have captian's call?? What is intresting is that engine seem's to benefit at the induction end of things also. Timing and a little spacer netted 63 once before you may have found the engine's peak..and water condition's may be the reason for the litte jumps I cant remeber if you actually tuned that carb...here is a little blurb on one person's experience and the fact that it wont idle low makes it a little suspious.

http://www.chevelles.com/forums/showthread.php?t=356645

Very detailed tuning thread: http://forum.grumpysperformance.com/viewtopic.php?f=55&t=109

Some insight as to how exhausting a engine work's
http://forum.grumpysperformance.com/viewtopic.php?f=56&t=495&p=613#p613

one of the most common and least tested for restrictions to building increased horsepower is in restrictive exhaust systems that can not effectively allow the headers to scavenge the burnt gases from the cylinders
is exhaust back pressure killing performance ?
obviously the volume of your engine exhaust increases with the rpm range, so while the stock exhaust may be fine under........5500......rpm it surely may be restrictive in the upper rpms, once you've installed better flowing heads and added a cam, after all the engineers at G.M. were matching the stock components not aftermarket parts.


As always the above is strickly a opinion your milage may very...

 

[greg82255]

Re: Here We Go: My 383 Stroker Winter Project

Well I didn't end up buying a shop tach but I did play with props this afternoon. I did some GPS runs with the 23" stilletto and the 21" mirage with 2 blades with some minor damage.

23" Stilletto - 63-64 mph @4600-4650
21" Mirage - 61-62 mph @ 5200 rpm
all readings from the gaffrig tach on the boat. I didn't expect a 600 rpm jump from 2" of pitch. Must be the type of prop as well. I'd assume they would provide about the same speed if the blades weren't damaged on the 21" prop. The handling is great with both props too.

I am looking into buying an alpha SS drive. It is 2.75" shorter than stock and has a nose cone. There is a guy up in Maine that has one and I'm actually going up there this weekend and could go over and buy it. Any guesses on what it would do for me? 70? I believe it is a 1.32 ratio so I would need to use the 21" prop or maybe even a 19.

 

[joewithaboat]

Re: Here We Go: My 383 Stroker Winter Project

Well I didn't end up buying a shop tach but I did play with props this afternoon. I did some GPS runs with the 23" stilletto and the 21" mirage with 2 blades with some minor damage.

23" Stilletto - 63-64 mph @4600-4650
21" Mirage - 61-62 mph @ 5200 rpm
all readings from the gaffrig tach on the boat. I didn't expect a 600 rpm jump from 2" of pitch. Must be the type of prop as well. I'd assume they would provide about the same speed if the blades weren't damaged on the 21" prop. The handling is great with both props too.

I am looking into buying an alpha SS drive. It is 2.75" shorter than stock and has a nose cone. There is a guy up in Maine that has one and I'm actually going up there this weekend and could go over and buy it. Any guesses on what it would do for me? 70? I believe it is a 1.32 ratio so I would need to use the 21" prop or maybe even a 19.

I think Tim has mentioned using an SS drive before. I'm not sure about the length. Are all SS drives shorter or has this one been shortened?
With those MPH/RPM and pitch differences I would guess that a good labbed prop of the appropriate pitch and dia would get you well over the 65mph hump with your current drive. Maybe time to get on the phone to some good prop shops.
Where in Maine, I lived there for 7 years.

 

[Scott Danforth]

Re: Here We Go: My 383 Stroker Winter Project

pretty respectable numbers there Greg. may want to actually talk to a prop guy to get you dialed in the rest of the way.

 

[Tail_Gunner]

Re: Here We Go: My 383 Stroker Winter Project

http://boatpropellers.iboats.com/Me...-143-22_Propeller/769/9547/?*******=425723598

That prop should be right on the number's..Not as much cupping as a stilletto so 4900-5000. Or labbing the Stilletto but that's some dough about 400. It's hard to find a even pitched 3 blade and the solas is a great prop

 

[greg82255]

Re: Here We Go: My 383 Stroker Winter Project

I think Tim has mentioned using an SS drive before. I'm not sure about the length. Are all SS drives shorter or has this one been shortened?
With those MPH/RPM and pitch differences I would guess that a good labbed prop of the appropriate pitch and dia would get you well over the 65mph hump with your current drive. Maybe time to get on the phone to some good prop shops.
Where in Maine, I lived there for 7 years.

pretty respectable numbers there Greg. may want to actually talk to a prop guy to get you dialed in the rest of the way.

All SS drives are 2.75" shorter. It is supposedly not uncommon to see 5-8mph speed increases just from bolting on the drive. I agree a labbed prop would also give me more speed. I bet with a combination of the 2 I could hit 70. The guy is up in Naples, Maine. I'm going to be in Fryeberg this weekend so it's only about a 30 minute drive - couldn't hurt to go take a look.

http://boatpropellers.iboats.com/Me...-143-22_Propeller/769/9547/?*******=425723598

That prop should be right on the number's..Not as much cupping as a stilletto so 4900-5000. Or labbing the Stilletto but that's some dough about 400. It's hard to find a even pitched 3 blade and the solas is a great prop

I have one more prop I can borrow from a friend - not sure of the make but its a 23" pitch. I want to try that out before I buy any more props. I also need to sell a few things to get some $ for new props. So far nobody wants to buy my Michigan Ballistic 19."

 

[88 206]

Re: Here We Go: My 383 Stroker Winter Project

Yep, alpha ss is almost 3 in. shorter. I have one on my 88 Rinker, upper gear case is shorter. If you get it, be careful as most parts are NLA.

 

[Tail_Gunner]

Re: Here We Go: My 383 Stroker Winter Project

Here is where you want to measure 2 twice before adding once..Trim you leg horizontally to the transom take a straight edge and mark where your cav plate sits in relationship to your hull. If the ss drive is 2.5 inches shorter raise the mark and from there make a determention how far your prop will be from the bottom of the keel...Aka will the prop be even with the keel will it set 1" above the keel where will it end up. You maight want to PM Dhadley with the info and see if he will give you input....Dhadley is one of the most knowledgeable prop people you will run into with a large amount of practical experience on setting up boats...your changeing a lot going where you planning....X dimension are conservative on I/O's but 3" might be over the top..While your not changing the actual x dimesion the effect is the same

Not all I/O's run the leg deep i posted a pic of a boat leaving a very small wake that was a factory setup. Hmm ok here

You cant see it to well but the tip of the blade is even with the bottom of the keel the cav plate is almost 1 1/2 " above the keel. Combine what with a stern lifting 4 blade and you get the small print....You also get chinewalking something you want to avoid if possible aka the boat cant balance anymore it actuall rock's left to right at 55mph and can snap either way hence the term wet wallet or other thing's...It could end up where you cannot even launch blow out on corner's just a lot a variable's

Your already running low slip number's 7% i believe that is a pretty strong number for a family I/O and indicates your already running high on the hull...rember the question are you running high...less wetted surface higher speed's

http://www.offshoreonly.com/forums/drives-lower-units/265162-raising-x-dimension.html

http://www.donzi.org/forum/showthread.php/746-Raise-the-X-or-shorten-the-drive?

 

[greg82255]

Re: Here We Go: My 383 Stroker Winter Project

Alright, I guess I'll hold off on it as an offseason project until I can measure the X dimension. I have the boat in the water right now and everything works, and the boating season isn't much longer, so I'll stick with what I have now. Maybe over the winter I'll pick up an SS or something.

 

[Tail_Gunner]

Re: Here We Go: My 383 Stroker Winter Project

Dont be discouraged be aware... it's pretty easy to mesure up the setup and determine where the prop will ride
then post back. You may however need to play with props again and you may not...there are a few guy's in here that are well schooled in x deminsion or prop height..Out board guys are all over it...But then again they can setback there engine and I/O's are pretty much stuck with what they have.

Now if i had a merc drive.....Id have a SS lower just for the adventure...Maybe..

 

[Scott Danforth]

Re: Here We Go: My 383 Stroker Winter Project

you can get a set-back boxes for Bravo's http://www.cpperformance.com/c-734-bravo-extension-boxes.aspx

 

[wca_tim]

Re: Here We Go: My 383 Stroker Winter Project

Yep, alpha ss is almost 3 in. shorter. I have one on my 88 Rinker, upper gear case is shorter. If you get it, be careful as most parts are NLA.

Most parts are same as an alpha drive... and available. the verticle shaft is the big one that's not around to find, although in a real pinch I would bet you could ave a standard alpha shaft shortened and resplined to work.

I have an ss drive that I need to finish rebuilding (haven't had much time for boats this year yet, but am just getting freed up to be able to play a little!), I've also got another land and sea stern jack for an alpha drive. I haven't run the stern jack yet, but the boat is a solid bit faster with the ss drive and handles a LOT better with the higher prop shaft and more rudder area. Note that when you start pushing faster, a standard alpha nose will blow out a long time before an ss will. I'm thinking I'm going to try the ss drive with 1.8 gears in the upper to see how fast I can go... ;-)

if you have a chance to buy one for a reasonable price (I assume I've seen the add for one you mentioned and that's probably a reasonable price... wink), I'm surprised it is still for sale. I toy with the idea of putting the ss drive and sternjack on together - it should increase speed a lot in my little boat. Unfortunately (perhaps) I have other priorities these days.

Cheers, Tim