1978 Wellcraft with 4 blade prop, not the speed I was expecting

[89cruisers]

Took my 78 Wellcraft Nova out for the first time today, opened her up and....was let down. I only topped out at 33 going with the current, 29 against. This thing has a 4 blade 15x16 aluminum prop, with a hydrofoil (I will take it off I believe) Boat is 21 foot, and weighs about 3500, with a 302 merc running 188hp. original engine was apparently a 233 (the outdrive that is on it), but I figured I could get more that 33mph, and she wouldn't go past 3k rpms. Any ideas what I should do? Or what the appropriate rpms and top speed should be, I gotta say with the 16 pitch prop it did get there fast, but im more interested in top end since I bought a semi-go fast boat, right now, my 19 bayliner goes faster....(lame lol)

 

[Bondo]

Re: 1978 Wellcraft with 4 blade prop, not the speed I was expecting

Ayuh,... The 233hp used a Taller gear ratio....
the 302 don't have the cookies to spin it... your already at the bottom of available prop pitches,...
It still needs a lower pitch, because of the Tall gearing...
You'll probably have to swap gears or outdrives...
Or,...
The 302 is just sick,+ down on power...

 

[Bob_VT]

Re: 1978 Wellcraft with 4 blade prop, not the speed I was expecting

Yup..... That is my first impression..... there may be an engine problem

 

[steelespike]

Re: 1978 Wellcraft with 4 blade prop, not the speed I was expecting

I don't find those motors in 78 but a 228 uses a 1:5.1 a 198 1:7.1.
You need at least about 1200 rpm.Really not practical though it appears.
Props are available down to 11" but while it may deliver the rpm your speed will
be pretty low.Only real solution is a gear or outdrive change change.I have a feeling the 4 bld. 16 was the most reasonable selection to produce some speed and hole shot.Maybe a 15" 3 bld might give a little more speed and rpm obviously nothing near what you need.

 

[89cruisers]

Re: 1978 Wellcraft with 4 blade prop, not the speed I was expecting

I had always thought that a higher pitch prop was more top speed, but in this case because of the different gearing its not? Would I don't think there are any engine issues that would cause a 1200rpm drop? would adding a 4 barrel carb give enough power top overcome the changed gear ratios? im just looking to be able to top put around 45ish, if possible, take off isn't important to me

 

[steelespike]

Re: 1978 Wellcraft with 4 blade prop, not the speed I was expecting

You should confirm the motor is healthy.Good compression,properly tuned,timing set right and advancing as it should.Throttle opening all the way at the carb.Usaually the gear ratio is stamped on the outdrive.
You can check the ratio by pulling the plugs and manually rotate the motor till the prop goes one revolution count the motor rotations probably will be1 and a1/2 revolutions.
Speaking very generally; yes if a motor can turn a bigger prop at the motors designed rpm it will increase speed.
The lower number ratio is harder for the motor to turn thus the lower rpm.If you go to a higher pitch your making it even harder to turn.
Removing the foil may help your speed a little.
If your motor is presently healthy a carb may help some but you need to get to that 230 hp area I don't think a simple carb will do it for you.
I did find a 230 hp in 78 with a 1.7:1 ratio.Perhaps intended for heavy applications.Your isn't likely but you need to confirm what it is.

 

[89cruisers]

Re: 1978 Wellcraft with 4 blade prop, not the speed I was expecting

The only thing readable on the drive is 233, How would I go abouts swapping the gears?

 

[Riegfrghtl]

Re: 1978 Wellcraft with 4 blade prop, not the speed I was expecting

The Ford 302 (mercruiser 888) should be operating in the 3800-42000 rpm range at WOT. I don't think adding a 4bbl is going to make up the 800-1200 rpm difference. Need to verify if its motor problem or outdrive problem because the motor is severely lugging and this is going to shorten its life span.

 

[Tail_Gunner]

Re: 1978 Wellcraft with 4 blade prop, not the speed I was expecting

Give this guy a pm... Lots of experince

http://forums.iboats.com/member.php?u=6318

 

[89cruisers]

Re: 1978 Wellcraft with 4 blade prop, not the speed I was expecting

I sent him a message, no reply yet. I will compession test the cylinders this week, and check the timing, but if all of that is fine, atleast it will be a more fuel effiecient boat until its fixed right? lol

 

[steelespike]

Re: 1978 Wellcraft with 4 blade prop, not the speed I was expecting

Actually a boat motor is working like its going uphill all the time
when the gearing is too high it like its going up an even steeper hill.
not the best for fuel use. Tough on the motor and mileage.

 

[Tail_Gunner]

Re: 1978 Wellcraft with 4 blade prop, not the speed I was expecting

http://www.supernova19.com/index.html

Theres a link to his web site..Novas look like a fun boat..With 300+hp.

 

[89cruisers]

Re: 1978 Wellcraft with 4 blade prop, not the speed I was expecting

Well but with an engine, if im doing 3k rpms, based on rpms alone shouldnt the fuel consumption be the same no matter how much weight or my ratio, 3k rpms is 3k rpms, or am I wrong?

 

[Tail_Gunner]

Re: 1978 Wellcraft with 4 blade prop, not the speed I was expecting

Took my 78 Wellcraft Nova out for the first time today, opened her up and....was let down. I only topped out at 33 going with the current, 29 against. This thing has a 4 blade 15x16 aluminum prop, with a hydrofoil (I will take it off I believe) Boat is 21 foot, and weighs about 3500, with a 302 merc running 188hp. original engine was apparently a 233 (the outdrive that is on it), but I figured I could get more that 33mph, and she wouldn't go past 3k rpms. Any ideas what I should do? Or what the appropriate rpms and top speed should be, I gotta say with the 16 pitch prop it did get there fast, but im more interested in top end since I bought a semi-go fast boat, right now, my 19 bayliner goes faster....(lame lol)

Sorry wasnt paying to much attention here...Ok a 302 about 180 hp on a 3500 lb boat 21 feet in lenght and i believe and 25degree hull.. It can only reach 3000 rpm...with a 16p prop..The boat is under powered Find a healthy 351 tuned up to 300hp things will come into focus quickly..

Using a 1.5 gear ratio and turning a 16p 4 blade shows a negative slip...More importantly there is no slip..Thats a good indicator that all is well with the prop and hull...You just need more steam sorry to say that but it is what it is

Your bayliner with a 4.3 carbed version is probably a 190 hp motor and a 1500 lb boat on a 17 degree v...More hp 1/2 the boat on a shallow v..Now that Nova can run to about 65-70 and be controlable....Can you imagine the bayliner doing 65mph and cutting say a 1 foot chop..........

High speed on the water takes brute force and a Hull that can take it.

http://www.supernova19.com/nova_marine_at_supernova19_com.htm


He also told me that most of the NOVA19's that he built came with a 426ci Chrysler and vee-drives. He did make a couple odd balls with different motors and even some with what Brownie considered

That Chrysler Hemi was one of the most powerful motors ever made now comparing it to a 302 ...Two motors would not be capable of what is was by itself.

 

[89cruisers]

Re: 1978 Wellcraft with 4 blade prop, not the speed I was expecting

well sadly I think a wellcraft nova is different from those novas?, the cheapest 351 I can find is $400 without a carb or manifolds, so thats another $800 atleast, I think adding a 4 barrel holley and possibly a 3 plade 14x13 might get to about 40mph?, the 4 barrel should about 15hp, I know on the 3.7 going to a 4 barrel adds 20hp

 

[Riegfrghtl]

Re: 1978 Wellcraft with 4 blade prop, not the speed I was expecting

I have a 1972 Cruisers, Inc. Bonanza 21 Foot with the Mercruiser 888 ( Ford 302 188hp). Currently I use two different props.

Prop 1: 15 1/2 X 19p Michigan Wheel 3 Blade 41 mph @ 4200 rpms
Prop 2: 14 1/2 X 18p Michigan Wheel Vortex 4 blade 38mph @ 4150rpms

Speeds are by GPS

My boat is a cuddy and weighs as much or maybe a tad more. I believe there is a motor issue because you keep wanting to go to a smaller prop to increase rpms. At this rate your prop is going to be smaller than whats on my 25 hp kicker motor. Adding a 4bbl right now will not get you to the proper rpms. Recheck motor condition (tune-up, compression test, dwell, Timing and advance). My marina has a dyno where motor can be tested out of water and on trailer. Maybe someone in your area has the same. It might be worth the money to check condition of current set up before throwing money into parts to increase horsepower. Just a thought and some data from my boat to consider.

 

[89cruisers]

Re: 1978 Wellcraft with 4 blade prop, not the speed I was expecting

Yes I will be checking out the engine, but this week has been muggy or rainy and so not much time to take the cover off to get checking things out.

 

[Tail_Gunner]

Re: 1978 Wellcraft with 4 blade prop, not the speed I was expecting

Here you go..Nova forums.... http://www.chinewalking.com/

 

[89cruisers]

Re: 1978 Wellcraft with 4 blade prop, not the speed I was expecting

Oh man, the colors on the forum hurt my eyes lol, okay here are my findings, The points were set a .010, should be at .017, and timing was set at 10 degrees btdc, set it to 0, compression was reading right around 100-105, except for one which was reading about 95, new plugs (old ones were fine however) the boat starts right up, with it in neutral, it would rev up to about 4500 when I would give it a quick hit, carb opens all the way. So it does not appear that I have any mechanical issues with the engine, The bayliner with a 3.0 OMC has a 13x14 I believe prop on it, would you guys suggest I try throwing that on there and seeing what difference it makes?

 

[fishrdan]

Re: 1978 Wellcraft with 4 blade prop, not the speed I was expecting

timing was set at 10 degrees btdc, set it to 0

compression was reading right around 100-105, except for one which was reading about 95,

with it in neutral, it would rev up to about 4500 when I would give it a quick hit, carb opens all the way. So it does not appear that I have any mechanical issues with the engine

What is the timing spec for the 302, 0* doesn't seem right. Check the spec and reset timing.

Compression is low

Revving in neutral doesn't really prove anything, as for the condition of the engine.

Have you checked the mechanical advance in the distributor to make sure it's working properly?