1986 Four Winns Horizon 190, Carb Linkage?

[MrHProblems]

I recently acquired this 1986 Four Winns Horizon 190 with a Mercruiser 230 V8 in it.

The motor runs and sounds good at idle but it feels underpowered, only goes up to 3,000 rpms and 30mph at WOT under load.

I noticed the throttle plates/butterflies don't open at all when I move the throttle. I disconnected the throttle cable so I would have full range of throttle abilities and they don't open that way either. I can use my finger and easily move them fully vertical though.

Here is a pic from what I believe is the throttle shaft(circled) with nothing connected to it.

I cant find a diagram that makes any sense online for what I am missing here.

*Crossposted*

 

[cyclops222]

Look all around the engine surfaces. You may find what is needed.
Is this a 4 barrel carburetor ? You are running on the primaries ?

 

[alldodge]

If it was on a auto, that is where the choke linkage would be. The piece missing is not found in a marine application. It keeps the 4 barrels from opening until the engine has warmed up

That carb uses a vacuum linkage to keep 4 barrels from opening until rpms come up, there is no manual connection

only goes up to 3,000 rpms and 30mph at WOT under load.

Start with the basics, compression test
What pitch and size prop is on the drive?
What is the drive ratio?

Your carb link

 

[MrHProblems]

If it was on a auto, that is where the choke linkage would be. The piece missing is not found in a marine application. It keeps the 4 barrels from opening until the engine has warmed up

That carb uses a vacuum linkage to keep 4 barrels from opening until rpms come up, there is no manual connection


Start with the basics, compression test
What pitch and size prop is on the drive?
What is the drive ratio?

Your carb link

Good compression,

Its not a prop issue(previous owner has videos of it doing 45mph last summer with this prop)

I don't know how to find/get the drive ratio.

 

[MrHProblems]

Look all around the engine surfaces. You may find what is needed.
Is this a 4 barrel carburetor ? You are running on the primaries ?

I believe it’s a 4 barrel carb.

 

[Bt Doctur]

a Rochester normal operation is primary with a choke plate, the plate in the rear is the secondary and the actual throttle plates that open are below the plate your moving with your fingers

Rochester Quadrajet Carburetor: A Complete Guide

www.carburetor-parts.com

 

[MrHProblems]

a Rochester normal operation is primary with a choke plate, the plate in the rear is the secondary and the actual throttle plates that open are below the plate your moving with your fingers

Rochester Quadrajet Carburetor: A Complete Guide

www.carburetor-parts.com

I understand that, the plates on the top do not move at all, not even under vacuum though.

 

[ESGWheel]

I understand that, the plates on the top do not move at all, not even under vacuum though.

To aid in the discussion its helpful to make sure there is common terminology. With this carb there are a total of four “plates”: the (1) Primary Throttle Plate, (2) the Secondary Throttle Plate, (3) the Choke Plate and (4) the Secondary Air Valve (this may not be the correct term, but useful for this discussion). See picture for these.

I believe you are saying the Secondary Air Valve does not open at all. Please confirm.

 

[alldodge]

Its not a prop issue(previous owner has videos of it doing 45mph last summer with this prop)

I don't know how to find/get the drive ratio.

Something has changed from last summer,

 

[MrHProblems]

To aid in the discussion its helpful to make sure there is common terminology. With this carb there are a total of four “plates”: the (1) Primary Throttle Plate, (2) the Secondary Throttle Plate, (3) the Choke Plate and (4) the Secondary Air Valve (this may not be the correct term, but useful for this discussion). See picture for these.

I believe you are saying the Secondary Air Valve does not open at all. Please confirm.

View attachment 408726

Yes the secondary air valves are not opening I believe.

 

[MrHProblems]

Something has changed from last summer,

I agree

 

[ESGWheel]

The last time I played with a Rochester Quadrajet was decades ago, so I am not the best to advise but let’s try some basic things on the carb.

Check to determine if the Secondary Air Valve is stuck. The device to rotate is the item the red arrow points to in the picture. You may have to remove the control rod (at the small red circle) to be able to manipulate the Secondary Air Valve fully open and close. The large red circle is the vacuum actuator for it (which may be bad, but this test first). With the control rod disconnected it should freely open and close. If no good, investigate (possible corrosion?).

Next ensure the Choke Plate operates freely as well. It’s controlled by the device in the blue circle but no reason to disconnect anything. On a cold engine, simply push the Choke Plate fully open and it will close on its own. Again, looking to see if it moves freely or is binding.

Next (and this is where I assume the Secondary Throttle Plate on a marine carb is mechanical) with the Secondary Air Valve and the Choke Plate propped open (use a piece of wood or some such, even a balled-up paper towel will work) move the helm throttle fully open (engine off of couse). Using a flashlight look to see if both the Primary and Secondary Throttle Plates fully open. They should be. If not, there is an issue.

Reconnect the rod for the Secondary Air Valve.
Post results.

 

[MrHProblems]

Did a lake test yesterday:

Carb is functioning properly it appears when it comes to the secondary air valves, the choke and the bottom side throttle plates as well.

 

[ESGWheel]

I am hoping others can join here as I do not have expensive experience with these carbs but I will keep trying to help. First off, I think I was mistaken on the blue circle being the choke pull off… in looking at the picture closer it looks like a lock out for the Secondary Air Valve to keep it from opening until engine warmed up that AllDodge was referring to in post no. 3.

And now we know all these various plates all are free to operate. Given your symptoms it’s possible that the Secondary Air Valve is not opening. While the plate itself is free to move perhaps the vacuum device is failed / stuck or the lock out is not unlocking keeping the Secondary Air Valve closed.

To test the vacuum device, I would normally use a handheld vacuum pump, but I assume you do not have one. So can try this > pull off the vacuum hose from the device and depress its rod into the device simulating that its is being activated by vacuum (the rod gets sucked in). See pic. With the rod pushed in, now put your finger over the hose connection sealing it up. Release the rod. It should stay in place or only move a little bit. Remove finger and rod should return to normal position. Two things being tested here: 1) that the vacuum device moves (is not frozen in place) and 2) that the rubber diaphragm on the device is not ripped.

For the lock out device, on a cold engine I believe you should be able to move its control rod up and down (you may have to open the Secondary Air Valve to do so, unsure). It should move freely as if against a spring and not bind.

Post results of these two tests.

Also calling all Quadrajet experts for other ideas, I am at the limit of my knowledge…. Thanks.

 

[nola mike]

@Lou C can help with the carb, although that doesn't sound like the issue anymore. At speed, try closing the choke a bit manually or covering the air intake. You should lose speed. What do the plugs look like?
"Compression is good"--numbers?
Timing--have you checked it, and make sure it's advancing?
Plug wire order--triple/quadruple check.
Spark--put a timing light on each wire while under way, make sure you're getting a consistent flash.

 

[Lou C]

So basically the problem is the engine won't turn up past 3,000 rpm but it has in the past. I would start with all the basics first, dump out the fuel filter, what does the fuel look like? water? crud/debris? check the antisiphon valve, if this is corroded and sticky the engine will idle ok and rev up with no load, but will not reach max rpm with a load on it. Also verify that the fuel vent is open. Lastly some have had trouble with the screen on the bottom of the fuel pick up tube clogging, some advise to remove that screen, might want to check that as well.
Next I'm assuming it's a mechanical fuel pump, have you tested the pump pressure? Should be 4-7 psi or so.
For the Quadrajet, there are a number of things that can cause problems, one is the idle air tubes, these can be hard to clean and cause unstable idle. Not accelerating can be a bad accelerator pump seal, is there any fuel pooling where the pushrod comes out of air horn? If so that's a sign that the pump seal is leaking, there are much better-quality pumps available.

The secondary air doors are vacuum operated and are held shut with spring pressure. When the manifold vacuum drops, then the doors will open. If the spring is adjusted too tight, they will open late, this may limit top end but won't cause a bog. If you get a bog they are opening too early, the secondary system can't provide enough fuel to combust with the inrush of air from the doors opening. The secondary throttle blades are mechanically operated.
The choke system can contribute to problems as well, first of all the most common choke on these is a manifold heated well type choke and if your engine is not reaching proper warm up temps the manifold won't get that hot (heat comes from the exhaust crossover in the pre-Vortec intake manifold) and the choke may never open all the way. I tend to set the choke on the lean side as this system was designed for auto apps where the engines always ran hotter than marine units, by at least 30 degrees.
The Q-Jet is a very good carb but keep in mind we are talking about carbs that are from 50-35 years old, so all of them will need work to run the way it should.
My family owned a '75 Olds full size with a 350 and a Q-Jet, we had that car from 1978 to about 1985 or so and we never had to have it apart. It ran a lot better than other cars we had from that era with primitive emission controls.

 

[MrHProblems]

So basically the problem is the engine won't turn up past 3,000 rpm but it has in the past. I would start with all the basics first, dump out the fuel filter, what does the fuel look like? water? crud/debris? check the antisiphon valve, if this is corroded and sticky the engine will idle ok and rev up with no load, but will not reach max rpm with a load on it. Also verify that the fuel vent is open. Lastly some have had trouble with the screen on the bottom of the fuel pick up tube clogging, some advise to remove that screen, might want to check that as well.
Next I'm assuming it's a mechanical fuel pump, have you tested the pump pressure? Should be 4-7 psi or so.
For the Quadrajet, there are a number of things that can cause problems, one is the idle air tubes, these can be hard to clean and cause unstable idle. Not accelerating can be a bad accelerator pump seal, is there any fuel pooling where the pushrod comes out of air horn? If so that's a sign that the pump seal is leaking, there are much better-quality pumps available.

The secondary air doors are vacuum operated and are held shut with spring pressure. When the manifold vacuum drops, then the doors will open. If the spring is adjusted too tight, they will open late, this may limit top end but won't cause a bog. If you get a bog they are opening too early, the secondary system can't provide enough fuel to combust with the inrush of air from the doors opening. The secondary throttle blades are mechanically operated.
The choke system can contribute to problems as well, first of all the most common choke on these is a manifold heated well type choke and if your engine is not reaching proper warm up temps the manifold won't get that hot (heat comes from the exhaust crossover in the pre-Vortec intake manifold) and the choke may never open all the way. I tend to set the choke on the lean side as this system was designed for auto apps where the engines always ran hotter than marine units, by at least 30 degrees.
The Q-Jet is a very good carb but keep in mind we are talking about carbs that are from 50-35 years old, so all of them will need work to run the way it should.
My family owned a '75 Olds full size with a 350 and a Q-Jet, we had that car from 1978 to about 1985 or so and we never had to have it apart. It ran a lot better than other cars we had from that era with primitive emission controls.

Lots of great info here, will dive into this tomorrow and report back!