last ditch effort

[mh11]

Hello there, it's me again

1978 galaxie 22xl with merc 260 chevy crate motor 350

Not getting rpms.

Replaced plugs, plug wires, set timing dwell, advance, etc at a shop.
Put new anti siphon valves in
Replaced water seperating fuel filter, and filter at carb
Propped down per members advice
New fuel in tanks
Exhaust bellow at risers are getting ready to be installed
Hull is totally clean
Risers and manifolds look good.
Fuel lines inspected, feel good, no cracks, etc.
Throttle plates appear to open fully
Temp is correct around 140 at all times when run in the past. I replaced the impeller when I bought the boat

Here is the dillema, when I pulled the risers off, there is NO evidence at all of flappers being in the exhaust. I mean there is nothing there. I suspect whoever put this motor in did not put flappers in.

All I see is two squares on the outside of each y-pipe that are parallel to the transom. Is this where the flappers mount?

I have run the boat 5 or 6 times with no water coming back in to the engine.

Do I need to run the flappers, or can I go without?

I am getting ready to take the boat to the lake and test it to see if I can get more rpms out of it.

By the way, one more question. I am currently getting around 3900 rpm out of the motor, do I really need to get to 4200-4600? Am I bogging the motor, or can I run it this way?

I have a buddy that is begging me to sell him this boat, and I am about ready to. I am a perfectionist, and I want everything to be exact.

Thanks again for all of your help.

 

[Anchor Management 1]

Re: last ditch effort

Well you have a ? about missing flappers and lower rpms.Are the old flappers stuck in the Ypipe or drive?

 

[cooter2506]

Re: last ditch effort

Remove drive and check for the old flappers the usually get stuck at the bottom of the y pipe or against the shift shaft in the outdrive

 

[mh11]

Re: last ditch effort

Ok, I understand. I need to check in the y-pipe for remnants of the flappers.

There is no evidence, I repeat, no evidence of any sort of flapper stuff in the y pipe.

Can I take off the outdrive without having to re-align the outdrive? I am on a budget, and I dont want to spend a bunch of money for something that i can do myself.

Thanks!

 

[danond]

Re: last ditch effort

If you haven't removed the outdrive to look for the flappers, then you don't know if they are in there. I found both of mine the first time I removed my drive.

Yes, you can skip alignment, but alignment is cheaper than a coupler or a driveshaft. You sure it's not worth the $65 tool and an extra 30 minutes?

 

[TilliamWe]

Re: last ditch effort

Yep, you need to pull the drive, and you might find the flapper pieces. If the alignment was done recently, and the drive goes back on, you don't need to align it again.
Yes, those little squares on the top of the Y-Pipes are where the flappers would mount.
You HAVE to get the WOT RPMS into the recommended range. If you don't, lugging the engine will cause excessive combustion chamber heat, which will tulip your valves. And if you ran it long enough that way, it would melt a piston.

 

[Bt Doctur]

Re: last ditch effort

compression test with carb wide open,post results
cylinder balance test, pull 1 wire at a time ,note rpm drop, replace and do another, post rpm drop on each cylinder
No drop in rpm with the wire off indicates a dead cylinder
your prop pitch and dia.
plug firing order wrong, 1,8,4,3,6,5,7,2

 

[JustJason]

Re: last ditch effort

There's no evidence of the flappers because at 1 point or another the engine overheated and the flappers melted off. They will get stuck at the bottom of the Y pipe where the exhaust comes out. Yank the drive and see if they are there. Yes you do want new flappers to put in there.
Now on to your rpm issue. Yes at wide open you want to be in the mid 4K's. But before we do this test and that test, what tach are you using to deterime your rpms... a 10 year old boat tach or a known good shop tach? Because you need the latter.

 

[mh11]

Re: last ditch effort

Ok, well, I bought a comp tester so I will take a comp test this weekend.

Funny, last time I took it out, it only pulled 3000 rpms, not 3900. Found plug wire off second cylinder on the right side of engine. So the rpms definitely drop with a wire off.

Question, can I pull the outdrive myself and look for the old flappers? How hard is it? I am very mechanically inclined. I would like to pull the outdrive myself, and just pay the shop to align the unit when I put it back on. They know what they are doing with the alignment.

Another question, do I really need to install the flappers? Can I run without them?

One final question.

Upon inspecting the risers, and manifolds last night again, I found there was a metal block off plate sandwiched between the gasket and the riser. They are aqua power 5701 risers with three holes in them. One in the front and two on the sides. Looks like the metal piece was blocking the water off.

Should I re-install with these metal block offs, or just put new gaskets in and let the water flow thru?

Thanks for all the help

 

[mh11]

Re: last ditch effort

Hopefully someone will help me with my questions above.

To answer justjason.

There are brand new gauges, and the shop that set the ignition tested the tach, and said it was spot on.

Any help to the questions in my last post would be appreciated.

Thanks!

 

[Anchor Management 1]

Re: last ditch effort

Yes you need to leave the metal plates between the gaskets. Yes you should put new flappers in it too,If you trailer the boat when you back it into the water,water can come into the engine.And when you are boating and need to stop fast water can come into the engine,flappers will stop this.

 

[Fishermark]

Re: last ditch effort

Bond-o has posted a picture before that shows where the flappers typically end up. If that has happened to you, then yes, you will be able to see them when you pull the outdrive.

Here is the pic he posted:

Do you need them? Do you have to replace them?

Well, the engine will run just fine without them. (Especially after you remove the pieces from the exhaust - IF they are stuck down there). They are there as a safeguard to keep water from backing up into the engine. Some manufacturers do not install them anymore. Some run for many years without them in with no problems. It is a roll of the dice for you... to be safe, it is probably wise to put them back in. But, as said, many don't. To quote the immortal Clint Eastwood - "Do ya' feel lucky?" I'll leave out the "punk" part. )

Question, can I pull the outdrive myself and look for the old flappers? How hard is it? I am very mechanically inclined.

The outdrive is easy to pull and is a skill that you will need to learn yourself. Download the manual and do a search here. It is something you need to do periodically for maintenance.

I would like to pull the outdrive myself, and just pay the shop to align the unit when I put it back on. They know what they are doing with the alignment.

Being mechanically inclined, you can easily check and even perform the alignment yourself. Buy an alignment tool/bar and keep it handy. It will more than pay for itself.

 

[miles917]

Re: last ditch effort

Check eBay for an alignment bar, very worthwile to have in your garage. While your waiting for it to arrive, call up your local boat shops and see if they will loan you one. Before I bought mine, a local shop lent theirs to me with a deposit.

 

[mh11]

Re: last ditch effort

So let me ask another question.

If the manifolds and the risers have matching holes in them, what purpose do the metal plates serve that block off the water flow in between the two of them????

The hose going from the t-stat housing goes to the riser, is the metal plate blocking that off?

One person said I need to leave the metal plates in.

 

[mh11]

Re: last ditch effort

Well here is the news. You all said take a compression test.

I was not getting full rpms, around 3900 to 4000 only.

Here is what I found.

Upon inspection, the throttle plates were opening about 80% of the way. I checked this before I did the compression test just for kicks. Glad I did.

Compression is as follows

Starboard side front to back
1) 120
2) 115
3) 113
4) 115

Port side front to back
1) 110
2) Dead nothing
3) 107
4) 110

What do I do now? Interesting thing is, the motor idles very smoothly, I can get 3900-4000 rpm out of it, the only thing is, it backfires at wot high rpms.

Should I pull the valve cover, and the coil wire, and turn the motor over and see if any of the valve train is not moving?

Also, it is pretty rare for on cylinder and the rings to just go bad when everything else seems to be in a 10% range it seems.

Please help!!!! I am ready to tow my kids around the lake.

 

[FreeBeeTony]

Re: last ditch effort

I am very suprised you are able to get 3900RPM's on 7 cylinders............

 

[proshadetree]

Re: last ditch effort

1st oil cylinder then retest compresion.Then pull valve cover and look for valve movement I bought a noce old once with a broken rocker bridge for a song.it backe off and popped out the intake.Then a ford truck with bent push rod it just missed like crazy.

 

[xltier]

Re: last ditch effort

1st oil cylinder then retest compresion.Then pull valve cover and look for valve movement I bought a noce old once with a broken rocker bridge for a song.it backe off and popped out the intake.Then a ford truck with bent push rod it just missed like crazy.

you may have a burnt valve on that cylinder as i did once on a 260 hp 350.pulled just that head and had it fixed and back together in a weekend.

 

[mh11]

Re: last ditch effort

Ok, pulled the valve cover, and turned the motor over. My brother in law watched the valve train. The valves appear to be opening and closing. At least the valve train looks to be functioning normally.

I tried oiling the cylinder, and the gauge doesn't even move. 0 compression.

What should I do next? It doesn't make sense that the cylinders can be almost within 10% of one another, but one is dead

Do I have a burnt valve? Is that what the problem is??

Can I run the motor with one dead cylinder? I don't want to really spend a lot more money on this boat.

Yes, I was getting 3900 to 4000 with a dead cylinder, I just want the motor to run properly.

Thanks for any advice!

 

[Bt Doctur]

Re: last ditch effort

Guess you could but would you really want to? Ever see a connecting rod go thru the bottom of a hull?
If you can walk on water ,then run it till it breaks.