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Help, 5.7 woes

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wildfrahm

Contributing Member
Yep it's me, I am still working this low rpm thing. I am about at my wits end. I guess I like putting this out here for help ofcourse but it also helps clear my head and look at from anouther angle.
A little background, I have a 1984 wellcraft 260 aftcabin cruiser with a 260R mercruiser sterndrive. Have had boat about 1 month. Am not new to boats or engines.
Have been unable to get boat above 2000 rpm's.below is listed what I have done so far;
*new carb, fuel pump, water seperator filter and fuel filter
new fuel lines from seperator input to carb.
* replaced distributor with marine application, Pewvious was dual point automotive.
installed electronic upgrade (hot spark) new (proper) coil, new wires and plugs. Although heat range is suspect for plugs (autolite 26)
*Replaced all wireing that was spliced in primary circuit and checked for shorts, drains, voltage loss, etc.
*Replaced lower shift cable
*nemours water pick ups in lower unit
* changed props from 16p to 15p.
Wow lost half of my post.
Have to take break. to summerize, I took out today with portable tank, ran worse, took right out brought home checked timing was well above TDC, readjusted to 8BTDC as spec. checked oil was quart low, performed compression check,
1-130, 3-140, 5-135, 7-133, 2,4,6,8 were all 130. Manifold vacume at idle (900 in neutral in driveway on muffs) was rock steady at 18. checked plugs 1,7,2,8, were all tan, 3,5,2,6 were all black but not fouled. Have clear fuel filter but not changed element, could not tell if gas was in filter was so full of fuel. not sure how normal that is.
 
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Test what tack or distributor. Dont set anything on tack or gages on dash have remote set up with real tack/dweel meter, oil,and temp gauges and remote starter.
 
Let me rephrase what I said. Assuming you have a Tach in your dash at the helm. Disconnect the signal wire from the coil to the tach and see if the engine comes up to RPM.

What ignition system does it have?
 
Prestolite contact breaker upgraded to electronic using hot spark ignition for that distributor. Am using correct coil for system.
 
as you say, should be. Other than removing cover and counting gears, I don't know. Plate is not on outdrive. Serial # is stamped into casing so I could id drive.
 
Would like to add that I have cheifalan's list and have been going through. Even installed dehumidifier in engine compartment and in cabin to look for hidden moisture. olny nomial amount pulled. These are not boat models but large freestanding models. (I own a resturant and water used to creep through block wall into office untill I fixed)
 
Look at the attached picture. This is where the info resides.

If the sticker is missing or unreadable the same info is STAMPED into the aluminium housing at the same location. Use a pencil and paper and do what people do to old head stones (I forget what it is called) and you should be able to get what you need.
 
Just a couple suggestions will it get above 2000 rpms in neutral, check fuel pressure if good maybe pull distributor and coil have them checked at a shop I have had bad distributors run great in neutral but under load were bad.
Good Luck
 
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Thanks for imput, there is no ratio stamp on housing. Have scraped paint off to verify. Took pic but have to upload pic from my computer. I have and still am working the distributor aspect as well as fuel.
 
Here is that pic
 

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Think it is my new carbon. Sitting at dock on netural today carbon has flat spot in the intermediate range. Big bog before secondarily open up. It's a eldebrock performer 1410. Am going to rebuild original unit and take out. Have been out of game for awhile but believe it is running rich.
 
Went out and checked, Is the same a elderbrock q-jet. Is probvably a 1410 which is marine as is mine. But am glad I went and looked had thought it was a holly.
Like I said I belive it is the intermeadiary springs and rod. I have used this carborator on my racing engines for years and are the hardest carb. to keep adjusted. Are very susceptable to temp. and humidity. Run a sniffer in exhaust with dash gauge to keep set in my racing apps. but they were all automotive setups.
Am going to pull the rods and springs from old unit and install in new. Must add have not been able to adjust idle mixture on new carb. ever, makes no diffrence when I adjust idle mixture screws. but have 18g of manifold vacume at idle. so may have problem with carb. Have anouther brand new still in box.
Like I said when in water in netural I opened up and it had hard time getting into secondariies unless I went slow. opening hard it bogged badly, but then perked right up. I belive under load will not come out of bog to get to the secondaries operating. so I am basically running around on the primary side of carb. good gas millage but little speed.
 
Docksidemarineservices said:
The drive ratio is not your problem. Your losing thousands of rpms not hundreds. What was the original carb?
Click to expand...


The reason for asking this question is he is running a large 26 ft barge...........a 350 260 hp (If that anymore) and a 1984, 27 years and a lot could have changed. if someone threw a different upper and propped it way out of what is needed he very easily could loose 1000 rpms..........add a misfit of parts that appear to be on this motor, just looking for all info.

Also I agree DUMP the edlebrock. YOU NEED A ROCHESTER QJET.

Either buy new or buy a remanufactured MARINE rochester quadrajet for that motor. This carb was used extrememly succesfully for almost 20 years!! they went to weber due to rochester stopping manufacturing. Now all v8/v6 is EFI

One more thing the ratio is stamped there you may need to look closer/harder...........

As most have leaned towards. Assuming gear ratio and prop is close.

Assuming motor is mechanically ok.

two things to keep from going past 2000 rpms under load

Ignition or fuel.

You need to determine which is the culprit.
 
Have been playing today. Among other things I replaced fuel line to carb. Unit I used had built in bung for fuel gauge. I installed one and pressure was all over the place. I use a stock mechanical shaft driven fuel pump. And pressure was at 8psi on stroke and 4 off I took video but needle was moving so fast couldn't see on video. Can't recall ever seeing that or the clear fuel filter staying so full u can't tell if there's gas in it.
 
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Try this, just for giggles.

disconnect the shift micro switch.

Won't hurt anything and is needed just for coming out of gear.

To be clear, the shift micro switch is needed for coming out of gear, see if it runs well with it disconnected.

When you go to come out of gear connected it again, it's just a plug.
 
kghost said:
I see 6792607

"BT" What is it you are looking for with the serial number?
Click to expand...
I was thinking I'd like to try and help out with finding the original gear ratio for the stern drive if possible.:)

DRV: # 06782607 is a MERCRUISER MC1 1.98:1

DRV: # 6792607 is a MERCRUISER MC1 1.50:1

Both made in 1984.

The number was just kind of difficult to confirm.:confused:
 
Disconnected tack lead. Ran hit wire to coil. Made no difference. Shift cut out lead to switch on dash so I can cut out at will. Am going To try in am.
 
wildfrahm said:
It is the 6792067.
Click to expand...
This number was a MERCRUISER MC1 1.50:1 as well.

This engine package looks to be original from new, it came in a 26 footer.
ENG: 06794763 Model# 02608344 MERCRUISER 260
DRV: 06792067 Model# 01507014 MERCRUISER MC1 1.50:1
TRN: 06789009 Model# 00010004 MERCRUISER MC1
 
You have a return line from the fuel pump to the carb?

It should be a clear hose, now i bet it's yellow.

That line have fuel in it ? If yes the fuel pump went.

I also bet you have a bell type fuel pump. Meaning it has a screw holding the bell on. Under the bell is a fuel filter.

You ever open up that fuel pump ?
 
BT, thanks for #'s everytime I order it's a pain. Chief my fuel pump went out and I put a auto unit on,I plunged off the vent on carb. Have another brand new carb. Am going to switch out also before I go outt.
 
It should be a clear hose, now i bet it's yellow.
Click to expand...

The nipple on the pump that it attaches to may be plugged w/a gummy substance preventing fuel from getting into the line. Clean w/GumOut carb cleaner to see if fuel is leaking from a ruptured diaphragm.
 
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