1984 470 initial carb set up to get idle

[shiloh87]

The engine is now in the boat, need to know how open the throttles need to be open to achieve an idle, can`t find that info anywhere.
Was cranking it the other day, it would fire than quit. I`ll assume the timing needs to be closer, I can do that with the timing light while cranking.
Carb is the rochester 2 bbl, completely rebuilt, squirts fuel real good into both bbls, brand new carter fuel pump, all good to go I hope.
Just need to know how open to have the throttles to get her to run, and how to achieve that initial setting.
Thanx, Rick

 

[dubs283]

first set dwell

then set remote handle at a point where the engine stays running, then set idle speed screw so engine stays running with remote handle in idle position

get idle as close to spec as possible, set timing, check dwell again - adjust if needed. now you can set idle to spec (usually in gear), fine tune with idle mixture screws

if the idle mixture screws don't change idle/how smooth engine idles then the throttle plates are set too far open

 

[shiloh87]

Sorry should have mentioned I`ve installed a pertronix ignition, so no points.
Maybe I`ll just disconnect the throttle cable for now and manually manipulate it to get it running, and once idling decently set the cable to that.
The manual only states the engine should start cold in neutral with the electric choke once set up properly, but dosn`t elaborate how to get to that point.
The manual I`m using is The Mercruiser service manual #3 obviously written for service techs not us mere mortals.
I`ll let you know how things go.

 

[dubs283]

keep in mind your engine is not fuel injected, you can't expect it to start by simply setting the choke and turning the key, there is a definite correct process to starting a carbed engine.

pump the throttle, turn the key, set throttle to 1200 or so rpm once engine fires, allow choke to open and engine to warm. then you can apply the proper settings

 

[nola mike]

Sorry should have mentioned I`ve installed a pertronix ignition, so no points.
Maybe I`ll just disconnect the throttle cable for now and manually manipulate it to get it running, and once idling decently set the cable to that.
The manual only states the engine should start cold in neutral with the electric choke once set up properly, but dosn`t elaborate how to get to that point.
The manual I`m using is The Mercruiser service manual #3 obviously written for service techs not us mere mortals.
I`ll let you know how things go.

The idle setting doesn't have anything to do with starting, the throttle is open and off the idle stop. When you pump the throttle that should set the choke. Confirm that the butterflies are closed. Then as dubs said crank the engine with the throttle open about ⅓ and it should start. Get the timing close, then once the engine is warm recheck the timing, adjust the carb idle screws, set the timing, set the idle.

 

[Scott Danforth]

so this thread was started after your thread on a motor missing on 1 cylinder?

 

[shiloh87]

Motor missing on 1 cyl, is not my thread.
T

 

[shiloh87]

To the other response, if the remote is moved out of neutral position the ignition lock-out is engaged.
I can advance the throttle to pump fuel into the carb, no problem there, but she won`t crank unless fully in neutral.
Even after it`s running, that would mean to advance engine rpm it would be in gear, is that normal? The throttle cable only moves shortly after gear engagement.

 

[Eric 3.7LX Alpha 1]

There most likely won't be any fuel in the bowl with a new engine so pumping the throttle will only help you set the choke. You'll have to either prime the fuel line or squirt some gas down the carb throat so you not sitting there cranking the engine on waiting for gas to fill the fuel bowl.

 

[nola mike]

To the other response, if the remote is moved out of neutral position the ignition lock-out is engaged.
I can advance the throttle to pump fuel into the carb, no problem there, but she won`t crank unless fully in neutral.
Even after it`s running, that would mean to advance engine rpm it would be in gear, is that normal? The throttle cable only moves shortly after gear engagement.

No. You need to increase your throttle while in neutral. Depending on your control that involves pushing a button in at the base of the handle and advancing it or pulling the handle out before advancing it. You'll never get it started otherwise.

 

[dubs283]

No. You need to increase your throttle while in neutral. Depending on your control that involves pushing a button in at the base of the handle and advancing it or pulling the handle out before advancing it. You'll never get it started otherwise.

im guessing op isn't aware of the "throttle only" function of the remote control

 

[shiloh87]

I was not aware of such function, being new to marine engines, and boats in general, this has been and continues to be a huge learning curve for me.
I have had this engine running on the stand after the rebuild, manually manipulating the throttle, ran well considering it needs to be fully broke in.
Now that its installed couldn`t figure out how to advance the throttle without engaging the gears, now I know thanx.
While installing the engine the distributor moved, didn`t have the clamp tightened I guess, that`s why I mentioned resetting timing while cranking to get it close so it will start.

 

[nola mike]

I was not aware of such function, being new to marine engines, and boats in general, this has been and continues to be a huge learning curve for me.
I have had this engine running on the stand after the rebuild, manually manipulating the throttle, ran well considering it needs to be fully broke in.
Now that its installed couldn`t figure out how to advance the throttle without engaging the gears, now I know thanx.
While installing the engine the distributor moved, didn`t have the clamp tightened I guess, that`s why I mentioned resetting timing while cranking to get it close so it will start.

Put the motor at tdc on the compression stroke and align the rotor with the #1 plug wire. That will be close enough to start.

 

[shiloh87]

OK cool, got a buddy coming over tomorrow, to help with this, it`ll be the blind leading the blind.... lol
We`re both motor-heads, me bikes him cars/trucks so hopefully we`ll get `er figured.
Dying to get this project floating.

 

[Eric 3.7LX Alpha 1]

There was a TSB on initial timing for the 470, see the attached file

 

[shiloh87]

been looking for that, thanx for posting it.

 

[shiloh87]

Turns out the purple wire that feeds the choke and coil was only getting 4volts, trace showed a dead short somewhere between the stern and the dash.
Isolated it and ran a new trace, engine fired right up, go figure,
problem solved, for now......
Thanx

 

[Scott Danforth]

most likely corrosion somewhere along the circuit

 

[shiloh87]

While we were at it we traced all the other wires in the harness running forward, no issues just the purple wire, kind of strange, as I refirbed the whole harness, double checked and then checked again to make sure perfect continuity, before wrapping it with 3 rolls of good quality electrical tape.
Why that wire failed who knows, gremlin I guess.
Next step is to get it floating and run it around for 10hrs at 1500rpms then drain the oil/filter change, then another 10hrs progressively increasing to wot for short then longer bursts, then an other oil and filter change.
Up here the oil and filter comes to a little under $100.
cheers

 

[Scott Danforth]

While we were at it we traced all the other wires in the harness running forward, no issues just the purple wire, kind of strange, as I refirbed the whole harness, double checked and then checked again to make sure perfect continuity, before wrapping it with 3 rolls of good quality electrical tape.
Why that wire failed who knows, gremlin I guess.
Next step is to get it floating and run it around for 10hrs at 1500rpms then drain the oil/filter change, then another 10hrs progressively increasing to wot for short then longer bursts, then an other oil and filter change.
Up here the oil and filter comes to a little under $100.
cheers

if you have a new cam, that is 20 minutes at 2000 RPM to break in the cam and lifters prior to the normal break in proceedure which is varying loads.