Bought a new long block and wondering about the coupling and gimbal bearing.

[Scott06]

Correction, 1:47 drive ratio.

I agree with Lou definitely want to prop it so it can swing 5k. You have the same base engine used on MPI motors that I think the rev limiter is 5200, so no issue. In a heavy boat like that you are way better off being slightly under propped. Since you are swinging a 15" now you may actually need a 1.62 drive as I suspect you will run out of prop options if you need to go lower.

I may be wrong but I was under the impression when you lug the engine exhaust gas temp gets higher, especially if lean which can wreck the valves like you have seen. Definitely keep it running a tad rich if anything

 

[tank1949]

Correction, 1:47 drive ratio.

That's a lot of boat for a single V8, even if it was "stroked."

 

[AKJohne]

Yep, Its pretty heavy, plenty of boats running around heavier with a single 350, 26 foot Tollycrafts come to mind, then again that was not enough engine for that boat.
However I have taken to heart what has been said here and its possible the old motors life was shortened if we were over propped. I was propped to hit 4600, I think mecr says 4400 -4800 is WOT. Certainly better to be underpropped. The day we tuliped a valve we were cruising around 3800 RPM, which is not something I normally do, it was a flat day and so what the heck. I was crossing over to a island and it was about a 10 mile run. Maybe that done her in...!

I got the OD back on and motor buttoned up, fired right up and ran it through 3 heat cycles. I installed a O2 sensor and a AFR gauge, will see if that is worthwhile. I ended up using a paper gasket for the T stat housing and running a ground wire, the gaskets with rivets is thick and ID matched OD of T stat... the intake has a recess for the T stat and seems like the T stat would be "floating" around...? I did have a nylon spacer of some type that is a OEM Merc thing, but did not fit my T Stat housing.
Now I just have to wait for the ice to go out!

 

[AKJohne]

something warped valves. 500 hrs is not really a lot if properly maintained. Good luck!

My Apologies for my earlier reply to this post, I was slightly offended by the transom comment as I spent 5 years getting this boat in the water. I was pretty methodical about what was done, plenty of learning along the way.
I did create a album here if your interested. https://forums.iboats.com/media/albums/glasply.737/

I have pondered your and other comments about propping, I thought I was on the mark at 4600. Maybe not at higher RPM...! In any case I am hearing I should see 5000 RPM at WOT with this motor. I am expecting to see a few more HP, so maybe my 15.8 X 15 will be OK.

 

[AKJohne]

I put 20 hours on the new motor last weekend, 10 hours of break in, change oil and retorque exhaust parts. Ran well, started, idled, all in all pretty happy. Wondering about a couple of things, propping, at WOT I saw 4700 RPM (41 mph). My ole pre Vortec listed WOT at 4400 to 4800. The new motor did not come with any WOT specs, what say you guys, is 4700 Ok, or do I need to get closer to 5K? Currently running a 15.25 X 15 aluminum Merc prop.
Second thing is the choke setting with engine off and choke closed, this info seems to be rather ambiguous, in any case I think I have too small of a opening as I had a couple of instances with black smoke on startup.
Typical procedure is one stroke of the throttle and the up from idle a inch and 1/2 or so, hit the key and then push the throttle to idle on startup. Typically start s right up, but not every time, when that happens I need to open the throttle more and crank some to get it some air.
Electric choke and it does fully open when warm. I dont think it is the thermostat stetting of the pull off, I think the choke plate is just too tight to start with. I think its now a bit over a 1/8" I seem to recall seeing 3/16 and one publication listed 3/64th, which I am sure is a typo.
I was just going to start opening up the gap, but thought I would ask the pros. Thanks in advance.

 

[achris]

4700 with a 'normal' load is pretty good. Because the revs specs is mostly governed by cam profile and the vortec and non-vortec engines use the same cam, the rev spec stays the same... And yes, 4mm (choke pull down) is about right.

 

[Scott06]

Agreed 4700 to 5000 maybe a tad over is fine. Have you verified tach against a shop tach?

dont think you can go lower in pitch not a lot available below 15” . Now if you wanted to go to stainless with more bite and cup than the black max you have on there i would definitely drop down.

 

[Scott Danforth]

4700 rpm to 5000 is fine.

 

[AKJohne]

I did check the tach once with a digital tach on the harmonic balancer. It was on then, good call, will check it again. Current prop is 15.25 diameter, would a 15 make any difference?
Sounds like I need to open the choke and give it more air.
Thanks gents

 

[achris]

I did check the tach once with a digital tach on the harmonic balancer. It was on then, good call, will check it again. Current prop is 15.25 diameter, would a 15 make any difference?
Sounds like I need to open the choke and give it more air.
Thanks gents

Diameter is fixed by the prop manufacturer, all you can do is select the right pitch for your application, the diameter is a function of that pitch and is 'predetermined'. Usually props go up and down in 2" increments (of pitch), and each 1" is worth about 200rpm, so a reduction of 2" would push you to about 5100rpm... I think that's a bit too much.

Chris...

 

[Scott06]

I did check the tach once with a digital tach on the harmonic balancer. It was on then, good call, will check it again. Current prop is 15.25 diameter, would a 15 make any difference?
Sounds like I need to open the choke and give it more air.
Thanks gents

Yes choke likely needs to be adjusted leaner. You really dont need much choke when its warm out

 

[achris]

Yes choke likely needs to be adjusted leaner. You really dont need much choke when its warm out

He's in Alaska, it's never 'warm out'....

 

[Lou C]

With the choke two things:
There is a vacuum operated vacuum break or choke unloader that pulls the choke open a fraction of an inch to give it enough air to keep the engine running. Usually you measure it with a drill bit. Apply vacuum to the vacuum break or choke unloader to make sure it works.
During a cold start you fully advance the throttle to allow the choke to close then set it at about 1/3 advanced. You must set the fast idle manually there is no fast idle cam on marine carbs for safety reasons. It needs the fast idle (1200-1500 rpm or so) to keep running after a cold start….
A lot of people who didn’t grow up with carbed cars are confused about this point…
I think your WOT rpm is OK.

 

[Lou C]

I'll never forget the first time I drove a US built car with EFI. My inlaws 1987 Mercury Grand Maquis with the Ford 5.0. Get in, turn the key and a nice smooth idle, no fast idle needed, no matter how cold it was out. Had to break all my time worn habits with carbs. Back in the carb days we liked, or hated our cars based on how well they cold started.
When they started with the primitive emission controls in the early 70s the cars ran really bad. It improved with cat converters because they could tune them a bit richer.
Then get the 1988 boat with the carb (QJet) it all comes back. 3 pumps set 1/3 forward crank over.

 

[AKJohne]

I'll never forget the first time I drove a US built car with EFI. My inlaws 1987 Mercury Grand Maquis with the Ford 5.0. Get in, turn the key and a nice smooth idle, no fast idle needed, no matter how cold it was out. Had to break all my time worn habits with carbs. Back in the carb days we liked, or hated our cars based on how well they cold started.
When they started with the primitive emission controls in the early 70s the cars ran really bad. It improved with cat converters because they could tune them a bit richer.
Then get the 1988 boat with the carb (QJet) it all comes back. 3 pumps set 1/3 forward crank over.

Yep, explaining carbs to most people under 40 can be interesting. Its pretty satisfying to get one dialed in. I installed a AFR gauge on this motor, pretty interesting to adjust idle mixture and see just how sensitive it is, also interesting to see how close I was W/O the gauge.

 

[AKJohne]

He's in Alaska, it's never 'warm out'....

Ouch !..... laughing!

 

[nola mike]

Yep, explaining carbs to most people under 40 can be interesting. Its pretty satisfying to get one dialed in. I installed a AFR gauge on this motor, pretty interesting to adjust idle mixture and see just how sensitive it is, also interesting to see how close I was W/O the gauge.

Where/how did you mount the O2 sensor? I've been toying with this (but still have a bunch of more important things to do to the boat), and then @achris mentioned this colortune deal, which also looks like a fun toy.

 

[AKJohne]

Where/how did you mount the O2 sensor? I've been toying with this (but still have a bunch of more important things to do to the boat), and then @achris mentioned this colortune deal, which also looks like a fun toy.

I bought a O2 plate made by Hardin marine, its 1 inch thick, I cut down and then machined my riser from 3" to 2" so it would fit under the doghouse, and I could use my existing elbow/riser studs. So far so good. I bought a AEM 30-4110 kit which included the wideband sensor, Bosch 17025.
I debated mounting the gauge permanently as once adjustments are made it should remain constant.
I was somewhat concerned about carb tuning as the old pre-vortec had a different intake and was not a "square bore" intake (if that's the right term). Also wanted to be sure I wasn't too lean as that may have contributed to the short life of the old motor. Now I doubt that was the case.

Regardless I wanted some real time info and the kit is relatively inexpensive. as mentioned earlier it made idle adjustments spot-on.
A/F ratio was typically 13.2 as a average through out most throttle settings, Slightly rich which is probaly better than lean and seemed ok for breaking in a new motor. If I accelerated hard I would see numbers go into the 12's and 11's, which is expected. I was going to make a spring change when the rich choke setting took out the sensor.

Merc set those carbs up with specific parts for them, they used a 3 step rod and a three step jet, and the piston for the rods are different as well.
No one could give me a specific conversion for a 2 step rod in a three step jet. Not a big deal as i could change all the parts out to a "out the door setting" for a Edelbrock 750.

That would require removing the air horn, which I was hoping not to do as it was all painted over when I rebuilt it a year ago. Not the end of the world, just trying to avoid and make adjustments with spring changes if possible. Which is the beauty of the Carter/Weber/Edlebrock carburetor.

At the end of the day, I think Merc has these set pretty spot-on for a 5.7, perhaps slightly rich, which is better than lean, however either condition can create more heat.

I will R&R the O2 sensor and probably try a different spring to see if I can get closer to stochiometric perfection......!

It takes time, but is easier and quicker than reading plugs.

 

[AKJohne]

With the choke two things:
There is a vacuum operated vacuum break or choke unloader that pulls the choke open a fraction of an inch to give it enough air to keep the engine running. Usually you measure it with a drill bit. Apply vacuum to the vacuum break or choke unloader to make sure it works.
During a cold start you fully advance the throttle to allow the choke to close then set it at about 1/3 advanced. You must set the fast idle manually there is no fast idle cam on marine carbs for safety reasons. It needs the fast idle (1200-1500 rpm or so) to keep running after a cold start….
A lot of people who didn’t grow up with carbed cars are confused about this point…
I think your WOT rpm is OK.

There is no external vacuum choke pull-off, I think the pull-off is a small piston inside the choke housing, there are some directions in my info about setting that to spec. Please correct me if this is wrong. Amounts to removing the choke cap and inserting a .026" wire to pull the piston against its limit of travel, then measure the gap. Once again my various info does not agree, but I think that number should be 6mm.

Thanks

 

[achris]

It's an Edlebrock 1410, yes? No vacuum pulldown, it's purely mechanical, and there is a specific set up procedure for it.

Chris......