Finally got a test run 94 Mercruiser 305, just got back from the lake

[Bry21317]

Well, I finally got a chance to drop the boat in the water tonight. Just got back in from about 2 hours of running. This is my first good run from putting on the Edelbrock 1409 4 bbl carb and the new intake on my 94 Mercruiser 305.

Well she finally got some extra speed and ran dead on 175 or just under so I don't have an overheat problem anymore.

Well with the Rev 4 Prop that I had, before I could get up to 48.3 with the 2bbl carb, now with the 4bbl carb I am running right at about 4950 RPMS, still a little high with 4 people on the boat and 3 of us are over 200lbs. Well tonight I hit an all time high speed of 51.8, so I was happy. With a 3 blade aluminum Hustler prop I used to get 5000 rpms and 50.8 mph. So I got some extra speed from the REV 4. So I gained 3.5 MPH. So to me thats a pretty good jump in speed for that upgrade. I was hoping to get a lil higher, but I will take it.

I did notice a little bogging at first and had to adjust the carb some, but I think its running good now. I think I am a little rich on the carb, which way leans these carbs out at idle, clockwise or counter clockwise? I saw it in the manual at one point, but can't find it now.

I did notice some extra Soot on the thru Hull exhuast pipes, does this show its running rich?

Thanks for all the help guys, She stayed right at or below 175, and I was running her pretty good. Still got some old gas in there, so I am hoping once I run that out it might run a little stronger. I did have a can of Seafoam in there from the end of the summer.

Bryan

 

[fixb52s]

Re: Finally got a test run 94 Mercruiser 305, just got back from the lake

For that adjustment you talk about, that is only for the idle mixture. Screwing it clockwise leans it out, and CCW will richen it up. You might want to throw a vaccum gauge on it when you adjust it. Adjust the screw for smooth idle and max. vaccum.

Assuming your idle mixture is correct, you might need to use a leaner metering jet. (Metering jets are what controls the amount of fuel with these carbs, and you adjust rich/lean conditions by swapping them to different sizes.) Even though the 1409 is only 600 CFM, 305s have a harder time with them as say a 350. Smaller valves and the short stroke kind of chokes them up on the intake side. That could explain the low RPM stumble. Then again, if the idle mixture is too rich, that will indeed lead to loading up. All it does is allows extra fuel in when the throttle plates are closed in idle, but could send too much fuel to the engine.

What intake are you using?

Clean it out, get the idle mixture correct and check for that soot again.​

 

[Bry21317]

Re: Finally got a test run 94 Mercruiser 305, just got back from the lake

Ive got the Croswinds Model 52025 located down this page http://www.professional-products.com/manifoldsProductSBchevy.php

It is close to the Edelbrock RPM Air Gap Manifold.

I will try cleaning up the soot and see what happens. Also take off was a little slower, it seemed than I had with the 4bbl, like it was slow to come out of the hole, still only about 4 seconds, but slower to me it seemed.

Bryan

 

[Bondo]

Re: Finally got a test run 94 Mercruiser 305, just got back from the lake

edit

 

[wca_tim]

Re: Finally got a test run 94 Mercruiser 305, just got back from the lake

read the manual that comes with the carb and although it seems complicated, following the tuning / jetting procedure in there (makinmg sure everything else, timing, etc... is right first. You'll be surprised how much better it will run. You've got different things to change / adjust for different ranges in rpm / throttle position. You can adjust the accelorator pump stroke, idle circuit, change metering rods and change main jets depending on where you're lean or rich. in addition to the procedure outlined in edelbrocks little book, there's really no substitute for reading plugs when jetting any kind of engine... just my two cents...

 

[fixb52s]

Re: Finally got a test run 94 Mercruiser 305, just got back from the lake

That manifold seems more suited for a larger displacement engine with some cam. If it like the RPM Air Gap, it doesn't really wake up until around 3000 RPM. It is more of a higher RPM intake than a low torque unit. The Performer dual plane manifolds are great for idle up power, but do give up around 48-5000 RPM.

The RPM manifold is great for a cammed 350, but maybe a little overkill for a stock 305 marine engine. If you can get that carb leaned out a little, it might work, but your holeshot might suffer.​

 

[Bry21317]

Re: Finally got a test run 94 Mercruiser 305, just got back from the lake

I see what you mean. I can plane in about 4 seconds, with a 4 blade Labbed Rev4 21 pitch prop, but midrange is incredible from plain to top end is a few seconds it seems. She will get up and run when she is out of the hole.

I will check the Carb adjustments again and see what is up with it.

I might even give Edelbrock a call to see what needles/jets they may recommend to try.

Its been a while since I have done jetting on a carb, I used to do them on bikes all the time, and had done it to my old outboard but its been at least 3 years since I messed with them.

Bryan

 

[WizeOne]

Re: Finally got a test run 94 Mercruiser 305, just got back from the lake

Once you get your mixture straightened out it will be nice to have the extra power. Your intake will undoubtedly cost you some lower end though. It is designed for midrange and higher rpm horsepower not lower end torque.

With 4$ gas, what you will quickly learn is to stay OUT of the secondaries. That will suck your tank and wallet dry in a hurry.

When I put a 4bbl Holley on my 302 my economy was on par with the 2bbl if I resisted getting happy with the throttle.

 

[Bry21317]

Re: Finally got a test run 94 Mercruiser 305, just got back from the lake

I hear ya on that. I usualy cruise around with the Family around 3-4000 RPMS so thats around 35-40, not usually all the way in it, like I was last night.

It ran great at those speeds, feels like a cadilac on water lol.

So I need to print the manual out then I found it online and go through trying to tune it out some more. I will see what happens.

Bryan

 

[10 FOOT INVADER]

Re: Finally got a test run 94 Mercruiser 305, just got back from the lake

My monterey 206 1994 with 305cid 4 blade prop 2bbl carb will hit 50.6 on gps at wot. Turns 4900rpm. Boat fully loaded with coolers and wife with kids. I would think with a good manifold and better carb it should do better than that. I had planned on doing what you just did but if that is all that is gained just does not sound worth it. May just have to repower with a 5.7. Did you change the cam with the upgrades?

 

[Bry21317]

Re: Finally got a test run 94 Mercruiser 305, just got back from the lake

I still need to do some tweaking on the Carb, to get it right. I did not change the cam out.

My boat is Heavy its a 94 Crownline 196BR. I checked the weight of yours and its 2650lbs and yours is a little longer than mine. Mine ways in at 2900 these weights are straight off of Nada. This is dry weight, and I have a 48 Gallon Gas tank.

So I think with a few more adjustments to the Carb and the Timing, being double checked I might get another 1-2 mph out of it.

I would go straight to the 350 if it was me and that was an easy option. I have seen others that did this same upgrade and they got around 4mph on average. So this is about all you should expect.

With the boost to a 350 I would expect close to 8, I would think if not more with the right prop and setup.

Bryan

 

[WizeOne]

Re: Finally got a test run 94 Mercruiser 305, just got back from the lake

Ive got the Croswinds Model 52025 located down this page http://www.professional-products.com/manifoldsProductSBchevy.php

It is close to the Edelbrock RPM Air Gap Manifold.

I will try cleaning up the soot and see what happens. Also take off was a little slower, it seemed than I had with the 4bbl, like it was slow to come out of the hole, still only about 4 seconds, but slower to me it seemed.

Bryan

I hate to be the bearer of not so good news but you ought to dump that #52025 (rpm range 1500-6500). This is the reason for your not so good performance out of the hole.

You should have gotten the #52010 (rpm range idle to 5500). You would see a signifigant difference with this intake and 4bbl right, out of the gate.

Your 305 already has respectable compression at 8.5:1 but a slightly snarkier cam w/ the above would really snap your neck from idle right on up to redline.

 

[Bry21317]

Re: Finally got a test run 94 Mercruiser 305, just got back from the lake

Got out on the lake again today, after tweaking the carb a little more, it runs great and seems to be coming out of the hole alot faster. Its back down to hit the throttle and its onl plane in 3-5 seconds. So this is good now.

Also did not have any chances to top it out as the fam was on board and today was not the day to go fast. The lake was packed and we cruised mostly around at 35, so that is my normal cruise speed.

I did notice that I am having a hard time starting the engine when cold, so I think I have an out of ajusted choke. I have the electronic choke, and will be checking on this, but it would not idle until I got it warmed up to 170 on the trailer, or it will die. Once It got warm, it was fine then it idled no problem, but until then it cut off when I tried to put it in gear. It also did this one time when I was leaving a beach after sitting for about 1.5 hours.

Bryan

 

[Coors]

Re: Finally got a test run 94 Mercruiser 305, just got back from the lake

Yep, adjust the choke.