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Mercruiser 228 bogs at 2200 RPM

C

CherryBomb

New member
Hoping you can help me -

1982 Century Bowrider 2000 (18')

Mercruiser 228.

Was having difficulty getting it over 3200 RPM at WOT, and it would bog and backfire through the carb if you punched the throttle too fast. Once you got to WOT at 3200 she would stay there just fine. Pulled the plugs and they were white, so lean condition. Found out the carb was for a 4.3 rather than a 5.0. Needed to be rebuilt anyway, so I went ahead and bought a rebuilt one

from National Carburetors with the proper jetting for my 228.



I swapped the carb today....she fired up quickly and purred nicely. Once I got her warmed up and out of the harbor, I hit the throttle at a decent speed and she responded with no bogging at all....very smooth! Then at 2200/2400 RPM, she started to bog and stutter. Pulled back, all was ok. Tried again - bog and stutter. She just wont pass 2400 RPM.



In neutral, there are no issues going up to 4500, so there is no binding in the throttle cable, etc.



Pulled the plugs and they were black. Rich?



I have one week of boating left before I have to pull her out of the water, so I can't get a mechanic in there to look before then. What should I look at first?



Note -

Distributor is a Pertronix Billet that has about an hour on it. Cap and rotor are new. Wires are new. Plugs are new. Advances fine, but I forgot my timing light when I installed the carb, so I do need to double check the timing.

New fuel filter. New Check valve. New fuel lines. Fuel is good. Variable is the carb - I made NO adjustments. Plug and play. I expect to maybe have to make a few.



Ideas?



Thanks much
PS - I searched the forum and couldn't find the exact same condition, so I am posting. I will keep searching!
 
Please specify what type of carb, 2 or 4 barrel, also did this lack of rpm exist before carb swap?

Pertronic billet does not specify if its a point or electronic ignition. It is also not and OEM distributor. Why the change?
 
I apologize - I didn't explain that above very well.

Quadrajet 4bbl. I swapped from another quadrajet 4bbl, but it was jetted for a 4.3

Before the swap, the engine would get to 3200 RPM and top out (note: it did not bog or die....it would sit there as though it was the top end)

Pertronix only does electronic distributors and electronic ignition systems.
I swapped because the old distributor needed to be changed, as the advance weights had become seized (it was the original distributor). I had heard good things about the Pertronix Billet distributor, so I went that route. I had suspected that may be the cause of the 3200 RPM WOT.

I know it sounds the same, but I want to express that topping out at 3200 before the swap and topping out at 2200 after feel VERY different. When it was at 3200, it just felt like that was it - like those were the max RPM. Now, it reaches about 2200 or so and then it hesitates and bucks. It doesn't backfire through the carb or feel like 2200 is the top end - it feels like it is being choked out.

I will add this - the reason I changed the carb was because when I would forward the throttle, it would bog and die and backfire through the carb unless I did it VERY slowly. The white sparkplugs confirmed a lean condition. After the swap, it will smoothly accelerate even quickly, and has no difficulty getting on plane.

One difference I noticed between the two carbs - the new one has what appears to be a fuel "outlet" on the front of it that has a rubber cap on it. I think it may even say "out to pump" or similar. It is above where the inlet and inline filter are. My old carb did not have this?


Thanks so much for your help
 
A V8 with a 2 barrel carb will reach max rpms.
1. Prior 3200 rpm is a problem. Should be 4400-4800. Tach in dash could be an issue. Confirm with remote tach.On back of dash tach, there is a small rotary switch ans a small flat head screw driver will turn. It will have three settings, 4, 6, and 8. For 4 cyl, 6 cyl and 8 cyl engines.
Switch it to anither setting from 8 which it should be and then back to 8.
My tach starts reading funcky once in a while and doing this resets the tach for correct pulse for 8 cyl. And confirm it with a remote tach or the use of a timing light with a tach built in or a tach meter.


2. Point ignitions use a resistor wire reducing voltage to coil.
Electronic ignitions typically use a internal resistor so you may want to get the running voltage at coil + and what is powering the pertronics distributor. Not sure what pertronixs specifies. So double check paper work.

3. Your prior issue was more than likely the accelerator pump (internal to carb) actuated by linkage external on carb was most likely not working properly any more and was causing a lean condition when accelerating. Very common issue.

4. If tach is accurate, will it rev higher in neutral? If it easily reaches 4400 rpm in nuetral and tach is good then low rpm in gear may be a gear ratio in outdrive. If you can acquire that info that would be good.

What type of advance does the pertronix dist use?
 
Just got back from the boat - Happy to say that the bogging was due to the secondaries not opening. I loosened the spring and it now goes smoothly past 2200.....but once again stops at 3200 RPM and about 32 MPH.

1) Yes, I know. I believe it says 4600 on the motor, which is why I was concerned. When I got the boat a couple years ago, the tach didn't work and it ran smoothly, but people told me I should be getting more than 32 MPH out of an 18' boat with a V8. When I went to tune her up this year I bought a functional (but still old) tach. I verified the RPM with a laser, and (at least at Low RPM, 650 or so) it is accurate. I need to try the higher RPM.

2) I bypassed the resistor wire with 12V per the distributor instructions. It advances smoothly but NOT the full amount. If I set her to 8 BTDC at 650 RPM, at 2500 RPM she is at about 20 BTDC. There are different springs I can change internally to increase the advance. I believe this engine should max out at 32-34 BTDC, so I will look into this.

3) I am now having the same issue as before, minus the bogging at quick throttle. Runs (and sounds great) up to 3200 RPM and about 32 MPH, even with the new carb/accelerator pump.

4) Yes, she will happily go up to 4500 RPM and she's really screaming at that point! Not in a bad way - but in the way a V8 at 4500 RPMs sounds when you stand next to it. The sound alone confirms that I am not getting 4500 on the water, even momentarily.

So here's my gameplan, let me know if I missed anything. I am going to
-install the springs allowing for more advance in the distributor.
-Double check the tach for accuracy. Move the dial in the back if necessary. I have another tach I can use for this.
- Find the gear ratio in the outdrive. I believe it is stock, but this hadn't even occurred to me. I assume I can find this on the tag (Or find a number on the tag and look it up)

I might be *slightly* over propped with a 19 pitch, but I believe the boat originally came with a 17, and I can't imagine 19 to 17 will make a significant difference in RPM or speed.

Again, I appreciate the help! Gale force winds predicted tonight through tomorrow, so it will have to wait for Monday.
 
19 to 17 pitch is only worth 300 ish rpm.

If you are not getting full advance by ~ 2400-2800 rpm the engine will not reach optimal performance.
32-34 total advance is good. Thats 8 initial + 24-26 advance.

So if the dist springs have rpm associated with them choose springs for full advance by around 2400-2700 RPM.

I Am not sure how to get more avance unless different wieghts are in kit. Or pins in plate to allow more movement.

See what you can figure out and let is know.
 
The pertronix distributors typically have springs and mechanical limiters...look in the instructions for the options they provided...I've had best results with setting max advance at 3000RPM and hitting 32 degrees (total advance) at that point...

The engine shouldn't need the secondaries to open until 3200-3400 RPM....so verifying the tach as accurate would be prudent.

Has the boat's WOT every been reached, that you know of?
 
I'd be curious about the gear ratio too. I'd think 1.5R and a 19 pitch prop with standard Black Max aluminum 3 blade. 4 blade aluminum, stainless, large diameter 3 blade..... may need to drop down 1 pitch size because they move more water.

Maybe I missed something, is this a new problem or a new to you boat that you don't know prior history of?

I'd think upper 40s to 50 MPH with that engine in an 18' easily.
 
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