Crusader CH 35O (454 Gen 4) harmonic balancer

[ron54]

Finally after a year we bought an 85 Carver 3697 Mariner, 16 years older than the 2001 350 I posted on over a year ago. Spent a lot less money of course and love the layout. All checked out with a few disclosed flaws, but those are being addressed. Port motor is LH rotation serial 46833 and had a “miss” at idle attributed to carb running rich. Also noisy alternator but that turns out to not be the issue, and don’t think the “misfire” is from the carb. After some closer diagnosis I am 99% sure it’s the harmonic balancer and it is vibration at idle causing the misfire. Fortunately plenty of room to pull it and I am pretty good mechanically. Question if anyone knows, this appears to be a standard GM 454 Gen 4 part, but I have also found an original new old stock Crusader part. Any reason to not just use a quality aftermarket. I am not worried about the extra cost for Crusader, bit since these have rubber in them could they deteriorate just sitting in a hot warehouse? Thanks, love this forum.

[km1125]

I'm a little confused with the post. A harmonic balancer can't cause a misfire. It may cause some additional vibration that might be construed as a misfire, but I think that's even unlikely to detect without some instrumentation on the crank.

I'd pull the plugs and see what they look like to see if anything is running rich or lean before I tried narrowing down what might be causing something. Get an overall indication of the plugs, check the distributor for wear and corrosion inside. Easy stuff to do and it doesn't cost anything. Does it still have points or was it upgrade to an electronic ignition? What condition are the wires in?

But to answer the last part.... I don't think it'd be any problem for the rubber in a harmonic balancer to be in a 'hot warehouse', as these things live in a 'hot bilge' for decades without deterioration. Ozone is more likely to cause damage to the rubber, or direct exposure to UV sunlight.

[ron54]

Thanks, thought I did a quick reply last week but failed to post it. I probably did confuse the issue by calling it a misfire, turns out there was some vibration from the harmonic balancer which has now been replaced. When attempting to time it before, mark was jumping all over the place, now steady and was off about 3 degrees to advance, now at 10. Still running a little rich, did check plugs, a little black, wires checked out, look new. The distributor is a Mallory Unilite that seems fine.

As far as the harmonic balancer goes, got the free loaner tools from Autozone to remove and install, they worked well. Glad I did, because at some time in its life the original crusader balancer had obviously been removed and then reinstalled by beating it with a dead blow hammer! you could see the marks all over the face of the balancer and outer ring also it was not seated all the way on the crankshaft. Appears to be no damage to the crankshaft. The front seal was leaking some so replaced that.

The carb was reported to have been rebuilt about five years ago, but not sure by who. That is my next project to pull it check condition and float level. Also a friend has a new (rebuilt) carb from same Crusader engine he had as a spare for me to try. Will probably replace plugs and install his carb to see if that solves the rich issue.
Any comments/advice welcome.

[ron54]

Update:

I have been having a lot of “fun” with this boat in the last month if working in a hot bilge is fun. Actually kind of satisfying, takes me back to my younger years when I worked on my old cars.

Replaced the port engine carburetor with my friend’s spare, running much better but still a little rich at idle when cold. Not the divorced chokes, disconnected them and tied open chokes to take that out of the loop. No cold start issues in this weather. Bought a digital timing light ( Innova 5568 pro) mainly for an accurate tach to set idle mixture and idle. Worked well, also much brighter and easier to use than old craftsman I used first. After some back and forth I think timing and idle mixture is about as good as I can get it with these carbs. My friend’s spare was an off the shelf rebuild so not sure if float settings, etc are correct. Timing was off some still so I used the flywheel timing marks and seems to be more accurate, now set at 10 degrees base at about 750 idle speed. Used the advance feature on the light and getting 22 degrees at 3100, so if I am correct that is 10 base plus 22 for a total of 32 degrees at 3100 rpm. I think that should be about right from specs I could find.

Seems to be running well only pushed it to about 2800 rpm for a few minutes, probably won’t push these old motors any harder. Getting about 9 mph on gps at about 1500 rpm.

Posting for info and of course any advice or comments more than welcome.

One question, Found some posts on the web about Cliff’s High Performance in Ohio and thinking of sending carbs to him this winter for overhaul. Seems he is the master on Quadrajets and rebuilds them specifically for your application, not just a generic rebuild. Had one email with him, great guy. Anyone ever use his rebuilds?

[ron54]

Forgot to add, replaced plugs with ac delco MR43T, one step colder than the MR44T manual lists, but seems that is better for safety to avoid detonation. You can see from pics it had ngk ur5 which while they seat same as the ac delco, much different overall length.

103D96ED-D209-4831-810F-BBBD341C0853.jpeg

[km1125]

Source of the post ... Used the advance feature on the light and getting 22 degrees at 3100, so if I am correct that is 10 base plus 22 for a total of 32 degrees at 3100 rpm. I think that should be about right from specs I could find. ....

That would be correct if you were measuring "0" when the base timing was set.

Did the boat get up on plane at 2800 RPM? I wouldn't have a problem pushing it much higher...well into the 3000's. I understand not wanting to go to WOT but you should easily get to 3500 or so.

Cooler plugs don't really stop detonation. They stop pre-ignition. While similar, there are distinct differences. Pre-ignition can lead to detonation though.

[bud37]

One thing, final base idle settings/timing should be set with the engine at idle in gear.....tied to the dock is just fine..

Sometimes the lean best idle can be set but is too lean when put in gear and will stall under load. Also remember marine engines have a specific timing curve to avoid detonation on acceleration, that is the reason for marine specific distributors.....actually the curves are very close to the old performance curves we used to use, but not quite.....totals are much less.....sounds like you are having fun....enjoy.

Oh and check to ensure your PCV system is good.....that can affect idle quality as well.