89. Mercruiser engine swap problems

karayj

Chief Petty Officer
Joined
Aug 4, 2002
Messages
471
So my old engine had a compression issue slowly declining I waited till it was seven to one compression 105. Which now I’m kind of regretting. So I purchased an engine compression was 155 in each cylinder beautiful.

No, I removed Parts from my old engine onto this block. I’ll call it. Exhaust manifold, alternator distributor intake manifold and carburetor combined. Did the top dead center on the compression stroke made sure that it was pointing at cylinder one.

Got the boat running, but it was idling poorly lotta shaking going on. Checked and recheck and triple checked the timing. It was definitely top dead center compression stroke, pointing on cylinder one.

I changed the points might as well I like to do it every season they’re cheap and simple to do. Captain Rota looked great. Started up. The boat ran a little crappy for a few minutes. Heard an exhaust leak tightened up the bolts. A little bit more exhaust leak is gone engine running rough.

Intake manifold bolts, nice and tight 27 pounds of pressure. It feels like a vacuum leak you put your hand over the carburetor runs a lot better idle goes up.
OK, I removed and take manifold check. The new gasket that I put on looks great. Added some RTV although I don’t like to read attached. Everything waited five hours

Started up the boat again seems slightly better when I sprayed brake cleaner in a looking for vacuum leaks. It wasn’t as prevalent as before, but still running like crap before when I sprayed the intake ports near cylinder one until the idle would go up for about 25 seconds now I sprayed the base of a carburetor and the idle would go up just a little bit telling me OK maybe it’s there.


Went into my old rebuild kit remove the carburetor and install the new base nice and snug start the boat still running like **** very shaky. The idle wasn’t surging as much as before there were times at the idle would just go to 1200 back down to 900 up to 1200 back down to 900.

I think that has been eliminated. I only ran it for about four minutes but just standing on the boat the shaking it’s not right I remember the boat with the old engine being a lot smoother at 900 RPMs.

I’m looking for some smart suggestions I got one of my buddies that are you know pointing my finger over here and there are crazy places like the intake manifold is warped always the extreme with this guy so I’m coming here instead

This shouldn’t be this difficult to figure out, but it’s driving me a little crazy because I’m installing new gaskets in places that are supposedly having vacuum leaks, but not much of a difference
 

Bt Doctur

Supreme Mariner
Joined
Aug 29, 2004
Messages
19,388
#1 cylinder on compression stroke, rotate engine until timing mark on balancer is at at 6 degrees, install dist pointing to #1 in the cap or if cap is not marked point to #1cylinder , time accordingly.
recheck compression readings, check for correct firing order
It works better if you tell us what your working on too
 

Kola16

Petty Officer 2nd Class
Joined
Jun 23, 2019
Messages
182
Might be a dumb question, but did you use a timing light after it was running to confirm timing, or are you just lining up the harmonic balancer with the timing indicator?

Another question, how long has it been since you ran the old engine? I am wondering how old the gas in the tank is.
 
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