Mercruiser vs Chevy 4.3 timing cover problem

fairshopperguy27

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Bought a 1995 mercruiser 4.3 balanced shaft project engine or what I thought was a mercruiser engine but turns out it's a automotive block that was swapped in at some point because it still has sensor on the side of the head, oil drain plug off to the side, It was a real mess of an engine, cracked manifolds, rats nest wiring, all has since been fixed. My big problem is I can't set the distributor in and time it because when they swapped the block they didn't give it the merc timing cover they just bent the timing tab up and put on the merc 6.750" balancer. I've tried setting the distributor in and timing it using the TDC mark on the balancer with the TDC tab on the cover but I'm off. Only starts if I turn the distributor to retard the timing. And idles way high and a bit rough. I've tried looking for a used timing cover PN 855400, but they are hard to find. Any help on how to time it would be appreciated.
 

alldodge

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Pick up a piston stop bolt, or make one
https://www.amazon.com/Competition-Cams-4795-Center-Bolt-Style/dp/B000CIOA0Q

Remove all the plugs and bring the engine around by hand until the distributor points to number 1. Now back the motor off TDC and install the stop bolt. Bring it up by hand until piston touches bolt. Make a mark on the harmonic balancer.

Rotate motor in opposite direction until piston touches stop bolt. Make a mark on the harmonic balancer.

The distance between the two marks is TDC.

Pick up some timing tape and install based on the size of your damper.

https://www.summitracing.com/parts/...zk-658sziRUII3JIGGg9SyuLqfOJiC3R_IaAn6e8P8HAQ

Your ready time the motor
 

wrench 3

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Just to clarify AllDodge's post.
"The center of" the distance between the two marks is TDC.
 

fairshopperguy27

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Pick up a piston stop bolt, or make one
https://www.amazon.com/Competition-Cams-4795-Center-Bolt-Style/dp/B000CIOA0Q

Remove all the plugs and bring the engine around by hand until the distributor points to number 1. Now back the motor off TDC and install the stop bolt. Bring it up by hand until piston touches bolt. Make a mark on the harmonic balancer.

Rotate motor in opposite direction until piston touches stop bolt. Make a mark on the harmonic balancer.

The distance between the two marks is TDC.

Pick up some timing tape and install based on the size of your damper.

https://www.summitracing.com/parts/...zk-658sziRUII3JIGGg9SyuLqfOJiC3R_IaAn6e8P8HAQ

Your ready time the motor

What if I'm starting from scratch with the distributor out??
 

alldodge

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What if I'm starting from scratch with the distributor out??

Actually it still works, and I should not have mentioned that, just was over thinking the issue again. Rotating the crank where the piston comes to the top is either TDC or 180 out. Reversing the direction is either 180 out or TDC.

Now installing the distributor, look for both valves being closed as the piston comes up
 

fairshopperguy27

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Actually it still works, and I should not have mentioned that, just was over thinking the issue again. Rotating the crank where the piston comes to the top is either TDC or 180 out. Reversing the direction is either 180 out or TDC.

Now installing the distributor, look for both valves being closed as the piston comes up

Ok here's what I've done so far and had no luck, still misfiring. I pulled all plugs, placed my finger over #1 rotated it until #1 came around with the hiss, I then put in the stopper and rotated further until it came to a stop. Then I rotated the other way until it came to a stop, measured the distance between the two marks and marked TDC. What I don't understand is when I rotate it left, stop and take my measurement do I mark that on the damper AND that same location on the timing cover?
 

NHGuy

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Put a zero mark on the damper AND the cover at the mid point between the two stops. Cuz that's your actual TDC.
 

wrench 3

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You can put a new mark on one OR the other. You're probably better to use the existing TDC mark on the damper and put a new mark on the cover. Lining your distributor up on these marks should get it running but to put a timing light on it you will need a degree scale. If there isn't on all ready on the damper you will need to get a stick on one as shown in post #2.

You will end up with three new marks. The two from the stop bolt and the measured one in the center. Once you get the center marked you can ignore the other two.
 
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fairshopperguy27

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Ok I was able to time it, took the boat out today and it starts cutting out over 3000 rpms. Idles fine and if I slowly climb with the throttle it's ok up to 3000rpms, now if I hammer down on the throttle it will pretty much immediately start cutting out because I'm at 3000 rpms when jumping onto plane. Doesn't overheat. Any ideas?
 

alldodge

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I Would start with checking fuel pressure, should be 4 to 7 psi
 

fairshopperguy27

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Can get one at several places, HF, any auto parts store or on line
https://www.amazon.com/Performance-Tool-W80594-Vacuum-Tester/dp/B000FW2O1G

Need to make a Tee and place it between the fuel pump and Carb

I know now the the pump is not able to pickup enough fuel from the tank. I can hear it struggling with a intermediate air suckling noise coming from the pickup on the aluminum gas tank. I've taken the 12volt pump off the boat and tested it off my portable 6gal tank and the outflow volume is twice the amount vs the the boat tank. How on earth do you clean this pickup tube out?? It's a welded 90degree barbed fitting.
 

Scott Danforth

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post a pic. the pickup should be attached to a threaded fitting (anti-siphon valve) and threaded into a hole
 

alldodge

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A pic would be great. Also if the pump is mounted above the tank, this could be part of the issue
 

fairshopperguy27

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OK I got a little excited. It does have a threaded barbed fitting that goes into the main pickup fitting that is also threaded into the tank. I took the pickup out and it's clean and clear, nice mesh filter on bottom too, there's plenty of fuel in the tank. I took the the barbed line connector off and I noticed a check ball in there. I blew into it and the check ball works but thats where the air suckling sound is com8ng from for sure. So I found a brass barbed fitting with no check ball in my spare parts bin, threaded it in and it, tested and draws normal volume. How important is it to have the check ball?
 

alldodge

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The check ball which is an anti-siphon valve is a safety device and is required on all boats. If the pump is having a hard time drawing thru the valve it should be replaced.

That said; if you were hearing air coming thru the valve then the fuel line may just need to be check for a bad connection at the hose
 
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