Tips for removing prop shaft coupler: Engine Swap

[68PearsonRenegade]

Hi Afourians,
Im replacing a cracked block A4 with another low hour A4 that I am doing some preventative maintenance on. I need advice on the best way to remove the prop shaft and engine coupler so i can drop in my new A4? Do i just place block on the prop to keep it from moving and then crank the bolts out?
Also any advice on things to take care of on the new engine before drop in?
the old engine is an early type the new is a late model

Things Ive done on the replacement engine:
new water jacket plate and alternator arm
High output alternator
new carburetor w/ polishing filter from electric pump
new plugs and wires
new plumbing
new wires
a coat of fresh paint(being applied soon)

[Peter]

Check and adjust valves

Peter

[Al Schober]

I've never had an issue removing the bolts between the coupler and the transmission flange. No need to block the propeller. Just put a box wrench (1/2" as I recall) on the bolt head and tap it with a hammer - bolt will loosen. Do the next one, etc. Once the three bolts are out, just slide the shaft and coupler back a bit.

[68PearsonRenegade]

I've never had an issue removing the bolts between the coupler and the transmission flange. No need to block the propeller. Just put a box wrench (1/2" as I recall) on the bolt head and tap it with a hammer - bolt will loosen. Do the next one, etc. Once the three bolts are out, just slide the shaft and coupler back a bit.

how do you stop the coupling/coupler and shaft from spinning?
ty for your help

[68PearsonRenegade]

Check and adjust valves

Peter

wouldnt that involve removing the head and potentially breaking a stud in the block/head possibly causing A LOT of additional headaches. The engine has 500 hours on it. I'm gambling the valves are fine.

[jcwright]

For removing the coupler bolts, the suggestion I found helpful is in post #9 in this thread:

https://www.moyermarineforum.com/forums/showthread.php?t=11092

I believe one of your earlier suggestions is referring to adjusting the valve clearances. This does not require removing the head. The cover that gives you access to the tappets is on the carburetor side of the engine.

Jack.

[68PearsonRenegade]

For removing the coupler bolts, the suggestion I found helpful is in post #9 in this thread:

https://www.moyermarineforum.com/forums/showthread.php?t=11092

I believe one of your earlier suggestions is referring to adjusting the valve clearances. This does not require removing the head. The cover that gives you access to the tappets is on the carburetor side of the engine.

Jack.

AH Thank You! I did not know that, very happy to have you all here to help.

[wagner]

Shaft/Prop/Coupler Removal

Hi
I had some similar difficulty when swapping A4’s in my 1974 Sabre 28. The engine had not been out in quite some time and the coupler was both very rusty and hard to reach in my boat. I ended up deciding to remove the prop and slide the engine forward, pulling the prop shaft and stuffing box along with it. In order to remove the prop, which was on a keyed taper on the shaft, I used a three jaw puller, a breaker bar with an appropriately sized socket and a mapp gas plumbers torch. I heated and cooled the prop several times and continues loosen and tighten the puller tool until the prop popped off.

I did a similar heat-and-quench operation on the output coupler after sliding the engine forward, but the coupler halves were pretty stubborn. I ended up grinding a small slot in between them and inserted a couple metal wedges opposite each other. The coupler popped apart, but both faces will need to be re-machined flat. This will be something I will do myself on a lathe.

Next I had to remove the the half coupler from the shaft. Another puller/heat/quench operation, but they did come apart. I bought a new half coupler from Moyer and brought that, the shaft and prop to Rose’s Marine in Gloucester to get everything checked for straight and for some minor machining for the new coupler key way and set screws. Probably cost about $300. Well worth it as I don’t have that machining capability myself.

It was worth pulling the engine forward so I could recon the stuffing box and stern tube.

However you get the assembly apart, it’s worth having a machine shop check the shaft for straightness. It would be disappointing to get your new engine in only to have to pull it all apart because your shaft has a wobble!

[Peter]

wouldnt that involve removing the head and potentially breaking a stud in the block/head possibly causing A LOT of additional headaches. The engine has 500 hours on it. I'm gambling the valves are fine.

The A4 is a flathead. The valve stems and springs are accessed via a plate on the manifold side of the block. So no need to remove the head to adjust the valves.

Most engines are installed in tight engine compartments where this job is awkward to do.

I am wondering if you have a copy of the maintenance manual that was produced by Moyer? It is an excellent investment and a nice way to support the hosts of the forum.

https://moyermarine.com/product/service-and-overhaul-manual/

Best,

Peter

[68PearsonRenegade]

The A4 is a flathead. The valve stems and springs are accessed via a plate on the manifold side of the block. So no need to remove the head to adjust the valves.

Most engines are installed in tight engine compartments where this job is awkward to do.

I am wondering if you have a copy of the maintenance manual that was produced by Moyer? It is an excellent investment and a nice way to support the hosts of the forum.

https://moyermarine.com/product/service-and-overhaul-manual/

Best,

Peter

Thanks Peter, I found a copy of the service manual on my boat. It's been a huge help, about to put in my third and hopfully final order with moyer.the parts have been excellent