Mercruiser w/ Ford 351w timing / runability / issue

I have another thread on here that was originally related to the boat stalling in gear. I have started this on due to the other issues I have running the motor currently.

I have recently acquired a 1976 sea ray boat with a Mercruiser 888 ( Ford 351 ) engine installed. My first outing on the boat the engine ran like a dog. 2000rpm at WOT most of the day. With the engine cover removed it slowly crept up to about 2800rpm ( 30mph ) on my gauge. At the end of the day something let go in the motor mount and caused my drive to dis engage and I had to get a tow in.



Engine specs
Ford 351 windsor
Rochester 2bbl carb
Prestolite Distributor
OMC outdrive

The damage to the boat was repaired. Since I had the engine out I did the following.

New freeze plugs. New Valve cover gaskets. New spark plugs (NGK) , New distributor cap-rotor-points, New starter, Carb clean and new gasket set.

The Engine serial numbered showed it to be a Mercruiser 188 ( Ford 302 ) . I am not a Ford expert, nor would I know the difference between the 302 and 351. So under the assumption of it being a 302 firing order we set it with the 1542... firing order. The engine started and ran at what happened to be TDC on the exhaust stroke. ( Which was incorrect ) It did idle smooth, it revved out of the water to about 4000rpm. Under load it died. The timing was set at 10 BTDC. At the end of the day I gave up trying to run it and towed it home.

A compression test showed the following

Cylinder 1 - 95psi
Cylinder 2 - 100psi
Cylinder 3 - 95psi
Cylinder 4- 110psi
Cylinder 5 - 95 psi
Cylinder 6 - 0 psi
Cylinder 7 - 100 psi
Cylinder 8 - 110psi

So the dead cylinder 6 was an alarm. I pulled the valve covers and checked the firing order to find that it is in fact 137265.... Reset the order accordingly, cleaned the plugs and ran it again to watch the valves on cylinder 6. They do move up and down, no air comes out of them. The piston is moving as well at this point however it still showed 0 psi.

So cylinder 6 aside I was trying to get it to idle where it would hold a timing mark. Currently the timing mark jumps all over from 5* ATDC up to 15* BTDC. The engine idles between 800 and 1100rpm. When you give it any throttle it backfires and dies. Sometimes through the carb, sometimes through the exhaust.

So frustrated, I did a leakdown on cylinder 6. Filled it with about 40psi and listened for the air leak. Nothing out of the valve train, nothing out of the carb. So for ****s and giggles I threw the compression gauge back on it and cranked it over. It then showed 110psi on cylinder 6. I tested cylinder 2 as well and it was around 105psi. So the gauge is still working solid. I pulled the rest of the plugs and thew some marvels mystery oil in each cylinder for the night. I am going to blow them out in the morning and try it again.

My current distributor positioning is questionable. I have a photo of its current position with cylinder positions numbered on the top of the cap.
http://overtwocustoms.com/wp-content/uploads/dist-pic.jpg
Is it possible my entire distributor is 180* out? How about timing chain jumped and the entire engine is out of time?

I have spent countless hours on this project and I am running out of viable options. All help is appreciated.

Re: Mercruiser w/ Ford 351w timing / runability / issue

I have spent countless hours on this project and I am running out of viable options. All help is appreciated.

Click to expand...

Ayuh,.... As I said in yer other thread,.... You have a rebuildable core motor...

It ain't gonna run right, it's mechanically Impossible...

Re: Mercruiser w/ Ford 351w timing / runability / issue

Couple of questions and observations.

1. an 888 is a 302 engine, not a 351.

The Engine serial numbered showed it to be a Mercruiser 188 ( Ford 302 )

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where did you find the serial number?
In the picture you posted, the valve cover (port side) has a 3 at the end not an 8. Is that number 233?
2. 100 psi is minimum compression on any V8.
3. You have 7 cylinders that are weak at best and one that is dead completely.
4. Distributor location has no effect on the compression, you could remove it completely and have the same compression.
5. I know you say you have an OMC outdrive, but from the looks of your engine picture, I doubt it. Could you post a picture of the drive, and a better picture of the inner transom shield.

Re: Mercruiser w/ Ford 351w timing / runability / issue

I understand that the 888 is a 302. The serial number was attached to the rear of the cylinder head. The boat shop I have been getting parts at ran the number through his catalog and matched to the 302 for the year /make / model. The motor is definitely a 351. Intake manifold is a dead on match to a 351. The valve covers were stripped and recoated , the original decal showed Mercruiser 233hp.

The compression test was done cold after multiple attempts at running the motor and flooding the plugs. Cylinder 6 has shown compression since the initial test done. I checked it twice. Even at 110 psi ( I understand that its low ) it should still attempt to run. I'll have to see if i have a photo of the drive and transom shield.
http://overtwocustoms.com/wp-content/uploads/engine-hang.jpg
The serial number plate is on the back of the motor. I looked at a 302 yesterday out of an F100 and its visibly smaller than the motor I have.

When I first got the boat it did run at WOT. It didnt show signs of engine trouble. Since the transom cracked I didnt get more than probably an hour of run time on it above idle.

Re: Mercruiser w/ Ford 351w timing / runability / issue

My other question would be would a 302 out of a ford truck work in the boat? The accessories do bolt up to both motors, the engine coupler fits, but the down tubes for the exhaust would be closer together than on the 351 due to the head stack size? I would have to swap the exhast manifolds, water pump, flywheel housing, starter, carb, and install an electric fuel pump. I have confirmed that the motor would sit in the same place as the 351 in the boat.

Re: Mercruiser w/ Ford 351w timing / runability / issue

ford had some strange numbers in the past. They did use several cams over the years. They did use 351 heads on a 302. I would check my firing order the old way. Pull a plug, put finger in hole. bump engine over and see if the rotor points to that cylinder when you feel the air come out. Now go to the next cylinder and see if you get the same results. check all of them. might even be 15426378

Re: Mercruiser w/ Ford 351w timing / runability / issue

I did do that. I even went as far as to pull the covers and rotate by hand to witness the firing order myself. Its definitely 137 and not 154 although I had it running pretty smooth on the 154 order on Sunday. Cranked right up and idled smooth. Under load it stalled out immediately , which we were attributing to the EAS switch ( I did not have it wired at all ) . With the 154 order the motor would rev, idle smooth out of the water. I tried that order today and couldnt get the motor to fire up at all. It does crank right up on the 137 order.

Re: Mercruiser w/ Ford 351w timing / runability / issue

do you know how to check the timing chain for wear? It might have jumped.

Re: Mercruiser w/ Ford 351w timing / runability / issue

Lyle29464 said:

do you know how to check the timing chain for wear? It might have jumped.

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Not without pulling the front of the motor. Water Pump etc. and visibly inspecting it. Talking with some car guys in my area its not an uncommon scenario for the chain to jump.

Re: Mercruiser w/ Ford 351w timing / runability / issue

if you put a breaker bar on your front pulley you can see how much slack is in the chain. look at rotor. pull till rotor moves now push bar the other way till you see the rotor move again. If the chain has enough slack to jump timing the end of your bar will have moved several inches. That would account for the unclear firing order and the compression being off a bit.

Re: Mercruiser w/ Ford 351w timing / runability / issue

I can't figure out what we're talking about. A 188 omc with a 351w? Lol. The easiest way to tell a 302 from a 351w is the deck height. Basically, if the block has a cast in rib behind the distributor that connects the timing cover to the deck just below the intake mounting surface, it's a 351w. The 302 doesn't have that rib.

Re: Mercruiser w/ Ford 351w timing / runability / issue

The engine in picture is a 351... the way i have always noticed right away is the proximity of the carb bolts in relation to the intake bolts. In a 289/302 they are right next to each other. 351 not so much.

It has been many years since i have had any small block fords but it was very common for aftermarket cam companies to use the 302 firing order on a cam sold/labeled as a 351w cam. Not sure if this is still the case.

The HO302 also used the 351w order.

As far as switching back to a 302, you wont be able to reuse your harmonic balance'r, flywheel, intake. I think everything else will work.

Stock Ford timing chains were bad about jumping...

Re: Mercruiser w/ Ford 351w timing / runability / issue

We are talking about a 351 in this case. I will check the rotor and see if there is any visible slack in the chain that way before proceeding to remove the waterpump and everything else in the way.

How about the springs under the points? Springs and weights? They look pretty rough under there. A lot of rust.

Re: Mercruiser w/ Ford 351w timing / runability / issue

Pulled the timing chain cover today and ended up replacing the the timing chain and gears. There was definitely excessive slack in the chain. Fired it up and it sounds better. It does idle smooth at 1000rpm but surges down to about 300rpm every few seconds and eventually stalls out.

Compression test this morning yeilded 130psi on almost all cylinders. Cylinder 6 is still a mystery. Last night it popped at 110psi, this morning, 0 again.

I have found someone in my area with a 351 Cleveland for sale. Motor has 50k original miles, 1970s motor. Has been in a basement for the last 20 years. Seller says he will crank it on the stand for me and allow compression test as well. This motor would be a direct swap for me so I am considering picking it up.

Re: Mercruiser w/ Ford 351w timing / runability / issue

A 351Cleveland is a completely different setup and wouldn't work well, especially because they were known for being higher- to make the power. It almost sounds like you have a valve sticking on that #6 cylinder.

Re: Mercruiser w/ Ford 351w timing / runability / issue

haulnazz15 said:

A 351Cleveland is a completely different setup and wouldn't work well, especially because they were known for being higher- to make the power. It almost sounds like you have a valve sticking on that #6 cylinder.

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Well damn. It does sound like a sticking valve. I am trying to keep the repairs the most cost effective and reasonable as possible. Being that I can do most of the mechanical myself. To get the head redone will set me back about $250 with gaskets for reassembly. I wouldnt habe to pull the motor for the repair but its time consuming by far. All things considered the motor should run well enough on 7 cylinders to diagnose number 6, yet it does not want to cooperate. The fuel pump is still suspect. How about the mechanical advance? Im not sure I can get my hands on a new one without an entire distributor.

Re: Mercruiser w/ Ford 351w timing / runability / issue

You can buy new weights and springs, etc. However, I went with a new Pertronix billet distributor on my 351w. It's mechanical advance but electronic ignition, so no points/rotor. Very nice unit, and not all that expensive. However, when I put my reman'd long block in, I'm guilty of doing the "while I'm in here" items. If you are doing one head, you might as well do both, because they both saw the same oil, the same temps, and the same fuel. If there's damage to one head, it probably isn't too pretty on the other side. Perhaps a leak down test is in order?

Re: Mercruiser w/ Ford 351w timing / runability / issue

haulnazz15 said:

You can buy new weights and springs, etc. However, I went with a new Pertronix billet distributor on my 351w. It's mechanical advance but electronic ignition, so no points/rotor. Very nice unit, and not all that expensive. However, when I put my reman'd long block in, I'm guilty of doing the "while I'm in here" items. If you are doing one head, you might as well do both, because they both saw the same oil, the same temps, and the same fuel. If there's damage to one head, it probably isn't too pretty on the other side. Perhaps a leak down test is in order?

Click to expand...

I shot some air into cylinder 6 again and I can hear it resonate out of my prop through the exhaust so the issue has to be there. The weights and springs were stuck in the outmost position and not returning in. I shot some PB Blaster on them to try and loosen them up. The head with the issue is the same one I pulled the exhaust manifold off while it was out of the boat so the gasket and studs wont be an issue. The other head is pretty ugly as far as studs go and I doubt it will come off without a fight. Being that I can pull the heads with it in the boat I might go that route. The compression has built up a bit more since soaking the pistons will oil. Im reading upwards of 130 on the other 7 cylinders. Even with 6 dead it should still try to run without falling on its face. I am still considering an electric fuel pump on this one.

Re: Mercruiser w/ Ford 351w timing / runability / issue

Disassembled the top of the distributor today and the spring / weight setup is beyond repair. The weight was so rusted it was broken inside the distributor housing. I was able to score another distributor with a decent set of springs and weights and no points, electronic instead. So I will throw that in tomorrow and see what happens.

Re: Mercruiser w/ Ford 351w timing / runability / issue

Be carefull #6 might stick open