Merc 888/302 firing order confusion

[racinrc14]

Allright, so I have thoroughly confused myself. I have a '77 merc 888/Ford 302. I am finishing up a complete rebuild. My 302 has mostly stock components with the notable exception of the Summit #4400 camshaft. My 888 came from the factory with 351 firing order, so I ordered a 351 firing order camshaft. 351 firing order is 1-3-7-2-6-5-4-8. So far so good. My Mercruiser manual (#2) shows two different firing order arrangements (Page 777, 8A-6). Standard 351 firing order for L.H. rotation engines, and a different one (backwards) for R.H. rotation engines. So do I have the right camshaft? This distributor I pulled off the motor before the rebuild has the wires arranged as the latter (RH rotation) firing order. What does L.H. rotation refer to? L.H. while looking at the front of the crankshaft? What's the difference between LH and RH engines (besides the obviously different rotation direction!). Why are there two? I noticed in my manual it has the same differences for the GM motors. I just want it all right before I fire it up the first time.

 

[WizeOne]

Re: Merc 888/302 firing order confusion

I think you are over thinking things. Counter rotating motors are rare and only used for twin engine applications. For left hand rotating engines (standard) if you are facing the crank pulley it turns in a clockwise fashion. I can only assume you got the right direction camshaft unless you specified otherwize.

And yes the 888 uses the 351 firing order.

 

[racinrc14]

Re: Merc 888/302 firing order confusion

The engine ran before pulling it out for the rebuild (water in oil, rod knock). The distributor/ignition wires are routed according to the R.H. rotation schematic in the Merc manual. That firing order is 1-8-4-5-6-2-7-3 (which is the reverse of standard 351 order). Who sells camshafts with that firing order?

 

[bruceb58]

Re: Merc 888/302 firing order confusion

The engine ran before pulling it out for the rebuild (water in oil, rod knock). The distributor/ignition wires are routed according to the R.H. rotation schematic in the Merc manual. That firing order is 1-8-4-5-6-2-7-3 (which is the reverse of standard 351 order). Who sells camshafts with that firing order?

Which way do you believe the distributor rotates?

Does this help?

 

[Don S]

Re: Merc 888/302 firing order confusion

The first thing you have to do is understand the manual.
Here is a pic of the tuneup specs for an 888 that you say you have.

Now, if we look at Figure 5, we see this.

 

[racinrc14]

Re: Merc 888/302 firing order confusion

I understand the manual and what it says I am supposed to have. What I don't understand is why my ignition wires don't jive with what figure 5 shows. For some reason, the wires on my distributor are routed as per figure 6. How can I check wether this engine turns backwards (it is an old boat, and quite possible that someone replaced the engine some time ago) before I actually try to fire it up the first time. Should I re-do the wires on the dist. according to figure 5?

 

[racinrc14]

Re: Merc 888/302 firing order confusion

Does the distributor turn the same direction on both the lh and rh engines?

 

[WizeOne]

Re: Merc 888/302 firing order confusion

Does the distributor turn the same direction on both the lh and rh engines?

No!

 

[racinrc14]

Re: Merc 888/302 firing order confusion

It does according to my manual.

 

[WizeOne]

Re: Merc 888/302 firing order confusion

xxxx

 

[WizeOne]

Re: Merc 888/302 firing order confusion

I understand the manual and what it says I am supposed to have. What I don't understand is why my ignition wires don't jive with what figure 5 shows. For some reason, the wires on my distributor are routed as per figure 6. How can I check wether this engine turns backwards (it is an old boat, and quite possible that someone replaced the engine some time ago) before I actually try to fire it up the first time. Should I re-do the wires on the dist. according to figure 5?

You can make the #1 distributor lug any one you want it to be. It does not have be in the same relative position that the manual shows. What matters is that the distributor is inserted properly in relation to the lug that you choose to be number one and the TDC of the #1 cyl.

 

[Bt Doctur]

Re: Merc 888/302 firing order confusion

reverse rotation motors use a gear drive not a chain drive,this allows the crank to turn in the opposite direction but the cam still turns normally.Crank the motor over and see what direction the flywheel turns and the rotor
report your findings

 

[racinrc14]

Re: Merc 888/302 firing order confusion

Thanks Doctor. To get my dist to turn the correct direction (CCW as viewed from the top), I have to turn the crankshaft CW (as viewed from the front). I believe this is normal SBF direction. I can't figure out why this engine ran with the wires in the order they were before. Would an engine actually run with the firing order backwards?

 

[Don S]

Re: Merc 888/302 firing order confusion

The engine ran before pulling it out for the rebuild (water in oil, rod knock).

I can't figure out why this engine ran with the wires in the order they were before.

Did you actually hear it run?

What does L.H. rotation refer to? L.H. while looking at the front of the crankshaft?

No, all engine rotations are viewed looking at FLYWHEEL direction of rotation.
CCW rotation (LH) of the flywheel is standard rotation and would mean that viewing the vibration dampner, it would be turning CW.

Since you completely rebuilt the engine, you should know if you had a timing chain or not on the front of the engine. Assuming you did, then you have a standard LH rotation engine and should be using the firing order shown in figure 5.

The engine ran before pulling it out for the rebuild (water in oil, rod knock).

I sure hope you don't have a cracked block after all that work. Did you pressureize the cooling system to check it before rebuilding?

 

[racinrc14]

Re: Merc 888/302 firing order confusion

Don,

I bought this boat last fall, took it to the lake (no, I did not ride in the boat before forking over the cash for it, lesson learned, first boat), and discovered the water in the oil among other misc. problems. Anyhow, I did see this motor actually running with the wires arranged as in figure 6 before I knew I needed to take it apart. Seems impossible.

I completely disasembled the motor, and had a local reputable machine shop do all the checking and machining. He told me the block and heads were both fine. It had a timing chain, no gears. I have had the machine work done, and everything else I am doing myself. I have the merc. manual, and two other Ford engine manuals for reference, and have been using them frequently.

Do reverse rotation motors require a special starter? Would the starter be marked somehow?

 

[racinrc14]

Re: Merc 888/302 firing order confusion

Unfortunately, no, I did not pressure check the cooling system before disassembly. I have strong reason to suspect a faulty intake gasket. When I disassembled the engine, I was very careful to have all the water drained out of the block and intake. When I removed the intake, there was both contaminated oil (milky) and clear water in the lifter valley. Also, when removing the intake gaskets, the starboard side had to be scraped off, while the other popped off with only a fingernail. The head gaskets revealed no evidence of leaking, and all 8 cylinders were uniformly coated with carbon deposits as were the tops of the pistons.

The engine ran, as I said. But looking back, it ran quite poorly. It backfired through the carb. if you advanced the throttle too quickly, and would not rev above 2000rpm while in gear. I figured it ran that way because the crankcase was full of water and oil (dipstick was coated all the way up, and I drained over 2 gallons of contaminated oil before disassembly) causing excess windage and drag on the reciprocating assembly. Also, as it turns out, the 'rod knock' that the local boat service place described when I had them winterize the boat actually turned out to be a motor/outdrive in very poor alignment, causing the u-joint to 'snap' once every engine revolution. They will never touch my boat again, for that and other reasons.