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Author Topic:   OMC V4 Cylinder Numbering

Gene in NC posted 03-24-2004 11:41 PM ET (US)
[This article was moved to this forum]
How are the cyninders numbered in an OMC V4? Can't find info in any of my three OMC factory manuals.
greyg8r posted 03-25-2004 09:36 AM ET (US)
Gene,
Starboard top is 1, port top is 2, starboard bottom is 3 and port bottom is 4. Weird, huh?
Richard
Chuck Tribolet posted 03-25-2004 07:59 PM ET (US)
What's so wierd? Tip the engine so the crank is horizontal
and the power comes out the aft end, just most truck
engines. Forward cylinder on the passenger's side is #1.

Chuck
jimh posted 03-25-2004 09:36 PM ET (US)
I'll bet the numbers are cast into the cylinder head. See if they're visible.
Chuck Tribolet posted 03-25-2004 09:52 PM ET (US)
I checked mine last night. They very nicely cast the cylinder
head bolt torque sequence into the tops, but not the cylinder
numbers.
I also checked my factory manual and was suprised that they
weren't there.

Chuck
Gene in NC posted 03-27-2004 01:18 AM ET (US)
Thanks Chuck. You're right. Perfectly logical to number cylindes like an auto engine. However, outboard engines often seem to defy logic and design seems to favor requiring dealer repair. Suppose a lot of it is packaging, and the rest is my '66 100 Johnson that ran for 25 years with little or no problems. No need for service/repair details.
Add power T&T, VRO, and rectifier/regulator and problems jump with no real increase in function. Too many engineers with too little real work to do.
Gene in NC posted 03-27-2004 01:29 AM ET (US)
Thanks Chuck. You're right. Perfectly logical to number cylindes like an auto engine. However, outboard engines often seem to defy logic and design seems to favor requiring dealer repair. Suppose a lot of it is packaging, and the rest is my '66 100 Johnson that ran for 25 years with little or no problems. No need for service/repair details.
Add power T&T, VRO, and rectifier/regulator and problems jump with no real increase in function. Too many engineers with too little real work to do.
jimh posted 03-27-2004 07:27 AM ET (US)
Numbers representing the sequence in which the cylinder head bolts should be tightened are also cast into the cylinder head of my 1987 Yamaha 70-HP engine. I have been told that this engine was copied in Japan by Yamaha directly from an identical OMC design. This is another piece of evidence that tends to confirm that.
jimh posted 03-27-2004 08:13 AM ET (US)
[Moved article to Repairs/Mods forum.]

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Author	Topic: OMC V4 Cylinder Numbering
Gene in NC	posted 03-24-2004 11:41 PM ET (US) [This article was moved to this forum] How are the cyninders numbered in an OMC V4? Can't find info in any of my three OMC factory manuals.
greyg8r	posted 03-25-2004 09:36 AM ET (US) Gene, Starboard top is 1, port top is 2, starboard bottom is 3 and port bottom is 4. Weird, huh? Richard
Chuck Tribolet	posted 03-25-2004 07:59 PM ET (US) What's so wierd? Tip the engine so the crank is horizontal and the power comes out the aft end, just most truck engines. Forward cylinder on the passenger's side is #1. Chuck
jimh	posted 03-25-2004 09:36 PM ET (US) I'll bet the numbers are cast into the cylinder head. See if they're visible.
Chuck Tribolet	posted 03-25-2004 09:52 PM ET (US) I checked mine last night. They very nicely cast the cylinder head bolt torque sequence into the tops, but not the cylinder numbers. I also checked my factory manual and was suprised that they weren't there. Chuck
Gene in NC	posted 03-27-2004 01:18 AM ET (US) Thanks Chuck. You're right. Perfectly logical to number cylindes like an auto engine. However, outboard engines often seem to defy logic and design seems to favor requiring dealer repair. Suppose a lot of it is packaging, and the rest is my '66 100 Johnson that ran for 25 years with little or no problems. No need for service/repair details. Add power T&T, VRO, and rectifier/regulator and problems jump with no real increase in function. Too many engineers with too little real work to do.
Gene in NC	posted 03-27-2004 01:29 AM ET (US) Thanks Chuck. You're right. Perfectly logical to number cylindes like an auto engine. However, outboard engines often seem to defy logic and design seems to favor requiring dealer repair. Suppose a lot of it is packaging, and the rest is my '66 100 Johnson that ran for 25 years with little or no problems. No need for service/repair details. Add power T&T, VRO, and rectifier/regulator and problems jump with no real increase in function. Too many engineers with too little real work to do.
jimh	posted 03-27-2004 07:27 AM ET (US) Numbers representing the sequence in which the cylinder head bolts should be tightened are also cast into the cylinder head of my 1987 Yamaha 70-HP engine. I have been told that this engine was copied in Japan by Yamaha directly from an identical OMC design. This is another piece of evidence that tends to confirm that.
jimh	posted 03-27-2004 08:13 AM ET (US) [Moved article to Repairs/Mods forum.]