CC 307Q plug/cylinder wiring

[WoodenBNut]

I have 2 307Qs in my 1962 CC Constellation. *it has been re-engined with the Qs - had 283s originally. Anyway, the port 307Q appears to me to have plugs wired incorrectly. I get a "popping" back thru the carbureator. I can't go back to the previous owner as we already have a "disagreeable" relationship over other screwed up items on this boat. My option here would be to hire a lawyer - but they are "pricey" too.
The port Q engine (this is the standard - counterclockwise rotating engine) is the "problem", what appears to be the incorrectly wired engine. From the distributor cap on the port engine, the firing order appears to be:
8-6-3-7-2-1-5-4 (if you can believe the numbers on the cap and that it is the correct distributor cap). However, I think that the wires from the cap are running to the wrong cylinders. You get a definite "popping/backfire" thru the carburetor coming from #4 wire (from the cylinder that #4 wire is going to). Here's how the spark pug wires go to the cylinders: from the front of the engine (pulley end to the rear of the engine - flywheel end: port (left) cylinder bank - plug wire 8 - 7 - 6 - 5 starboard(right bank) - plug wire 1 - 2 - 3 - 4 *** I know the spark plug wiring is not correct as the starboard - reverse - clockwise rotating engine has the plug wires wired different - that engine does not backfire thru the carb. And I think the plug wiring on the engines should be identical and the firing order would just be reversed for the opposite engine as the distributor would rotate counter clockwise for the standard rotating engine and clockwise for the reverse rotating engine.
If you know the proper plug wiring for the 307Q, I would sure appreciate that info.
Thanks

[pcford]

I'm pretty blurry this morning but I can tell you that the firing order of plugs is different on normal and counter rotating marine engines.

Someone else may posses a sharper brain.

[WoodenBNut]

Yes, I do have the documentation for a CC 283 & 327 V8 engines. And the firing order for those engines for the port (standard - counter clockwise rotation is 1-8-4-3-6-5-7-2 and the firing order for the starboard - reverse - clockwise engine is: 1-2-7-5-6-3-4-8 * which is just the opposite of the port engine - as I would suspect - it has to be. The cylinder numbering is from front to engine rear , left hand bank then right hand bank 1-2, 3-4, 5-6, 7-8 . And the cylinder numbering for the 282, 327 is the same for the standrad rotating engine and reverse engine.
I don't have the CC engine manual for the 307 - I had better get one quick! Now, if I look at a Chilton's automotve manual for 1974 to 83 Pontiac auto, they have a 307 engine spec for cylinder & firing order and it is the same (for auto standard - counter clockwise rotation) as the CC 283 & 327 engines.
So what gives???? Has someone installed the incorrect distributor caps on my 307s. Nothing seems to match the way these 307s distributos/plugs are wired??? But yet the starboard engine runs great? A mystery.

[brad9798]

The 307 was a goofy engine ... couple of thoughts- the 307 specs should be identical to a pre-1985 350 ... with regard to firing order, etc.

Check your points ... your rotor. Clean out your carbuerator too. Hairline crack in distributor??

Or, you could have some bad plug wires.

I sure would have NEVER repowered and gotten rid of the 283 blocks. :(

[Ross M]

"sure would have NEVER repowered and gotten rid of the 283 blocks."

Ironically, he still has 283 blocks smile.gif

The 307 is a 283 block with a 327 crankshaft. A "stroker" 283, as it were.

Opposite the 302, which was a 327 block with a 283 crankshaft.

Not a bad engine, IMO, just a relatively low performer. The longer stroke emphasized low end torque, and the induction system was sized accordingly.

Really one of the smoother running small blocks, IMO.

Ross

[brad9798]

Your are correct, Ross. I almost went back to correct it.

I should have said the whole 283 set-up. They run forever, have parts galore (like the 327 and 350).

Plus, all that trouble to gain 15 more horse per engine ... doesn't seem worth.

Heck my 283's have over 2,000 original hours and will still pull high rpm's.

I guess you could say I am very happy with them!!!

[Stiletto]

If the worst comes to the worst you could take the rocker covers off and see when both valves are closed on any cylinder, just after the inlet valve closes the rotor arm should point to the lead for that cylinder.

[WoodenBNut]

*** I ordered the 307 engine manual today, just to make sure of what I already suspect (that the 307 will have the same cylinder numbering and spark plug wiring and firing order as the other GM V8 small blocks(283, 327, etc.). If that is so, then my engine is definitely wired wrong, but should be easy to fix. **I'll post the results when the engine manual comes in (about a week).

[brad9798]

Forget waiting ...

Download the manual ... along with dozens and dozens of other useful CC stuff.

Or at least I think you can download ...

cc manuals (http://www.crosswinds.net/~ccmanuals/sbul.htm)

[ 07-05-2005, 07:24 PM: Message edited by: brad9798 ]

[Peter Malcolm Jardine]

It should be the same as the 283 and 327.

Is your timing close? That would give you a backfire if it's off. Check points setting.

[WoodenBNut]

Brad,
Yes, that is where I ordered the CC manuals from. But you cannot download the manuals. They come on a CD. Couple of days to ship. Yes, I think the cylinder numbering and spark plug wiring should be the same for the 283, 307, 327, and maybe all the GM V8 small blocks. I'll post back when the manual(cd) arrives. If that is the case, then my port (stnd rotation - counter clockwise - left hand) 307 engine definitely has the plug wires going to the wrong cylinders. I'll check the timing, dwell & points too.

[Canoeyawl]

Just a thought...
Automotive engines generally have the flywheels mounted at the rear of the engine. The marine versions often have the flywheel on the “front”. Perhaps there could be some confusion?
Or; marine engines are backwards – LOL

[brad9798]

Thanks woodenbnut ... keep us posted.

Brad

[WoodenBNut]

Well, I gotta "eat my previous words"! I do that a lot. I've been browsing through some CC engine manuals and have found out that CC 283 s have different firing orders depending upon whether they are fly wheel "forward" or fly wheel "rear" engines. I believe that will probably hold true for 307 s, etc., depending upon whether you have a flywheel "forward" or fly wheel "rear" type of engines. But I don't have the 307 engine manual as yet. Oh, the CC 283 F version is a flywheel "rear" engine and the non F 283 versions seem to be fly wheel forward. Interesting - so all CC small block v8 s do not have the same firing order.
I'll post more info when I get the 307 manual, etc.

[Peter Malcolm Jardine]

That's true. The 283F and 327F are flywheel rear. The 283H is flywheel forward.

[WoodenBNut]

Well, the engine manual(s)/CD finally came in yesterday - it took a week to ship. The manuals/CD are very good and definitely worth the $10. Here's web web URL if you want to order the manuals. http://www.cafepress.com/ccmanual_cd.10929994

Anyway, the timing for the 307Q, 327Q and 350Q (all flywheel forward) is Left Hand(Counter Clockwise/Standard Rotation)Port Engine is 1-8-7-2-4-3-6-5 and the Starboard Right Hand(Clockwise/Reverse Rotation) Engine is 1-5-6-3-4-2-7-8 . * The distributor rotates clockwise on both engines. The Timing is 10 degrees Advance(BTDC).
As it turns out my #8 & #7 Cyl wires were reversed and Timing was around 20 degrees BTDC instead of 10 at idle. It made for a lousy running engine to say the least. Back firing and shaking apart. Everything seems fine now. Also had to replace a leaky remote oil filter line, two wrong sized alternator belts(you couldn't get the squeek out of the old belts no matter what you did) and a bad fuel pump. But all is OK now.

[brad9798]

Thanks for the update!!

Easy fixes are a GREAT (albeit rare) thing!

[Peter Malcolm Jardine]

:cool:

[Canoeyawl]

"The distributor rotates clockwise on both engines."
Now isn't that clever...LOL -Good job-