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Chris Craft Engine Rotation

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Starfishkiller (Starfishkiller)

Posted on Wednesday, January 28, 2004 - 05:53 pm:

I have two chris craft 350 c.i. chevy engines model 3500Bl15 and 3500B15. The engines have the firing order on their manifolds listed as 15634278. Could someone tell me if these engines are lefthand rotation or right hand rotation engines?

Thanks
eric

croozertoo

Posted on Wednesday, January 28, 2004 - 08:40 pm:

Hmmmm....interesting order. Standard Chevy small block rotation (LH) is 1-8-4-3-6-5-7-2. RH rotation is the reverse, 1-2-7-5-6-3-4-8. These are the standards, but I suppose other combinations are possible IF the cams really have that timing. I'd confirm that firing order since it's unusual.

I take it the engines aren't running. You can tell rotation from the timing scale (if they each have one - not always the case with older CC engines) by noting which way is BTDC and ATDC. Check the distributor wiring to the plugs for firing order if you think that's reliable. Lastly, you can pop the valve covers and note the cam timing by watching the rockers as you turn the engine through. The props are also a hint if they were on when the boat ran.

Chevy has cylinders 2-4-6-8 on the starboard side, 1-3-5-7 on the port side, facing the rear of the engine.

mylogo

Geo. E

Posted on Thursday, January 29, 2004 - 11:50 am:

Most CC engines are installed with flywheel fwd.
Both of the firing orders 1-5-6-3-4-2-7-8 and 1-8-4-3-6-5-7-2 are the same only referenced from the other end. where as 8 becomes 1.
Therefore the manifold with the firing order 1-5-6-3-4-2-7-8 should be [LH].
The manifold on the right hand rotating engine should read 1-8-7-2-4-3-6-5.

starfishkiller

Posted on Thursday, January 29, 2004 - 09:27 pm:

That helps a great deal. I,m a little confused about the cylinder numbering. Is it numbered like this:

1 2
3 4
5 6
7 8
-------
flywheel end

or is it numbered like this:

8 7
6 5
4 3
2 1
-------
flywheel end

Thanks
eric

Geo. E

Posted on Friday, January 30, 2004 - 11:36 am:

Eric
If my memory serves me correctly this is the layout.[as per a CC i owned in 1978].
cylinders 1-3-5-7 on the port side,and 2-4-6-8 on the starboard side.

[BOW]
flywheel end
------------
1 2
3 4
5 6
7 8

[stern]

starfishkiller

Posted on Friday, January 30, 2004 - 02:59 pm:

Thanks for the clarification.

eric

james ollis
Visitor

Posted on Monday, January 14, 2008 - 12:02 am:

I am working on a350 right hand rotating motor.some one has rebuilt the motor and has never been started firing is 1256438 and is done corectly. still engine will not start no backfires . I was wondering if cam is different on r.h than on left hand rotating motors and if it is possible that they installed wrong cam causing valve timing to be incorrect.

dogsharks38
Member
Username: dogsharks38

Post Number: 75
Registered: 12-2005

Posted on Friday, January 18, 2008 - 03:41 pm:

Hi guys,

I am always concerned when an automotive mind wanders into boat mechanics. Yes, indeed, the RH and LH cams are different, so are the pumps, seals, timing, firing order, etc. Raw water and circulating pumps must be hooked up properly, and the circulating pumps are rotation specific, with an arrow on them pointing in the proper direction. Using an automotive circ pump is most likely a problem waiting to happen. Here is a link to my personal files, hope it helps identify some issues for you.

http://www.network54.com/Forum/503931/thread/1149537985/last-1149537985

Here's a flywheel forward with an aft distributor installation.
http://img.photobucket.com/albums/v472/Dogsharks/283aftview.jpg

I am running a 327F now, which is flywheel aft with the distributor in the standard GM location.

The Q series of CC motors used an all differnt intake, and the cylinder IDENTIFICATION and TIMING is different than any GM small block motor, so is the cam.

Regards,

Dogsharks

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