1976 cc 307 questions

I recently got yet another "free boat", if you want to call it that. I need to go to free boat rehab because I never learn! Anyway, it's a 1976 CC 25 with a 307k. Decided to tear the motor down because i want to see what I've got because I have no records on its previous 36 years and I don't want to find out bad things on the water. Have done a Chevy 350 build before and a 5.9 cummins diesel on previous boats, yet this 307 is reall different. Its reverse rotation, yet the firing order stamped on the intake, and the distributor order(determined by removing the wires) is standard 18....also took off the thermostat housing and there's no thermostat, there's not even any indication that there ever was one. Next, starter goes in the back of the bell because of the reverse rotation, but it's a ford starter? Any one have any experience, or two cents about this motor? Thanks in advance

Geopop,
Yes... I would get yourself into re-hab ASAP. Free boats are NEVER Free!

The RH Reverse Rotation intake will be a std LH Rotation engine manifold and will show the std firing order.
Pay no attention to this firing order for this REV RH engine.
The correct firing order will simply be reversed of the Standard LH engine firing order..., beginning with #1.

Instead of 1 8 4 3 6 5 7 2.... it will be 1 2 7 5 6 3 4 8.... both beginning with #1, and in the same CW direction from #1.


You should be able to build a 5.7L more cost effectively than the 307.
Note that there are several methods for driving a RH rotation engine camshaft.... std chain, double gear set, etc.
Note that piston wrist pin offset is reversed for the RH engine.
Also note that the front/rear main seals are unique to the RH engine.

You definitely want a thermostat installed. We need to maintain a certain and consistent engine temperature.

The cover at the rear of the engine is a "Flywheel Cover". Bell Housing is an automotive term.
The I/B (in-board) starter motor may look like a Ford because these older ones were typically Bendix Drive starter motors.

NO... the starter motors are not necessarily at the aft of the flywheel cover due to LH or RH rotation.
This is a result of these being In-Boards, rather than In-Board/Outboards... such as stern drives.

Both engine flywheel covers will position the starter motor in the same location.
One will be for LH rotation, and one will be for RH rotation.

Suggestion: DO NOT spend one dime on over-hauling a Bendix drive starter motor.
Instead..... replace them with a HTGR/PMGR starter motor for I/Bs.

[FONT=Tahoma, Calibri, Verdana, Geneva, sans-serif]Thanks Rick for the info. I didn't know about the wrist pin offset being reversed and the seals were different. I guess the firing order question was kind of a stupid question...duh...that makes total sense. I started tearing down the motor last night. It looks awesome inside. Theres not even a noticable ridge in any of the cylinders! Will be doing the oilpan tonight to look at the bottom end. If everything measures well i may hone and do a standard size rebuild. Is there any other parts that you think may be different in a rh motor and do you have a supplier that you could recomend for a rebuild kit. Can the heads be rebilt since they are probably pre-unleaded valve seats or should I replace them? The boats a '76, but they stoped production of the 307 in '73. I've heared that the valve seats are not as much of a problem in lower rpm, lower load situations like in a car, but high speed and load like a boat will make them burn up pretty quickly. Thanks again,
George[/FONT]

George, I'd take the cylinder heads in to a good machine shop. They can tell you what needs to be done. Tell them what you intend to do with them.

But again, I'd like to mention that you'd be better off to build a 5.7L, and can probably do it for less.

Yes, wrist pin are slightly offset due to rotation. Std engine is LH, Rev engine is RH and this is when viewed from the flywheel end.... auto/marine... doesn't matter.

Pistons for a Rev RH rotation engine will be offset in the opposite direction.

Regarding the front/rear seals, look closely at the seal lip. You'll see tiny little spiral serrations that wick the oil back towards the lip.
These are spiral directed differently for each rotation engine.

Ignition distributors and oil pumps all turn CW.
Camshafts can be found to rotate in either direction..... depends on how the cam is driven.

Chain drive..... cam rotates same as crankshaft. You'll see this in both RH and LH engines.


Double gear drive..... cam rotates opposite crankshaft. You'll see this in REV RH engines.
Cam rotates opposite same as LH rotation engine, but valve timing and operation is for RH engine.




Four gear drive... one crank, one cam w/ two idler gears.... cam rotates same as crankshaft. You'll see this used in Automotive.