What is the function of the vertical baffle plate in the front of the valley cover? Reason I am asking is I have one cover that takes a road draft tube and it has no baffle.I have another that does not take a tube and it does have the baffle.I thought the baffle was to help keep oil out of the road draft tube?

I am not completely sure about this but I thought it was to help the air flow to vent crankcase gases.

The baffle plate on the valley pan is intended to redirect the air flow through the rocker arm chambers. The following is text from a 1957 Ford shop manual regarding crankcase ventilation:

"Air enters the engine crankcase through the oil filler cap located in the front of the valley pan. The filler cap contains a filtering element which filters the incoming air.
From the filler cap, air flows into the front section of the push rod chamber where there are few gases. Hence, the incoming air has a chance to warm up before contacting contaminating vapors originaing in the crankcase. Warm ventilating air minimizes the formation of crankcase sludge.
The ventilating air is directed by a baffle on the front of the valley pan, upward into the front of both rocker arm chambers. The air is forced to the rear of the rocker arm chamber and down into the rear section of the push rod chamber and through an opening in the block into the crankcase. Air is also diverted from the front section of the push rod chamber through holes in the front wall of the cylinder block to ventilate the timing chain chamber.
The air from the crankcase is directed through a filter into the road draft outlet tube by the forward motion of the car which creates a partial vacuum at the road draft tube outlet."

Hope this helps with the need for the baffle plate in the valley pan.

Regards,
Dave

I wonder if Ford did some sort of air flow analysis through the block or is this theory?


Mark

1956 Mercury M100
1955 Ford Fairlane Club Sedan
Delta, British Columbia

That's a good question as to whether the crankcase ventilation air flow was developed as the result of actual lab testing or as theory. The T-bird engines used a draft tube that was located in the rear portion of the valley pan, so the flow would definitely be different than the description in the Ford manual for the road draft tube location on the lower left front of the block.

I have replaced the original draft tube on my 57 (292 engine) with a PCV valve that is located in the rear of the valley pan (using a T-bird valley pan). The air flow would not be as described in the manual using the PCV valve either, but I do believe that the baffle in the front of the valley pan does enhance the flow of air from the fill tube through the rocker arm cavities and back to the location of the PCV valve. The flow through the lower portion of the crankcase is somewhat dependent on the vacuum created by the PCV valve and it provides a more positive ventilation of the crankcase than the original draft tubes in either location, particularly when the car is traveling at low speeds or stopped. Without the baffle in the valley pan, the air flow would have a direct path from the oil fill tube through the valve lifter cavity to the PCV valve and not be directed to the rocker arm cavities.

Regards,
Dave

Ford's crankcase ventilation engineering may have been effective in theory. However, in service, the weak link was the filter screened air intake thru the oil filler cap. Early units featured a large filtered cap with an air deflector to assist air flow. Later, I believe that cap design was dropped or when it got plugged up with dirt flowing into the engine compartment, it was often replaced in service with a smaller cap which had less air flow. And, because the filter screen faced downward towards the engine, owners & service people often missed ensuring it was clean. Older engines in service, often had little if any proper crankcase ventilation, leading to serious sludge buildup problems.      


Paul

Thank you all for your help.I have both a motor and a Chilton manual from the period but neither of them explain the function of the baffle plate.I reckon I will have to buy a reprint of the Ford manual!