Oil Pan to Crossmember Clearance

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Parkka

Well-known member
Joined
Jan 12, 2019
Messages
129
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Location
New England
My Car
73 Mustang Convertible
[url=https://ibb.co/cgCFb3N][img]https://i.ibb.co/j6WMVfL/IMG-20190713-145003409.jpg[/img][/url]
When the engine was installed by the machine shop, two Prothane Motor mounts (6-503) were installed to replace the original worn ones from Ford.  According to the machine shop, the Prothane mounts have a slightly lower profile than the Ford originals due to the polyurethane material.  As a result, a clearance of approx 1/8 of an inch was now created between the oil pan outer corners and the cross member.  My question is what should the proper clearance distance be on a 302 engine to the crossmember?

The machine shop would like to install 1/4 inch plates between the motor mounts and the engine block which are shown below (black).  Also below is a photo of the present clearance between the oil pan and the crossmember (1/8 inch) without the plates.  The plates would raise the engine; hence an increase in the clearance would occur.  They are not worried about the drivetrain, but rather any lateral torqueing of the engine during startup and whether or not the oil pan will contact the cross member if the plates are not installed.  Below is the Prothane motor mount and the black 1/4 inch plate.  Numerous phone calls to Prothane have been made where they indicate the mounts are the correct ones.

IMG_20210311_113642667.jpg

IMG_20210215_091620104_HDR.jpg

 
I can't help much here. I have the Prothane mounts but I have an aftermarket Kevco oil pan with no clearance issues. When I measure the Prothane vs the OEM (Edit: 71 mounts) I considered them the same since the difference is very small and my OEM was not completely flat. This picture I took shows the Prothane slightly lower but it can be deceiving because the ear of the OEM is slightly bent. I am surprised that small of a height difference is making such a large effect on the oil pan clearance. Hopefully someone else can chime in, but maybe there is something else going on.

20180402_135442 (moutns comparison).jpg

 
Last edited by a moderator:
Did you think about the frame mounts (supports). Is there a chance they have been changed at some point for the wrong ones for a 302? I'm just grabbing straws there, but that thought occurred to me. I don't have any knowledge of the 302 set-up, but if the frame mounts are lower, then the engine will sit lower regardless of the minor difference in the motor mounts. I would definitely look at the frame mounts.

 
The 73 convertible mount looks shorter to me but I don't have both mounts to actually compare. If the Prothane mounts are designed for the 71-72 that may be the reason the clearance is tight since the 73 mount is physically thicker. I don't see an issue with adding the 1/4" spacer to gain back the clearance. It won't affect the driveline angle much. 

 
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