How Thick are Motor Mount Spacers?

[ramseyt]

I've read somewhere that there should be spacers betweem my motor mount and the motor to raise it to center the fan in the shroud. I only have the heat shields between my 302 and the motor mounts. The plastic fan has hit the open ends at the bottom of the shroud and it is obvious that the fan is not vertically centered in the shroud. I plan to order new motor mounts that may help a little but meanwhile would like to put the proper spacers in. Are the spacers made from a single bar of steel with the proper hole spacing or are they made from round stock with a hole through? Does it matter? More importantly, how thick are the spacers?

Thanks in advance for any help on this.

 

[0neoffive]

I've read somewhere that there should be spacers betweem my motor mount and the motor to raise it to center the fan in the shroud. I only have the heat shields between my 302 and the motor mounts. The plastic fan has hit the open ends at the bottom of the shroud and it is obvious that the fan is not vertically centered in the shroud. I plan to order new motor mounts that may help a little but meanwhile would like to put the proper spacers in. Are the spacers made from a single bar of steel with the proper hole spacing or are they made from round stock with a hole through? Does it matter? More importantly, how thick are the spacers?

Thanks in advance for any help on this.

Spacer thickness is "as needed" to get the job done. More important is you are better off leaving the motor mount-to-block location alone and place large washer shims on the angle single bolt between the frame hanger and motor mount.

 

[cadreamn67]

Spacer thickness is "as needed" to get the job done. More important is you are better off leaving the motor mount-to-block location alone and place large washer shims on the angle single bolt between the frame hanger and motor mount.

First, I realize that Randy is much more an authority than I will ever be. That acknowledged, I can confirm with confidence the factory put washers between the block and the four mounting holes of the mounts. My motor is out of my car and I could not find a ruler handy. My dial caliper tells me the washers are .130 inches thick, so say 1/8 inch in round numbers.

I for one am reluctant to put a washer where Randy, and in a prior post Duke, recommended. It seems to me it would be better to have the entire plate on the mount in full contact with the frame hanger than concentrating the contact (and forces, at least in compression) over the surface of just a washer. But apparently that has not been a problem for others. Still, there is no reason I can think of to not put thicker washers where the factory put them if needed...

BTW, the reason you may not have the washers there is because the prior owner wanted to lower the engine to get more room for a thicker air cleaner or air cleaner element. Be sure in raising the engine for the fan clearance that you do not create a hood to air cleaner housing clearance problem.

BTW, I have heard of people shimming the cross-member to frame mounting to gain fan clearance from the rack without compromising hood to air cleaner clearance. I realize your question is really about fan shroud clearance. But if you do go that route for whatever reason, do not do it with washers. You should have full load bearing shims made to fit that interface.

All just MHO, respectfully submitted.

Gene

 

[0neoffive]

More 2 cents

[QUOTE=cadreamn67;9506
I for one am reluctant to put a washer where Randy, and in a prior post Duke, recommended. " End Quote . . .

The bolts in the block are stubby and each washer means less threads hanging on in an already fragile cast boss location. Whereas motor torque will be pulling up on the left side hanger using a fully threaded bolt/nut where the use of a shim washer will not affect the tensile factor.

 

[cadreamn67]

Colleagueal discourse

Randy,

As I measure it, the stock bolt to the block extends 3/8 inch into the the block mounting boss by the time it has passed through the lock washer, engine mount flange and a 1/8 thick spacer washer. On my old 260, the mounting boss is threaded to a depth of almost 1 inch. Those facts lead me to conclude there is enough depth to simply use a 1/4 or even 1/2 inch longer bolt to solve any minimal thread engagement concerns and maintain the factory configuration if a spacer greater than 1/8 inch proves warranted.

I agree with you that a washer on the bolt in tension will not affect that side.
However, for the metal back of the mount that is in compression, normally that entire surface is held flush against the 3.5 inch wide flat frame hanger surface. Consequently the force is distributed across a very large area. By putting a washer/spacer between the frame hanger and the mount, all that compression force is concentrated on the 1 inch or so wide washer. The remaining part of the motor mount that would normally be in contact with the frame hanger is now unsupported. Whether the metal there on the mount is strong enough not to deform around the washer is an unknown to me. And even if it did, I do not know what problems that might cause. The point I am making is it is not really necessary to try and find out.

Gene

 

[Duke Mk1a]

By putting a washer/spacer between the frame hanger and the mount, all that compression force is concentrated on the 1 inch or so wide washer. The remaining part of the motor mount that would normally be in contact with the frame hanger is now unsupported. Whether the metal there on the mount is strong enough not to deform around the washer is an unknown to me. And even if it did, I do not know what problems that might cause. The point I am making is it is not really necessary to try and find out.

With my engine's 450+ HP and 445+ ft/tq, I have not had any issues with the large washer between the mount and hanger. I have ~10K miles on this setup now to include multiple 1/4 miles runs and Auto-Xes.

With that, you will have no issues.

 

[cadreamn67]

Think We Are Done!

Nothing better than a field confirmation!

Gene

 

[ramseyt]

No luck raising the engine--New problem!

Thanks guys for all the discussion about how to better center the fan vertically with the fan shroud center line. First of all, like someone said, I also found the motor mount threads to be tapped into my 302 block about an inch deep. My bolts only penetrate about 3/8" deep. I think the spacers between the block and motor mounts were left out because my rear carb float bowl hits the edge of the OE trianguler shaped stiffening member across the firewall. It appears to have been rubbing during acceleration/under load. There is a Ford spacer under my Holley 4150 carb that would solve this new problem if I could leave it out. It is cast iron so probably not much good for heat insulation for the carb. Could someone please look at the photos and advise me as to what you think this is and if it has any function today? The previous owner had this engine built 12 years ago and doesn't know much about it. He didn't drive it long enough to get all the bugs worked out before he put it into storage. I've got it running pretty good now and hope this piece isn't required.

 

[0neoffive]

We used to cut em'

I think the spacers between the block and motor mounts were left out because my rear carb float bowl hits the edge of the OE trianguler shaped stiffening member across the firewall. It appears to have been rubbing during acceleration/under load.

The Holley road race bowls (AKA center float mount) were/are always a SNAFU with the Tiger firewall. We used to simply notch the firewall and be done with it. BUT, unless you are intent on aggressively bending thru corners, the Holley flat-back bowls work just as well and leave lots of room. . . . . .