correct K member?

[63SplitWindow]

I'm working on an H code 73 Dart sport that is extremely clean and appears to be correct low mileage car (59k). The original 340 motor is gone and replaced with another small block. While in the process of installing TTI headers, I have come across an issue with the location of the motor in the body. TTI says the small blocks need a minimum of 5 1/4" space from the center of the crankshaft bolt to the top of the K member for the header to make all clearances. I'm more than 1/2" short of that. I have the spool type motor mounts which I am skeptical about holding down a potent small block. Is that correct for a 73 small block?

 

[72bluNblu]

Spool mounts are correct for 73+. And the spool mounts are an improvement over the earlier biscuit style mounts, which failed quite often unless replaced with aftermarket locking mounts, through bolted or whatever.

If you’re really worried about your engine somehow pulling up out of the spools, you could always add a Schumacher style tie down, or chain if you’re old school. Both would be even more necessary with the earlier mounts.

I have Doug’s headers on the 340 in my Duster, which has a spool mount K, and no issues with them fitting beyond the usual.

 

[Professor Fate]

The advantage of spool type mounts is that they are not susceptible to catastrophic failure like stock biscuit mounts can be- even if the insert totally fails (which they can do), the engine is still retained in position. The only way for a spool mount to fail is if you forgot to put in the through bolt, or used a standard bolt without the necessary oversize washers- then the engine could lift out of the pedestals when torquing over...

 

[63SplitWindow]

The advantage of spool type mounts is that they are not susceptible to catastrophic failure like stock biscuit mounts can be- even if the insert totally fails (which they can do), the engine is still retained in position. The only way for a spool mount to fail is if you forgot to put in the through bolt, or used a standard bolt without the necessary oversize washers- then the engine could lift out of the pedestals when torquing over...
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Thank you Professor.....I feel better about them now

 

[63SplitWindow]

The advantage of spool type mounts is that they are not susceptible to catastrophic failure like stock biscuit mounts can be- even if the insert totally fails (which they can do), the engine is still retained in position. The only way for a spool mount to fail is if you forgot to put in the through bolt, or used a standard bolt without the necessary oversize washers- then the engine could lift out of the pedestals when torquing over...
View attachment 1715962467 View attachment 1715962468
View attachment 1715962470

Have you ever heard of these engine mounts allowing the motor to shift lower? Maybe a failed bushing?

 

[Professor Fate]

Good bushing

Not-so-good bushing

Yes, they wear out or deteriorate over time.

 

[MoparMike1974]

Yes, pretty much the only thing that can go wrong with a spool mount is the rubber gives out and the engine sags down. Its only going to drop about 1/2" before it bottoms out.

 

[autoxcuda]

Yes, pretty much the only thing that can go wrong with a spool mount is the rubber gives out and the engine sags down. Its only going to drop about 1/2" before it bottoms out.

Hmmm, 1/2"... sound familiar.

You can also fill the air void inside the spool mount with common silicon window caulking. It was recommended by Rich Ehernberg of Mopar Action magazine. I did that in 1997. My mounts have never separated and slid down. Probably because they can't. It's been 25 years.

 

[72bluNblu]

I replaced my rubber spool inserts with poly, that’s not gonna sag. They were a little tight going into the mounts (shoulders on the poly bushings might be a bit too thick). But once they settled in it was fine.

 

[63SplitWindow]

I replaced my rubber spool inserts with poly, that’s not gonna sag. They were a little tight going into the mounts (shoulders on the poly bushings might be a bit too thick). But once they settled in it was fine.

Replaces the mounts with new poly units and the motor now sits about 3/4" higher. Headers should now have the proper clearances.
Thanks everyone for the input