Engine mount bolts, washers and nuts

[Randy Folsom]

I am in the process of bolting together SBF engine mounts to RCR40 adapters. The bolt hole size is 7/16. My question is what type of nut locking system should be used. Choices I am aware of are serrated flange, Nyloc, or spring washer. If Nyloc, is there a specific type? Thx in advance.

 

[Mark Turner]

aviation recommends nylocks not be used in engine compartment i would use all metal hex stop nuts available from aircraft spruce

 

[Jean-Marc]

No Nylock, but spring washer but I preferer Loctite, it is the best. Aviation component is may be too much.

 

[Randy Folsom]

Thx much. I am going with the all metal locking hex nut. Maybe not as good as the ones from Spruce, but they are grade 8. Combined with Permatex Orange thread locker should keep things together.

 

[Ryan L]

Jet Nut or K Nut of some description, or maybe a Nord lock nut.

A standard Nylock would probably degrade with the heat of the exhaust. Most locknuts are a one-time use item in critical locations as well.

 

[Jean-Marc]

I checked how my engine was assembled on the engine mount (done by the previous owner) and it was done with lock wire on the engine side (hot) and nyllock ont the frame side [cold)

 

[Randy Folsom]

I checked how my engine was assembled on the engine mount (done by the previous owner) and it was done with lock wire on the engine side (hot) and nyllock ont the frame side [cold)

Thx much. Nyloc on the inside makes sense to me. The chassis is a pretty big heat sink so should be fine. I am planning to add a steel doubler on the inside of the tub to make it a bit more robust.

 

[Cliff Beer]

If you want to lock it good but don't want to use red loctite then castellated nuts can be a good option. You can buy grade 8 hardware of set lengths which have already been drilled for the split pin. Just an idea.

 

[Martin]

Thx much. I am going with the all metal locking hex nut. Maybe not as good as the ones from Spruce, but they are grade 8. Combined with Permatex Orange thread locker should keep things together.

 

[Martin]

I am in the process of installing my engine as well with the same mounts, however, I was planning on using 1 bolt that goes thru both sides of the mount. Never thought of using two bolts. Any problem using one bolt?

 

[Brian Kissel]

Martin, the OEM's have been doing it for many many years, so I see no reason it wouldn't be great. One less fastener to worry about and better alignment on the mount.

Regards Brian

 

[Martin]

Good - one less trip to Ace.

 

[Randy Folsom]

If one bolt, then it can’t be tightened down. There would be total reliance on the locking nut. Over time the tabs would likely bend inward allowing the engine to move back and forth. That would get progressively worse.

The solution is to insert a piece of pipe between the tabs.

I found out that using these mounts requires unbolting them at the tub mount because of the oil pan. A single bolt with a spacer pipe will make that much easier because reaching the nuts inside the mount takes a bit of contortion.

I am considering making mounts like these:
https://www.ruffstuffspecialties.com/R1943.html

They are solid but the spacer could easily be replaced with a bushing.

 

[Martin]

I used a 20 ton press to "squeeze" the Prothane mounts together a bit to fit inside the RCR mounts. The steel used on the Prothane mounts is way overkill in my mind for this application. A steel spacer/bushing will solve any concerns, but these mounts are massive compared to the stock 67 Mustang mounts suggested by RCR.

 

[Randy Folsom]

My RCR mounts were bowed from welding heat. A couple of strategic wacks with a 3# sledge was all it took to make things fit.