[JEC3039]

Putting together a '68 Firebird RAII clone. Time to select motor mounts.

Mity rubber mounts used to have a good reputation, but of late the reviews on this and other forums are mixed. Poly from Butler is supposed to be strong, but I'm leery as I failed a set of those on my A-body car a few years ago (although that's a 462 making +500 TQ everywhere from 3000 thru 5000, so that's a different animal).

What's everyone using that works? My 400 makes an honest 400 HP @ 5300 and 440 TQ @ 4200.

[JLMounce]

I have had original style non-mighty mounts on the car, but they were parts that were likely from the mid to late 90's and of better quality. I then had mighty mounts on the car and although they functioned properly, they dropped the engine into the cradle enough that the oil pan was resting ever so slightly on the cross member.

When I built my new engine I put in Butler's steel/poly interlocking mounts that they rate for around 600hp. So far these have been good. They are quite a bit beefier than the mighty mount and they moved the engine back up where it was supposed to be. I have not noticed any melting of the poly with Doug's ceramic coated headers, nor have I had any trouble with them pulling apart at 580hp/600tq. I also have not noticed an increase in NVH, but the car has solid body and suspension bushings everywhere already.

[RocktimusPryme]

To be honest, Ive had over the counter rubber mounts on my 462 making more power than yours for almost a decade and they are still in one piece.

[rdl]

Originally Posted by JLMounce

… they dropped the engine into the cradle enough that the oil pan was resting ever so slightly on the cross member. … I put in Butler's steel/poly mounts… they moved the engine back up where it was supposed to be.

Interesting topic. I just replaced worn motor mounts on my 69 noticing the same problem. The engine sits low and lightly touches the cross member. I thought perhaps the cradle mounts had just splayed out over time. Is it just that the repro mounts aren’t as thick as originals? Are the Butler mounts a better option?

[JLMounce]

Originally Posted by rdl

Interesting topic. I just replaced worn motor mounts on my 69 noticing the same problem. The engine sits low and lightly touches the cross member. I thought perhaps the cradle mounts had just splayed out over time. Is it just that the repro mounts aren’t as thick as originals? Are the Butler mounts a better option?

Yes, the reproduction mounts are not 100% accurate. My guess is the removed just enough material from them to save a cent or two on manufacturing costs.

Adding a shim to the top side of the mount will get the pan off the crossmember in most cases.

[rdl]

I fabricated shim plates that were 1/4” thick. When inserted, the stock bolts were then too short to catch the threads in the mounts. I’m not sure now what I’ll try next.

[RocktimusPryme]

I also had to use shims. I used some body wahsers to elevate it a little and bought a longer grade 8 bolts from Fastenal.

I used to blame the new mounts, and it may be the mounts. But I also think there is a chance that the frame mounts by design on the first gen F body may sag over time with the weight of the engine. I think mine touched the pan even with Butler solid mounts in.

If I ever have the unfortunately remove the engine Im going to buy some fresh frame mounts and see if it raises the engine.

[JEC3039]

Wanted to provide an update.

I went with the poly engine mounts from Butler, they arrived Monday. Engine with trans went into the car today. The mounts look plenty beefy and yes they prop the engine up high enough to more than adequately allow the pan to clear the crossmember and the strg center link as well.

Will report back with any road issues when car hits the street in a few weeks.

[triathlonx13]

Originally Posted by RocktimusPryme

To be honest, Ive had over the counter rubber mounts on my 462 making more power than yours for almost a decade and they are still in one piece.

Agreed. If you are not running anything wild - go with stock type

[MerrittE]

Anybody use the Firebird Central motor mounts ENC-2016S ? Are they really better than the pioneer or DEA rubber mounts available locally? https://www.firebirdcentral.com/Prod...2016S&CartID=1

[RA1John]

Originally Posted by MerrittE

Anybody use the Firebird Central motor mounts ENC-2016S ? Are they really better than the pioneer or DEA rubber mounts available locally? https://www.firebirdcentral.com/Prod...2016S&CartID=1

One would think that with all the complaints about repro engine mount isolators not being dimensionally accurate to prevent oil pan to cross member interference, that someone would make changes.