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Old 04-15-2018, 12:27 PM   #1
JMD
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Big block engine mount question

Hi all,
I'm getting ready to stab the 454 back into my '68 K10, but I'd like to address a problem I've been having with the engine mounts first. I believe I didn't have the mounts installed correctly, and now that the engine has some power upgrades I want to make sure it's done right.

Previously I just ran a bolt with a large washer up through the frame, through the hole in the mount, and capped it off with a washer and a nut. This proved to be a giant pain because there's no room to fit a wrench between the block and the mount. I had to tighten it by hand and then hope it bit enough to tighten with a wrench. Not ideal.

I've attached a couple pictures of what I'm working with, as well as a picture of the parts that I believe I need. My question is, what's the proper way to intall this type of mount?
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Old 04-15-2018, 12:40 PM   #2
WIDESIDE72
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Re: Big block engine mount question

These things are a royal PITA. I have never found a resolution to the same problem you have. I got tired of dealing with them and only use the 73+ mounts from now on.


BTW, they were the source of a recall for GM back in the day. If a mount broke, the engine could shift, causing the throttle to hang open. (Not good)That is why the 72 sbc trucks went to a cable throttle linkage and BBC went to the clamshell mount design AND cable throttle. Somewhere in my junk I have several "recall kits" for the pre 72 trucks, which consisted of a cable that wrapped around the motor mount and connected to the engine. This was on the driver side, IIRC. (whichever side of the engine torques in an upward direction.)
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Old 04-15-2018, 12:42 PM   #3
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Re: Big block engine mount question

You might be able to get a "tite reach" wrench in there...

https://www.walmart.com/ip/Tite-Reac...&wl13=&veh=sem
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Old 04-15-2018, 12:52 PM   #4
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Re: Big block engine mount question

Is that really how it's supposed to be installed though? Seems like there should be something to keep the bolt head from spinning, then there would be no need for a wrench.

In the last picture, where is that little clip supposed to go?
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Old 04-16-2018, 03:36 AM   #5
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Re: Big block engine mount question

I have a 70 longhorn with a big block 400 with what appears externally to be this same setup. I have never had it apart though. I reread the original post and realize that the small block mounts must be slightly different. The have a nut in the mount that bolts to the block. The onlt trouble with the sbc set up is getting a wrench up in to the frame tower to tighten the bolt. That is what i used the tite reach wrench for.

I have a pair of 72 big block frame stands from a truck I parted out that i plan on using on my truck if the need should arise.
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Old 04-16-2018, 09:51 AM   #6
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Re: Big block engine mount question

Quote:
Originally Posted by JMD View Post
Is that really how it's supposed to be installed though? Seems like there should be something to keep the bolt head from spinning, then there would be no need for a wrench.

In the last picture, where is that little clip supposed to go?
It's a locking tab that goes under the head of the bolt. You bend it so that the bolt can't back out, just like on exhaust manifold bolts, back in the day.
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Old 04-16-2018, 10:12 AM   #7
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Re: Big block engine mount question

I have a 70 Longhorn with a big block 400 as well, same as Wideside, and I have the same setup.

I had to fight with these, but it's been five years! Here's what I remember:

- I think the bolt supplied is TOO LONG and will punch into the block if used as-is
- I think the bolt they supply is METRIC

I had no problem getting a wrench on it or access to it, though, so double-check you're doing it the right way, I don't remember that at all!

A pair of NOS or original mounts would have saved me a great deal of time, these reproduction mounts are awful, but they're all we have at the moment I think for this weird mount.
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Old 04-16-2018, 11:17 AM   #8
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Re: Big block engine mount question

The big block mounts you are showing are 2wd application and will not work with your 4x4. The steel frame mounts are not bent correctly to fit the lower cushion. All you can really do is use the small block cushions the way you had it before and maybe put a torque strap on the engine if you are worried about tearing a mount, Looks like you moved your engine forward for the big block placement. If you have the time I would replace the 3/8 bolts frame/x-member bolts with 7/16. The extra weight and torque will loosen them up. Don't know why, but they do. I just finished moving a member forward over the weekend on a K5.
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Old 04-16-2018, 03:29 PM   #9
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Re: Big block engine mount question

Thanks for the replies.
I guess I'll just use what I have and figure out a better way to get a wrench behind the mount. It still blows my mind that there are only 2 bolts holding this engine to the frame.
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Old 04-16-2018, 06:58 PM   #10
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Re: Big block engine mount question

I run a set of Prothane 7-509-BL on all my trucks. My big block 4x4 hasn't had any problems with them.
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Old 04-17-2018, 12:36 AM   #11
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Re: Big block engine mount question

Quote:
Originally Posted by JMD View Post
Thanks for the replies.

It still blows my mind that there are only 2 bolts holding this engine to the frame.
Gravity has a lot to do with it
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Old 04-17-2018, 08:30 AM   #12
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Re: Big block engine mount question

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Originally Posted by ajviper View Post
I run a set of Prothane 7-509-BL on all my trucks. My big block 4x4 hasn't had any problems with them.
This was going be my suggestion as well. The Urethane mounts are captive so if the mount rips it goes nowhere. I think you can buy modern captive style 4x4 mounts these days. As well.
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Old 04-19-2018, 11:18 AM   #13
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Re: Big block engine mount question

Quote:
Originally Posted by ajviper View Post
I run a set of Prothane 7-509-BL on all my trucks. My big block 4x4 hasn't had any problems with them.
I really like the looks of those...Just to be sure, the bolt threads up into the mount from the under side and nothing goes on the backside of it? And is there some kind of bushing between the bolt head and the frame or would I just throw a big washer on there and call it a day?

Pictures would be helpful
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Old 04-19-2018, 11:23 AM   #14
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Re: Big block engine mount question

The bolt just threads up from the underside. I just run a lock and flat washer on them. Easy on and off with a socket and extension. It isn't easy to get pictures of them up in the cross member.
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Old 04-19-2018, 11:29 AM   #15
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Re: Big block engine mount question

That's exactly what I'm looking for, thank you.
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