I'm going to drop a BB Chevy tall deck block engine into my 1970 Chevelle, and when I went to place an order for a set of polyuerathane motor mounts, I was told that I have to specify whether I need the taller/narrower ones, or the wider/shorter ones. But since I bought the car w/out an engine, I have no idea which motor mount size I need.

Can anyone tell me what determines the motor mount size on a 1970 Chevelle? Or doesn't it matter which ones I use? I'm not talking about the choice of rubber vs. polyeurathane vs. solid motor mounts. I'm talking about the choice of the two different sizes available. Does the frame, or the engine block being used determine what's needed? (BTW, this is a Mark IV type block).

There are 6cyl mounts, 307 mounts and everything else mounts. Let me know if your vin starts out 135.

The 307 mounts use the low performance non-interlocking mounts and the frame mount is taller. Everything else uses the interlocking design and it's shorter. You just need to match frame mounts with engine mounts. The 307 non-interlocking mounts will bolt right up to a BB.

There was a post about a BB not fitting into a 71 that got into a discusion about the mounts and someone posted pics.

I've been meaning to measure the frame mounts that I have on my car (factory 307) and a set that I got off a supposedly 350 car just to make sure before I swap them. I'll let you know what the measurements are if no one else posts them.

David

Billy,
they are talking about the frame mounts that the motor mounts bolt to.
307's used a different frame mount than all the other chevy motors, thus a different motor mount. i think 307 is short and wide.
some where on this forum, someone posted a pic of the diff between the two styles w/ measurements.
do a search and this should help you.
david

cobra,
you and i were typing at the same time.
i am unsure of what i said about the 307 mounts.
david

Billy,
they are talking about the frame mounts that the motor mounts bolt to.
307's used a different frame mount than all the other chevy motors, thus a different motor mount. i think 307 is short and wide.
some where on this forum, someone posted a pic of the diff between the two styles w/ measurements.
do a search and this should help you.
david I don't think so, because if you go onto the Energy suspension website, and look up their polyurethane motor mounts, it gives a diagram of two different motor mount heights. I believe that one is 1 3/4" tall, and the other is 2 3/16" tall, and that's the motor mount itself. So I just didn't know which one to use. Gee this stuff can be confusing!!

here's a link to that webpage......

http://www.energysuspension.com/pages/mt_tr1.html

billy,
here's a link that should help...
http://www.chevelles.com/forums/showthread.php?t=83718&highlight=difference+motor+mounts

read thru it and look at the pics.
david

billy,
you are correct what you posted.
but it is the width of the frame mount that decides what motor mount to use.
david

billy,
you are correct what you posted.
but it is the width of the frame mount that decides what motor mount to use.
davidThanks GTO. So if I'm using the 350/396/427/454 frame mounts, then because they're wider and lower, I have to then use the wider and lower motor mounts. Is that correct? If so, then I've learned what I needed to about this topic, thanks.

The mounts that I have that are supposed to be 350 mounts are 2" high, 2-7/16" wide.

I got them for free after a friend of mine did a frame swap on his 69. It had a 350 and it had 350 badges, but who knows what it started as...

I'll try and get to the shop tonight and measure my 307 stands. I know for a fact that it's a 307 car.

David

BTW, Tall and Narrow is for a 350, Short and wide is for the 307. Referring to the energy suspension linkabove.

Had the same question when I installed a 454 in place of the 350 in my 71. After a lot of research I bought a set of "tall" mounts that went on the engine and fit the stock 350 frame mounts. Turns out that if I had used "short" mounts the 2" primaries on the Hooker Super Comp headers would have hit the upper control arm on the passenger side. As it is, I have marginal clearance between the primary and the steering shaft on the driver side. Also had to clearance the bell housing on the 350 transmission for the 3 1/2" header collector. All things I didn't know until I got there.

Had the same question when I installed a 454 in place of the 350 in my 71. After a lot of research I bought a set of "tall" mounts that went on the engine and fit the stock 350 frame mounts. Turns out that if I had used "short" mounts the 2" primaries on the Hooker Super Comp headers would have hit the upper control arm on the passenger side. As it is, I have marginal clearance between the primary and the steering shaft on the driver side. Also had to clearance the bell housing on the 350 transmission for the 3 1/2" header collector. All things I didn't know until I got there.AAAAAH, okay, so I guess tall and narrow is the way to go for all V8 engines except the 307's. And you're scaring me with the TH350 transmission clearence for the 3.5" header collectors, because I'll be using the 3.5" collectors with a TH400 transmission, and my guess is that the TH400 will need more room than your TH350 does!!!! It's always something!!!

wait a minute......how do yall explain this??? click on the link below...it looks to me like it's the frame brackets for the 307 engine that would need the taller motor mounts. So now I'm still confused about all of this....


http://www.chevelles.com/showroom/MarkJ/framemount2.jpg

wait a minute......how do yall explain this??? click on the link below...it looks to me like it's the frame brackets for the 307 engine that would need the taller motor mounts. So now I'm still confused about all of this....


http://www.chevelles.com/showroom/MarkJ/framemount2.jpg

The tall engine mount goes with the short frame mount and vice versa. If you use the 350 engine mount with the 307 frame stands the engine is too high. 307 engine mounts and 350 stands the engine too low.

David

Hmmmm....... so according to what you're saying, as long as you have the right combo, then you're good to go, and in that case, either one of the two correct frame bracket & engine mount combinations will likely yield close to the same height. And that really makes me wonder, then why in the world did Chevy do things like that. (???) I mean, from a car mechanic/restorer's point of view, it only serves nothing more than to make things downright rediculously confusing!!!!

My 71 originally had a 307. When the big block (454) was installed the same mounts were used (short and wide). Later I replaced these mounts with energy first mounts, short and wide. No problem....

My 71 originally had a 307. When the big block (454) was installed the same mounts were used (short and wide). Later I replaced these mounts with energy first mounts, short and wide. No problem....Thanks. Did you have a stock capacity oil pan on your 454? Because the big block that I plan on installing has a 6 quart pan that look to be about 1/2" deeper in the front where it has to clear the cross member, and it also kicks out about 1 3/4" to the passenger side in that same area where it has to clear the cross member. But maybe that won't matter anyway. In fact, I guess that's really a whole other issue entirely. I appreciate everyone's help on this.

Hmmm, it looks like i might have to change my frame mounts then... My car was originally a 307 car and now had a 327. Unless they changed the frame mounts it probably had the short/wide motor mounts and the tall frame mounts. The motor mounts i bought are the tall/wide stype typical to the BBC i am installing... Where do you buy new frame mounts?

Daniel

here's a set...
http://www.ss396.com/mm5/merchant.mvc?Screen=PROD&Store_Code=chevellecamino&Product_Code=ACE-9794&Category_Code=

david

Hmmm, it looks like i might have to change my frame mounts then... My car was originally a 307 car and now had a 327. Unless they changed the frame mounts it probably had the short/wide motor mounts and the tall frame mounts. The motor mounts i bought are the tall/wide stype typical to the BBC i am installing... Where do you buy new frame mounts?

DanielI bought mine from www.goodmarkindustries.com but the problem with their website is that there isn't any search feature. So ther than somewhat of a table of contents, you have to sift through much of their site to find what you need. it's a hassle, but you can always call them up to order instead.