The Stovebolt Site Forums The Shop Area The HiPo Shop 350/TH400 in a '49

1949 3100. I have a 350/TH400 in place on the frame using the front engine mounts from Classic Performance Products.
I did not touch the the center riveted-on crossmember.
I moved the original bolt-on transmission crossmember back 3 1/2 to 4 inches in order to line up with the rear mount of the TH400.
I placed the rubber transmission mount between original transmission crossmember (in its new, rearward location) and the transmission.
I mounted the cab to check for clearance and the cab hit the transmission.
I only have 3/8" clearance between the center riveted-on crossmember and the bottom of the transmission, preventing me from lowering it any more to facilitate cab clearance.
I decided to alter the contour of the bottom of the cab, moving it one inch rearward (easy to reverse if someone in the future wants to go back to the original shape).
The carb mount surface is now parallel to the floor.
So what is my question?
I have read many posts about this modification and none of them described it as being as simple as this to do.
There are posts referring to removing the center riveted-on crossmember, using aftermarket rear crossmember or notching out the original one, or cutting out a huge hole in the cab.
What am I missing?
Carl

Most people are not willing to modify the doghouse area of the cab for transmission clearance. One pretty slick way to do that is to use a wheelbarrow tub for the firewall modification and trim it to fit the opening you create in the cab/floorboard area. It's usually simpler to modify the center crossmember to allow a lower engine mounting position. Also, unless you fabricate a crossmember to support mounts in the center engine position, there's a risk of breaking the bellhousing. Don't try to support the engine/trans assembly at the ends without using the mid-block mounting position.
Jerry

I just finish the eng swap,but i used 327 & and the old 4 sspeed trans to set up eng mounts.used the tubular eng mount.removed 4speed.next is to bolt up 700r4.there about 1 1/2 gap between caband dist.hope this makes seince to some of you..i also used front mounts,which i will not be using with 700r4

Carl, I think I told you earlier but just in case.... I used those same side mounts and did not have to modify my firewall on my 52panel and I'm running the big distributor. However, when I raised the rear of the tranny I had to trim about 1/2" off the top of the toe board. However, when I put the tranny cover back on you couldn't see where I trimmed it.

Ditto on that,I'm running an HEI distributor and did not require to change/alter/dimple the firewall in any way other than the slight trimming above the bell housing Alvin mentioned.
With the trans cover back on you'd be hard pushed to tell there were any modifications at all.

Alvin,
I know that you told me earlier, but that doesn't mean that I was paying attention.
I chose to reform the toe board rather than cut it off in case someone ever wanted put it back in the original shape. I have a home made transmission hole cover which I can reshape to fit the modified toe board.
I will tell you this, I wouldn't be as far along as I am without your help!
Thank you,
Carl

Doing same swap 305/350 in 53 GMC Longbed. My plans are to cut center rivet crossmember but leave ends on frame , use center motor mount on engine and new rear trans crossmember. I have a mustang 11 ifs and it looks like side mounts will be partially welded to new ifs crossmember. has anyone done this? Would like to move back to avoid cross member also when you refer to cutting toe board do you mean the lip on bottom of cowl. Thanks

Where, and how much to cut depends on how far you plan to set back the engine and how low you go with the engine/transmission. You'll need to mock the engine/transmission on the frame and then place the cab into place, scratch your head, and start cutting.
Carl

Got Thanks