Positioning engine crossmember help.

[rsb5772]

I just ordered my bolt-in engine and trans crossmembers from Brothers, for my '57, and need help on how to position the engine crossmember. What do you measure from to center it between the frame rails, and how do you determine the angle of the motor mounts? Do you make them level with the frame rails, or should they be angled downward? Do I need to have the block and trans bolted together and in place with the trans sitting on the crossmember to set the position of the motor and crossmember? Thanks for any help.

I ordered the crossmembers, and power disc brake conversion, and new wire harness. I have a TH400 trans from an 80's model one ton, and a mock up block. I have a few more parts to order, that are required for state inspection, and will be buying a motor once I have everything else on or ready to go on. I hope to have it on the road soon, and will start the body work afterwards.

[mr48chev]

Originally Posted by rsb5772

I just ordered my bolt-in engine and trans crossmembers from Brothers, for my '57, and need help on how to position the engine crossmember.

What do you measure from to center it between the frame rails, and how do you determine the angle of the motor mounts?

Do you make them level with the frame rails, or should they be angled downward?

Do I need to have the block and trans bolted together and in place with the trans sitting on the crossmember to set the position of the motor and crossmember?

Thanks for any help.

I ordered the crossmembers, and power disc brake conversion, and new wire harness. I have a TH400 trans from an 80's model one ton, and a mock up block. I have a few more parts to order, that are required for state inspection, and will be buying a motor once I have everything else on or ready to go on. I hope to have it on the road soon, and will start the body work afterwards.

You can measure from inside to inside or outside to outside of the rails to figure out the center line.
I've seen guy do about everything to know where the center is including clamping a piece of flat bar to the frame rails and marking the center on it to just keep measuring with a tape or yard stick.

If those are the crossmembers I think they are they you don't have to worry about angle too much.

What I would do is bolt the dummy block to the trans and set it in place in the engine compartment. Then I would put the trans crossmember in place and get the height of the trans on the crossmember exactly where I wanted it. If you still have the original engine and trans in the truck you might do some measuring and note taking so you know pretty close to the height the output shaft was on the original trans. That would be the best height for the output shaft on the new trans to be. You may have to drop it down just a bit so that the trans will clear unless you are going to modify the floorboard though.

Once I had the trans in place and the engine setting right as far as fore and aft and firewall clearance I would put the front crossmember in place and set it up.

Make sure that the carb mounting surface on the intake is level when you do this. You are leveling the carb and not the valve covers as they will be a bit lower towards the rear when the engine is positioned correctly.


the reason I like to start at the trans mount rather than the motor mounts is that it has just been a lot easier in the past for me to get the trans in position and mounted where I want it and then level the carb flange and set up the front mounts. Others may do the engine mounts first and then the trans mount as there is no wrong procedure as long as the end results are the same.

[Amorget]

Curious, what is the need/advantage of the bolt in cross members from Brothers in a TF?

[rsb5772]

Originally Posted by mr48chev

Once I had the trans in place and the engine setting right as far as fore and aft and firewall clearance I would put the front crossmember in place and set it up.

Make sure that the carb mounting surface on the intake is level when you do this. You are leveling the carb and not the valve covers as they will be a bit lower towards the rear when the engine is positioned correctly.

Thanks! I was thinking it would be better to set the rear in place first.

Originally Posted by Amorget

Curious, what is the need/advantage of the bolt in cross members from Brothers in a TF?

I'll be pulling the I-6, which is mounted on the front of the motor, and putting in a small block.

[meter swinger]

Do a mock up with the engine/trans in if at all possible. A couple things to watch for is the dizzy to firewall clearance (im assuming sbc) so hopefully you have the cab on. The tube crossmembers have 3° or so slope to the aft of the rig
built in where the bolts tie the motor mounts and crossmember together. So no worries there. As mr48 said with factory slope to rear your carb mount should be level.

Youll have to trim the ends of the trans crossmember tube. Just bolt the mount onto the trans, the crossmember to the mount set the end peices on the frame rails next the the tube ends and itll be obvious how much to trim. Mine was around 5/8 per side IIRC.
For the front, bolt the mounts to the block, then fit (wrestle) the crossmember into position with the end pieces on. Then run your bolts through the mount and crossmember.

This way the last thing to bolt is the crossmember ends to the frame rails
once these are in you can get all your adustments and clearances set, then drill holes in your frame rails and bolt those up last.
If your brake line on the driver side is still in the stock location penetrating through the frame rail. it may be close the end plate of the new crossmember but at the worst you can move you brake line.
I also like mr 48 prefer to do the trans first. Then the motor.
Once you get to doing it it will be pretty easy.
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[Amorget]

Originally Posted by rsb5772

I'll be pulling the I-6, which is mounted on the front of the motor, and putting in a small block.

Thanks, I think that helps me greatly with what setup my truck seems to of come with. Engine and trans were already gone, I was told it had a V8 in it, but from your description it seems like it may of had the I6.

[rsb5772]

Double post

[tmoble]

the ears that go inside the frame act as lever arms with a 700 lb weight mounted on the end. not a good thing. caused my non-rusted frame to crack. never again. use the crossmembers.

[Amorget]

Did the V8's mount the same way then using some sort of bracket? Sorry, never seen how the engines mounted from the factory

[rsb5772]

From what I understand, the Gen 1 small blocks had front mounts, and we're moved back on the Gen 2 blocks. I hope someone will correct me if I'm wrong.

Tmoble, are you talking about the trans crossmember tabs that sit on the rails, and you wouldn't use that type?

Thanks for the help everyone.
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[Amorget]

Gen II small blocks didn't come out until 1992 in the Corvette and had the mounts in the same place as the Gen I.

As far as I know the engine mounts on the SBC never moved, but I don't know the early SBC.

[rsb5772]

Thanks for clearing it up.
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[72Mountaineer]

Anybody else mount their SBC about an inch or so to the passenger side to help with the steering shafts?

[rsb5772]

Originally Posted by 72Mountaineer

Anybody else mount their SBC about an inch or so to the passenger side to help with the steering shafts?

I haven't come across anything about that, but will look into it when I hang it in place. Which reminds me that I need to find some headers to bolt on for the mock up. Thanks.
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