Installing 518 into 70 Challenger with 340.
The speedo cable is blocked by the crossmember.
Guy who built the crossmember says it sometimes happens because of the motor mounts.

Is there at least 1/2" of front-to-back play in the motor mounts?
Is it possible to loosen and push the whole thing back?

Seems like a lot to move?

Angle drive....some factory apps used them.

I installed a 518 behind a 440. I used a 1/2" adapter plate to marry the big block with the small block bell housing. Without the adapter, that is exactly where my speedometer output was as well. I seriously doubt there is a 1/2" play with the mounts, probably closer to 1/8". Depending on how low your transmission is set, you may also have interference with the transmission tunnel frame. I had to clearance a lot in the transmission tunnel to get the transmission to sit close to level. If you try the adapter shown in the previous post, get the one like the picture, a single 90 reverses the direction the speedometer cable is spinning.

Good luck,

The only way to get a 1/2" of rearward movement from the motor mounts, is to remove them from the engine, re-bolt the mount brackets to the front of the engines ear tabs, that should give you about 5/8" rear movement.....but keep in mind there may be interference moving the engine this way?...depends on a lot of variables you need to look at, linkage, fresh air induction, etc, etc, I'll assume your shortening the drive shaft?

Mike

Adapter looks interesting, but from what I can see it would actually take up more space than just the cable.

Moving the mounts on the engine sounds possible.

What about redrilling the motor mount to shift the position of the insulator?
I'm not sure what the mount looks like apart. Anyone have pics or experience with this?

There's actually more room than I thought, but this speedo problem popped up.
It's never easy is it?

Thanks for the replies

[quote

Moving the mounts on the engine sounds possible.

What about redrilling the motor mount to shift the position of the insulator?
I'm not sure what the mount looks like apart. Anyone have pics or experience with this?

There's actually more room than I thought, but this speedo problem popped up.
It's never easy is it?

Thanks for the replies

---

Why drill?....I just offered you a "bolt-on" solution, if it don't work, just un bolt it, and re bolt it back on...1/2 hrs work at most

Mike

could the xmember be cut/notched/trimed to allow the cable to fit the speedo output?

unhooked it will keep miles from adding up on the odometer

I cant see well enuff in the pic if it would be able to clearance any.

I cut a xmember and welded in a pipe so the cable could go thru it one time on a mud truck.

my self I would be looking to mod the xmember, not moving the engine back from stock location.

Could you share a little info on the cross member? Who built it and how much was it?

Thanks!

I only needed 1/4" or so, and I already have air cleaner / hood problems, so moving the motor back 5/8" wasn't my 1st option.

I think I found something workable.
Original 727 was at 0deg and rear-end is at 0deg, I know this isn't optimal and might be reason for annoying vibration at 70mph?

So, I lowered the 518 tranny to -3deg, to clear hump brace.
With the tranny at -3deg and rear-end at 0deg, the new set-up is a net -3deg? Not the desired -4-5deg, but better.

I then notched the mount to allow the cable to connect.
It's tight, so please don't tell me I have to worry about forth/aft movement?

Thoughts?

that's what I would have done. can you clearance it a bit more then maybe box/section the xmember where you have it notched.

like slicing a pipe in 1/2 then weld it in to fill the backside of the notch.

looks good in the pics.

Again, who made the X-member? For sale? What mount does it use?

Thanks,

Rick

Yes it's available, nice piece. It uses standard GM mount.

Look here:

https://squareup.com/market/rory-fontana/e-body-crossmember-kit

So how about some feedback, any issues with what I've got so far?
And where can I find a longer speedo cable, I'm thinking it needs to be 18-24" longer.

Thx

$367 for the mount and then you have to clearance it for the speedo cable.








Now if we could just get the bells for the big blocks.

I was a little upset at first; but nothing to do with mount.
Problem is the stack-up puts the speedo right near the body tunnel.

Most work without mods, for what ever reason, from what I've read 340 seem to be worse.

I'd like to find a 1/2" spacer for the bell housing to engine?
But I guess this might cause other issues, flex plate spacer..........

do you have the correct tooth count gear in the speedo? that may re-clock the speedo plug a little either way depending on what is needed. (round & offset)

Oh crap, didn't take that into account!
Where do you clock/line up the mark.

Sitting in airport now, won't be able to look at it for a week.

Never ends does it!

it is gonna drive you bannanas for a week Huh?

I will go check the 727 and see which way the different tooth count moves the pionion around in the hole and let you know.

do you know the tooth count in the 518 now? what rear axle gear tire size?

IIRC, you should just swap gear from the trans coming out to the 518 so no biggie there.

waiting a week to know which way it moves...

Were you able to avoid cutting the torsion bar crossmember at all? That's pretty cool for installing a 518 in an e-body, but how far down does the rear of the motor/trans drop from stock?

I found these other pictures on Fontana's Facebook page.

...and the transmission.

ps: You can buy a speedometer extension of either size you want on ebay. Just do a quick search.