Iron block with Aluminum heads, can you still run the ground strap off the Aluminum heads to the firewall for a good ground, or should I go off the block..??

The head is fine.

It's only there for radio noise suppression. That big fat black cable coming from the battery grounds the engine. The short pigtail coming off the negative going to passenger side front fender grounds the chassis.

It's only there for radio noise suppression. That big fat black cable coming from the battery grounds the engine. The short pigtail coming off the negative going to passenger side front fender grounds the chassis.
Hank, the reason why I asked is because I have been having an intermittent total loss of power with my car, so I added a LARGE ground strap from the block to the frame. Next I am checking the junction lug/plug at the firewall for corrosion. It was also suggested to add a ground strap from the block to the firewall. Now I don't have any radio feedback so if that is the case I would rather not drill another hole in the firewall for a ground strap IF ITS NOT GOING TO HELP WITH MY POWER CUTTING ON AND OFF.

THANKS...

Hank, the reason why I asked is because I have been having an intermittent total loss of power with my car, so I added a LARGE ground strap from the block to the frame. Next I am checking the junction lug/plug at the firewall for corrosion. It was also suggested to add a ground strap from the block to the firewall. Now I don't have any radio feedback so if that is the case I would rather not drill another hole in the firewall for a ground strap IF ITS NOT GOING TO HELP WITH MY POWER CUTTING ON AND OFF.

THANKS...

If you're car didn't come with a radio it didn't come with those ground straps. They may help cover up another problem but I would try to find the source of the problem.

I would add a ground to the firewall. A lot of things are body grounded, but not necessarily good grounds to the frame since it sits on rubber bushings.

[QUOTE=bracketchev1221;2628268]I would add a ground to the firewall. A lot of things are body grounded, but not necessarily good grounds to the frame since it sits on rubber bushings.[/QUOTE

Ray, I installed a LARGE gauge Marine grade ground strap from the block to the frame. I used the marine lugs crimped down at both ends. The strap is bolted to the front of block (top} hole along side the fuel pump in front of block. The frame mount consists of a SS bolt through frame,(bolt head inside frame), SS washer and nylock. That baby's not going anywhere.I will install the new firewall ground, just to cover my butt...:D

I would add a ground to the firewall. A lot of things are body grounded, but not necessarily good grounds to the frame since it sits on rubber bushings.

Not a lot of things grounded to the frame. Look at your car, just about everything is grounded to the chassis, not the frame. There are a few items, some lights, like the front parking lights but primarily everything is grounded to the chassis.

Adding a ground to the firewall does nothing for the frame, it's another ground to the chassis. Again, the pigtail off the negative battery cable should be attached to the passenger side front fender. That's how the chassis is grounded. Stock it should be a 10g wire like the pigtail that comes off the positive post to junction block. The engine itself is grounded through the negative battery cable, it can handle the current draw of the starter.

Check your battery cables, see if the insulation is puffed up, not smooth, near the ends. That's a good sign there's corrision underneath the insulation that may have eaten through a lot cable. Check the connection from battery positive to junction block. Connections at horn relay. Connection to front passenger side fender. Bulkhead connector.

A total loss of power indicates loss of positive at one of the points mentioned above. Since the engine is grounded through the negative battery cable and the rest of the car is grounded through the chassis, both those connections would have to fail to shutdown the engine and kill everything else. If you lost engine ground the engine would die but you would still have lights and other accessories. If you lost chassis ground the engine would still run but you would have no lights or accessories. Lose of positive would kill the engine and everything else. Not sure what year car, the positive path I mentioned is for 70 and earlier. In 71 or 72 they moved the main splice from near the horn relay down to the starter.