Technical jumpstarting 6V from 12V

Just tried to jumpstart a 6V positve earth 51 Mercury from my 12V negative earth truck
I put the negative jump cable from my truck and put it on the ground on the block and then took the live jump cable from the live terminal on my truck and put it on the input side of the starter solenoid.
after a short time the live jump lead was melting and the solenoid was smoking.
The old Merc is now as dead as dead can be.
I'm guessing i will be needing a new solenoid but what did i do wrong and is it likely i've toasted anything else
Thanks
Neil

 

You messed up - always go - to - & + to + I always have someone help - put the cable - to - first - then take the + cable and just touch the 6 volt car long enough to start it.

 

thanks for that
In my head i did.I put the truck negative to the ground on the engine block. i presume what you're saying is because it is positive earth the negative should have gone to the solenoid and the positive gone to the engine block
what am i likely to have fried

 

Was the Merc battery involved at all?
If not - should go to the solenoid and + to the block just like the battery would. Maybe the solenoid was already toast?

 

Didn't go near the Merc battery but think i did it the wrong way round and toasted the solenoid.Hoping i didn't take anything else with it

 

Does a Ford solenoid "care" either way?

 

I think it cares 6 vs 12 volts but let's hear what the others say

 

Yep. Hooked it up backwards with double the voltage = cooked.

 

When I jump a 6v from a 12v Always go neg to neg. Hook up the 12v and the ground cable on the 6v. I then have someone engage the starter and touch the 12v hot lead to the starter or output terminal on the solenoid. Gary