I wouldn't do it! I ran E85 in my Fury's 440 once just to see how it responded.
That is 15% alcohol. Engine temps dropped, but the exhaust temps jumped
and burned out the gaskets on one side of the headers. The motor is a fresh,
total, high performance rebuild, increased compression ratio, MSD ignition,
and MSD adjustable timing control, it still ran awful at lower speeds and only
ran decent on the Interstate. I tried it for the 108 octane rating. Indeed there
was no pinging and I was able to add almost 10 extra degrees to my timing!
A lower compression, older engine will not be happy!
If you want to clean out the chambers, do the Seafoam smoke machine!
Get 2 cans of Seafoam, with the engine running at a high idle, dump half a can
slowly down the carb, keep the engine running. Then dump the last half of the
can down fast as you can, so the engine stalls out and dies. Make sure the
windows in the house are closed! Wait 20 minutes and restart the motor.
There will be an incredible cloud of white smoke out the tail pipe! Then dump
the other can in a full tank of gas and let it clean out the rest of the system.
The Seafoam can really work! I talked to guys that said they had chunks of
carbon come out the tail pipes! By flooding out the engine and letting it set,
the Seafoam has time to soak the carbon deposits in the chambers.
Mopar also makes a chamber cleaner that comes in aerosol. It can be bought
at the dealer, and is about the same cost as Seafoam. It really works well also.
The aerosol is better for fuel injected vehicles and small engines. We used it on
my dad's riding mower last year when it started running rough, and it has ran
like new ever since. I used it on my Dakota also, and it picked up some pep also.