6066 (1960-1966) GMC Truck Club Bitcoin now accepted here! 
Pay Dues
Pay Dues or become a Site Supporter
 



Go Back   6066 (1960-1966) GMC Truck Club > 6066 GMC Truck Club Forum > GMC V6 and V12 Engines


GMC V6 and V12 Engines Engine repair and rebuilding

Reply
 
Thread Tools
  #11  
Old May 16th, 2017, 08:35 PM
POWERSTROKE POWERSTROKE is offline
Senior Member
 
Join Date: Sep 2014
Location: Madison, WI
Truck: I don't own one - YET!
Posts: 118
Rep Power: 93
POWERSTROKE is on a distinguished road
Default Re: Fuel additives

I've followed the no lead and fuel additive controversy since no lead gas first was announced. Used to be monthly articles by technical people like CJ Baker or Gordon Jennings in Hot Rod Magazine or Cycle magazine that could explain the difference between detonation and preignition, or how octane actually worked to prevent your engine from detonating. Or how oil or grease was the best lubricant for specific purposes. From what I've read, very little tetra ethyl lead is needed to protect exhaust valves and valve seats. The V-6's are rather low compression engines, what gets them in trouble is the duty cycle they were built to endure. If you don't drive your GMC much, I'd fill it with straight gasoline, no ethanol, ethanol is hydroscopic, attracts water which causes storage problems. Then add a couple gallons of leaded race gas, Unocal, Sunoco, VPN, even low lead 100 octane aviation gas. For most light duty these trucks see anymore the blend of leaded gas and a good non ethanol gas is the best you can feed them. They should run like it's 1965 all over again. I'd suggest 15-20% race gas is enough. I find it is about $2- $2.50/gallon more than straight gas.

Back when I was running gasoline farm tractors wide open, pulling as hard as they could 8-10-12 hours a day the inside of the exhaust would be a medium gray, if you were letting them loaf they would be coal black. Excellent indicator of your combustion chamber temp. With the mixed gas they will have a nice medium gray color inside the tailpipe after an hour at 65 mph.
Reply With Quote
  #12  
Old May 17th, 2017, 02:00 AM
bigblockv6 bigblockv6 is offline
Senior Member
 
Join Date: Jan 2013
Location: Rohnert Park, ca.
Truck: 1968 KM2500
Posts: 1,325
Rep Power: 415
bigblockv6 will become famous soon enoughbigblockv6 will become famous soon enough
Default Re: Fuel additives

The 68 305E doesn't have hardened seats, you'll find hardened seats came with the bigger cubic inch V6 engines
Reply With Quote
Reply

Bookmarks

Thread Tools

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off


Similar Threads
Thread Thread Starter Forum Replies Last Post
Fuel sending unit 66 gmc fleetside with cab fuel tank Archiver Previous Forum Posts 1 March 15th, 2011 02:42 AM
Re: [6066 GMC] 305D fuel pump and fuel rate Archiver Previous Forum Posts 0 December 15th, 2007 04:13 AM
305D fuel pump and fuel rate Archiver Previous Forum Posts 0 December 13th, 2007 04:20 AM
Re: [6066 GMC] 305D fuel pump and fuel rate Archiver Previous Forum Posts 0 December 13th, 2007 02:35 AM
Antifreeze additives Archiver Previous Forum Posts 0 March 13th, 2004 03:48 AM


All times are GMT +1. The time now is 09:33 PM.


Powered by vBulletin® Version 3.8.7
Copyright ©2000 - 2013, Jelsoft Enterprises Ltd 681711554703|1710448423|0