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 April 25th, 2013, 08:12 PM
6066gmcguy's Avatar
6066gmcguy 6066gmcguy is offline
-= Site Supporter =-
 
Join Date: Jan 2013
Location: Honeyville, Utah
Truck: 1965 3500 Rescue Squad
Age: 63
Posts: 613
Rep Power: 226
6066gmcguy is on a distinguished road
Default Re: 305C-305E Difference?

Engine number stamped on the block, check this page of My site for more info; Engine Data Page.
__________________
Links to Other Places:

To view links or images in signatures your post count must be 0 or greater. You currently have 0 posts.
on FacePage.

To view links or images in signatures your post count must be 0 or greater. You currently have 0 posts.
.
the
To view links or images in signatures your post count must be 0 or greater. You currently have 0 posts.
on FacePage.
Owner of:
1965 GMC 3500 Custom Rescue Squad {Black Built Bodies}
1968 Ford Galaxie 500 Convertible
2006 Yamaha Rhino 450
2008 GMC HHR Panel.
Reply With Quote
  #12  
Old April 28th, 2013, 11:00 AM
LEWISMATKIN's Avatar
LEWISMATKIN LEWISMATKIN is offline
-= Site Supporter =-
 
Join Date: Jan 2013
Location: RIDGE MANOR, FLORIDA
Truck: 1965 1002 GMC V6-305E
Age: 64
Posts: 307
Rep Power: 173
LEWISMATKIN will become famous soon enoughLEWISMATKIN will become famous soon enoughLEWISMATKIN will become famous soon enough
Default Re: 305C-305E Difference?

The 305C engine was the heavy duty version of the 305 line. It was mostly found in the 3000-4000 series 60-66, then in 4500-6500series through '74. The main differences with the E series engines is all sodium filled valves on the Exhaust (called stellite), rotators under the valve springs, and 4-ring pistions. The E series was the light duty or Economy (pick up) version and lacked the things that the C engine had and also was equipped with 3-ring pistons (the only engine in the V6 line to come that way factory).
Reply With Quote
  #13  
Old April 28th, 2013, 03:17 PM
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: 305C-305E Difference?

My understanding is all GMC V6 engines 351 through 478 came equipped with Sodium cooled valves, all 305 engines did not and my factory GMC manual confirms this, stellite is a hard alloy used on the valve faces that come in contact with the valve seat. There was an HD305E V6 that was available in pickups, my 68 was equipped as such and this engine used valve rotators.
Reply With Quote
  #14  
Old April 29th, 2013, 03:06 AM
LEWISMATKIN's Avatar
LEWISMATKIN LEWISMATKIN is offline
-= Site Supporter =-
 
Join Date: Jan 2013
Location: RIDGE MANOR, FLORIDA
Truck: 1965 1002 GMC V6-305E
Age: 64
Posts: 307
Rep Power: 173
LEWISMATKIN will become famous soon enoughLEWISMATKIN will become famous soon enoughLEWISMATKIN will become famous soon enough
Smile Re: 305C-305E Difference?

Thanks Pete, for reminding me about the valves, in that regaurd you are right. However only the "E" series ever came with 3-ring pistons, which as you have said before have been replaced with the 4-ring pistons of the A-B-C-D engines. I hope you have had a blessed day today. BTW, how is that 478LD of your running??
Reply With Quote
  #15  
Old April 29th, 2013, 05:05 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: 305C-305E Difference?

Lewis, the 478M finally got fired up on this last President's day, after getting things dialed in like the valve lash and timing the engine sounds great, it's good to hear it running after some 16 years and the 478 does sound somewhat different from the 305. I have yet to finish the power steering conversion before I get the truck on the road, working 6 days a week is making things difficult at this time but hopefully next month will be better. As far as the 4 ring piston issue, what I was talking about was in the early seventies GMC issued a service bulletin that stated 3 ring 305 pistons were discontinued as a replacement part. From that point the 4 ring 305C pistons were to be used in prior 305A,D and E engines for replacement and the purpose was for standardization. This all made sense at the time since only 305C engines were in production. Of course aftermarket suppliers more than likely offered the 3 ring piston.
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
RE: [6066 GMC] 305E vs. 305C Archiver Previous Forum Posts 0 March 11th, 2006 10:40 AM
Re: [6066 GMC] 305E vs. 305C Archiver Previous Forum Posts 0 March 11th, 2006 05:39 AM
305E vs. 305C Archiver Previous Forum Posts 0 March 11th, 2006 02:27 AM
Re: [6066 GMC] 305E vs. 305C Archiver Previous Forum Posts 0 March 11th, 2006 01:53 AM
Re: [6066 GMC] 305E vs. 305C Archiver Previous Forum Posts 0 March 11th, 2006 12:08 AM


All times are GMT +1. The time now is 06:06 PM.


Powered by vBulletin® Version 3.8.7
Copyright ©2000 - 2013, Jelsoft Enterprises Ltd 681711554703|1710435986|0