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
  #1  
Old June 17th, 2013, 03:19 PM
GMCNUT's Avatar
GMCNUT GMCNUT is offline
-= Site Supporter =-
 
Join Date: Jan 2013
Location: Arab Alabama
Truck: 60 1001 Wideside Custom BBW, 62 K1001 Wideside BBW and 1966 1001 Wideside BBW w/ Sport Trim option
Posts: 688
Rep Power: 254
GMCNUT will become famous soon enoughGMCNUT will become famous soon enough
Default Timing setting for 305E

Hey guys - until I bought my 64 2500 series I had never really got to drive a 305E equipped truck any real distance and have been racking up the miles on this one since it runs like a top. However, it seems to be idled up more than it should be and will "cadillac" some when you turn it off occasionally, so I think the timing must need to be adjusted - I have no idea what the timing is supposed to be set to though - can someone tell me? its completely stock if that matters - Thank you for your help
__________________
My 60-66 GMC Projects:

1960 1001 Custom Cab short wideside BBW, 305A V6, factory PB, Hood Jet, Radio and Hydramatic.

1962 K1000 4x4 short wideside, BBW, 305D w/ SM420, PTO Winch

1966 1001 Custom Cab short wideside, w/ super rare Sport Trim option interior (bucket seats)
Reply With Quote
  #2  
Old June 17th, 2013, 05:14 PM
raycow raycow is offline
Senior Member
 
Join Date: Jan 2013
Location: San Francisco, CA
Truck: 1960 C-10 Short Fleet
Posts: 129
Rep Power: 102
raycow is on a distinguished road
Default Re: Timing setting for 305E

I have never before heard the term "cadillac" used to describe what I think you are talking about. Does the engine continue to run (very roughly, and with loud splitting or cracking noises) after you turn off the switch? If yes, this is usually caused by carbon (or other deposits) building up in the combustion chamber and being heated to the point where it serves as an ignition source.

This is not a timing issue, because, if you think about it, there is no spark with the switch off. If the engine is idling faster than normal, it couldn't hurt to reduce the idle speed and see if that helps. The next step would be to pull the plugs and see what they have growing on them. If they look bad, a plug change MIGHT make the problem go away for a while. If nothing else works, you will have to pull the heads and clean out the offending deposits.

If you have a manual transmission, it is a lot less work to just put it in gear and engage the clutch with the engine idling and your foot on the brake. It is a real problem only if you have an automatic, because then you have no easy way of killing the engine.

Ray

Last edited by raycow; June 17th, 2013 at 05:29 PM.
Reply With Quote
  #3  
Old June 17th, 2013, 05:25 PM
FetchMeAPepsi's Avatar
FetchMeAPepsi FetchMeAPepsi is offline
-= Dues Paid =-
 
Join Date: Jan 2013
Location: Edmond, Ks
Truck: 1962 4x4 GMC CECILIA
Posts: 1,724
Rep Power: 545
FetchMeAPepsi is a glorious beacon of lightFetchMeAPepsi is a glorious beacon of lightFetchMeAPepsi is a glorious beacon of lightFetchMeAPepsi is a glorious beacon of lightFetchMeAPepsi is a glorious beacon of light
Default Re: Timing setting for 305E

You can try cleaning your plugs if they have deposits on them. It can cause that too. And make sure your gap is right.

You might pour some b12 chemtool in it too to clean it out more in spots you cant reach.
Reply With Quote
  #4  
Old June 18th, 2013, 02:08 AM
ghoff ghoff is offline
Temporarily Suspended
 
Join Date: May 2013
Location: Stetson Maine
Truck: 1962 K1000.....1964 K1000 suburban..rebuilt my 64 in1979...changed bodies with one from Arizona.rebu
Age: 74
Posts: 5
Rep Power: 0
ghoff is on a distinguished road
Default Re: Timing setting for 305E

The plugs should tell all....do a compression check before removing heads.....gas is really yukie compared to back in the 60's....some additive or even octane booster run through a couple tank fulls....google can give you timing setting
Reply With Quote
  #5  
Old June 18th, 2013, 03:39 AM
GMCNUT's Avatar
GMCNUT GMCNUT is offline
-= Site Supporter =-
 
Join Date: Jan 2013
Location: Arab Alabama
Truck: 60 1001 Wideside Custom BBW, 62 K1001 Wideside BBW and 1966 1001 Wideside BBW w/ Sport Trim option
Posts: 688
Rep Power: 254
GMCNUT will become famous soon enoughGMCNUT will become famous soon enough
Default Re: Timing setting for 305E

Thanks guys - I do not know what is causing it so I will try changing the plugs - its due for that anyway. Do you guys know what the gap setting is for V6's? I would still like to check the timing and make sure its right - what is a 305E supposed to be set at?
__________________
My 60-66 GMC Projects:

1960 1001 Custom Cab short wideside BBW, 305A V6, factory PB, Hood Jet, Radio and Hydramatic.

1962 K1000 4x4 short wideside, BBW, 305D w/ SM420, PTO Winch

1966 1001 Custom Cab short wideside, w/ super rare Sport Trim option interior (bucket seats)
Reply With Quote
  #6  
Old June 18th, 2013, 03:47 AM
GMCNUT's Avatar
GMCNUT GMCNUT is offline
-= Site Supporter =-
 
Join Date: Jan 2013
Location: Arab Alabama
Truck: 60 1001 Wideside Custom BBW, 62 K1001 Wideside BBW and 1966 1001 Wideside BBW w/ Sport Trim option
Posts: 688
Rep Power: 254
GMCNUT will become famous soon enoughGMCNUT will become famous soon enough
Default Re: Timing setting for 305E

Quote:
Originally Posted by raycow View Post
Does the engine continue to run (very roughly, and with loud splitting or cracking noises) after you turn off the switch?

Ray
yep - I kill the switch and the engine continues to try and run supposedly from late spark occurring at the time I kill the power - I was told if the timing was off it would cause this....maybe not. I do not know what the official name of this is, always heard it called cadillacing. Never heard anyone say it was caused by engine deposits that's for sure....hmmmm
__________________
My 60-66 GMC Projects:

1960 1001 Custom Cab short wideside BBW, 305A V6, factory PB, Hood Jet, Radio and Hydramatic.

1962 K1000 4x4 short wideside, BBW, 305D w/ SM420, PTO Winch

1966 1001 Custom Cab short wideside, w/ super rare Sport Trim option interior (bucket seats)
Reply With Quote
  #7  
Old June 18th, 2013, 04:11 AM
raycow raycow is offline
Senior Member
 
Join Date: Jan 2013
Location: San Francisco, CA
Truck: 1960 C-10 Short Fleet
Posts: 129
Rep Power: 102
raycow is on a distinguished road
Default Re: Timing setting for 305E

Quote:
Originally Posted by GMCNUT View Post
I do not know what the official name of this is, always heard it called cadillacing. Never heard anyone say it was caused by engine deposits that's for sure....hmmmm
The names I have heard most frequently for this behavior are "running-on" or "after-run". There really is no spark once you turn off the switch and the fuel-air mixture has to be ignited by something. Well that something is a hot spot in the combustion chamber, and most often that hot spot is a deposit that has been heated to the fuel ignition temperature.

Don't forget to try reducing the idle speed. This can often be enough to fix the problem.

Ray
Reply With Quote
  #8  
Old June 18th, 2013, 12:36 PM
ghoff ghoff is offline
Temporarily Suspended
 
Join Date: May 2013
Location: Stetson Maine
Truck: 1962 K1000.....1964 K1000 suburban..rebuilt my 64 in1979...changed bodies with one from Arizona.rebu
Age: 74
Posts: 5
Rep Power: 0
ghoff is on a distinguished road
Default Re: Timing setting for 305E

Quote:
Originally Posted by GMCNUT View Post
Thanks guys - I do not know what is causing it so I will try changing the plugs - its due for that anyway. Do you guys know what the gap setting is for V6's? I would still like to check the timing and make sure its right - what is a 305E supposed to be set at?
The plug gap is .030----ignition timing degrees----7.5B------idle speed 525rpm
Reply With Quote
  #9  
Old June 19th, 2013, 12:06 AM
GMCNUT's Avatar
GMCNUT GMCNUT is offline
-= Site Supporter =-
 
Join Date: Jan 2013
Location: Arab Alabama
Truck: 60 1001 Wideside Custom BBW, 62 K1001 Wideside BBW and 1966 1001 Wideside BBW w/ Sport Trim option
Posts: 688
Rep Power: 254
GMCNUT will become famous soon enoughGMCNUT will become famous soon enough
Default Re: Timing setting for 305E

Quote:
Originally Posted by ghoff View Post


The plug gap is .030----ignition timing degrees----7.5B------idle speed 525rpm
Thank you - will check this on mine
__________________
My 60-66 GMC Projects:

1960 1001 Custom Cab short wideside BBW, 305A V6, factory PB, Hood Jet, Radio and Hydramatic.

1962 K1000 4x4 short wideside, BBW, 305D w/ SM420, PTO Winch

1966 1001 Custom Cab short wideside, w/ super rare Sport Trim option interior (bucket seats)
Reply With Quote
  #10  
Old June 19th, 2013, 02:07 AM
George Bongert George Bongert is offline
Senior Member
 
Join Date: Jan 2013
Location: Oshkosh Wisconsin
Truck: Former owner Repowered by GMC 305 V-6, 1963 Chevy 30 Series SM420 Long Bed (9') Step/Fenderside
Posts: 210
Rep Power: 141
George Bongert will become famous soon enoughGeorge Bongert will become famous soon enoughGeorge Bongert will become famous soon enough
Default Re: Timing setting for 305E

Hello GMC Nut!

What you are describing, (engine run on after switching off) is also, and more commonly known as "Dieseling" which can be caused by, or contributed to by engine idle speed being too high, and/or carbon deposits in the engine reaching a point of incandescence which will be hot enough to ignite the fuel. High idle speeds exacerbate this problem. Usually, reducing idle speed fixes the problem if hot carbon deposits are not a factor. Ignition timing has no bearing on "Dieseling" or "Cadillac" as you put it.
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
[6066 GMC] Re: setting timing using vacuum gauge Archiver Previous Forum Posts 0 July 6th, 2007 04:05 AM
Re: setting timing using vacuum gauge Archiver Previous Forum Posts 0 July 4th, 2007 12:56 PM
Re: setting timing using vacuum gauge Archiver Previous Forum Posts 0 July 4th, 2007 01:25 AM
Re: setting timing using vacuum gauge Archiver Previous Forum Posts 0 July 4th, 2007 01:21 AM
setting timing using vacuum gauge Archiver Previous Forum Posts 0 July 3rd, 2007 01:23 AM


All times are GMT +1. The time now is 12:38 PM.


Powered by vBulletin® Version 3.8.7
Copyright ©2000 - 2013, Jelsoft Enterprises Ltd 681711554703|1710502693|0