The 1947 - Present Chevrolet & GMC Truck Message Board Network







Register or Log In To remove these advertisements.

Go Back   The 1947 - Present Chevrolet & GMC Truck Message Board Network > 47 - Current classic GM Trucks > The 1960 - 1966 Chevrolet & GMC Pickups Message Board > projects and builds

Web 67-72chevytrucks.com


Reply
 
Thread Tools Display Modes
Old 07-26-2013, 10:53 AM   #101
Andice
Registered User
 
Andice's Avatar
 
Join Date: Oct 2009
Location: Austin, Texas
Posts: 241
Re: 1966 GMC 305 V6 Service

Rufton: I am impressed by the work you've done on your 305 V6 engine! Do you happen to have a part number for the oil filler cap? I could use a new one and yours looks just like what I need.
Andice is offline   Reply With Quote
Old 07-27-2013, 03:11 AM   #102
DouglasRaymond
Registered User
 
Join Date: Jun 2013
Location: Mesa AZ
Posts: 39
Re: 1966 GMC 305 V6 Service

Interesting, not sure I would get it right!
DouglasRaymond is offline   Reply With Quote
Old 07-29-2013, 05:03 PM   #103
Rufton
Registered User
 
Join Date: Apr 2013
Location: Knoxville TN
Posts: 1,170
Re: 1966 GMC 305 V6 Service

Thanks. Maybe you can find a match at swap meet, ebay, etc.
Attached Images
   
Rufton is offline   Reply With Quote
Old 07-29-2013, 05:25 PM   #104
Rufton
Registered User
 
Join Date: Apr 2013
Location: Knoxville TN
Posts: 1,170
Re: 1966 GMC 305 V6 Service

Strange road trip 305E V6 HWY milage.

1. 9.3 mpg (about 60 mph I-75)
2. 17.1 mpg (about 70 mph I-75)
3. 16.7 mpg (about 70 mph I-75 return trip)
4. 9.5 mpg (about 60 mph I-75 return trip)

Mileage calibrated against map quest.
Triple checked full tank when I got the 17.1 mpg; even saw gas in tank through filler neck.
Thought I was home free until the last 9.5 mpg reading.
I suspect the carb or distributor is misbehaving under 70 mph.
Maybe I'll advance timing a bit more than stock and verify timing advance is functioning. I'm a little suspicious of carb power valve function.
Rufton is offline   Reply With Quote
Old 07-29-2013, 06:29 PM   #105
Andice
Registered User
 
Andice's Avatar
 
Join Date: Oct 2009
Location: Austin, Texas
Posts: 241
Re: 1966 GMC 305 V6 Service

Rufton: Thanks for the detailed images of the oil filler cap. The cap in my 305E has two thinner mounting tabs on the underside. It kind if resembles the tabs on a breather/oil filler cap. I will consider trying a cap like yours. Can't explain your spotty fuel consumption, but mine is in the shop right now getting a proper tune since it has been backfiring a little. I may have damaged the power valve in my Holley carb
Attached Images
 
Andice is offline   Reply With Quote
Old 07-29-2013, 06:59 PM   #106
Rufton
Registered User
 
Join Date: Apr 2013
Location: Knoxville TN
Posts: 1,170
Re: 1966 GMC 305 V6 Service

I've got a spare Stromberg. When time allows I hope to rebuild it for comparison. I hope to install an UEGO O2 AFR gauge because it takes away a lot of guess work. I'm willing to consider holley as well. Don't think Stromberg power valve is affected by back fire but it's design does look primitive. Not sure how to test power valve function; suppose one could wire open/shut to see how it affects performance.
Rufton is offline   Reply With Quote
Old 07-29-2013, 07:19 PM   #107
Rufton
Registered User
 
Join Date: Apr 2013
Location: Knoxville TN
Posts: 1,170
Re: 1966 GMC 305 V6 Service

The Stromberg power valve actuation rod ( looks like nail ). Moves up and down w/ vacuum to stroke spring loaded power valve (looks like jet w/ wire in center). Don't know if hangs up.

The old Stromberg suffered plenty of back fires through the years but power valve still functioned on the bench.
Attached Images
  
Rufton is offline   Reply With Quote
Old 07-31-2013, 02:22 PM   #108
Rufton
Registered User
 
Join Date: Apr 2013
Location: Knoxville TN
Posts: 1,170
Re: 1966 GMC 305 V6 Service

Distributor seems to be behaving. I wanted to dial in a couple more degrees but advance already looks good relative to some other engines. Not sure if I ever hit mechanical advance stop; didn't wan't to spin it faster cause not confident in tach accuracy (indicates low compared to car tach).

7-31-2013 66 GMC 305E V6 timing data:

Timing (vacuum advance connected, cold engine):
6* 490 RPM
24* 1000 rpm
42* 1500 rpm
45* 2000 rpm
48* 2500 rpm

Timing (vacuum advance connected, warm engine):

9* 600 rpm
16* 1000 rpm
16* 1000 rpm
42* 1500 rpm
46* 2000 rpm
49* 2500 rpm
55* 3000 rpm

Timing (vacuum advance plugged, warm engine):

9* 600 rpm
16* 1000 rpm
25* 1500 rpm
29* 2000 rpm
33* 2500 rpm
38* 3000 rpm

Dwell (warm engine):

31 dwell 620 rpm
30 to 31 dwell from 620 to 2500 rpm.

Timed vacuum port Stromberg WW:

<2 Hg 620 to 900 rpm
4 Hg 950 rpm
6.5 Hg 1000 rpm
13.5 Hg 1200 rpm
15.5 Hg 1500 rpm
18.5 Hg 2000 rpm
18.5 Hg 2500 rpm
Rufton is offline   Reply With Quote
Old 08-12-2013, 12:10 PM   #109
TommyDuncan
Registered User
 
Join Date: Feb 2013
Location: Boulder City NV
Posts: 214
Re: 1966 GMC 305 V6 Service

Quote:
Originally Posted by Andice View Post
Rufton: Thanks for the detailed images of the oil filler cap. The cap in my 305E has two thinner mounting tabs on the underside. It kind if resembles the tabs on a breather/oil filler cap. I will consider trying a cap like yours. Can't explain your spotty fuel consumption, but mine is in the shop right now getting a proper tune since it has been backfiring a little. I may have damaged the power valve in my Holley carb
I have a couple spare caps. I never compared them but they appear the same. When I get home I will compare them. PM me your address and I'll send you one.
Posted via Mobile Device
TommyDuncan is offline   Reply With Quote
Old 08-12-2013, 09:27 PM   #110
duallyjams
PICS IM MY PROFILE
 
duallyjams's Avatar
 
Join Date: May 2007
Location: Deale Md
Posts: 4,530
Re: 1966 GMC 305 V6 Service

Quote:
Originally Posted by Rufton View Post
Strange road trip 305E V6 HWY milage.

1. 9.3 mpg (about 60 mph I-75)
2. 17.1 mpg (about 70 mph I-75)
3. 16.7 mpg (about 70 mph I-75 return trip)
4. 9.5 mpg (about 60 mph I-75 return trip)

Mileage calibrated against map quest.
Triple checked full tank when I got the 17.1 mpg; even saw gas in tank through filler neck.
Thought I was home free until the last 9.5 mpg reading.
I suspect the carb or distributor is misbehaving under 70 mph.
Maybe I'll advance timing a bit more than stock and verify timing advance is functioning. I'm a little suspicious of carb power valve function.
what's the rpm on the engine when your running 60-70 mph
__________________
James

2002 GMC cc dwr sporting alcoa D-max 22MPG
63 GMC V6 4speed carryall
64 GMC lwb 3/4 V6 4speed seeking factory optionSOLD
65 chevy swb bbw V8 auto
66 GMC swb bbw buddy bucketsSOLD

IG duallyjams

The only thing that stays the same is constant change!
duallyjams is offline   Reply With Quote
Old 08-12-2013, 11:24 PM   #111
TommyDuncan
Registered User
 
Join Date: Feb 2013
Location: Boulder City NV
Posts: 214
Re: 1966 GMC 305 V6 Service

Quote:
Originally Posted by duallyjams View Post
what's the rpm on the engine when your running 60-70 mph
I did the math and 60mph should be about 2150rpm. 70 should be pushing 2500rpm.
Posted via Mobile Device
TommyDuncan is offline   Reply With Quote
Old 08-13-2013, 06:46 PM   #112
Andice
Registered User
 
Andice's Avatar
 
Join Date: Oct 2009
Location: Austin, Texas
Posts: 241
Re: 1966 GMC 305 V6 Service

I must have been smoking crack because my oil filler cap is just like Rufton's and likely the same as all other oil filler caps for this era GM vehicle. Sorry for the stupid posts and thanks for the offer T Duncan.
Andice is offline   Reply With Quote
Old 08-13-2013, 08:30 PM   #113
awbrown
Senior Member
 
awbrown's Avatar
 
Join Date: Aug 2009
Location: Detroit MI
Posts: 1,196
Re: 1966 GMC 305 V6 Service

rufton , what port do you have the vacuum on now ?? From what you are telling us it looks like it is on the ported vacuum , it should be on manifold vacuum .. all the vehicles I have had got much better milage on manifold vacuum than ported...
__________________
If ever the Time should come, when vain & aspiring Men shall possess the highest Seats in Government, our Country will stand in Need of its experienced Patriots to prevent its Ruin.
awbrown is offline   Reply With Quote
Old 09-16-2013, 05:48 PM   #114
performo
Junior Member
 
performo's Avatar
 
Join Date: Jul 2008
Location: Corona, CA
Posts: 25
Re: 1966 GMC 305 V6 Service

Hello, Does anyone know the factory weight of the GMC 305 v-6?

Thanks in advance.
performo is offline   Reply With Quote
Old 09-16-2013, 05:57 PM   #115
TommyDuncan
Registered User
 
Join Date: Feb 2013
Location: Boulder City NV
Posts: 214
Re: 1966 GMC 305 V6 Service

Quote:
Originally Posted by performo View Post
Hello, Does anyone know the factory weight of the GMC 305 v-6?

Thanks in advance.
the number I keep hearing is 800 lbs and judging by how the two I have on stands feel when I try to move them I believe it!
Posted via Mobile Device
TommyDuncan is offline   Reply With Quote
Old 09-16-2013, 06:28 PM   #116
performo
Junior Member
 
performo's Avatar
 
Join Date: Jul 2008
Location: Corona, CA
Posts: 25
Re: 1966 GMC 305 V6 Service

That works for me. I have been scouring the internet and can not find the weight specs. Thanks Tommy.
performo is offline   Reply With Quote
Old 09-16-2013, 06:33 PM   #117
TommyDuncan
Registered User
 
Join Date: Feb 2013
Location: Boulder City NV
Posts: 214
Re: 1966 GMC 305 V6 Service

Quote:
Originally Posted by performo View Post
Hello, Does anyone know the factory weight of the GMC 305 v-6?

Thanks in advance.
I just stole this from Jolly's site:

The "GMC Replacement Engine Catalogs" lists the following dry weights:
305A = 738 lbs.
305B = 771 lbs.
305C = 840 lbs.
305E = 795 lbs.
351 = 860 lbs.
401 = 880 lbs.
478 = 925 lbs.
702 = 1485 lbs.
637 = 1219 lbs.
Posted via Mobile Device
TommyDuncan is offline   Reply With Quote
Old 09-17-2013, 01:44 PM   #118
performo
Junior Member
 
performo's Avatar
 
Join Date: Jul 2008
Location: Corona, CA
Posts: 25
Re: 1966 GMC 305 V6 Service

Great weights reference, Thank you
performo is offline   Reply With Quote
Old 12-03-2013, 11:29 PM   #119
3/4ton Randy
Registered User
 
Join Date: Jul 2012
Location: Denton, Tx
Posts: 54
Re: 1966 GMC 305 V6 Service

Rufton, I would like to thank you for all the hard work, pictures, and detailed information you have put into this thread. I recently purchased a '66 with the 305 V6, and I have been a little worried about how to take care of it. You have saved us so much time and probably wasted effort. You are great!
3/4ton Randy is offline   Reply With Quote
Old 12-04-2013, 12:31 AM   #120
raylube
Registered User
 
raylube's Avatar
 
Join Date: Jan 2012
Location: Preston Idaho
Posts: 103
Re: 1966 GMC 305 V6 Service

X 2. Do you have a list of
part numbers and vendors?
raylube is offline   Reply With Quote
Old 12-04-2013, 03:35 PM   #121
b.sharp
Registered User
 
b.sharp's Avatar
 
Join Date: May 2006
Location: Frankfort, Kentucky
Posts: 510
Re: 1966 GMC 305 V6 Service

I have just purchase a 1ton with one of these engines. I have no idea what exact motor it is. Is there a way to tell one from another. I know it's the V6 but do not know which one. It there anything major to check before trying to turn these engines over? Truck is junk and for parts but hoping to save the motor for a '68 GMC. Great thread!!
b.sharp is offline   Reply With Quote
Old 12-04-2013, 06:54 PM   #122
MusicMan70
Senior Member
 
MusicMan70's Avatar
 
Join Date: Feb 2011
Location: Corona, CA
Posts: 1,585
Re: 1966 GMC 305 V6 Service

Look here BSharp;
Attached Images
 
__________________
MusicMan70
1961 GMC Suburban
MusicMan70 is offline   Reply With Quote
Old 12-04-2013, 07:14 PM   #123
b.sharp
Registered User
 
b.sharp's Avatar
 
Join Date: May 2006
Location: Frankfort, Kentucky
Posts: 510
Re: 1966 GMC 305 V6 Service

I will check it out this weekend. Truck is at my in-laws. Thank you for the information.
b.sharp is offline   Reply With Quote
Old 12-04-2013, 07:20 PM   #124
TJ's Chevy
Registered User
 
TJ's Chevy's Avatar
 
Join Date: Mar 2013
Location: Next to my bench at the shop, Oregon.
Posts: 10,194
Re: 1966 GMC 305 V6 Service

One sweet 305 E! Doing fantastic work!
__________________
"6 in a row makes it go!"
"I prefer a buzzin half-dozen"
1966 Chevy C10 "Project Two Tone" http://67-72chevytrucks.com/vboard/s...d.php?t=596643
1964 GMC "Crustine" semi-build:http://67-72chevytrucks.com/vboard/s...d.php?t=665056
My youtube channel. Username "Military Chevy": https://www.youtube.com/channel/UC_h...fzpcUXyK_5-uiw
TJ's Chevy is offline   Reply With Quote
Old 12-05-2013, 10:12 AM   #125
Tx Firefighter
Watch out for your cornhole !
 
Tx Firefighter's Avatar
 
Join Date: Jun 2003
Location: Texas
Posts: 14,059
Re: 1966 GMC 305 V6 Service

This threads sets the bar.

Thank you for taking the time to stop and photograph the various steps along the way. A picture really is worth 1000 words.

That said, I'll go back to lurking and learning.
__________________
Kevin -

My Instagram
Tx Firefighter is offline   Reply With Quote
Reply

Bookmarks

Thread Tools
Display Modes

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

Forum Jump


All times are GMT -4. The time now is 06:45 AM.


Powered by vBulletin® Version 3.8.11
Copyright ©2000 - 2019, vBulletin Solutions Inc.
Copyright 1997-2013 67-72chevytrucks.com