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GMC V6 and V12 Engines Engine repair and rebuilding

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  #1  
Old August 8th, 2017, 02:53 PM
gwtaylor gwtaylor is offline
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Default What type engine?

I am new at this so forgive the stupid questions. I recently obtained a 1963 GMC 1//2 ton step-side, manual trans. Looking at the engine its a V-6. The engine numbers are '305E234776". I am told this is the "E" model 305 yet when I look at all the various GMC/Chevy manuals I purchased they list two v 6's, the 230 and 292. I was told the 305 is the standard engine. What am I interpreting that is wrong? Which engine do I have? I am sure I will need to repair and even rebuild this engine so I need to know what I have. Forgive my ignorance.
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  #2  
Old August 8th, 2017, 03:21 PM
bigblockv6 bigblockv6 is offline
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Default Re: What type engine?

You have the GMC 305E V6, the 230 and 292 are not a V6 . These are Chevrolet engines they are inline sixes and should be listed as L6. In 63 the 305E was the standard engine exclusive in light duty GMC trucks and Chevrolet engines were not yet integrated in the line up other than in Step Vans.
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  #3  
Old August 8th, 2017, 06:39 PM
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Ed Snyder Ed Snyder is offline
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Default Re: What type engine?

Quote:
Originally Posted by gwtaylor View Post
I recently obtained a 1963 GMC 1/2 ton step-side, manual trans. Looking at the engine its a V-6. The engine numbers are "305E234776". I am sure I will need to repair and even rebuild this engine so I need to know what I have.
Congratulations on the acquisition of your "new" truck, and for finding our forum! You'll get lots of help from lots of knowledgeable people here.

Unless there's something wrong with your engine already, you'll likely never have to do any major work on it. I like to call these V6s GM's most over-engineered and under-appreciated engines they ever produced. With proper care yours should outlive you. I've posted to the forum several times about a fellow member of our local Chevy/GMC truck club who has a '65 panel truck with 305E that has over 600,000 miles on it without a rebuild and is still going strong.

About the only way to kill one of these V6s is to over-rev it or run it out of oil. Personally, I use 3200 RPM as my redline for safety's sake, although 3500 should be OK. And I always use high-zinc Amsoil 10W40. Of course, everyone has their favorite oil. Modern engine oils are light-years better than the oils available in the '60s, and greatly enhance engine life.

So treat yours right and you should get many years' enjoyment out of it.
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1962 K1000 Suburban 401M & SM420
1965 2500 Suburban 351C & SM420 with Watson overdrive
1967 CM1500 pickup 351E & NP435
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  #4  
Old August 8th, 2017, 09:16 PM
AZKen AZKen is offline
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Default Re: What type engine?

GWTaylor, Yep, that is the whole reason for this site. Or most of the reason. To promote the V6 special Big Block GMC only motor. You have one now. Don't get confused. As said, there are straight 6's (L6) and there are 305 V8's.......but you have a 305 V6.
Your motor may surprise you if you just "service it" properly. Carb rebuild, fresh oil...maybe water and fuel pump. It will run 250,000 miles. Most trucks back then never saw big mileage like they do today. They were not family vehicles much back then.
Clean it up and drive it. If it has not been started in a long time, use proper restart procedures before starting. The experienced members on here will advise how to do that if you need that info.

P.S. You may have "plaid" valve covers!!!! That's really good!!!!!

Last edited by AZKen; August 8th, 2017 at 09:26 PM.
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Old August 10th, 2017, 03:48 PM
gwtaylor gwtaylor is offline
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Default Re: What type engine?

Restart procedures? I'd like that if possible. Thanks!!
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  #6  
Old August 10th, 2017, 03:52 PM
gwtaylor gwtaylor is offline
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Default Re: What type engine?

No plaid valve covers. Just red. I noticed the block is red along with the valve covers but the heads are blue. I am guessing they were replaced. My wife seems to remember that her father replaced the "engine" several years ago. She is not mechanical at all. Not sure if she knows the difference between the heads and entire motor. Is there a story behind plaid valve covers?
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Old August 10th, 2017, 08:03 PM
AZKen AZKen is offline
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Default Re: What type engine?

Plaid cover were in 63. Stories are: GMC wanted to snaz up sales and/or designate some update change. One year only. Never seen any actual documentation as to why plaid except some say Scotts were frugal and so was the GMC? or something like that.

I am not an expert on this, but have done it a few times. Others will have further ideas/suggestions/procedures.
Start up is generally making sure the motor is not frozen by hand turning it, with plugs out, to see that it is free. Then making sure there is fresh oil/filter and that the oil is circulating. You can squirt oil all over valve train. You can crank motor and see oil flowing up there which tells you the oil pump is working.

Depending on the known history and last time run, some folks will spin the oil pump using a drill to observe a gauge or see flow in valve train. Some will install a new pump. Some will take their chances and be sure to rig up a pressure gauge at the gauge sensor hole on filter housing. Some will squirt some oil into each plug hole and soak for a little while before cranking with plugs out. It is good to do this cranking using the starter, before actual fire up. Take off center tower wire on distributor, so it won't have spark.
You can search on this web site and others for general start procedures for motors that have been sitting. It's basically the same for all older motors, Chevy, GMC, etc.

Starting up and running a motor that is not circulating oil will cause damage. Don't get paranoid, just do the diligence. If you can not turn motor by hand using a socket on the crank pulley (plugs out), there will be a whole new procedure.

Last edited by AZKen; August 10th, 2017 at 08:25 PM.
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  #8  
Old August 11th, 2017, 07:46 AM
George Bongert George Bongert is offline
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Default Re: What type engine?

Quote:
Originally Posted by AZKen View Post
Plaid cover were in 63. Stories are: GMC wanted to snaz up sales and/or designate some update change. One year only. Never seen any actual documentation as to why plaid except some say Scotts were frugal and so was the GMC? or something like that.

I am not an expert on this, but have done it a few times. Others will have further ideas/suggestions/procedures.
Start up is generally making sure the motor is not frozen by hand turning it, with plugs out, to see that it is free. Then making sure there is fresh oil/filter and that the oil is circulating. You can squirt oil all over valve train. You can crank motor and see oil flowing up there which tells you the oil pump is working.

Depending on the known history and last time run, some folks will spin the oil pump using a drill to observe a gauge or see flow in valve train. Some will install a new pump. Some will take their chances and be sure to rig up a pressure gauge at the gauge sensor hole on filter housing. Some will squirt some oil into each plug hole and soak for a little while before cranking with plugs out. It is good to do this cranking using the starter, before actual fire up. Take off center tower wire on distributor, so it won't have spark.
You can search on this web site and others for general start procedures for motors that have been sitting. It's basically the same for all older motors, Chevy, GMC, etc.

Starting up and running a motor that is not circulating oil will cause damage. Don't get paranoid, just do the diligence. If you can not turn motor by hand using a socket on the crank pulley (plugs out), there will be a whole new procedure.

Greetings Fellow Club Members!

Adding to AZken's suggestions, it is also highly advisable to use compressed air to blow any dirt or other debris from around the spark plugs before removing them so that it (dirt) does not wind up in the cylinders. The GMC Big Block V-6 engines are the only ones that I know of where the location of the spark plugs would allow this to happen.
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  #9  
Old August 11th, 2017, 08:25 AM
AZKen AZKen is offline
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Default Re: What type engine?

Very good point George. I had to tape a small diameter plastic tubing (3/16 or 1/4) to the end of my shop vac hose so as to get down in there to clean while plugs were still in. Worked really well as I dug with an ice pick at same time. Also worked in other nooks and crannies throughout.
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