GMC 305 V6 rebuild-come in ya might learn something

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1LOW4X4

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Rebuilding a rare engine. The 305 V6 out of a '64 GMC. Torque monster, first of its kind, first V6 to be used in a truck. A little history....

The 305-cubic inch (5.0 L) 305 had a 4.25 in (108 mm) bore and 3.58 in stroke (90.9 mm). The 305 V6 was the standard pickup truck engine for GMC from 1960 to 1966, and was one of the first V6 engines produced by an American company.

FIrst 60 degree V, of course the 1st. V-6, (what SUV and Trucks have now)
High mounted Cam shaft (YOU CANNOT DRY SCUFF the cam, sits in a bath of oil at al times. (I wish they did this now, would not need special oil)
4 ringed pistons (3 compression and 1 oil ring)
The stock oil pump is capable of pumping out an incredible 14 GPM
The water pump can do 135 GPM

These engines were so over engineered that it was mind boggling to the regular truck driver and so reliable that you could only get a I-6 or V-6 from GMC unless you went out of your way to have a V-8 put in. Then you lost all the torque. In 1959 this engine made the cover of the September issue of "Popular Science"....

I'll be updating this as I go, I have a few engine rebuilds under my belt and basically it goes like this. I pull it apart and clean everything. Figure out whats good, take everything thats bad but can be fixed to my machine shop. Have him machine it all, get it back, buy what parts I need new, then paint everything and start reassembly.

But this will be more of a challenge because its not your everyday small block 350. Parts are more hard to find. I have a few good websites where there are a few guys who are willing to give me some real good pointers along the way. Motor spun a bearing back about 7 years ago, pulled it out and it sat under a tarp in the woods since then. Went and plucked it today. Left a trail of water all the way home....

Got it out of the back of the truck onto the lift, took the ls1 off the stand and got this one on it. First thing I did was put a half full drain pan under the motor, and pull the oil pan plug. I figured, whats gonna come out, maybe 4-5 quarts of oil?

WRONG.

As soon as I pulled the plug the hole started GUSHING water. For at LEAST a good minute. Then came the milky oily substance. Filled the tub, gushed over onto the garage floor and out into the driveway. The motor was full of water all the way to the top. I couldnt believe it!:lolup:

Anyways I didnt get video of that (wasnt expecting it) but I did get a small vid of when I pulled the oil filter bolt, and there was a pretty good amount of water in there too lol.

On to the pics. Didnt have much time tonight to fool with it, tomorrow is a new day.

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63chevystepside

High speed low drag.
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Good thread-liked the pics-keep us tuned. Man i had found a engine out in the sticks that yours reminded me of(455 olds rocket). It turned out pretty sweet and it looks like you got a sweet project on your hands:thumbs:.
 

Zembonez

живи свободно или умри
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Excelent.

Other than a little age, the thing looks solid. Cool old engine for sure. What are the long term plans for it?
 

Texas Jim

Texas..It's a Whole 'nuther Country
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Years ago, my Dad had a school bus business.
Most of his buses were GMC V6's.
Usually the 401ci or the 351ci.

They would run almost forever....:thumbs:
 

CJ Hungus

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That has seen better days but it should turn out bitchin when you are done. Just don't use any green paint. :D2
 

nubuilder

Why buy new when you can restore?
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Interesting engine. How does it compare in size to a 305 V8? I've never heard nor seen one of these before.

Subscribed! :tmc:
 

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