1966 GMC 305 V6 Service
 

Thought I'd post a few 305E pics since you don't see em every day.

Blew head gasket 2012. There was enough cylinder ridge to warrant rebuild. I just did head because I didn't want disabled truck in garage.

Hope to complete lower half soon.

Re: 1966 GMC 305 V6 Service
 

Bronze guides, shaved heads, cleaned rockers, etc.

Re: 1966 GMC 305 V6 Service
 

verified oil flow

Re: 1966 GMC 305 V6 Service
 

I might be a weenie but those 305 V6 heads are heavy:)

Re: 1966 GMC 305 V6 Service
 

Not the best spring compressor but it worked.
DE1607 looks about right to my eyes.

Re: 1966 GMC 305 V6 Service
 

Installed and tested the heads.
Runs good; still has personality and drinks too much.
I am servicing short block now.

Re: 1966 GMC 305 V6 Service
 

Opted for a short block that was rebuilt by machine shop but never installed.
To be safe I tore it down to check critical specifications.

BTW: Drain the oil before flipping block.

Re: 1966 GMC 305 V6 Service
 

Crank grease was thick but still wet.

Re: 1966 GMC 305 V6 Service
 

Crankshaft is huge and weighs a ton.
Bore starts at 4.25"

Re: 1966 GMC 305 V6 Service
 

I used inside and outside micrometer to check cylinder wall clearances and bearing clearances.
These pistons have 4 ring grooves.
Two pictures of oiling slot which is under oil ring.

Re: 1966 GMC 305 V6 Service
 

Pistons in 305E V6

Re: 1966 GMC 305 V6 Service
 

Of course its heavy I read it weighs about 800 lbs and lucky for me it failed in the truck I got for free otherwise it wouldn't be my free truck.

Re: 1966 GMC 305 V6 Service
 

All the galley plugs came out pretty easy except the big one. Broke a 1/2" bolt. Finally came out after I melted wax into threads. looks like machine shop didn't remove rear plugs.

Re: 1966 GMC 305 V6 Service
 

This is what gets trapped in rear galley plug pockets.
There is no flow in this pocket and some don't bother to clean.
Don't forget galley plug hidden by distributor; thankfully it came out w/ mild steel 5/15" square bar.

Re: 1966 GMC 305 V6 Service
 

Wow. People:)
I was starting to feel like Wilson.
Can't beat a free.

Re: 1966 GMC 305 V6 Service
 

Cleaned all important threads w/ tap and die.
Dirt or burs can affect torque specs.

Re: 1966 GMC 305 V6 Service
 

Cleaned w/ pressure washer and detergent after rag clean.
Payed attention to debris in cooling channels.

Re: 1966 GMC 305 V6 Service
 

Failed deck blind plug may cause 305E heating issue so I replaced.

Re: 1966 GMC 305 V6 Service
 

Sharpened razor frequently to remove burrs and avoid scratches.
Made hone depth gauge w/ tape to avoid breaking stones and damaging bores.

Re: 1966 GMC 305 V6 Service
 

Thanks for the write up. I have always been curious about these motors but most people say it's a boat anchor.
I know where there is a really clean 66 with this motor. The owner says he dropped a bolt down the intake manifold and it has been sitting ever since(6 years that I know of). Maybe he will sell it to me one of these days?
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Re: 1966 GMC 305 V6 Service
 

I've always enjoyed driving the 305 V6 GMC.
I like the sewing machine sound of the solid lifter engine.
Proved to be more durable w/ less maintenance than all our other 60's vehicles.
Loves to cruise at 70mph.
Satisfying torque.
Not for the races though.

Re: 1966 GMC 305 V6 Service
 

Such a cool write up!
You explain and show everything so well, makes me tempted to think I could do this!

I am ready to see more :metal:

Re: 1966 GMC 305 V6 Service
 

Very well done thread. Now how about some pics of the truck

Re: 1966 GMC 305 V6 Service
 

Measuring deep cam bearing clearances is difficult w/ inside micrometer.
Need special equipment to verify cam bore alignment.
As a minimum verify lubed cam rotates w/o excessive drag and check end play.

Re: 1966 GMC 305 V6 Service
 

Cleaned cam w/ kerosene. WD40 to avoid dry spots.Assembly lubed distributor gear,bearings and lobes on first 1/4th shaft then began install. Lubed remaining bearings and lobes during install to minimize mess. Used coat hanger to balance cam.

Re: 1966 GMC 305 V6 Service
 

Mark cap address before removing from worn engine.
Easy to verify connecting rod clearance w/ inside and outside micrometer.
Don't forget to make sure cap is on it's mate in original orientation.
Crank main bearings over 3" and crank pins over 2.8" which is hefty.

Re: 1966 GMC 305 V6 Service
 

Lightly polished crank.
crank end play.
Cleaned all oil passages.

Re: 1966 GMC 305 V6 Service
 

Used newfangeled rear main seal RTV, pipe cleaner thingy, and H2O to initiate cure.
OEM rear main side seal style more difficult to install and was phased out of my gasket kit.

Re: 1966 GMC 305 V6 Service
 

Excellent write up so far! With that much meat between the cylinders I bet it could hold a lot of boost with the right head gasket setup and a forged bottom end. How large can they be bored out to?

Re: 1966 GMC 305 V6 Service
 

Didn't forget the hidden galley plug:)

Re: 1966 GMC 305 V6 Service
 

Maybe, if this freshened engine behaves.
Truck is camera shy.
Lil rough around the edges:)

Re: 1966 GMC 305 V6 Service
 

Mine is 40 over.
Some versions came w/ advanced metallurgy crank.
All cranks are over designed and super heavy.
You could improve power a bit for kicks just check pockets first.

Re: 1966 GMC 305 V6 Service
 

With that hefty bottom end and the low end torque these engines make I can only imagine one with a supercharger!
Is there a good source for parts for these? Are most wear items readily available?
I have always liked the "unique" engines. I had a Jeep with an odd fire V6 and although it was sometimes frustrating, it was a fun engine to work on and it had a sound all it's own.
Your build thread really has me thinking...
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Re: 1966 GMC 305 V6 Service
 

Can't just buy every part at wally world but I was able to source everything pretty quick and easy; maybe I got lucky just this one time. There were some parts on ebay that came and went. I had all new parts sourced but didn't buy because I found a built short block.

Executive summary: The easy way is Chevy 350.

Re: 1966 GMC 305 V6 Service
 

Before pulling tired 305E I took pics of coil, alternator, etc.

Re: 1966 GMC 305 V6 Service
 

Siphoned coolant to avoid mess and for possible reuse.
Knocked out front seal.

Re: 1966 GMC 305 V6 Service
 

Punched out dip stick tube w/ drill bit.
Tagged push rods.
Crank pulley.
Trans bleed.

Re: 1966 GMC 305 V6 Service
 

I went ahead and stripped short block in truck; not typical.
Just got started and couldn't stop.
Everything so easy to access.
Ran into zero frustration which is nice.

Re: 1966 GMC 305 V6 Service
 

Not every day you see someone remove the engine and trans and leave the bell.

Re: 1966 GMC 305 V6 Service
 

Sludge not bad for a few decades.
I didn't touch inside pan; just propped it up over night.
Only possible sludge issue I saw was rocker arm shaft which can easily be serviced after removing valve covers.
In the future I will verify rocker arm flow every time I adjust lifters.
In the past only adjusted lifters about once per decade or two.