1966 GMC 305 V6 Service

[Rufton]

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.

[Rufton]

Bronze guides, shaved heads, cleaned rockers, etc.

[Rufton]

verified oil flow

[Rufton]

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

[Rufton]

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

[Rufton]

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

[Rufton]

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.

[Rufton]

Crank grease was thick but still wet.

[Rufton]

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

[Rufton]

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.

[Rufton]

Pistons in 305E V6

[BigDan3131]

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.

[Rufton]

Originally Posted by BigDan3131

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.

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

[Rufton]

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.

[Rufton]

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.

[Rufton]

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

[Rufton]

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

[Rufton]

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

[Rufton]

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

[TommyDuncan]

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?
Posted via Mobile Device

[Rufton]

Originally Posted by TommyDuncan

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?
Posted via Mobile Device

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.

[McMurphy]

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

[1963c-10]

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

[Rufton]

Originally Posted by 1963c-10

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

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

[Rufton]

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.