'65 GMC 1500 project. From the Netherlands

[Prowbar]

Still working on preparing everything for re-assembly.



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Found the culprit of the dirty oil issue... used the wrong oil filter gasket.
Fel-Pro doesn't supply the right gasket for a spin-on oil filter adapter in their gasket kit and I never bothered to check. This allows some oil to bypass the gasket from dirty to clean side. Live and learn.
Decided to not run the bypass blocker, I'll stick to the OEM bypass from the get go. I found the specs for the differential pressures in the filter I'm using on Bob Is The Oil Guy forum (I've did a lot of reading and research on oil and filtration)

Instead of the typical Wix 51049 I'm going to run a Baldwin filter instead.
I cannot find any reliable filtration data on the 51049. Only found a "micron rating" of 21 (I'm assuming that's nominal, meaning absolute should be higher) I'm sure its a good filter but I don't like "not to know things".
I'm going to run a Baldwin B1428. It has the same 13/16-16 thread and diameter and gasket location. This filter has an anti drain back valve as well.

Specs from BITOG:


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B1428

BX=2: 12 microns (nominal rating, 50% efficiency)
BX=75: 25 microns (maximum reliable filtration ratio, 98.67% efficiency)
Established Micron Rating: 12
Average Efficiency: 89.44 %
Burst PSI: 300

Flow
3PSI: 2GPM
5PSI: 5GPM
10PSI: 9GPM
15PSI: 11.5GPM

The V6 has a 14 GPM oil pump according to the GMC advertisements. This is probably the rated max flow at 3800 rpm. Now this isn't the actual flow to the filter and bearings. A large part of the flow goes back to the pan without passing the filter via the oil pump pressure regulator. Oil pumps are oversized to account for worst case scenarios.

Filtration with the B1428 is excellent. Even the max. particle size at 25 microns is smaller than half of the bearing clearance. This isn't gospel but should put it in perspective.

With a 11 psi bypass valve I'll need a flow of at least 9 GPM for the bypass to open. Pretty sure the oiling system isn't capable of flowing 9 GPM. Only time the bypass opens it at a very cold start when the oil is thick and you decide to rev the engine to the moon or when the filter is clogged. Oil, even most multigrade oil, is thicker when cold so there's more resistance to flow through the filter. 11 psi is quite the differential pressure. I don't expect it to open anytime soon.

I don't know what viscosity of oil and the temperature they tested this with though. I'm assuming 10W-40 at operating temperature. But judging by the provided data and comparing flow numbers above I'm pretty sure the bypass will rarely open.

Except the intake and head gaskets I'm making all my own gaskets. Head gaskets are the 305 V6 gaskets that I'm converting using my little setup that I showed before. The old head gaskets that I did that way look mint so that gives me confidence.



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Making gaskets is fun I think. I like doing it.

Here's ones of the old head gaskets. Looks mint, as you can see I used some additional sealer. Got it as a recommendation, basically don't use that stuff because all it does is plug up the coolant holes in the cylinder head. Fel-Pro doesn't recommend any sealer either so no need.



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The timing cover protruded .016" above the oil pan gasket rail on the 478 block (this is the 305 timing cover) With the cork gasket this didn't pose a problem, but now that I'm using the oil pan spacer I went ahead and milled the surface to even them out. See the result below.



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Gapped all the new piston rings. Made sure I gapped them to spec at the bottom of the bore, just below where the top ring stops at BDC. Only needed to gap the chrome plated top rings, the cast iron 2nd and 3rd rings needed no gapping, they were right in the middle of spec already.
Have a little trick up my sleeve so I can freshen up the old oil control rings. I'll share that when I get to it.



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Right now I'm working on the cylinder heads. Will be covered in a later post. Have some interesting things to share there as well.

[Prowbar]

Well, all that theory is fine and dandy if the filters actually fit...
Read on the forum that there's 2 spin on oil filter housings types (thanks BobBray)

Originally Posted by BobBray

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Now time for some trivia- some late production spin-on oil filter housings were slightly larger in diameter and took a Chevy style filter (PF35) instead of the Buick/Pontiac/Olds (PF24) type. Extra points if you score one of those!

My oil filter adapter is the smaller PF24 style. This takes the Wix 51049 filter with the small gasket size. The PF24 filter is outdated now.

The PF35 style adapter takes all the filters I bought

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Notice the difference in gasket diameters.



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Anyway, I've ordered new filters and an oil filter cutter to inspect them after use.

These are the filters I'll be using.
Wix 51049 - known and loved

Fram Extra Guard PH11 - turns out these actually have excellent filtration (99% @ 20 microns)

AC Delco PF61E - this filter should fit my adapter. Its a smaller diameter filter with the right 13/16-16 thread.

BOSCH 0 451 104 026 - has an anti drainback valve

MAHLE OC 103 - has an anti drainback valve as well.

After all the reading I've done it basically boils down to this:
To make an engine last, you should:

Avoid excessive cold starts and short trips - most engine wear occurs during the warm up phase - less starts and warm up cycles = less wear. Short trips = bad for cylinder walls and engine oil.

Never beat on a cold engine, let it warm up. Drive gently and avoid high load until at operating temp.

Load = wear - at any temp.

Make sure the engine is well maintained. Right oil at right level, periodic oil and filter changes. Fuel system is right. PCV works right.
Oil filters get worse when they age, air filters get improve when they age (until a certain point).

It is sure easy to lose yourself in heated internet debates about the most minute things.

Can't say my engineering mind will approve of any oil filter that lets a bigger particle size than 30 microns pass - the Baldwin B9 for example (fits the PF24 style) has an absolute rating of 40 microns - don't need a rock catcher, but an actual oil filter please. Will that filter make an engine last - probably so, and you'll never notice a difference in engine performance.

Your thoughts?

[Jim A]

I am enjoying this thread, even though I doubt I will rebuild any more engines,
Thanks.
I love that massive 4 main support system GM gave our 305 crankshafts.

[Prowbar]

Originally Posted by Jim A

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I am enjoying this thread, even though I doubt I will rebuild any more engines,
Thanks.
I love that massive 4 main support system GM gave our 305 crankshafts.

Thank you Jim! It makes my day to recieve some positive feedback. I enjoy making these writeups as well.

Did you rebuild a lot of engines back in the day?

Yes, the GMC has massive mains and rods, a sturdy bottom end for sure. Nothing wrong with a beefed up engine! Adds to the reliability and doesn't need fancy oils to make it last.

Hoping that after all this work it'll go for the 200.000 miles without a major rebuild - as was advertised in the 1960's. I love these engines.

[Jim A]

Using my GMC to make most machine shop and parts runs, I rebuilt (in no particular order) 2 VW,s, 2 Packards, 1 Bristol (AC), 1 Ford, 1 Triumph (TR3), 1 Mercedes, 1 MG (TD) and maybe some forgotten.
Other work on other makes.

[Prowbar]

Originally Posted by Jim A

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Using my GMC to make most machine shop and parts runs, I rebuilt (in no particular order) 2 VW,s, 2 Packards, 1 Bristol (AC), 1 Ford, 1 Triumph (TR3), 1 Mercedes, 1 MG (TD) and maybe some forgotten.
Other work on other makes.

Nice Jim. Looks like you have a lot of experience. Did you ever do any work on the GMC V6?

[Prowbar]

Been a little while. Got a new job as a machinist so that takes up quite a bit of time.

Been working on the cylinder heads and the crankshaft.

Took the cylinder heads apart and cleaned them. Valves and valve jobs looked good, none of them leaked a drop of brake cleaner when I sprayed it in the ports. There was quite a lot of carbon build up on the intake valves. I used EGR cleaner to clean the valves, combustion chambers, and ports.



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I needed to regrind the exhaust valve as they had the weird concave wear, which is often attributed to weak valve springs which was something I already suspected.

Decided to regrind the intake valves too, because I had it all apart. I then checked the valve stem to seat runout in the lathe using a dial indicator. All except 2 were within .0015". I touched them up again and they were were good to go, too.



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I reground the exhaust valve seats and lapped the seats until I had a good contact pattern. I then made a valve seat runout gauge. The book mentions that they should be within .002". Quite a few were outside the spec, around .0025". I touched them up until there were all .0015" or less.



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Knowing all the valves and seats were good, I could move on to the springs.
The Impco article that I posted years ago about 401 V6's on propane foreshadowed that the stock valve springs are too weak. They upgraded to a Ford valve spring using a spacer.

Went ahead and ordered Melling VS840 springs. These are stock replacement springs for a Ford 460 V8. They are too almost identical in dimensions but a little shorter. I went ahead and tested the stock and Ford valve springs using my redneck setup in the drill press to find out what the actual pressures are.



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The GMC manual lists 76-84 pounds of seat pressure. When I tested mine I got 64 pounds of seat pressure. The Ford spring without spacer got around 40 pounds of seat pressure. The GMC springs didn't make the free length spec either. Looks like they have been getting weaker over the years. Better to replace them now.

I wanted around 100 pounds of seat pressure and less than 280 pounds over the nose. Mike Jones recommended me to not exceed 280 pounds open pressure, otherwise break in springs are needed to break in the camshaft.
A little extra seat pressure should aid in heat transfer and prevent the valve from bouncing on the seat.

Using these springs I designed a spacer and made it out of chromoly steel that I had laying around. Old hydraulic cylinder rod makes for great bar stock. It locates on the valve spring rotator and in combination with the Ford spring gives me 100 pounds of seat pressure and 220 pounds of open pressure. I'm about 1/4" away from coil bind at full lift, so plenty safe.
The spacer in the picture sits cockeyed, was due to a locating bore that was too tight, fixed that later.



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I milled a small groove in the nose of the spacer to aid in oil drain.



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Installed new valve stem seals and reassembled the heads. I already cleaned up the rocker arms and polished the rocker arm shafts.

[Prowbar]

I mentioned before that the crankshaft rear main seal area had pitting and needed to be welded up. I had a company lined up that would do it for me. Even did the prep work that they requested - then the company didn't want to do it.



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Fine, I'll do it myself. Getting sick of these companies not living up to their word. I try to learn and do everything myself, and for good reason. No BS, fast turn around, a learning experience and all that for a fraction of the cost

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Because of the flywheel flange I cannot use a Speedi sleeve or repair sleeve out of 1 piece - impossible to install. The sleeve needs to be split.

Took a scrap piece of honed cylinder material that we use at work. Its made out of 304 stainless. Made a repair sleeve out of it.



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I undercut the area for the sleeve in the crankshaft. Its about 9/16" wide. I made radiused relief cuts at the ends to prevent stress risers.

Lifting that massive crankshaft in the lathe is a 2 man job - its a beast of a crank for sure.



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I split the sleeve and degreased crankshaft and sleeve halves. Loctite 648 was applied to the sleeves, but kept away from the split line. The sleeves were then installed on the crankshaft and clamped in place.



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Using TIG welding, I tacked and welded the sleeves together. Contraction from the welding pulls the sleeves tightly together, resulting in a very strong mechanical bond to the crankshaft in combination with the Loctite. Made sure I got good penetration as there quite a bit of material to be machined away. I ended up with about .0043" wall thickness.



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The crankshaft was then reindicated in the lathe and turned down to the original diameter and polished. Didn't run into any inclusions or problems with the sleeve moving or coming loose - all looks well.



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I'm very satisfied with the result, I didn't expect it to work this well. In combination with the NOS rubber lip seal this should be more than fine.
By the way, the bearing journal is dirty with dust and WD40. It looks fine when its all clean.

Only have got a few jobs left before the engine can be put together. More to follow soon.

Hope you guys enjoy.

[James]

Originally Posted by Prowbar

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The GMC manual lists 76-84 pounds of seat pressure. When I tested mine I got 64 pounds of seat pressure. The Ford spring without spacer got around 40 pounds of seat pressure. The GMC springs didn't make the free length spec either. Looks like they have been getting weaker over the years. Better to replace them now.

I wanted around 100 pounds of seat pressure and less than 280 pounds over the nose. Mike Jones recommended me to not exceed 280 pounds open pressure, otherwise break in springs are needed to break in the camshaft.
A little extra seat pressure should aid in heat transfer and prevent the valve from bouncing on the seat.

Using these springs I designed a spacer and made it out of chromoly steel that I had laying around. Old hydraulic cylinder rod makes for great bar stock. It locates on the valve spring rotator and in combination with the Ford spring gives me 100 pounds of seat pressure and 220 pounds of open pressure. I'm about 1/4" away from coil bind at full lift, so plenty safe.
The spacer in the picture sits cockeyed, was due to a locating bore that was too tight, fixed that later.



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A few years ago I researched for a replacement valve springs. I ended up using Comp Cams 972-16

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(this is for a V8, so I have four spares). I tested the spring and got slightly better than stock specs requirement.

[Prowbar]

Originally Posted by James

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A few years ago I researched for a replacement valve springs. I ended up using Comp Cams 972-16

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(this is for a V8, so I have four spares). I tested the spring and got slightly better than stock specs requirement.

Thanks James. I too looked around for springs that were a drop in fit but settled for a stock replacement spring thats a fraction of the cost. With access to machinery it's easy to whip up the part you need to make it all work.

Melling does offer a more heavy duty spring (Melling VS280) with an inner damper. This is probably the better spring to use as you can use a thinner spacer to obtain the same seat pressure.