Fresh A15 no oil to cylinder head?

[Dave Lum]

I rebuilt an A15 and matched it to a 728 casting cylinder head (round port, dry manifold (Tech Wiki - A-series Cylinder Heads : Datsun 1200 Club). It seems to have very slow oiling to the cylinder head. Since the block and heads are both later than 74, oil to the head is supplied via the same bolt hole that gets the long cylinder head bolt, correct?

We ran the engine for probably a minute, and while there is oil pressure at the bottom end, there was no apparent oiling at the top.

If we crank the engine over with the rocker arm assembly off, only a small amount of oil is coming out of the brass plug feed area. Is there a way to determine how much is enough?

[KELMO]

4 hours ago, Dave Lum said:

oil to the head is supplied via the same bolt hole that gets the long cylinder head bolt, correct?

I can't remember if it is longer but, the shaft of the bolt has a smaller diameter. This is as I remember for an A12 motor, and I thought the design was the same for all "A" motors.

[Stoffregen Motorsports]

4 hours ago, KELMO said:

I can't remember if it is longer but, the shaft of the bolt has a smaller diameter. This is as I remember for an A12 motor, and I thought the design was the same for all "A" motors.

Yes, the bolt is slimmer, allowing for oil flow.

 

But, there are also variations on where the oil passage is in the gasket.

[datzenmike]

I don't think the oil holes vary in the pre '74 gaskets or it would mean blocks would have to match heads. The oil hole is simply large enough to cover any casting/drilling variations, just like the L series gaskets oil hole.

 

Early (pre '74) have an oil jet in the block and oil is fed up into the head where a passage connects to the head bolt hole.

 

If using a later block the oil is connected directly to the head bolt hole. You can use the early head with this.

 

If you have an early block with a later head then just cut the head gasket between the oil jet in the block and the head bolt or Dremel a groove in the head in the same place. In both of these cases an early gasket with oil hole must be used or punch an oil hole in a later gasket.

 

It.s as simple as this...

 

[Dave Lum]

Block and head are both late style.

I pulled apart the rocker shaft, cleaned all the holes in the shaft and in each rocker arm (and yes made sure to reassemble everything in the same order it came off), so there is nothing blocking it once it's in the tube, which is to be fed by the center tower

My question is how long should it take to see oil finally coming out of the rocker support down onto the rockers on first startup after a rebuild?

[datzenmike]

It will run pretty well on assembly lube. There's virtually no load. Oull the oil pressure warning switch from the external oil pump, pull the coil wire off so it won't start and crank a few turns with the starter. Oil should shoot out the hole so have rags ready.

 

There should be oil on the top end, if none.... maybe it's trying to tell you there is no oil pressure at all.

[Dave Lum]

There is certainly oil pressure - we had to pack the pump with grease to get it to prime, but the oil pressure light now goes out while just cranking.

On the cyl head, oil does *not* shoot out - more like oozes.  Am going to pull that oil feed head bolt to make sure I don't somehow have some oddball in there that isn't smaller diameter.

[datzenmike]

Yes oil pump should make enough pressure during cranking to turn light out.

 

There is a restriction in the block to limit the oil flow to the rockers but not that much.

 

There are 9 bolts the same and one odd ball part number. They appear to be the same length so possibly this could be the problem.

[Dave Lum]

I have *two* of the longer bolts, one is 6.9mm think and the other in 7.8mm.   The 7.8mm one was pulled from the A14 I was running before dropping in the A15, but I don't even know where the thinner one came from.  I have tried both in that oil feed hole and I get basically the same amount if oil at the head.

[datzenmike]

Try without the head bolt and turn engine with starter. Is oil getting up there?

 

 

This shows a narrow bolt up to the rocker arm shaft. Pull that bolt out and turn the engine with the starter. Got oil???

 

 

 

 

This is the oil jet for an L series. It lubricates 4 cam tower bearings, 8 cam lobe/rocker arms and one oil squirter for the timing chain. That's a lot more than an A series. It looks to be about 1mm.

[Dave Lum]

Yeah the whole question is is that the right amount of oil I am seeing.  I kind of suspect if I pull the bolt and crank it I'll get a spectacular amount 🙂

[datzenmike]

I know the L series will fling oil like there's no tomorrow.

[Dave Lum]

Yeah, it also has a spinning camshaft bearings and lobes to lubricate though, the A-series just has rockers and valves and doesn't really need any pressure anywhere, only enough to keep things wet with oil.  

[datzenmike]

32 minutes ago, Dave Lum said:

Yeah, it also has a spinning camshaft bearings and lobes to lubricate though, the A-series just has rockers and valves and doesn't really need any pressure anywhere, only enough to keep things wet with oil.  

 

Yes but not with the oil going up into the head. The L series is OHC and like I say if running with the valve cover off at idle, you'll take a bath.

[Dave Lum]

3 hours ago, datzenmike said:

 

Yes but not with the oil going up into the head. The L series is OHC and like I say if running with the valve cover off at idle, you'll take a bath.

Goggles on, slip and slide ready!  lol

 

[Dave Lum]

OK we fired up the car and after about 3 mins we can see the oil is actually starting to puddle a little in the head.  While running the oil is not shooting everywhere, but it's slowly coming out of all the little rocker orifices, so we're good.  Not like an L-series at all.

[datzenmike]

And it might not. The L series is overhead cam and needs lots of splash oiling. The A series only needs oil for the rocker arms on shaft. Very little for the push rods and rocker tips. This may be normal.

[Stoffregen Motorsports]

On 10/22/2023 at 7:43 PM, Dave Lum said:

There is certainly oil pressure - we had to pack the pump with grease to get it to prime, but the oil pressure light now goes out while just cranking.

On the cyl head, oil does *not* shoot out - more like oozes.  Am going to pull that oil feed head bolt to make sure I don't somehow have some oddball in there that isn't smaller diameter.

Grease? I use Redline assembly lube which eventually breaks down and mixes with the engine oil. Some grease formulas will not mix witht he oil and could actually be blocking the oiling hole.

[Dave Lum]

Good points. I used lithium grease so should be OK.   The engine has been run for about 30 mins and driven a few miles and oiling at the top looks great. Time for oil change #1