L16 queries

[Rays74]

Hi All,

My '72 wagon's L16 has begun showing an issue with dislodging it's #4 intake valve lash cap (happened last Feb that I chalked it up to POSSIBLY too loose valve clearance) that I now suspect is a failing valve seat. The engine has approx 25k on a rebuild (I bought it rebuilt) which included .75mm OS flat top 240z pistons. The head that's on it is a std 210 semi closed casting with no port work and a std 510 cam (no square lugs in the middle). I've never taken any compression readings on it but this engine pings a lot even with 91 octane and backing the timing off a skoash to 10deg (Matchbox btw)..... still rattles at anything approaching a hill or lug of any sort. The flat top Z pistons wouldn't cause that much of a difference would they?   

Anyways.....my question... keeping in mind the engine doesn't use water or overheat ever.

 

I have another head I could use...... a W53 open chamber (which is known good, has bad valve but otherwise is a good builder candidate)

What could I expect from that head? I am looking to eliminate the pinging on pump fuel at normal timing settings (approx 12 to 15deg).

 

This is strictly a cruiser not a ricky racer so reliability takes precedent over everything else 🙂

 

 

Edited November 21, 2019 by Rays74

[banzai510(hainz)]

Adjust the lash to .006intake .008exhaust to keep the lash tighter. COLD

 

you have a another distributor to try.?

if you have another try that . Yes try 10deg on timing. Hopefully to get 10deg the dist isn’t crank all to one side to get this.dist could be off a tooth and barely catching.im winging this one.

 

a W53 is less prone to detonation and bigger valves but not a huge power gain. It’s a better head.

flattops with a 38cc open chamber is going to be higher comp try 93 if you live in that area that sells that then you know

[Rays74]

Thanks Hainz, yeah my first experience with that lash pad prob last Feb I did just that...tightened up the clearances and it seemed to solve it but now it's happened again just the other evening with the tighter settings. Both times it's happened at higher rpm's on the highway..... that's why I'm thinking now it may be a loose valve seat ...IDK.

 

I don't have another matchbox dist to try but this one is working 100% no issue.... it's timed correctly where I have plenty of twist to get to any degree within reason I need so no issue there. It does run better the higher octane I use but the way it pings on 91 it would take straight 100 octane white gas to eliminate all the pinging...lol. I've checked the timing over and over again and it's fine...... I'm fortunate that I'm a small engine mechanic so I have lots of experience with engines in general.

Could this combination of flat tops and 210 head be just detonation prone?

thanks

[datzenmike]

Yeah, that's 9.75 compression so probably could use some higher octane gas and keep the timing at 12 for best efficiency.

 

The older L heads used a bronze exhaust valve seat that used the tetra ethyl lead additive in the gas to lubricate the valves. Well, lead is no more so it's common for the valves to recede up into the head. If they were rebuilt the seats would normally have been replaced with modern hardened ones. As they wear the valve lash clearance would slowly get tighter and tighter.

 

 Get a U67 open chamber head from an old L20B. Compression would be 8.6, larger valves and ports. Win win

 

 

See if the valve spring is broken.

[banzai510(hainz)]

I am winging it if you have another distributor. I finally wore out mine with excessive wiggle so I put another in there and I don’t have detonation going up hill anymore.So it must be a different adv weights in there or something .12 deg

I have a L16 w U67 head. I do have run on with my Weber carb

Is the lash pad flush on the retainer?

the W53 would help and less prone to detonation plus you could match port the head and intake bigger 

[Rays74]

That's what I thought......pretty high for today's ethanol laced crap 🙂

The sinking valve issue I have delt with on another W53 (closed chamber) and it's a bummer to live with a good performing head that's slowing chewing through a valve seat. 

You mention the U67 Mike, would the open W53 be comparable compression wise? That number sounds on target.

Hainz I will see about swapping the dist between my pick up and the wagon for a day just to see if there's diff..... and yes the lash pad is very close to flush level with the retainer bucket.

Thanks fellas

Edited November 21, 2019 by Rays74

[datzenmike]

The W-53 is a closed chamber (AKA peanut) head in that the combustion chamber does NOT extend entirely over the entire cylinder like a dome. There is a large area where the piston at TDC is only separated from the head by the thickness of the head gasket. Closed chamber heads on your engine would have a compression of 9.3.

 

 

If you have an open chamber W53 then yes, try it.

[banzai510(hainz)]

I also have a spare W53 with a sinking valve  Or maybe when they rebuilt it cut too much off the valve seat.

key on this is finding a good machine shot that will install the new ones and get it prefect across all the valaves so the stem height is same across the board so your lash pads all fit close to perfect.

[wayno]

I also had an issue with knocking/pinging when I built my LZ23(Z22 block, Z24 pistons), I was told it has a 8.9 to 1 compression ratio and it has one of my W53 super heads(closed chamber, 280Z valves, port matched to a dual SU intake manifold), at first I had the cam timed wrong and as I  recall I had it timed at 6 degrees BTDC, keep in mind that this work truck of mine gets regular gas.

One day I seen a photo if a correctly timed cam Dmike posted, I had a fresh rebuilt engine available that I checked and it was timed wrong, so I went out and checked my 520 ute engine(L20B with 219 head) and it was also wrong, I always wondered why that engine had no power, timed correctly it now has power, then I checked the work truck engine(LZ23 mentioned above), it was timed wrong also, I timed the cam correctly and that engine started knocking like crazy, I had to time the distributor(matchbox) at 0 degrees/TDC to get it to stop knocking, it was awful, and it didn't really run that great, I actually thought about putting the cam back to where it was before as it had been doing the job for 6/7 years with the cam timed wrong, anyway I mentioned a couple times that my engine was timed at 0 degrees and a member here that I had sold a rare part to mentioned I could re-curve my distributor myself or he could do it for me if I sent it to him, I asked how and he told me, I had to take my distributor almost completely apart and weld up one of the slots a pre-determined amount, I put it back together and installed it, I believe I have it set at 7 degrees BTDC now and it is a great engine, I have more power also, every once in a while I re-time it 1 or 2 degrees more advanced and it has not knocked/pinged yet, it sounds like a different engine also.

You have choices, either buy the best gas available, try it at 10 degrees instead of 12 degrees, you can have your distributor re-curved and leave it at 12 degrees and buy the cheaper gas, you do have choices just like I had choices, I burn regular with a re-curved distributor and the engine runs the best it ever has.

Edited November 21, 2019 by wayno

[Rays74]

3 hours ago, datzenmike said:

The W-53 is a closed chamber (AKA peanut) head in that the combustion chamber does NOT extend entirely over the entire cylinder like a dome. There is a large area where the piston at TDC is only separated from the head by the thickness of the head gasket. Closed chamber heads on your engine would have a compression of 9.3.

 

 

If you have an open chamber W53 then yes, try it.

 

Thanks Mike, yes it's one of the weird W53's that are semi open chamber (not closed but not as open as say an A87 US spec open)........ I ran it years ago on an L18 in my '74 pickup and liked it, no pinging and had good power on an otherwise std eng. I'm wondering what my compression ratio might be in the L16 with this head with the Z pistons and with std dished? Both .030 over (.75mm)

This engine needs to run well on todays fuel.

 

3 hours ago, banzai510(hainz) said:

I also have a spare W53 with a sinking valve  Or maybe when they rebuilt it cut too much off the valve seat.

key on this is finding a good machine shot that will install the new ones and get it prefect across all the valves so the stem height is same across the board so your lash pads all fit close to perfect.

 

My go-to machinist knows exactly what I want when I bring him an OHC Datsun cylinder head for valve work 🙂

Thanks Hainz

 

 

Thanks Wayno..... that helps, I know the matchboxes aren't curved for anything but emissions related running so I can imagine limiting the mech advance would help. I have thought of respringing the advance mech to delay the curve some but haven't given it any time.

 

Thanks for the thoughts All, appreciate your insight 😉

[banzai510(hainz)]

I heard of a guy who JB Weded the slots then filed off what he needed to get it right.

Edited November 21, 2019 by banzai510(hainz)

[wayno]

I also have one of them weird W53 open chamber heads, when I removed it and seen it was open I was stunned, but I bought it anyway, I figured if I ever built a flat top piston L block that would be a good head for it.

[datzenmike]

6 hours ago, Rays74 said:

 

Thanks Mike, yes it's one of the weird W53's that are semi open chamber (not closed but not as open as say an A87 US spec open)........ I ran it years ago on an L18 in my '74 pickup and liked it, no pinging and had good power on an otherwise std eng. I'm wondering what my compression ratio might be in the L16 with this head with the Z pistons and with std dished? Both .030 over (.75mm)

This engine needs to run well on todays fuel.

 

 

 

 

An 'open chamber head' is assumed to be 45.2cc combustion chamber displacement.

Crushed gasket thickness is assumed to be 1.2mm

Stock oversize pistons are assumed to have the same dish as the standard pistons they replace.

 

Stock L16 7.01cc dish.............................  8.58

Above L16 with 1mm over....................... 8.76

Stock L16 with open chamber head....... 7.85

 

Stock L16 with open chamber W53 head....

L24 flattop pistons..................................... 8.63

L16 / L26 7.01 cc dished pistons............ 7.7

 

L16 / L26 1mm (84mm) oversize 7.01cc piston.......... 7.88*

L16 1mm (84mm) L24 flattop piston............................ 8.8*

 

*A 0.030" or 0.75mm bore will be very slightly less than the numbers posted. It was just easier to use 1mm.

 

 

 

 

 

 

[Rays74]

Thanks again Mike, that list is just what I was looking for 🙂

Appreciate it!

-- Ray

[wayno]

My W53 head chamber looks a lot like a 210 head, I do not have an open chamber head(U67/A87) here to compare it to.

 

The head with the valves is the W53 head, the one with no valves is a 210 head.

 

 

 

 

Edited November 22, 2019 by wayno

[datzenmike]

The W53  closed chamber head was 41cc so by default the open chamber ones would be the same as our U67 and W58 heads. Like the A87 it was an L18 head and only used on our 710 and 620 L18s in '74 and the very first L20B in our '74 610.

[Stoffregen Motorsports]

On 11/21/2019 at 10:53 AM, banzai510(hainz) said:

I heard of a guy who JB Weded the slots then filed off what he needed to get it right.

A simple spot weld is just as easy and lasts forever.

[banzai510(hainz)]

True but not everybody has a welder

[datzenmike]

I don't think I would go to all the bother of JB 'weld'. It's basically 2 part epoxy and metal power mix. Great for patching and filling holes and 'gluing' things together, but not sure if it will wear well.

[Rays74]

I am looking to work with the mechanical advance a bit, along with limiting it's max adv as mentioned I'm also looking to play with the springs a bit too and possibly lighten the weights a little to see what it runs like. This will all happen of course after I decrease the static compression a little...... my ultimate goal is not power so much as ability to run cleanly on the sh*tty fuel avail locally.

🙂

[Rays74]

I found an NOS set of L16 pistons & rings so I def will be pulling the flat top Z pistons out of it.

It's been using a little oil lately so a fresh set of slugs should be good for it.

 

[datzenmike]

I would relieve the combustion chambers around the valves to unshroud them. First cc them to know the exact compression then grind away material. This will make them breath better than stock, rounding any corners will reduce pinging and the material removed makes the combustion chamber larger and reduces the compression.

 

There is also the unknown cylinder wear that has to be measured. If the cylinders are worn too much they will need to be bored to the next over size and over size pistons and rings used.

[Stoffregen Motorsports]

On 11/25/2019 at 6:04 AM, datzenmike said:

I would relieve the combustion chambers around the valves to unshroud them. First cc them to know the exact compression then grind away material. This will make them breath better than stock, rounding any corners will reduce pinging and the material removed makes the combustion chamber larger and reduces the compression.

 

There is also the unknown cylinder wear that has to be measured. If the cylinders are worn too much they will need to be bored to the next over size and over size pistons and rings used.

Any L engine can be made to run well on pump gas at 10:1. It just takes a bit of fiddling with the timing curve.

 

L engine blocks were cast with superior metals and hold up well to years of abuse. Not like the crap GM and Ford used in their blocks at the time. Standards can be relaxed a bit if you're on a budget. If the cylinders are within a couple thousandths of spec, I'd stick new rings in (gapped accordingly) and run it.

[banzai510(hainz)]

I would keep the flattops myself if you can still run them