Rays74

Thanks for the replies.....once in a while I do top up the coolant but it's not often and less than a pint when done, I will redo the head bolts just to rule it out. This is def a problem after it's set overnight as well as after sitting in between errands and such, I hadn't thought of the intake or it's gasket so I will def check that. I have seen moisture in that cyl overnight once I figured out what cylinder was affected and pulled it's plug, I did swap entire ignitons from my other truck just to rule out the EI dizzy being a problem...no change of course. In the the other car I mentioned (72 wagon with L16) the milkiness was only in the radiator.... I had never encountered this (I'm an M/C tech) but it finally ended up being the head that was the problem (A87 peanut, I bought the eng complete from Datsun parts so yeah) as I bolted on a std 210 head and the problem went away (25k ago). The radiator full of that mixture but not the crankcase was a head scratcher! LOL _Ray

Hi all, My '74 620's L18 has begun doing a strange thing .......... in the morning and sometimes upon restart after an hour or so the engine will miss and run on 3 cyl for approx 5-10secs then clear up and run fine. I rebuilt this engine 6 years ago and for the last 30k has run great with no oil or coolant probs. I pulled the plugs (all look same nice latte coloring) and did a compression check and they are all within 5psi of eachother (150-155.... I used L20B pistons in the build, a little lower comp but runs great). There is no water in the oil or viseyversey. No.1 piston top does have the classic steam cleaned look when viewed through the plug hole. Some years ago I DID have a coolant and oil mixing problem in my 510 wagon which turned out to be a cracked A87 head so I'm worried this may be a repeat..lol. Anyone ever encounter this ? thanks, -Ray

Thanks Ice, appreciate the offer 🙂

I knew the GL-3 was a reach but it was better than the GL-5 I had avail 🙂 Ford and Mazda have used ATF in their 5spd's for many years so I do understand it's more than up to the job in any manual trans (I'm a motorcycle MC too and we also use it in some of the dirt bikes as well). I realize there is no magik elixer here for worn out sychros so we'll just hope for the best. Thanks for the help. -- Ray

Hi Mike, Did an oil swap last month.... used some GL3 synchromesh I had here at the shop hoping for the best but it's actually seemed to aggravate it further...lol. Maybe the atf should next..... Ford F type I assume?? thanks, -- Ray

So 3rd gear synchro in my wife's '72 wagon is on it's way out (grinds with any quick shifting...getting worse through the last few weeks).... anyone got a stock trans in decent shape kicking around? I'm in So Cal. Thanks! -- Ray

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.

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. 🙂

Thanks again Mike, that list is just what I was looking for 🙂 Appreciate it! -- Ray

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. 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 😉

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

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

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 🙂

Be aware as well that the square manifold will have likely come from either an L16 or L18 and may end up pointing the downpipe at the bellhousing since the L20B is a touch taller. It's workable but just know 😉

As a 40+ year motorcycle and small engine mechanic I've had lots of experience with different types of sealers......used with gaskets and without (many engine case halves are assembled using only semi hardening sealants such as Yamabond 4, Hondabond 4 or Theebond 1184 all gray colored). I tend to error on the side of caution and use a very thin layer of sealant ( I say thin as in not seen when the part is assembled it's only there to supplement the main gasket not replace it) on most critical gaskets and it has worked very well for me for this many many years. Of course the sealants I use are gray colored as to not be seen so easily and anything that happens to squeeze out gets wiped off immediately with a rag or perhaps a drop of gasoline on a towel (easily done before it sets up, impossible afterwards) ....... I don't understand the fascination with using neon orange or blue RTV so much so that it squeezes out of the surfaces you're trying to seal! LOL As a Datsun owner and rebuilder of my own engines I can tell you they all were built the same way using either Yamabond 4 or Threebond 1184 on their gaskets, they don't leak and thats the way I like it 😉 Just one mechanic's way