Datsun Roadster Forum-311s.org

Went through and checked all the valves today. Everything looks like you'd expect 100 mile valves to look. Passed leakdown, moved smoothly in the bores, stem seals are good.

Did find a little wear on a couple of the spring cups.

Also cleaned out my oil pan as well as I could. If I find any new metal I'll be pretty sure it wasn't in there to start. I opened up my oil filter (that I drove on for probably 3-4 days) and only found 2 or 3 lil pieces of metal.

Dean at Datsunparts.com has ndc rod bearings, part# 1615B. I just ordered a set for my U20. Please pull the timing cover, a lot of moving parts under there. Pat

I'd also put a piece of Plastiguage accross the journal with the odd edge wear, and torque it down a little. You might find the journal not ground evenly. Pat

Got new rod bearings in tonight. They all mic'd exactly the same as the old set and passed plastigauge. None of the other 3 rod halfs looked particularly bad. The piston rings were all fine.

Tomorrow I should at least have time to put the pan on when my gasket comes in and make sure I'm getting good flow out of the block.

Be sure to use a quality assemble lube on your bearings. Don’t want to ruin anything in case your oil flow problem still exists.

Confirmed I was getting oil up thru the block. It is more like a 'seep/ooze' with pulses as the cam hole went by, but at the low RPM the starter turns over at I suspect that's normal?

I am still getting the odd jumping as the engine turns over. It seems to line up with TDC on each cylinder or maybe some degrees after?

https://vimeo.com/596344607

https://vimeo.com/596344949

You can see it in the slow mo..I don't know WTF it's all about. I understand that valve spring resistance on the cam isn't the same throughout the rotation, but it still seems odd.

So wait a minute... is the snapping sound the valves sticking in the guides and then popping up? Also, the slo-mo really showed the delay as the distributor rotated... that cannot be right (?). Its gear driven, so I'm not sure how that can happen without broken teeth (?) WTF is right.

I know you said you had checked the valves... did that include removing each spring and inspecting the stems and guides? If the concern was that the engine was not oiling properly, then they could have galled themselves as there is very little oil allowed past the seals to lubricate the stems/guides to begin with. Could they be that dry? I don't know if this will wok, but you can try spraying some WD40 type lube on the stems above and through the port and see if that has any effect. However, unless they completely free up, I think the head will have to come off for more inspection. A bent valve will also do this. If the snapping sound is from a sticking valve I'd be concerned, but I am not an expert.

On a U20, when turning by hand with the plugs out there are areas of a natural resistance as you compress the springs. With the upper tensioner off or not properly shimmed to take the slack in the chain, the bottom half of the engine will actually rotate quite a bit with the cam staying stationary, and then it will suddenly snap and rotate. I don't know if that is possible on a push rod, single chain engine, but if so I would think that there has to be a lot of slack in the chain that is not being taken up by the tensioner. We need other experienced R engine owners to chime in...

Man, I feel for ya. Been there.

I think the distributor is just reflecting what the whole assembly is doing, ie not turning over evenly.

All of the valves moved smoothly, certainly nothing that would hold up an entire rotating assembly and cause it to jump forward.

Only time I've ever had an engine turn over smoothly is with the head off. Even with plugs out it wants to stick because of the valve train.

Curtis wrote: Thu Sep 02, 2021 11:25 am Only time I've ever had an engine turn over smoothly is with the head off. Even with plugs out it wants to stick because of the valve train.

I am very tempted to just assign it to that, but the noise associated def has me worried.

Area that #1 jumps to just to give you an idea in relation to the crank. Basically the firing position

With the head on and trying to crank it with the button it NEVER lands on TDC. Either stops before it or jumps past it. I get close and then turn it with a wrench.

Curtis wrote: Thu Sep 02, 2021 12:27 pm With the head on and trying to crank it with the button it NEVER lands on TDC. Either stops before it or jumps past it. I get close and then turn it with a wrench.

Does yours have any noise associated with the 'jump' past TDC? I am just turning it by the fan cuz I don't have a 1.5" socket yet lol.

No. I use a wrench. socket is a pain and doesn't fit except coming in from the front and then it's hard to hit the mark.

Probably obvious, but it turns over normally with the starter without the rocker shaft on. It also still makes the noise with the distributor off. It also makes the noise with all of the valve adjuster nuts very loose.

Also confirmed I'm getting oil up through the head (once it primed I could even turn it by hand and see it being pumped out).

Did you get a chance to remove and inspect under the timing cover?