L20b cured! (thanks guys!)

[herculesinwyoming]

I have had my truck almost 3 years, it has been put on the back burner many times because of money and family.

 

I had tried everything i could think of to get this engine sorted out. It would idle way too high, ran way rich, and when i checked compression it was running average of 130 per cylinder.

Today i decided to adjust the valves before i made the leap to swap in Mr Raiders engine.

All the valves were way over tight, After adjusting the valves and double checking them, i ran compression test and got, 155,152,155,160.

The idle is now where its supposed to be, it isnt running so rich, and it has much more power!

 

I must assume someone adjusted them wrong in the past, Dont valves get loose with wear?

any way it was a good day for me because this has been a long battle tring to get this engine to run like it should.

[Eagle_Adam]

winning is winning man! i cant tell you how many times ive adjusted ppls valves after i learned how. it can be a night and day difference

[datsunaholic]

Valves get tight when the seat wears in. Sometimes the seats recess, which makes the stems move up higher, hence tight.

 

When valves get loose, it's from cam or follower wear.

 

Some folks complain that the stock Datsun valve seats are too soft for Unleaded fuel, but with over 300,000 on several engines, I've never had the problem. I think perhaps using heavier valve springs may be causing the seat issues on some engines, since they're also running hot cams and a lot more RPMs than a normal street engine would do.

 

The real issues with "soft" valve seats was old cast-iron heads, where the valve seats were cut directly into the head (no seat inserts) and cast iron is far harder than brass (or bronze). . Hardened seats are generally only on the Exhaust side, made from Stellite or other harder metals. Brass intakes are still fairly common. What burned the valve seats wasn't the lack of lead, but poor heat transfer, (along with preignition, caused by running too low of octane). Lack of heat transfer got the valves so hot they burned pits in the valve seats, once a pit forms it grows very fast, and hence burned valves and seats.

[herculesinwyoming]

well its running better in some ways and worse in others, its pretty rough at idle and bogs down when i hit the gas,

Maybe i should go back in an recheck the valves since i have run it a while now.

 

at least i can get the idle right and its not so rich now, it acts like its only running on 3 cylinders.

[Eagle_Adam]

did you do the valve hot or cold?

[EricJB]

If you found 8 tight valves, I would guess human error. Not yours, the last set of hands to touch it. With that in mind, I would go through all the specs. I cant tell you how many cars I have found with the timing set at 0.

[herculesinwyoming]

yeah, i did it cold, and then hot when i double checked them. all are good, its running a bit better , but still chugs like one cylinder isnt firing.

The plugs are pretty black from running rich, so i will change them, and the gas smells stale so i will try some fresh fuel.

 

Distributor most be off a notch because i have to put it at full advance to get it to run. so i will check all of that...

any other ideas?

[Eagle_Adam]

check ur fuel filter

[herculesinwyoming]

i was about to say it seems fuel starved, fuel filter and jets will get checked next, carb is rebuilt, and last summer i had the fuel tank cleaned by a radiator shop. but sitting for 20 years im sure it had junk in the feed and return lines.

yesterday it didnt want to start because the needle valve was stuck closed,

thanks i will check fuel system.

[banzai510(hainz)]

As you know L motors are pretty basic/

Mecahincally ck the cam timming.

doing this the valve cover must be off then ck the valve lash. way I do it is if the lobe is pointing up just see if the rocker wiggles. If tight adjust that MOFO. then hit starter to rotate cam(coil wire ou) then ck the next lobes.

 

dail motor up to TDC and ck the dizzy timming. rorotr should be right on #1 plug wire . If not maybe you dizzy timming plate needs adj, are dizzy just needs adj or maybe pull the whole dizzy out and ck for the 11.28 position. if 11.28 then I will assume its good.

 

if this point ignition hopefully everything is stock and adjust the points and ck the condensore or bushing wear.

 

replace the plugs also if you havent. but to ck if a cylinder is missing is the wire you pull off noting will happen. this is usally a bad plug, or lash pad fell off that cylinder beside a burnt valve or soemthing but you got good comp so its not that

[herculesinwyoming]

thanks banzai, every ignition part is new, i will get fresh plugs and check the timing and all you suggested.

I watched the how to video on valve adustment multiple times so im pretty sure i did that part right.

I will just check fuel, ignition, and timing. Gotta be one of the above or maybe multiple issues.

[banzai510(hainz)]

I dont know how much pollution stuff a 76 has as I never deal with that stuff.

once you ck the cam timming .valve lash and dizzy timming that pretty much the extend of it, thn you can move on to other ecessory stuff.

 

when cking for idle I always put a timming light and adjust the dizzy and miixture.

[herculesinwyoming]

Valves are all in spec now, i didnt realize the timing chain could be adjusted, i think that is what i need to do next i expect that may be whats needed.

[herculesinwyoming]

Looks like im getting fuel in my oil, i guess time for a fuel pump too.

[herculesinwyoming]

Ok heres what the chain looks like at TDC. looks a tick off.

[Silky_Johnson]

Ok heres what the chain looks like at TDC. looks a tick off.

 

What you need to look at for cam timing is the V notch and dash that will be visible through one of the holes on the cam sprocket. In your picture, it's the upper left hole of the three on the sprocket... It looks like it may be lined up, but you're going to have to get a picture from a different angle.

[datzenmike]

How did you set TDC?

 

Has to be by the timing notch on the rear of the pulley at the O (zero) on the timing scale. I find it odd that the bright link just happens to be close to same position when installing it.

 

Set TDC and this....

 

... is the proper position for correct cam timing. You can move it a tooth, you can change the cam pin number you can sacrifice a chicken... but the above relationship of the notch on the back of the sprocket being below or just to the right of that horizontal etch line is what you hold to.

 

 

If you found 8 tight valves, I would guess human error. Not yours, the last set of hands to touch it. With that in mind, I would go through all the specs. I cant tell you how many cars I have found with the timing set at 0.

 

After 3 years I would hope the valves were checked at least once.

[herculesinwyoming]

like this?

[datsunaholic]

The bright link only lines up on initial install. Once the engine has been cranked at all, it's going to end up somewhere else. Look for the V-notch as stated above.

[datzenmike]

 

That's much better. I'd say that's fine. Moving it ahead one pin position on the cam is 4 degrees or about the width of the horizontal line. I think moving the V notch to the left that much would be too much.

.

[herculesinwyoming]

Problem is it wont run unless the distributor is at full advance, and then it runs like crap.

[datsunaholic]

Take the dist adjuster bolt OUT and see if you can get it running better going past the limit. If that solves it, you either have the dist spindle off a tooth, or you have the wrong distributor/adjuster plate/pedestal combination. If you have to go 90 degrees, you have the wires in the wrong spots.

[herculesinwyoming]

Ok its getting late and its cold out there, i was thinking the same check the distributor tomorrow. truck has been running just never have been able to get it dialed in.

[banzai510(hainz)]

its in the dist if you haves to crank it all the way or the spindal is off a tooth.

Something was change or installed wrong.

[herculesinwyoming]

I always assume when a vehicle is parked in a persons yard for 20 years, its usually because something was wrong.

the front timing cover and water pump look like they were put on just before it was parked, lots of blue silicone haha. i agree after sleeping on it i will check the distributor setting.