Power Problems...Not Bogging? L-16

[That4doorKiD]

I was test driving my 510 today and in neutral it revs fine all the way. Test driving it in to 1st gear is fine but a little weak on power and revs good, but 

once I shift into 2nd it slows down and the power is really weak. While I give it gas in second the speed stays and doesn't rev higher. 

 

I checked if it was the vacuum advance, but the carb vacuum was working fine. So plugged it into the intake manifold vacuum line(stronger) and the idle sounded wayy smoother and reving was better responsive, but only in nuetral. So I test drove it again with a stronger vacum advanve, but it still lacked power, no changes but the sound of my exhaust, which sounded smoother.

[bananahamuck]

Have you adjusted your valves??

[That4doorKiD]

Have you adjusted your valves??

Yupp

[bananahamuck]

Distributor vacuum advance won't work with manifold vacuum signal except at idle.  .. How about your choke is it all the way open??

 

When you have timing light on it , does the mark advance when you rev the engine?

[That4doorKiD]

Distributor vacuum advance won't work with manifold vacuum signal except at idle.  .. How about your choke is it all the way open??

 

When you have timing light on it , does the mark advance when you rev the engine?

I've been checking the timing myslef, haven't had someone rev it for me when I'm looking at the timing. But it's at about 10 degress at idle. Will check if it advances tomorrow.

[datzenmike]

Two things. Neither difficult to do but must be eliminated.

 

1/ Replace your fuel filter. It's part clogged and the engine is using fuel faster than it can be supplied to the carb. Costs $4 and if not the cause, no harm done.

 

2/ Primary jet is part blocked causing a lean condition under load.  This is why it revs in neutral... no load.  Drive it for a mile or two as hard as you can and pull over. Remove a spark plug and examine. If the porcelain insulator at the tip is bright white this indicated a severe lean mixture. Normal color is light tan/brown. Black dry would be too rich. Stock carb?

[banzai510(hainz)]

haven't had someone rev it for me when I'm looking at the timing????????

 

rev throttle with your other hand and look at timming

 

choke closed or fuel filter.  or above as mentioned( pull eht choke and drive hard if drives btter then the main jet is plugged as your running more on 2nd barrel)If this weber DGV.. stock carb might be harder as vaccum advance

 

 

ck point distributor also but really wont be related

[DanielC]

Get a vacuum gauge, this will tell you more about the engine than anything else.  It will also be a huge help when tuning the engine.

The distributor normally does not get any manifold vacuum at idle.  It does as soon at the throttle comes off idle.  The engine RPM must also be below 700 RPM, when setting ignition timing, or the distributor starts to add centrifugal advance, and makes it hard to set the timing.

 

Make sure the compression is good.  Poor compression cannot be fixed by timing, or carb changes.

Make sure the ignition secondary wiring is good, including the spark plugs.   Our old engine need spark plug changes every 12,000 miles, and checking every 3,000 miles.

Make sure the fuel filter is good.  If you have the stock plastic fuel filter, with the inlet on the bottom, and the outlet coming sideways off the top, you can remove the fuel filter, shake it, hold it upside down, and gently blow air in the outlet, and clean some crud out of it.

Stock Nissan fuel pumps are very reliable.  But it would not hurt to check the fuel flow, about a quart, a minute, at 1,000 RPM, and then the pressure, about 3 or so PSI.  Too much pressure is not good, it will just push too much gas past the carb needle and seat,

Check the fuel level in the float bowl.  This will be hard in many cases, you cannot put a load on the engine to use enough gas to empty the float bowl, with out driving the car.  But if the fuel level drops in the carb float bowl, while you are working on it in your driveway, you definitely have a problem.

It is also possible you have crud in the gas tank, covering the gas pick up tube.  This could also restrict the fuel flow.  blowing air backwards into the fuel line will temporarily fix this, but unless you clean out the gas tank, the problem will quickly return.

[That4doorKiD]

My gas tank is cleaned, and my lines were flushed along with a new filter.

 

FYI: this be the prob?... With the car off, I give the carb throttle, and I only see gas squirt in the first, smaller barrel, the second one didn't seem to be squirting even with the throttle all the way down. 32/36 DGV weber

[serum114]

I had a similar issue for a while (engine revved fine in idle but not under load). I kept messing with the fuel delivery/Carb (DGAV) but it ended up being an electrical/charging issue.

I rewired and swapped my externaly regulated alternator with a higher amp internally regulated unit and it's pulling hard now. New Plugs/Wires helped a little too.

[banzai510(hainz)]

accel pump only squirts in the main barrel. This is the enrich the circut as it gets more air. then vacuum sucks the gas from the fuel bowl. 

2nd barrel is vacuum only

[datzenmike]

My gas tank is cleaned, and my lines were flushed along with a new filter.

 

FYI: this be the prob?... With the car off, I give the carb throttle, and I only see gas squirt in the first, smaller barrel, the second one didn't seem to be squirting even with the throttle all the way down. 32/36 DGV weber

 

See, it would sure help if this was mentioned at the start. I assumed the stock carb which would be jetted perfectly. A 32/36 weber??? who knows?

 

 

No vacuum advance at all would not stop the engine from revving in every gear.  In fact at full throttle there would be no difference or almost no difference as there is very little manifold vacuum. Vacuum advance simply varies with load. It primarily affects part throttle driving.

[That4doorKiD]

-My compression is fine checked it

-Cleaned some gunk out of my 32/36 with compressed air, took it apart... had insect eggs inside alot and INSIDE the 2nd jet gas tube

-Venturis correct position

 

I'm completely lost and I don't know whats wrong so... I'm going to swap my wagon's Electric Ign Dizzy, coil and it's clean carb to my 4 door,  and see what happens.

[banzai510(hainz)]

if you had spark with the last dist then most likely its fine unless its worn badly.

 

I would have swapped the dist first before the carb. But thats if tou didnt see and squirting gas in main barrel but its pretty simple

[That4doorKiD]

I changed the carb to a stock Hitachi first and didn't solve the issue.

Second, changed the dist. to electronic matchbox and didn't help.

 Everytime i shift into second it loses power, but it still creeps up if I drive down the block.

 I dont know what the problem is, maybe the L-16 is weak for a dogleg 5 speed, I don't know.

[bilzbobaggins]

Bad plug or wire? Right distributor cap?

[That4doorKiD]

Ahh it creeps up when I flutter the pedal in 2nd/3rd AND I haven't checked my fuel pressure.

I think my fuel pump is bad.

[datzenmike]

1/ Replace your fuel filter. It's part clogged and the engine is using fuel faster than it can be supplied to the carb. Costs $4 and if not the cause, no harm done.

 

 

Do this yet? Easier than changing a distributor. Let us know when you try stuff or why bother?

[That4doorKiD]

Do this yet? Easier than changing a distributor. Let us know when you try stuff or why bother?

I said fuel pump

[datzenmike]

I changed the carb to a stock Hitachi first and didn't solve the issue.

Second, changed the dist. to electronic matchbox and didn't help.

 Everytime i shift into second it loses power, but it still creeps up if I drive down the block.

 I dont know what the problem is, maybe the L-16 is weak for a dogleg 5 speed, I don't know.

 

 

Ahh it creeps up when I flutter the pedal in 2nd/3rd AND I haven't checked my fuel pressure.

I think my fuel pump is bad.

 

See, changing things on the fly hoping to get lucky wastes time and effort. Poor fuel delivery could be the pump but a blocked fuel filter can also do this and more likely. It's also easy, cheap to do and part of an elimination process.

 

Lots of good suggestions here also.

 

Get a vacuum gauge, this will tell you more about the engine than anything else.  It will also be a huge help when tuning the engine.

The distributor normally does not get any manifold vacuum at idle.  It does as soon at the throttle comes off idle.  The engine RPM must also be below 700 RPM, when setting ignition timing, or the distributor starts to add centrifugal advance, and makes it hard to set the timing.

 

Make sure the compression is good.  Poor compression cannot be fixed by timing, or carb changes.

Make sure the ignition secondary wiring is good, including the spark plugs.   Our old engine need spark plug changes every 12,000 miles, and checking every 3,000 miles.

Make sure the fuel filter is good.  If you have the stock plastic fuel filter, with the inlet on the bottom, and the outlet coming sideways off the top, you can remove the fuel filter, shake it, hold it upside down, and gently blow air in the outlet, and clean some crud out of it.

Stock Nissan fuel pumps are very reliable.  But it would not hurt to check the fuel flow, about a quart, a minute, at 1,000 RPM, and then the pressure, about 3 or so PSI.  Too much pressure is not good, it will just push too much gas past the carb needle and seat,

Check the fuel level in the float bowl.  This will be hard in many cases, you cannot put a load on the engine to use enough gas to empty the float bowl, with out driving the car.  But if the fuel level drops in the carb float bowl, while you are working on it in your driveway, you definitely have a problem.

It is also possible you have crud in the gas tank, covering the gas pick up tube.  This could also restrict the fuel flow.  blowing air backwards into the fuel line will temporarily fix this, but unless you clean out the gas tank, the problem will quickly return.

 

Try replacing the pump, maybe you'll get lucky.

[banzai510(hainz)]

YOU have the oil pump  out?

Maybe it off a tooth?

 

re cheak the timming with a light

 

the L16 and 5 speed it not it. otherwise they wouldnt put 5 speed in the 1200s

[That4doorKiD]

See, changing things on the fly hoping to get lucky wastes time and effort. Poor fuel delivery could be the pump but a blocked fuel filter can also do this and more likely

 

 part of an elimination process.

 

 

 

Try replacing the pump, maybe you'll get lucky.

I am doing an elimination process, that's why I did the carb first, then dist. after.

I had been running gas line out of a bottle WITHOUT a fuel filter before, and  it was already bogging. last week I had bearly put a fuel filter

[datzenmike]

Carb swap, the distributor swap and now back to fuel pump???? You're just swapping parts hoping to get lucky. Before swapping the carb the fuel filter and pump delivery should have been checked and eliminated.

 

How is the distributor anything to do with the fuel? Before the distributor gets swapped the plugs, wires, cap and rotor need to be checked or replaced,  Only when the distributor has been shown to be the problem do you replace it.

 

Good suggestions have been made and you have either ignored them or failed to confirm that you checked them off as the cause. How can one keep making suggestions if the ones made aren't checked? Post what's been checked.

[banzai510(hainz)]

ck the enigine mechanical. timming of block and the head ,valve lash. oil pump spindal timmed correctly when at number 1.

 

Install the dist and hope its good. Single point or dual. If dual point use the main points not the 2ndary one as the condensore is small. If EI dist make sure timming and wired correctly.

 

then carb.

 

does it rev up in 1gear ok then sendond is bad?  Find this hard.

 

to me going out of time(distributor issue), or out of gas when you load it up.(try running with the choke ON. If run better thru the gears then the main barrel is plugged)

[bilzbobaggins]

Any updates? Need closure