My 1971 521

[d.p]

Been fucking with it for the past hour and so trying to learn by adjusting the idle mixture screws and the throttle stop.  Got it idling fairly well buts its like 3-3.5 turns out on the idle screws and 2-3 turns in on the throttle stop screws.  Anything less and it didn't want to idle at all.

 

However, when I rev it up and on deacceleration I hear what sounds like someone burning rubber for a second while the RPMs drop.  When I say burning rubber I mean laying scratch or doing a burnout, that kind of sound.   I do see what looks like to be rubber shavings around the timing cover and the oil filter but my only thought is the belt.  Really hoping its not something in the block but who knows.  

 

 

 

[banzai510(hainz)]

look at the belt and maybe smell it.

 

the idle circut I try not to mess with them and alwasy count for where I had them but on this I DONT KNOW MESELF what to do.

 

How ever went thru this maybe put it at best setting already.

 

did the alt light come on on this time after the ground swap. I personally hate those screw down end clamps what I see in the photo. and use molded end battery cables.

 

also with a new motor you might get some smells and alwasy ck the radiator temp as some new motors run hot till it loosens up.

Edited March 9, 2021 by banzai510(hainz)

[d.p]

I do smell something foul but I just assumed it was the carbs giving off the fuel/burnt smell.   Couldn't see anything by looking at it though.  

 

Waiting for carb synch tool to really dig into them but I figured I might as well teach myself as best I can while I wait.  Didn't check the light but I will now that you mentioned it.  And yeah it smells and I left some tape on the exhaust from when I cut it that problem doesn't help and I think the carbs smell as well?   This is outside in my driveway with the hood off and it still stinks.  

 

Oh and I did notice it seems the belt is looser than it was when I installed it, but the alt is tight in place so not sure what that means.  

Edited March 9, 2021 by d.p

[banzai510(hainz)]

Loosen the alt belt and make sure the alt spins.

or fell the belt or look if burnt

[mainer311]

Dumb question: 3-3.5 FULL turns out? It's easy to count a half turn as "1" with flat head screws. I catch myself doing it all the time. 

 

If you are a true 3-3.5 full turns out on the pilot screws, then your pilot jets are way too small. The thing is 60 is already in a good spot.

 

If you're counting half turns as 1, then I'd say you're in a really good spot.

[datzenmike]

The alternator is probably spinning 2X what the crankshaft is. That's a lot or kinetic energy and it's going to resist slowing down when you let off. Belt might slip.

[d.p]

Just now, mainer311 said:

Dumb question: 3-3.5 FULL turns out? It's easy to count a half turn as "1" with flat head screws. I catch myself doing it all the time. 

 

If you are a true 3-3.5 full turns out on the pilot screws, then your pilot jets are way too small. The thing is 60 is already in a good spot.

 

If you're counting half turns as 1, then I'd say you're in a really good spot.

yeah I might be doing that. So if it’s like this | and I turn that 180 I count that as a turn.  Is that right? 

[d.p]

Alt spins and so does the belt.  I should loosen it ? If too tight could cause the belt to slip? 

[datzenmike]

Push hard with your thumb half way between alternator and fan pulley. Tight is a belt width deflection. Too loose will slip. Too tight (really too tight) shortens the life of the belt and the bearings in the alternator and/or the water pump.

[banzai510(hainz)]

too loose belt will get that burning smell and the alt light till it catches up on speed.

[d.p]

I don’t know man sound does seem like it’s coming from the alternator so I may just get another one and see what happens.  I tightened it up but the sounds seems to be getting progressively worse.  

I got it idling well but still falls flat with any kind of load.  Going to give it a little more attention tomorrow and see if I can’t get it driving well.  Done for the day but will be back at it tomorrow.  

[mainer311]

38 minutes ago, d.p said:

yeah I might be doing that. So if it’s like this | and I turn that 180 I count that as a turn.  Is that right? 

No, 180 is half a turn. 1 turn is 1 360 degree revolution.

 

So you’re actually 1.5-1.75 turns out. That’s mint.

[d.p]

Just now, mainer311 said:

No, 180 is half a turn. 1 turn is 1 360 degree revolution.

 

So you’re actually 1.5-1.75 turns out. That’s mint.

yeah thanks for clearing that up man. The entire time I was doing it I was thinking to myself “is this 1 or half a turn?”  

[banzai510(hainz)]

falls flat? seem like it was ok on the 1st vid I saw

vedio of this falling flat.

 

 

I heard of a guy who put the accel pump diaphrame in upside down in Mukunis. If that even possible. So there was not squirt of gas going in carb when one cycles the linkage.  But it obvious one can hear the gas being squirted when motor off.

[d.p]

4 minutes ago, banzai510(hainz) said:

falls flat? seem like it was ok on the 1st vid I saw

vedio of this falling flat.

 

 

I heard of a guy who put the accel pump diaphrame in upside down in Mukunis. If that even possible. So there was not squirt of gas going in carb when one cycles the linkage.  But it obvious one can hear the gas being squirted when motor off.

Yeah when I actually drive it and go

up the small hill by my house it struggles getting up it in second.  On flat it just seems to miss or not have much power above 2k while moving.  
 

I tried to just mash the gas up to 3k but it really just doesn’t have any power above 2k.  

[mainer311]

Actually, if you went to 55 pilots and 2 turns out, it would be damn near perfect. The pilot controls the transition, so if you want the transition leaner, switch to 55’s. Otherwise, what you have sounds fine.

[banzai510(hainz)]

15 hours ago, d.p said:

Yeah when I actually drive it and go

up the small hill by my house it struggles getting up it in second.  On flat it just seems to miss or not have much power above 2k while moving.  
 

I tried to just mash the gas up to 3k but it really just doesn’t have any power above 2k.  

 

Im not thinking its the jets. As privios owner rans these carbs on a L20

I had a set of 44mikunis I never ran that was sold thru Nissan back in the day and the guy ran it on a stock l16 and actually the faster it went the better the carbs worked(over carb but it drove around.

 

you make sure the valves are adjusted?

try advancing or retarding the distributor. is this distributor even good? was it run before?

you sure the fire order is correct.

[d.p]

21 minutes ago, banzai510(hainz) said:

 

Im not thinking its the jets. As privios owner rans these carbs on a L20

I had a set of 44mikunis I never ran that was sold thru Nissan back in the day and the guy ran it on a stock l16 and actually the faster it went the better the carbs worked(over carb but it drove around.

 

you make sure the valves are adjusted?

try advancing or retarding the distributor. is this distributor even good? was it run before?

you sure the fire order is correct.

 

I adjusted the valves to 0.008 and .006 according to the CAM when I put the head back together so pretty sure they are right.  I advanced the dizzy to get it to 12 BTDC and the dizzy was ran on my L16 for 2-3 years prior with no issues.  The dizzy and the coil are the only things that were left from my L16, everything else is new.  If the firing order is 1342 counter-clockwise then yes its correct.  Would a wrong firing order or ignition problem only show up under load? 

 

Could it be fuel delivery or starvation?  Running a mechanical pump but the PO ran an electric one which didn't come with the engine, just the fuel pump block off plate.    

 

 

[datzenmike]

Like Hainz said, carbs were running on an L20B so got to be close.

 

Sound, belt scrapings and red charge light = piece of shit $60 rock auto alternator.

 

 

 

If fuel pump, they would be running out of fuel. This presents as a surging ahead and falling back or a struggling and very noticeable. I don't think this is the case.

 

Try retarding the timing. It may be pinging and you can't hear it over the carbs. Max advance at 2,500-3,000 should be around 32⁰ and is the 12⁰ plus the mechanical (aprox 20⁰) Try with and without vacuum advance hose on.

 

Pull and look at plugs.This is a window into the combustion chamber and can tell you a lot.

 

 

Last.... check and set the valve lash HOT. Cold setting assumes too much and that the expanding metal parts will assume the correct hot settings. Cold settings are for initial 'get it running'. Re-check the cam timing. Cam timing would explain the lack of power over 2-3,000 RPMs. What number did you set the cam sprocket on???

 

[d.p]

Just now, datzenmike said:

Like Hainz said, carbs were running on an L20B so got to be close.

 

Sound, belt scrapings and red charge light = piece of shit $60 rock auto alternator.

 

If fuel pump, they would be running out of fuel. This presents as a surging ahead and falling back or a struggling and very noticeable. I don't think this is the case.

 

Try retarding the timing. It may be pinging and you can't hear it over the carbs. Max advance at 2,500-3,000 should be around 32⁰ and is the 12⁰ plus the mechanical (aprox 20⁰) Try with and without vacuum advance hose on.

 

Pull and look at plugs.This is a window into the combustion chamber and can tell you a lot.

 

Last.... check and set the valve lash HOT. Cold setting assumes too much and that the expanding metal parts will assume the correct hot settings. Cold settings are for initial 'get it running'. Re-check the cam timing. Cam timing would explain the lack of power over 2-3,000 RPMs. What number did you set the cam sprocket on???

 

 

I ordered a NEW not reman'd alternator which will be here tomorrow.  It does kind of surge above 2k, almost bucking like, hard to describe or film as I am so worried about getting stranded lol. I will take my son with me today and have him film it.  

 

I set the advance to 12 at idle and at 3K its right around 32 which is expected IIRC.  Vacuum hose doesn't seem to change anything.  I pulled the 5s on Monday and 234 and were black and 1 was white and looked good, like a plug is supposed to look but that is only after idling it a lot and driving around the block 1 time so probably not the best picture of what is going on.   

 

Will check the lash again and just to confirm, the cam card says to set it at the valves and not the rockers, does it matter? Cam sprocket is on #3 (I think) and it was on #3 when I took the engine apart.  I will double check though sometime today but from looking at my pics it looks to be identical to when I took it off.   But who knows if it ran well prior to being taken out of the 510 it came out of.  

[mainer311]

Speaking of cam timing: Is it true that L20b's are on the #2 hole from the factory?

[d.p]

@datzenmike now that I think about it it really does buck and surge above 2k.  In second gear going up the hill as soon as I hit 2k it starts bounce around, if I shift to 3rd the RPMs drop below 2K to 1500 or so and it still does that same thing, bucks and surges.  

[banzai510(hainz)]

yes sprocket #2 from factory but i believe it was more a emmisions issue to set it to number 2.

Since this is a 521 I think you want power later as the gear ration is so low. Im only guessing on this one But really I dont think this is the proplem.

 

I personally would have ran the truck with the stock set up weber DGV to break in the  motor then put the sidedrafts on then one can isolate the issue faster.

 

maybe there is a float bowl issue. But then again its a guess.

 

if the alternator is giving 14volts with the meter when driving I think your fine. however the belt scraping I dont know what would cause that besides a tight alternator or pulleys.

[banzai510(hainz)]

Just now, banzai510(hainz) said:

yes sprocket #2 from factory but i believe it was more a emmisions issue to set it to number 2.

Since this is a 521 I think you want power later as the gear ration is so low. Im only guessing on this one But really I dont think this is the proplem.

 

I personally would have ran the truck with the stock set up weber DGV to break in the  motor then put the sidedrafts on then one can isolate the issue faster.

 

maybe there is a float bowl issue. But then again its a guess.

 

if the alternator is giving 14volts with the meter when driving I think your fine. however the belt scraping I dont know what would cause that besides a tight alternator or pulleys.

 

Open the top of the carbs to make sure the jet blocks are tight.

[d.p]

Ill check and make sure they are tight today.  Will check the lash and do a compression test as well.  Figure I might as well check everything that I can to rule it all out.  Not sure to determine if its fuel related as well, would I need to get a fuel pressure gauge and watch it under load?  

 

And I can install the weber + intake no problem, but that would mean I would I need a water line to the intake/carbs?  If so I would need to swap the lower water inlet or t-stat housing to get that.  But I would prefer not do that and get to the point the carbs are right and move on from there.