My '76 710 Goon

[datsunfreak]

Any chance you did before and after pics of it lit up?

 

 

Well, removed the front amber parking turn signal lamps and replaced the bulbs with LEDs. Eight for the bright flashing turn signal and two for the running lamp. Brighter too I think, makes the usually orange lens look yellow.

 

.

[datzenmike]

No. I figured it's hard to get a picture during a flash and both have to be exactly from the same position to be relevant. I had the 4 ways on when one was done and it was brighter. Bright enough it made the orange lens appear yellow ... and it's instantly on and off like newer cars. On a job I was looking at some business sign lighting that was being taken down and replaced by the new tenant. The guy doing the reno said it was a shame, the LEDs were only a year old. The were on a string and had their own small 120 to 12 v ballast. I mentioned that I was just looking at anything 12v for use on a car and he said to come over to his shop and take my pick for a buck a lamp. I got those 20 and he threw in another 30 that were smaller and came in groups of 3. 12 were on a clear strip with double side tape. Maybe make a dome light?

 

 

 

Very pleased with how the car runs now. Had it for 4? years or so and while it run well it seemed lacking, but you get used to it very fast. Now there's a much more pronounced pull through the mid range and it just keeps accelerating instead of leveling off. Damn 25 extra MPH top end!!!! That's big by any standard.

[LenRobertson]

datzenmike -  So cool you got your carb problem sorted out. I'm in hog heaven that my different carb is so much better than old one. It really sounds like we had pretty much the same hesitation problem. I still would like to give the old one I took off a good soak in the bucket of carb cleaner and see if there is a blocked passage in the accelerator pump circuit that will clean out. But that is time spent I could being doing other things to the 510. One thing I remember is taking the accelerator pump out of the 200SX (which didn't have any hesitation) and sticking it in the old 510 carb. That did not cure the hesitation leading me to think of a blockage.

 

I recall something about the Hitachi carb having a transition circuit that the 32/36 Weber doesn't have. For smoother acceleration or something. I have no idea if this were blocked if it would cause the mystery hesitation.

 

I still think (maybe) I have a little less power with the different carb. The one I took off has a #104 main jet. I feel stupid I didn't look at the main jet # in the new carb before I put it on. I suspect it may  be a smaller one. But I don't know if I care enough to pull the carb again. I think I can pull the jet access plug with the carb on the car, but whether I can read the jet number with a mirror and a flashlight is doubtful. I also want to reread the Dime Quarterly carb article. I think he had jetting info there.

 

I'm also not sure my secondary is opening. I plan to put a vacuum gauge on the secondary vacuum canister and see if it is good. I don't know how obvious it is when the secondary opens - if it is so gradual that it isn't easy to tell, or if there is a definite push when it opens at full throttle. As we talked about in the carb thread in the 620 section, I've had no power valve in the old carb, but if the secondary isn't opening I don't think the power valve functions since the vacuum supply to the power valve comes from the secondary bore. But I'm guessing on that one.

 

It is kind of spooky to have a car without the hesitation AND a working idle cut solenoid. If it wasn't for all the usual rattles and loud exhaust I would think it is a different 510!

 

Len

 

[datzenmike]

Man I'm so excited to drive it. It's so funny how we adapt to what we have. I always had a truck and it was s  l  o  w.... so when I got this car I was really impressed how fast it would take off. I had nothing to compare it to.

 

 

The vacuum for the power valve  is actually intake vacuum it might be from under the secondary barrel but below it is intake vacuum. When I found the hollow screw was swapped all I did was clean and put together. I noticed a small increase in acceleration power but the stumble was, if anything, worse. I did not remove all the emulsion tubes and air bleeds so maybe some of those were swapped around? I would need a second one to compare it to anyway. So the 620 carb I replaced it with was the 'non California' one with the set screws holding the venturies in.

 

You will feel a slight pull when the secondary comes in on the Hitachi and an exhaust note change. It's not dramatic but it's there. Hold the throttle at least half open to release the interlock, and then pull down on the secondary vacuum diaphragm to open the secondary throttle plate to see if it will actually open or is stuck. The secondary vacuum diaphragm receives a vacuum signal from both the primary and secondary venturies. 

 

 

So, I checked my FSM and the 710 did indeed come with 99/160 primary/secondary jets as I found. It also lists the main air bleed, slow jet and power valve sizes so somewhen I'll check that they are in place properly. Just curious about the poor running it has.

 

My '78 FSM for the 620 shows a 103 primary jet... the '79 carb has a 108!!! huge difference. The plan is take it out on the highway for a few miles and pull over and check the plugs. A smaller jet might be better for mileage.

[LenRobertson]

Now that you have mentioned it, it is obvious the hollow screw has access to manifold vacuum since it is BELOW the secondary butterfly. When I was young I had vague ideas about becoming a mechanical engineer. But I have miserable math skills, and even worse I have trouble visualizing things like the above/below vacuum. When I attempt to design even something simple I need to hold the components in front of me to try to see their relationship. Of course now that I have worked with some genuine engineers of questionable competence, I might have been good enough to work in the profession.

 

Datsun guys I know ask me why I don't throw the Hitachi in the creek and put on a Weber. I tell them I'm not ready to admit I'm not smart enough to fix a Japanese carb. Although I've come very close over the last year or so to going Weber.

 

I don't know if any of the air bleeds or those other little thingies need to be somewhat matched to the size of the jets. I think the DQ two part article covered that.

 

I really should pull the new carb back off. I didn't Loctite the screws up through the base like I always tell everyone else to do. "Do as I say, not as I do". I suspect one thing that causes those screws to loosen is not bolting the air cleaner to the brace on the manifold. I keep leaving those bolts off in case I need to pull the air cleaner again. And it becomes easy to leave them out for months or years.

 

Len

[datzenmike]

The DQ article... will have to look at that. Yes the Hitachi is the best carb for a Datsun, period. However it is complex in order to meet the requirements of performance/economy and emissions all at the same time. The weber isn't 'better' it's just simpler and economy and emissions are less important than performance. 

 

Everyone raves about the weber when switching from their Hitachi. Mostly it's an unfair comparison. That Hitachi is likely 30-40 years old, in need of a rebuild or needs to be adjusted properly and yes, sometimes just plain wore out. The weber is new. It's also larger than the 340. It's the AK-47 to Nissans M-16

[LenRobertson]

Here is the link to the DQ carb articles:

https://docs.google.com/folderview?id=0ByCvxnHNk90SYzc4N2E1MWEtMzg0MC00YTE4LTkxZGQtM2RjODA5ODA1YjU1&tid=0ByCvxnHNk90SMzIxZWIwYWYtYzljNy00ZGU2LWI3ODctYzRjMmE0MGY3NTA1

The issues are Vol.1, Issue 3 and Vol.2, Issue 1.

I just skimmed the articles this morning. Looks like a lot of interesting information. I need to take time to read it and ponder.

 

Len

[datzenmike]

Thank-you Len I went through it today. Yes there is more to the idle circuit that the idle mix screw. There is a small slit port just at the throttle plate that is exposed to vacuum as you step on the gas and the plate rises. This sucks in more gas as it begins to suck in more air. This is that point where there is no where near enough air going through the venturi to suck more gas in.

 

I guess mine on the original carb is blocked.

 

Well I took for a 55 mile cruise today and pulled the plugs. With a 108 primary jet I expected them to be darker but they are a very light tan with a slight orange cast. I went just over 55 miles on 6.39 liters or 39 MPG (Imperial) or 32.5 US. This is probably not that accurate as it's hard to fill right to the top of the fill spout. In fact 39 is insanely off.

 

Checked my speedo against one of those radar (Your Speed Is...) sine things and it's reading 34 MPH at 31 so 8.8% out.

 

Tomorrow I'm going to adjust the float to get the fuel level from the bottom of the glass to the middle. See it this as any affect.

[datzenmike]

Replaced my wipers with rubber refills keeping the original arms with the deflectors.

 

My rubber air duct from the heater to the dash windshield vent has always been missing on the right side. Now it will defrost.

Vacuumed out the goon and threw away all the junk I left in the car last Canby. Found a sticker with ...

 

'Hello, My Name is...

SMOKE' 

[KoHeartsGPA]

Ahh.....smoke sighting!

[datzenmike]

Set float and fuel height precisely.

 

Noticed the engine temp seems rather low on the scale so for fun pulled the thermostat out. Not stuck open so put back. Cut my own gasket from a cheerios box. Took more time to find my hole punch that to actually make it. Both housing and thermostat cover bolts got anti seize treatment. Cleaned glass and used RainX. If nothing else that shit keeps stuff like tree sap and bugs from sticking.

[datzenmike]

Well

 

Started to fix my annoying exhaust leak.

 

Ended the day with the head off.

[datsunfreak]

Bit of mission creep there?  ^_^

[Lockleaf]

[datzenmike]

Zackly.

 

Both front and rear exhaust studs are broken, have been broken all along. Exhaust noise is annoying. Only way to do it right is with the head off. Gasket is half missing on the #4 exhaust. Cut the studs off flush and punched and drilled them. Probably will drill and tap to some oversize stud.

 

BTW the only way to get the two lower middle bolts with the cone washers out was from above. Even with the block vent pipe out there's no way to get at them from under. Tried to find a 12mm swivel socket.

 

Bonus.... set TDC and the odd thing is the cam is set on the #1 hole. Here's another.... the bright link is also on the #1 hole. What are the chances?

 

 

The '75-'77 L20Bs used the co-joined intake and exhaust manifolds with the heat riser valve. They also have the U67 heads that do not have coolant flow into the intake. The plan is to drill out the water passages on the U67, swap a '79 intake and an L16 cast exhaust header on and run that.

 

.. and set the cam on the #2 hole.

[KoHeartsGPA]

That should also improve her performance :thumbup:

[datzenmike]

The heat riser valves always rust open and over heat the intake. Or closed (had an L20B from a car in my 521) fucker was slow to warm up. Or the spring rusts off. This was Ontario where it's frozen solid for 3-4 months of the year. I like the coolant 'warmed/cooled' intake much better.

 

The L16 exhaust I had Skib grab for me about 5 years ago. Naturally it needs the twin into one down pipe which I don't have, but I gots ideas.

[KoHeartsGPA]

You definitely benefit from having those holes for the mani in those extreme cold conditions, my datto has manual choke (Mikuni) and even on temp as high as 50° she requires choke...

[datzenmike]

Cleaned block surface so that's ready.
 
Undid the air con hose.... gently... nothing came out. Took the 30 pound compressor and mount off. It's just dead weight. 
 
Gasket matched the L16 cast header. Has those air pump holes but someone already put allen head plugs in. Inside there is a large boss to support the tubes, so I ground them away. Will check the gasket one more time tomorrow.
 
Cleaned the head surface. Started gasket matching the head but the carbide burr clogs with soft aluminum if I run too high a speed and if I don't the little dremel is too slow. I saw a lager burr yesterday that fits my electric drill but do you think I can find it today??? .
 
Still have to drill and tap those two broken studs, but that will have to wait until the stores open Tues.

 

 

 

 

 

BTW the only way to get the two lower middle bolts with the cone washers out was from above. Even with the block vent pipe out there's no way to get at them from under. Tried to find a 12mm swivel socket.

 

Has anyone done this too? remove the inner two lower bolts that hold the cone washers from above???

[datzenmike]

gasket matched L16 cast header...

 

[datzenmike]

Drilled and tapped new exhaust studs. Had to oval the holes on the two outside holes in the manifold. Ordered new HG, it's in tomorrow.

[Grahem]

any chance you want to part with the a/c bracket? or maybe let me borrow it to compare to my z-24 bracket? 

[datzenmike]

I can drop it off on way to Canby for you to look at. Pick it up some year.

[Grahem]

that would be awesome, when are you heading to canby? 

[Duke]

 Cleaned the head surface. Started gasket matching the head but the carbide burr clogs with soft aluminum if I run too high a speed and if I don't the little dremel is too slow. I saw a lager burr yesterday that fits my electric drill but do you think I can find it today??? .

 

Just looking through this thread and saw this.  The trick to keep carbide burrs from clogging with AL is to fill them with soap or wax before using them.  The soap keeps the from getting clogged up.  Saves the pain of picking out aluminum from the teeth of the burr.