My 1971 521

[datzenmike]

Coolant ports are below the intake so water can't flow up hill into them. Could maybe be sucked in by vacuum when running but how many times this actually happen??? If not on right it will leak when you fill it up.

 

Buy a new car... they smell for a while too. Engines don't blow up from smell. It'll go away.  

[banzai510(hainz)]

21 minutes ago, datzenmike said:

Coolant ports are below the intake so water can't flow up hill into them. Could maybe be sucked in by vacuum when running but how many times this actually happen??? If not on right it will leak when you fill it up.

 

Buy a new car... they smell for a while too. Engines don't blow up from smell. It'll go away.  

It happen to me on my 521  intakes got full on coolant taking the intake off.  I so wont do that again.Ut more from the intake side where the water drains in to the head while LIFTING it up.

my 510 the head is plugged so I dont worry about it.  Intake bolts get loosee on my lower center exhaust ports blowout(Felpro gasket) over time start leaking exhaust fumes giving me a headache

 

521 my Y pipe gasket finally gave out but its the usually exahust smell and headache

Edited March 19, 2021 by banzai510(hainz)

[datzenmike]

You're right. I see that now. The water in the head is higher than the intake runners. My bad.

[thisismatt]

Did you install the crushed asbestos cabin air filter?  

[mainer311]

29 minutes ago, thisismatt said:

Did you install the crushed asbestos cabin air filter?  

 

I don't know about him, but I did. Came in dirty cougar scent. Scratch and sniff.

[thisismatt]

3 hours ago, mainer311 said:

 

I don't know about him, but I did. Came in dirty cougar scent. Scratch and sniff.

 

Me too. I wasn't going to, but I succumbed to the pier pressure.

[d.p]

Drove it some more today a fair amount.  Tried to go get coffee in it but forgot my damn mask so I had to nix that. On the way home the lug nuts on my drivers side front worked themselves loose which was a scary feeling.  Felt the wheel was going to fall off.  thankfully I had the key and a socket to tighten them up.  
 

But other than that it seems to be good.  It’s loud and lots of noises but I guess that’s expected.  Trans shifts well but the Speedo is way fucking off. Like 10-15mph off at least.  Didn’t notice the smell so much today either which was good. 
 

Not sure my throttle and gas pedal is right.  Meaning not sure if I can get the butterflies completely open with the pedal to the floor.  Would I need to bend the bottom of the pedal towards me to give me more distance? 

[d.p]

Drove it further and longer today and performed just fine and I am worrying less and less as I put more miles on it. 

 

I will say its a completely different experience vs the stock l16 and 4 speed but not sure its showing its full potential just yet.    It doesn't snap or take off when I mash the gas, if I ease into it it goes but mashing the gas results in a somewhat slow climb in RPMs up the band.  Never driven or ridden in anything other than a stock L16 I think I expected more but maybe its just not setup right yet.  I mean it runs and drives fine, but I want it to scream and run like a bat out of hell but don't have any kind of reference to go off of.   Is that a pipe dream for a street driven L motor? 

 

There is a really god reputable Z engine dyno/builder/service shop https://datsunspirit.com/ about an hour away who will tune it on the dyno for a $120/hr.  Will probably do that to give me some peace of mind and expertise.  

 

 

 

 

 

 

[datzenmike]

Put a brick on the throttle then adjust the carburetor linkage to full open and release, the return spring will lift the pedal to it's new location. 

 

What color speedometer gear was in your 4speed?

Or better yet if you are not using stock diameter tires, or a different ratio differential,  now's the chance to totally correct the speedometer. Exactly how much 10 or 15? and at what speed?? Go through one of those school radars at a steady exact speed.

[d.p]

Put a brick on the gas pedal?  I adjusted it before but the total travel to open the butterflies appears to be farther than my pedal will allow  The FW right where the throttle cable comes into the cab is caved in towards the cab thus shortening overall travel (i think)? 

 

I tried my best to illustrate it from memory.  

[datzenmike]

So if the firewall is bent inwards your gas pedal is much closer to the floor that it should be??? I guess bend the pedal rod above the fulcrum point away from the firewall. When installed, the pedal will now be farther from the floor and have more travel before bottoming.

[d.p]

Yes I think so.  Basically the distance between the top of the pedal and the firewall is reduced because it's caved in.  Ok I will try that but does anyone know how to uninstall the gas pedal?  After looking at it and fucking with the throttle cable I was never able to figure it out.  

[d.p]

Found this in another thread, so you are saying bend the top section away from the firewall? 

 

 

[thisismatt]

Two sides of the same coin. Make the pedal angle more acute. Or make the pedal end shorter. Or make the diameter of the crank smaller at the carbs. Or adjust where the cable is mounted...

Edited March 21, 2021 by thisismatt

[d.p]

23 minutes ago, thisismatt said:

Two sides of the same coin. Make the pedal angle more acute. Or make the pedal end shorter. Or make the diameter of the crank smaller at the carbs. Or adjust where the cable is mounted...

 

[datzenmike]

 

[Mattndew76]

Levers and wheels!!

[datzenmike]

Yup. My 710 gas pedal has enough travel to pull an Hitachi throttle plate through 90⁰ from idle to full throttle, say 3". The motorcycle carbs I put on had a smaller circle to pull through than the Hitachi. It needed less than 2" from idle to full throttle so the pedal was much closer to the floor and a small movement made a big change in throttle. It felt like an on off switch and was hard to drive away from a stop gradually because of this much shorter travel.  As in dp's drawing I removed the fulcrum and welded it higher. This shortened the pull and lengthened the pedal travel. Now it has the same travel as the Hitachi and in more docile to drive.

 

 

Had to add an aluminum plate for the old mounting bolts. The fulcrum is welded higher, was down by my index finger.

 

 

 

[mainer311]

If you want to retain the modulation, just bend the pedal assembly.

 

or

 

Shorten the radius of the lever arm on the throttle shaft.

[d.p]

I thought about making the radius shorter on the throttle arm but that won’t help because it doesn’t change the distance of how far it has to travel to fully open them right?  I mean because that is set.  I need to make it so the gas pedal pulls them completely open and that is what I am struggling with. 
 

I can’t wrap my head around it. 
 

 

[mainer311]

If the moment arm on the throttle shaft is smaller, it increases the ratio of throttle shaft movement to gas pedal movement, but lessens the modulation of the gas pedal.

[mainer311]

See how your cable is connected at the very top of this lever? This means your moment arm has the largest radius. You need to bring the radius down closer to the shaft. This is one solution, the other being the bent gas pedal.

 

[datzenmike]

THIS!!!

 

Moment arm. That's the term I couldn't remember. It has to be the same as the Hitachi the pedal is designed to open. Or it will open abruptly with little pedal movement and be hard to regulate or not open enough. Thanks mainer.

[Stoffregen Motorsports]

Super important tip - be sure to set the throttle pedal stop!!!! If your pedal can travel further than the carbs, YOU WILL bend a throttle shaft. Bent throttle shafts can ruin the tune and are hard (for the novice tuner) to identify.

[d.p]

Got my exhaust fixed today and fiddled with the throttle linkage a little bit yesterday.   I moved the ball to the middle part of the throttle arm and shortened the cable a little bit to fit.  I also took off the return spring I had attached to the arm and the spark plug holder doohicky on the valve cover.  That helped a little making it a little more snappy but not perfect.  

 

Its better but I think the truck still needs to get tuned as its just not what I expected.  It also seems to run hotter than my L16, now its past the slash mark vs before the slash with the L16.   One the way back from the exhaust shop stopped at a light the idle dropped down to 6-700 RPMs when I had set to 800 or so.  Seem liked it was misfiring so I am assuming the plugs are fouled but over it for today so I just parked it.   

 

Question?? how much timing can I throw at this thing?  Right now its 13-14 BTDC and roughly 32-3400 at 3k RPMs.  When I got it the dizzy pedestal was cut to give it move advance so I assuming the PO had to advance more than I have for whatever reason.   

 

I did make an appointment with Datsun Spirit in a couple weeks and will probably just have it towed there as its really not that fun to drive right now, just seems labored on any long trips.   Hopefully I have it figured out by then or they can.