New Truck - '71 521

[thisismatt]

5 minutes ago, Stoffregen Motorsports said:

L series valve adjusters are known to come loose, and I try to get the jam nuts as tight as humanly possible. I use a pair of Snap-On wrenches for the job. If the jam nut is so close to the pedestal that it needs a thin wrench, your rocker arm geometry is probably off.

Or your 💩 exhaust valve seats are all sunk

[Stoffregen Motorsports]

Good point.

[thisismatt]

Just now, Stoffregen Motorsports said:

Good point.

Speaking from experience. I'm out of adjustment on mine 😆

[andyZ00m]

45 minutes ago, thisismatt said:

Speaking from experience. I'm out of adjustment on mine 😆

Here’s what mine look like. 
 

[Stoffregen Motorsports]

That's pretty low on the pedestal. I bet your valve seats are shot. Or your valves are worn thin. Or it has a hot cam in it and someone didn't properly set the rocker arm geometry.

[datzenmike]

 

 

 

This is the lock nut. The top one is how much I ground it down, about 1/2 size. Now the ball pivot can be turned down into the head more. Good idea to grind a few threads off the bottom of the pivot so it doesn't bottom out.

 

 

 

Probably way more than I needed but show what can be done to get a few tens of thousands of miles out of a head with sinking valves.

 

[andyZ00m]

I still have plenty of room, was just trying to fit wrenches around the springs and such. 
 

This motor is in good shape and it’s totally still adjustable. 
 

I have no problem admitting that I didn’t realize at first that there are three nuts on there…. I’m a dingus but I figured it out. 

 

Edited December 5, 2023 by andyZ00m

[andyZ00m]

Can never keep a girl from new shoes…

[thisismatt]

Ah, I see you've got an extra pocket ripper on the bed 😅

[andyZ00m]

5 minutes ago, thisismatt said:

Ah, I see you've got an extra pocket ripper on the bed 😅

Ha! I haven’t ruined any pants yet! 

[datzenmike]

Depends on how low it is.

[banzai510(hainz)]

love the white walls

[Stoffregen Motorsports]

Looks great!

[andyZ00m]

Been driving the truck a lot all week and it’s so fun!! After I realized these motors want a higher RPM I’m finding My groove. It’s definitely not without power. 
 

Im Noticing that it seems a lot happier and has much better/more smooth power band when the choke is out just a little bit even after warm. 
 

What does this mean? Seems like it wants a richer mix. 
 

With the choke fully disengaged it lags a bit in second gear whereas is its engaged just a bit then second gear is POWER

[Crashtd420]

6 minutes ago, andyZ00m said:

Been driving the truck a lot all week and it’s so fun!! After I realized these motors want a higher RPM I’m finding My groove. It’s definitely not without power. 
 

Im Noticing that it seems a lot happier and has much better/more smooth power band when the choke is out just a little bit even after warm. 
 

What does this mean? Seems like it wants a richer mix. 
 

With the choke fully disengaged it lags a bit in second gear whereas is its engaged just a bit then second gear is POWER

Generally yes It sounds like it wants a richer mix...

did you rebuild the carburetor yet?

Could be as simple as that or possibly something up with the secondary too.... 

A lot of people, including myself, have added a wide band 02 sensor and gauge...

This helps pin point rich and lean conditions alot easier.... 

[andyZ00m]

23 minutes ago, Crashtd420 said:

Generally yes It sounds like it wants a richer mix...

did you rebuild the carburetor yet?

Could be as simple as that or possibly something up with the secondary too.... 

A lot of people, including myself, have added a wide band 02 sensor and gauge...

This helps pin point rich and lean conditions alot easier.... 

 

Have not rebuilt the carburetor! Maybe this is a good time to do that. I was thinking about getting a Weber 32/36 anyway, maybe I just go that route. Will work with a L20 if I ever go that route as well...

[datzenmike]

57 minutes ago, andyZ00m said:

Been driving the truck a lot all week and it’s so fun!! After I realized these motors want a higher RPM I’m finding My groove. It’s definitely not without power. 
 

Im Noticing that it seems a lot happier and has much better/more smooth power band when the choke is out just a little bit even after warm. 
 

 

 

I assume this is at full throttle? If so then you are well into the secondary and it may be the secondary jet is slightly blocked so it is not getting all the fuel it needs... but there is an even better cause. On the under side of the carburetor, the bottom casting with the two throttle plates is secured to the main body with 4 philips head screws. The one to the front and the one at the rear are long and the same length so they are easily mixed up and can be put in the wrong location. Which would be fine but the very front one is hollow. The bottom end is open to the intake vacuum and sends this vacuum signal to the power valve which opens under heavy load and makes the mixture richer for more power.

 

 

 

My 710 L20B was this way. Someone had presumably rebuilt it and mixed them. It ran fine but it ran way better when the secondary opened. You could feel it on the ass dyno. Like a Quadrajet kicking in... well not quite.

[andyZ00m]

2 hours ago, datzenmike said:

 

I assume this is at full throttle? If so then you are well into the secondary and it may be the secondary jet is slightly blocked so it is not getting all the fuel it needs... but there is an even better cause. On the under side of the carburetor, the bottom casting with the two throttle plates is secured to the main body with 4 philips head screws. The one to the front and the one at the rear are long and the same length so they are easily mixed up and can be put in the wrong location. Which would be fine but the very front one is hollow. The bottom end is open to the intake vacuum and sends this vacuum signal to the power valve which opens under heavy load and makes the mixture richer for more power.

 

 

 

My 710 L20B was this way. Someone had presumably rebuilt it and mixed them. It ran fine but it ran way better when the secondary opened. You could feel it on the ass dyno. Like a Quadrajet kicking in... well not quite.

 

Crazy! Totally possible. This truck was clearly worked on by the owner (some funky hoses and dangerous in line fuel filters etc).

 

Not out of the question that they could have rebuilt the carb and switched those screws.

[andyZ00m]

Just for.... reference... this is the kit I would want right?

 

https://www.piercemanifolds.com/product_p/k657.htm?CartID=1

 

Need this thing too if I want to use the original air filter (which I do)

 

https://www.californiadatsun.com/carburetor-parts/weber-32-36-dgev-adapter.html

Edited December 9, 2023 by andyZ00m

[datzenmike]

K657 will work but K660  I think is an electric choke which makes things much easier. I know the '71 was manual but '72 on were electric. Just a thought.

[andyZ00m]

Was on vacation with the fam this week but back at the truck tomorrow. Got the K657 kit to replace the hitachi. Gunna keep it of course and probably rebuild it but at a nice pace so I can learn it. 
 

Gunna flush radiator and replace the heater hose that I believe is leaking. The bottom of the hose is not really wet so I’m hoping it’s not the heater core itself that is leaking. It’s a super small amount of fluid but it’s pretty consistently overnight after I drive it as the engine cools. 🤷‍♂️

 

Then I’m gunna do shocks and bushings. 
 

Also found another good Hitachi 60A regulated alternator from a buddy gunna try. Will be putting it in with the new carb. 

[mainer311]

On my L16, there was a coolant leak from the back of the head gasket that was running down the back of the block and making it look like the hoses were wet. Sometimes leaks travel. Don’t rule anything out.

[datzenmike]

I had a gasket coolant leak blow out between 3 and 4 spark plug. Never over heated, W58 head, replaced and it was fine.

[andyZ00m]

Do I use the throttle lever from the hitachi? Or use the swiss cheese thingy with the supplied bolt? Seems like the swiss cheese is easier.

 

She cleaned up nice!

 

 

Here is the coolant leak below the heater inlet. The hose isnt wet though so I dont think its traveling from the engine down the hose.

 

[datzenmike]

Preferably use the Hitachi.