Jump to content

My 1971 521


d.p

Recommended Posts

1 hour ago, datzenmike said:

Did you swap the 2 and 3 wires see if it moves to the #3 plug? Easy and cheap.


yes and no difference whatsoever. 

  • Like 1
Link to post
  • Replies 3.8k
  • Created
  • Last Reply

Top Posters In This Topic

Top Posters In This Topic

Posted Images

Ok got the leak down tester.  Anyone got tips on how to do this the right way?  And easiest way to get #2 to TDC? 

567F1678-C14F-4919-A083-0FA25ED776C9.jpeg

  • Like 1
Link to post

Why the tester? didn't you say your compression was 180 across the board? Leak down is for identifying where compression loss is.... intake or exhaust valve or rings, possibly a blown HG.

  • Like 2
Link to post
1 hour ago, datzenmike said:

Why the tester? didn't you say your compression was 180 across the board? Leak down is for identifying where compression loss is.... intake or exhaust valve or rings, possibly a blown HG.


yes but was told need to do leak down to see what is causing #2 to foul. I guess when you do a leak down test and air escapes out the valve seal you’ll hear it.  
 

Am I wrong? 
 

 

  • Like 1
Link to post
1 hour ago, d.p said:


yes but was told need to do leak down to see what is causing #2 to foul. I guess when you do a leak down test and air escapes out the valve seal you’ll hear it.  
 

Am I wrong? 
 

 


more likely you’ll hear it out the exhaust or intake, not specifically the valve seal.

  • Like 1
Link to post

Ok so when I first did #2 it wasn’t at TDC which allowed air out fo the carb. 
 

So I got both lobes pointing up and it came back like below.  All 4 cylinders came back with less than 10% loss so now what? 

 

 

FE9EF244-A465-4023-9B30-69BB534EC039.jpeg

  • Like 1
Link to post

Did you have the head rebuilt? Sounds like you have bad guides and/or seals based on the Ratsun facebook page. Time for the rope method, like Mike suggested. 

  • Like 1
Link to post
13 minutes ago, mainer311 said:

Did you have the head rebuilt? Sounds like you have bad guides and/or seals based on the Ratsun facebook page. Time for the rope method, like Mike suggested. 


yeah man.
 

I just finished swapping the carbs from front to back and will see if #4 fouls now.  If still #2 then I know the problem is that cylinder/valve. 
 

 

  • Like 1
Link to post

Alright well it’s defiantly carb related.  
 

Number 4 on the right number 2 on the left after swapping them. Can clearly see #4 is now fouling. 

C0A54378-8CCC-42A6-AA39-0886EA08D8E1.jpeg

  • Like 1
Link to post

Compression is good at 180 so valves/rings are sealing. Can't hear air out a valve guide it's on the other side of the valve face.

 

 

Well good on the carburetor, know you know.

  • Like 1
Link to post

One thing I did notice is the problem side of the carb has a vacuum port on it.  But I was told not to use it so I just capped it off.  I am under the impression that it’s not needed with dual mikunis.  

  • Like 1
Link to post
Posted (edited)

Well I think I cracked this case. Can anyone guess what the difference is here??

 

 

5C8EE207-3C57-4722-A318-87C6BB4587CE.jpeg

Edited by d.p
  • Like 1
Link to post
21 minutes ago, d.p said:

Well I think I cracked this case. Can anyone guess what the difference is here??

 

 

5C8EE207-3C57-4722-A318-87C6BB4587CE.jpeg

Left is you, right is the guy she said not to worry about?

  • Like 1
  • Haha 3
Link to post

Yeah crazy that’s what it ended up being. Amazing what an engine will do when the carb isn’t dumping fuel into one of the cylinders.  But good cause it means I built this fucker right and everything is as it supposed to be 

 

Oh boy!  This fucking thing rips now in every gear.  I have the tach set to 7K and I have bee reviving it up close to that and it hauls.  Until now I had no idea what a cam’d and bored L20b was supposed to feel like and it is fucking titties.  Runs cooler and so much smoother now as well.  
 

Even though it took me nearly a month to figure all this out after getting it running it was well worth it.  Part of me just wanted to sell it if I couldn’t figure out out of pure frustration.  I didn’t want to spend another dime on it either but all that is dust in the wind (for now).  For sure the suspension is suspect with how fast the truck is now.  Lots of roll into turns. 
 

 

  • Like 4
Link to post
1 hour ago, d.p said:

Yeah crazy that’s what it ended up being. Amazing what an engine will do when the carb isn’t dumping fuel into one of the cylinders.  But good cause it means I built this fucker right and everything is as it supposed to be 

 

Oh boy!  This fucking thing rips now in every gear.  I have the tach set to 7K and I have bee reviving it up close to that and it hauls.  Until now I had no idea what a cam’d and bored L20b was supposed to feel like and it is fucking titties.  Runs cooler and so much smoother now as well.  
 

Even though it took me nearly a month to figure all this out after getting it running it was well worth it.  Part of me just wanted to sell it if I couldn’t figure out out of pure frustration.  I didn’t want to spend another dime on it either but all that is dust in the wind (for now).  For sure the suspension is suspect with how fast the truck is now.  Lots of roll into turns. 
 

 

Wahooo! Now the fun begins! 

I just threw FutoFab sways on the 620. Only one quick drive on it so far, but felt a difference there. Truck is blocked in right now... but maybe next week Ill get to truely take it for a spin! I suspect the sway are going to really make a difference.  I dont really want to stiffen up the suspension much, since part of what I like about it is how soft it is compared to the 510.

  • Like 1
Link to post

The sway bar has no effect on bumps felt by both tires such as a speed bump across both wheels. It acts only when one wheel drops into a dip or goes up over a bump, then it applies resistance from the other wheel to try and even it out. It's main purpose is in a hard turn where the body tries to roll over onto the outside wheel and the inside wheel resists this averaging it out. It won't feel stiffer in the ride but it will sit more level on tight fast turns.   

  • Like 2
Link to post

I guess I never drove my truck this fast with the l16 and 4 speed so it was fine.  But now it just seems loose at high speed which is new to me and the truck.  
 

took my son for a drive and he loved it.  It really is night and day compared to the stock drivetrain.  
 

Now I need to figure out the trans tunnel cover and get a Nardi steering wheel.   Need to put the hood back on as well.  

  • Like 2
Link to post

So, they forgot a jet on the end of an emulsion tube?  Or it had backed out?  Unfamiliar with these carbs.

 

If it was dumping a turd ton of fuel in, hows the oil in the block?

Link to post

It fell/backed out and I turn was dumping fuel into the cylinder.  Oil is fine just changed it not too long ago.  

Link to post
49 minutes ago, d.p said:

It fell/backed out and I turn was dumping fuel into the cylinder.  Oil is fine just changed it not too long ago.  

I think he asked because that much fuel can wash the cylinder walls and also get into the oil...

  • Like 2
Link to post
1 hour ago, thisismatt said:

I think he asked because that much fuel can wash the cylinder walls and also get into the oil...

Concur. 
id be changing that oil to protect that peppy new power plant of yours

  • Like 2
Link to post

Join the conversation

You can post now and register later. If you have an account, sign in now to post with your account.
Note: Your post will require moderator approval before it will be visible.

Guest
Reply to this topic...

×   Pasted as rich text.   Paste as plain text instead

  Only 75 emoji are allowed.

×   Your link has been automatically embedded.   Display as a link instead

×   Your previous content has been restored.   Clear editor

×   You cannot paste images directly. Upload or insert images from URL.

Loading...
×
×
  • Create New...

Important Information

By using this site, you agree to our Terms of Use.