Mani-cure … finally fixing the leaks (1 Viewer)

[fyton2v]

It takes me such a long time to get around to recreational wrenching. I’ve finally tackled the exhaust leak at that shaft in the exhaust manifold heat riser. My truck is only out and about on weekends so I procrastinated on this repair for YEARS. Also, while the manifolds were off, I cleaned and rebuilt the carburetor. And I now know why my 2F seemed to lack oomph in 3rd and 4th… I’m pretty sure I know why. I do not believe my vacuum secondary was air tight before disassembly.

Anyhow, I took out the leaky manifold flap-shaft and added some bolts in the holes left behind. I’m going to use that SOR blocking plate instead of making an attempt at adding new bushings to the shaft and deal with the more leaks down the road. I basically copied the fix from @Chestcutter ’s post on the same topic.

Here’s a pic before it goes back on. I used VHT’s very high temp paint in “aluminum” and “cast iron” colors, naturally.

 

[EWheeler]

I do not believe my vacuum secondary was air tight before disassembly.

Can you explain this more?

Reason I ask is that I took apart my first carb this weekend ('71 Aisin), and although it is earlier than yours, the thought crossed my mind that air should be able to get drawn in through all of the shafts in the lower carb body. The carb I'm playing with is a "spare" and all three shafts in the bottom steel piece were locked up. After working them loose and removing/reinstalling, it seems like air could easily get drawn in through these unsealed holes? Should some type of grease (white lithium, petroleum jelly, ec) be used on these upon reassembly to try and seal them up? I used penetrating oil to lube them up before reassembly.

 

[mattressking]

Can you explain this more?

Reason I ask is that I took apart my first carb this weekend ('71 Aisin), and although it is earlier than yours, the thought crossed my mind that air should be able to get drawn in through all of the shafts in the lower carb body. The carb I'm playing with is a "spare" and all three shafts in the bottom steel piece were locked up. After working them loose and removing/reinstalling, it seems like air could easily get drawn in through these unsealed holes? Should some type of grease (white lithium, petroleum jelly, ec) be used on these upon reassembly to try and seal them up? I used penetrating oil to lube them up before reassembly.

There's 3 areas it needs to seal:
1. Top and bottom half of secondary diaphragm shell
2. Seal between secondary shell and carb body
3. Carb gasket on base of carb.

If those three are tight, then you need to make sure the secondary buttery fly opens just a bit at full throttle, mechanically. Use a paperclip on the diaphragm shaft under load, full throttle to see if and how much it actuates. @Pin_Head has a great video depicting it all on Youtube

 

[fyton2v]

What mattress king said. All the little holes are there for a reason. Check out Pin Head’s YouTube channel for a pretty thorough overview on how stuff works. He walks you, step by step, through a rebuild process.

 

[fyton2v]

PSA: Remember to put the heat shield on before the manifold is installed. I was able to put it on afterwards, but the process involves more swearing.

 

[EWheeler]

@mattressking @fyton2v

Gotcha on the secondary vacuum stuff. The carb I'm working on has the mechanical secondary with the little weighted arm, so I don't have a secondary diaphragm to worry about. I was more curious if the shaft penetrations through the throttle body are a potential source for vacuum leaks as they have no sealing mechanism, just a tight tolerance. Should they be greased when re-assembled?

I only made it through part 4 of the Pinhead videos last night before i dropped my phone and fell asleep. I awoke 3 hours later to some yahoo rebuilding a chevy carb, so I may have actually listened to the rest of the Pinhead videos in my sleep!

 

[Chestcutter]

Manifold looks great. Still searching for heat shields that fit my '78...