Installed Bottom Plug Kit- now massive vacuum leak

[Stripes]

I was rebuilding our 7028276  and felt like now would be a good time to plug the wells as the epoxy that was on the plugs before was loose. I bought the Bottom Plug kit, removed my secondary plugs, tapped the housing until the tap bottomed out, installed the supplied plugs with threads coated in Marine-tex, and coated the outside plug in the same stuff. (just like the instruction indicate to do)

On reassembly, the base plate would not flush fit to the housing as the epoxied plugs were causing interference. I began removing epoxy until I reached the metal plugs and then reassembled the carb.

It now has a huge vacuum leak that can only be coming from the gasket between the throttle plates and the housing. I took photos during the repair, and I can see the steel plugs do not sit flush to the housing bottom. What did I do wrong? It appears to me the supplied plugs in the "kit" were too long, as there wasn't any additional room to cut deeper threads? How should I repair it? Grind the steel plugs flush or heat the housing and try and remove the plugs and start over with thinner plugs???

[Stripes]

I disassembled the carb. It is obvious the gasket wasn't compressed and the two plugs left witness marks on the throttle body base. Vacuum leak verified.

I sure would have thought the instructions would have let me know the plugs supplied in the kit needed to be cut flush or the plugs supplied in the Bottom Plug kit would be thin enough not to have caused interference. 

I think the instructions need an update. Sure if you have done 100 of these you would know. But those people are buying Marine-Tex in bulk and their threaded plugs elsewhere.

[Stripes]

Ok, reassembled, still have a massive vacuum leak! Any ideas about what to do next?

Running 10 inches at idle, was 14-15, running rough. Hand over primaries and idle goes from 750 to 1800.

[tayto]

i custom made plugs out of a threaded portion of a bolt. used a bottoming tap and then custom ground the plug until it fit just below flush. i cut a slot in the top so it could be driven in with a flat screwdriver. i lightly filed them for clearance once the marine-tex had cured. you may have cracked the housing somewhere when you tried to fit the throttle body and main casting together. the cast is very easy to destroy.

i'll let cliff chime in here, but if the threads have marine tex on them i don't see what piling extra on top will accomplish?

[77cruiser]

Should be able to file them flush.

[Cliff Ruggles]

Can't see it all coming but I'll modify the instructions to include a test fit for protrusion before you glue them in place.

Once in a while you'll run into that issue.  I just use a cut off wheel on my die grinder and take a little off the plugs so they don't bottom out against the baseplate and effect sealing of the gasket.

Then I'll apply the Marine Tex and install the plugs. 

Not really a big deal to file or grind them down a tad if you end up too high.

I get carbs in here all the time freshly rebuilt with a big glob of JB Weld on them holding the baseplate away from the main casting.  Even if they don't leak the pressure applied can cause the secondaries to stick or not fully close each time. 

I love JB Weld, doesn't work for chit to seal up leaky bottom plugs and has made me a lot of money over the years pealing it off and doing a better repair in that area.......Cliff

[Stripes]

After I cut the plugs flush and ensured it fit flush, I have a huge vacuum leak.
Any idea how warped it can be and the gasket not seal it? I broke, bent, or screwed up something in this process, as it leaks bad now....

[Cliff Ruggles]

If the plugs aren't sticking up the main casting and baseplate should easily seal on the gasket. 

It's would be pretty difficult to tighten the screws hard enough to warp one of those baseplates without cracking it first......Cliff

[Stripes]

I finally figured my carb issue out. I re-assembled the carb with the longest power piston spring, and didn't realize it was there to be cut to length. I removed the long spring and put the stock power piston spring back in, it runs very well now.

The kits come with 4 springs, and the book really only instructs to use the strongest spring possible to still have the rods down at idle. I never saw one spring was provided to be cut to length, so I selected the wrong spring. Carb idles well, seems great.

[tayto]

i believe the black spring should be used for stock or near stock applications