Petcock elimination question

[willis]

I have a '78 Special tank with dual vacuum petcocks. I am switching over to a single non vacuum system, and am wondering how should I go about blocking off the other petcock opening on the tank. I know I could cut a piece of steel plate to block, but am curious how to seal it from fuel leaking out. I have the old stock petcocks and don't plan on re-using. I though of cutting the base of it off and filling the hole with JB weld. I like the idea of the base and utilizing the stock o-ring to seal, but also concerned that the JB weld wouldn't be leak resistant. Anyone have a good suggestion for a good seal?

 

[Brassneck]

I think cutting a block-off plate is the cleanest/most simple thing to do. You can get the bolt pattern from your petcock, even cut it to the same size of the petcock base. Then get some fuel resistant gasket and bolt it on or use the stock screws Shouldn't leak with a heavy enough steel plate (so it doesn't flex).

I'd save the other petcock in case you need it (or someone does down the road).

 

[Brew]

the only reason you are wanting to get rid of it is aesthetics right?

 

[willis]

Partly asthetics, mostly cleaning up and simplifying. Just going to run single petcocks with a y split. Don't want to fuss with rebuilding the vacuum units. I thought I read somewhere that the 78 units were different than other vacuum petcocks. Probably just sell them to another in need of them.

 

[nj1639]

I though of cutting the base of it off and filling the hole with JB weld. I like the idea of the base and utilizing the stock o-ring to seal, but also concerned that the JB weld wouldn't be leak resistant. Anyone have a good suggestion for a good seal?

This is what I've done. 8 years now and still holding.

 

[racerdave]

 

[DogBunny]

I think cutting a block-off plate is the cleanest/most simple thing to do. You can get the bolt pattern from your petcock, even cut it to the same size of the petcock base. Then get some fuel resistant gasket and bolt it on or use the stock screws Shouldn't leak with a heavy enough steel plate (so it doesn't flex).

Standard composite cork-rubber gasket material from any auto parts store will work fine.

Partly asthetics, mostly cleaning up and simplifying. Just going to run single petcocks with a y split. Don't want to fuss with rebuilding the vacuum units. I thought I read somewhere that the 78 units were different than other vacuum petcocks. Probably just sell them to another in need of them.

You do not need a "y split". The two carbs are already connected with a crossover tube which acts exactly as tee would. Run your single petcock to one carb inlet, and cap off the other carb inlet. BTW, rubber caps don't work well for me. O'Reillys has started selling colored nylon vacuum caps, they do work well. Or use a short piece of fuel line with a piece of un-threaded rod, such as the shank of a long bolt, in it to block it off. Either way, secure with tie wraps.

 

[willis]

Thanks for the feedback all. i've got some 1/4" aluminum plate in the shop i will use. Maybe see if I can pop a couple of these out with what I have if anyone else need one.

 

[Rob G]

I know this is an older post but looking to do same with my 77 . came across this while searching, how did it work out and did the cap off plate seal well.

 

[weekendrider]

Yes, it works and the blank plate can seal with the right materials.

 

[Rob G]

thanks for the response, good to hear. I have a solid piece of scrap steel that I will cut to size and give it a try. I tried rebuild kits on the petcocks and it has been a futile process. just replacing the left side with a Mikes XS part and call it a day.