Offy O-ring troubles....suggestions?

[Anonymous]

I have the Offy up and running on my Ranchero, but I have run into a vacuum leak problem. I'm using the 70 and later Offy on a 75 head. The O-ring at the rear carburetor wants to squeeze out of its groove every time it is tightened down. I have tried slowly criss-crossing as I tighten the bolts, but nothing I do seems to make much difference. I am now convinced I need to ditch the o-rings and make gaskets for the ends. I think it will work, since the top of the log had to be ground flat anyway. Anybody ever tried it? Or does anyone have a better idea? I gotta get this thing back on the road, summer came to Oregon early this year!

 

[Asa]

maybe some RTV sealant?

or just some new o-rings?

 

[Junk-Falcon]

ppp

 

[Anonymous]

Thanks. I plan on making gaskets with vitor rubberized gasket paper, and coating each side with RTV. Off to the garage.....

 

[JOHN G]

mount the manifold loosley with a couple of gaskets on the middle hole only-manifold should rock front to back about an eighth of an inch. That being said, what I did was lay a bead of high temp jb weld around the first and third holes. I then placed saran wrap over the weld, put the o-rings on the manifold and mounted it down (not completeley tight, but just enough the create a mold) Once the jb dried, I pulled the manifold off, trimmed up the jb and voila, instant grooves for the o-rings to sit in! I,m pulling 15-16 inches of vac at idle so I,m going to assume it works.

 

[Anonymous]

Well, the gaskets I made worked. I cut them out of some good gasket paper, coated each side with RTV, and installed the manifold. I then let it sit all day to allow the sealer to set up. Installed the carbs and fired it up last night. It idles now, so I assume its fixed. I haven't put a vacuum gauge on it yet, but I'll do that today....

 

[CobraSix]

At first, I used RTV. After a big back fire...that blew out, so I ended up using some JB Weld like epoxy to seal it up. Didn't have an issue after that. Don't worry, so long as you don't go crazy with the epoxy, you can still pull the manifold off.

Slade

 

[Anonymous]

My o-rings started leaking after 4-months . . . and I don't want to pull the manifold 4 months from now so I had to try something else. After reading this post I decided to follow cobra six off the cliff. . .


I used jbweld at the outer carbs with no o-ring and bolted the manifold on finger tight- then after letting it dry for 12 hours cranked the bolts down. It sealed up good and I have been driving it for a week or so. . . we'll see how long it lasts. The jb weld is supposed to ber good to 600 degrees and it remains somewhat flexible so I figure it wont go anywhere.

. . . kinda scary, but I had to try something other than the o-rings when I saw how smashed and cracked they were already.

 

[Anonymous]

when i installed mine the o-rings wanted to squeeze into the throttle bores.
i reworked the o-ring grooves in the problems areas slightly with a tiny dremel endmill-type cutter. until the groove had a better tendency to hold the o-ring. i also used the copper rtvaround the outside of the o-rings.
i still may have a leak. i heard the best method to test for these leaks was using a propane torch( unlit). any better ideas for checking?

frankie

 

[CobraSix]

I decided to follow cobra six off the cliff. . .

Careful...sometimes it's a long drop.

For checking for leaks, use some carb cleaner and with the engine running, spray the bases. If you here the RPMS go up when you spray around a base (or o-ring seat) then you have a leak there.

Slade