Hi everyone - 1979 Mercury Colony Park w/351. On both the catalytic converters, I have a leak where the air pump tube connects to the cat. It is causing a bad chugging sound and might be contributing to my rough idle. This photo shows the situation. Anyway, I don't really see a way to effectively close this hole (like wrapping it with insulation) due to the high temperatures that this area of the cat reaches. I looked into getting 2 new cats, but it seems that they only make them for the 302 engine with the air tube fitting. So - any suggestions on closing this leak? And would I be able to use a cat for a 302 on my 351? Thanks!
Having worked at an exhaust supplier, I know there's repair kits available, but their mostly made for the used car trade, because they don't last. Do it right, and it'll last three times longer. And yes, it attributes to the bad idle, as they're vacuum tubes! A good exhaust shop should be able to fix it for around $300. [both sides]
My guess is that the 302 cat would probably fit.......... A/M for sure the way to go on this.........
The cats are the same for both the 302 and 351. I know, because I have had both engines in 79 Fords, just not the Panthers; all 4 were Thunderbirds. A good muffler shop should be able to fix them. The other alternative, if you plan to keep the car long term, is to get new cats that don't have that fitting at all. If your Colony Park is the same as my Thunderbirds, the thermactor system only supplied air to the heads in 79, so those are later cats anyway. The biggest problem with those air tubes not being on is that you are shooting hot exhaust gases at your floor pan, and eventually the heat will burn off the paint, exposing bare metal and causing holes in the floor. Been there, done that repair on a used car. The missing tubes may be contributing to rough idle, because of the reduced back pressure. It shouldn't have anything to do with vacuum, sine the tubes deliver air directly to the cat to promote the burning off of any hydrocarbons that make it that far through the system. The vacuum control for the system are all under the hood.
check out Walker Exhaust web site They have individual parts to the whole single or dual exhaust system I put duals on my Colony Park by looking up the part #s on the site and purchasing them from rockauto.com - shipped to my house, cheaper than any local parts store or exhaust shop. I did from exhaust manifolds to the rear w/ cats- the back two cats do have air hose ports.
