ford 460 v8 exhaust leaks

As to the exhaust manifold leaking, it is a common problem with the 460's. I replaced the exhaust manifold gaskets (and inevitably some of the broken bolts) on my current and last (I stepped up to the 6 liter diesel) 460 truck

4 times within a half a dozen years. The last leak I decided to live with, it has had the same small leak for over 2 years...

The Sheet metal heat shields were one of the biggest contributing causes of CRACKED exhaust manifolds on the 460's. When I was a teenager I worked as a parts puller in a wrecking yard, about 8 out of 10 460/429 exhaust manifolds had cracks under the heat shields. These were the ones I pulled off of generally unmolested Lincolns and pickup trucks. The heat shield bolt over the exhaust manifolds, using threaded studs in some holes rather then bolts for the exhaust manifold. I would not bother to put them back on if I was you.

Good Luck

Are your manifolds leaking at the head or at the connection to the exhaust pipe? If they are leaking at the "donut" gasket to the exhaust pipe, then check for a missing liner (for lack of the correct term) that slides inside the exhaust pipe, from the cast iron manifold, for approximately 3-4 inches. This liner keeps excessive heat from burning out the "donut" gasket and causing a leak.

If your manifold leaks at the head, check your gasket. The gasket may be laminated and should indicate a head side and a manifold side. A laminated gasket installed backwards (left side on the right side, and vice versa) may leak.

Good luck

Frank

Thanks for the update! I have been debating with several other mechs, to the cert. of the heat sheilds. To the time of this ex. leak, I was not running any heat sheilds.I had discarded these years ago, then everyone says You have to run em! This is my first leak since removal. I had switched carbs 650 C- AFB to my stand-by Holley 500 V-S. I have installed my afb again! Is it possible I was leaning out and running higher temps pulling loads, and this made the gasket burn away? Would a better gasket be calle for? What would that be? I used Fel-Pro or McCord Would Mr. Gskt. Engine Works make a better Gskt. Being an old line mech. I am thinking thickerer may be better, or Neo comp. Maybe some other I have not heard of? Numbers to You snipped-for-privacy@webtv.net

William,

I have not found a satisfactory gasket. I do know that I put 302 exhaust manifolds on a Bronco metal to metal, no gaskets, fresh engine rebuild against freshly milled manifolds and went well over 100,000 miles without leaks or problems. But then again the 302 is not prone to exhaust manifold leaks anyway... I will say double gaskets seams to exasperate the problem...

William, You may want to try Summitt Racing here on the net. They have an 800 # there if you want to call. I think you may find they have a copper or similar gasket may for severe/racing duty that may be an improvement for you. If they have them for this application, it will probably be a good bit more expensive than regular gaskets. If they work, the cost will be made up in replacement cost. The cracking of 460 manifolds is common. There are a few aftermarket replacements that may be better - just dont' know as OEM parts are generally better - not always. The only solution to cracking is headers but, they have their own problems and are not usually preferable in MH apps. If you are entertaining the idea of headers as a solution, you may want to try Doug Thorley Headers - good quality - not cheap. They have recently been bought by another maker but, at one time, had a nice set of 429/460 headers designed for MH apps to increase the mid range torque which would be a plus. IIRC, they had both mild steel and stainless versions as well as Jett Hot Coated available. The Jet Hot offers some benefit in heat retention w/o heat shields. Gale Banks Engineering may also be a source of help as they have done extensive work with the 460 engines over the years. You can also get a header insulating wrap from Summitt to replace the heat shields on headers. I, personally, would not use a wrap on a painted steel header because of the possibility of collecting moisture especially on a MH that may be parked extensively.