'93 Ford 460 - 2 broken exhaust bolts (pic attached)

I assume the stock manifolds are cast iron. Am I right?

Cast or pipes-with-flanges, if they are not sitting flat against the heads, you are ripe for faster bolt failures.

If you have access to a large flat surface like a machined table saw top, place the manifold on it. I am sure your local Sears won't mind you using one of their table saws. Just make sure your manifold is clean. You better not see much of a gap in any of the lobes. If you do, you should take it to a metal shop and have the lobes machined flat to each other. You want to torque the bolts using a torque wrench with everything seated perfectly flat to each other for proper torquing and extended longevity. And don't count on the manifold gaskets to fill-in the variances for they will blow out, then burn out.

I have the broken passenger side one. When it heats up the leak stops so its not high on my priority list.

When I do fix it I am going to get a Thorley header kit for our rig, copper gaskets and high flow performance exhaust to help the heat escape.

Here is a link to the headers - includes cross pipe and Y pipe!

A good indicator of how difficult it will be to unscrew the broken piece with an easy-out is how hard it was to unscrew the other bolts that did not break off. Once you broke the bolts loose from their "set torque" did they unscrew the rest of the way easily or were they hard to turn all or most of the way like they were rusted or corroded? The answer to this will tell you if a 3/16 or 1/4 inch easy-out will be able to unscrew them.

I have used my TIG torch to heat broken exhaust bolts. Set the amps to 150 and put the arc on the bolt only. This will heat the bolt and help break the rust free. It will draw the temper from the bolt so you won't have to use all your vocabulary when removing the broken bolt.

Fwiw- years ago, the local Ford dealer was using the local EDM tap remover to remove sheared manifold bolts.

Norm

I do feel Ryans pain. In my young years there was a period where I thought I needed headers and I learned a lot. First of all that the Ford and GM engineers had a leg up on me and I was gradually educated through hot firewalls/floorboards, blown gaskets, broken bolts and such. I also learned a tough one....the answer to broken bolts is not to put in tougher bolts. Drilling out grade 8 bolts will extend your vocabulary considerably.

We had an OP who made removing and reinstalling his manifold bolts a periodic maintenance operation.

I used to buy little gadgets called "Pass Master" (nothing to do with Hockey) that was a micro switch inside a plastic chamber with a metal diaphragm. When engine vacuum dropped below its design, it opened the circuit to the A/C Clutch. There were 4, 6 and 8-cylinder "flavors."

As I've looked at 454/460 discussions, the 454 guys wanted more power and the 460 guys wanted better mileage. Might be that the 454 owners were more of a hot rod crowd.

I pretty much figured it was a heat issue where the standard pickup with the 460 has more room for air flow,not much, but any counts.The 460 has a wonderful reputation for being powerful and trouble free with the proper care.

Most class C's are overloaded or at max on the 350/450 chassis..I run at 10,800 with a 10,500 GVWR loaded full of water/gas/clothes/food/the wife and two dogs etc, ready to camp with a 21ft C.Ad towing and your working your engine, which needs the air flow to work properly without heating up..

I can remember the days of turning off the AC when going up a steep hill or even running the heater for the water to circulate better and using the gears and not pushing it..All that remains in my noggin and I still use it when needed.Appropriate transmission coolers also are a must.

It is clear to me now why it happens more in RV's than in pickups,if at all, with the same 460 engine.

I hope the opp of this thread has an good outcome to his 460 problem.His problem has me, and I am sure,others with the 460 in a class C, wondering how not to have this same problem.

@jayco - I don't think there were the sheer number of 454's in Class C's that there were 460's. First set of manifolds I ever brought to a shop to be re-surfaced after warping and starting noisy leaks, was from a 318 small block MoPar engine. Machinist asked "These out of a Van?" and I told him they were. He said the van doghouse is so limiting on air flow around the engine, that vans tend to be the ones that warp manifolds. Now, take all those far larger 460's, stick them in van "noses" and load them to max GVWR, maybe towing something besides. Recipe for manifold failure. I've heard of it on 454's too, but I think there might just be that many less of them.

@john&gloria - Ryan has emailed me, and he's making slow progress. Found a drill press he could use to accurately make a drilling template on the idea of those commercial ones. Last report, the LH bits he bought would NOT cut the steel in those bolts so he used another brand of RH bits. I believe he got through to the blind end of both broken bolts.

For an OP wanting to re-surface an exhaust manifold: Most machine shop "milling machines" are for heads, and most exhaust manifolds have the pipe connection where it interferes with the plane the milling machine needs to reach the sealing surface. The shops that have been able to do manifolds for me, have a "belt sander." It's a precision machine shop tool, not what we use for woodworking and furniture refinishing. It's called "sander" but it's capable of producing an accurately flat and true manifold gasket surface.

Best I say again, I believe we can reduce manifold problems, by letting the engine stabilize at reduced speed/load, or idle, before shutting down after a hard run.

Also, Engine Cooling System has to be 100-pct including Fan Clutch and Radiator Core inside and out.

And, no exhaust system restrictions.

I'm starting to worry. It's been a week since Ryans last post. I hope he has worked through his problem to a good outcome.

HEY RYAN! you still there?