16-bolt headers coming loose

[60sIron]

Is there a tightening order to 16-bolt exhaust flange, or should I just start from the middle and work outwards?

[My427stang]

Start from the center, but more important is evenly and in steps. With two opppsite each other, at least, on every port

[67428GT500]

You actually use all 16? If so, why?

[My427stang]

 Most headers can’t use all 16 but I use as many as I can . I’m one of those guys who have never had any issues with header leaks with any gasket.  16 or 8 doesn’t matter but I all of them that I can. I’ve never had 8 bolt headers leak but I figure the more bolt the more clamping force and the more uniform load

[67428GT500]

I just use the lateral pattern on my Shelby. The Remflex gaskets seal wonderfully.

                                                                                        -Keith

[427LX]

He mentioned they were loosening up. I use stainless lock washers on my setups.

[Rory428]

I am also one of "those guys" who installs as many of the bolts as possible, usually 13 or 14 per side with CJ heads. I have always found that new header gaskets take several tightening sessions , as the gaskets compress for a period of time, so the bolts need to be retightened periodically as the gaskets take a set. Usually it take 3,4, or 5 times until the gaskets stop compressing, and from that point on, the bolts stay tight. If you install the locking tab style header bolts, the bolts won`t technically back out, but as the gaskets compress after a while, you can still have blown gaskets if you do not snug the bolts down as the gaskets compress. I have always used regular header bolts, and have found that if you keep tightening occasionally until the gaskets stop compressing , the normal bolts tend to stay tight. On my old 74 F350, I had the same headers and gaskets on for over 14 years with no issues using this method, and they were only 2 bolt per port heads. Although a specific bolt tightening sequence may be a good idea with cast iron exhaust manifolds, I can`t see it be much of a concern with steel tube headers. I always snug all the bolts up in a couple of steps, but still go over all the bolts after the first few driving heat cycles.

[Bolted to Floor]

I will make use of all the bolts I can too. With the next motor  ,  I will be following Rory’s example also. 

Before we left for Michigan, I was laying under the car fiddling with something and looking at other stuff. And noticed that one of the bottom row header bolts had backed out to the point that the curve in the header tube was all that was keeping it from dropping on the ground.  . Going across all of the header bolts, there were a bunch that were loose to some extent.

[67428GT500]

With the Hooker type gaskets and those by Mr. Gasket and a couple others I used to use all but the two centered underneath.   I absolutely love the Remflex graphite gaskets. They are about 9/32 thick multi-layer gaskets. They are burn proof up to 3000 degrees. They torque to 27lbs and compress to about an 1/8 inch. I used the ARP polished 3/8 bolts that are 3/4" long with the 6114 and they stayed tight for a year. Pretty impressive and no burn-throughs or leaks. They also cover all the port variations.  They're worth the 38.00 unless you're tearing down the engine regularly.

                                                                                                             -Keith

[70tp]

I found that if the bolts come loose often and the headers have a one piece flange, cut the flange at least in the middle once , or between every tube.    Last one that I did, I cut it once in the center and left about a 1\4” holding it together .   That seemed to work as well as cutting the flange all the way through

[plovett]

I don't know of any order.  I always do all 16.  More important than the order is to re-tighten them once or twice, in my opinion.  It is for sure a pain.

paulie

[My427stang]

I don't spend any extra money on header gaskets, ever, I buy regular Hedman for Hedman, regular Hooker for Hooker. If a car comes in, I generally use what comes in the box....tighten evenly and in steps, no shortcuts, with lubed bolts, usually silver antiseize. 

Then I start the engine, let it get hot idling, and while hot, go back through them all again with gloves on.  I have a combination of wrenches that always gets me a good grab somewhere. 

Then literally, never, ever touch them again.  Mustang headers have been on since 2006, truck headers from 1991 to 2007, headers rusted out, replaced them, only time the bolts are even thought about is if I am doing head work

[Ranch]

I use Remflex gaskets, they work great but are fragile. I would recommend the use of 1” long header bolts with the use of the thicker flanges of today’s headers, would rather see the bolt peeking out the back then not using all the available threads, especially if you use aluminum heads.  Some flanges have slotted bolt holes to make it easier to hang your headers so there I use a flat washer and of course a high temp never seize such as Jet lube 550 on all the bolts.  They have these special header bolt 'Stage 8'  but they look to be more trouble than they are worth, but maybe worth a look.

[67428GT500]

I am using the cross pattern. It doesn't go through the Edelbrock head. I bought the ARP 3/8 polished stainless that are 3/4" long. They are a bitch to start in the engine compartment. They come with washers and I used them. They are fragile, I agree. They DON'T LEAK! I love them Vs. the standard Mr. Gasket or Hooker crap.

                                                                                                                -Keith

[Falcon67]

I use Felpro header gaskets on the 351Cs and 302s with grade 8 lock washers under the heads that will clear the pipes.  Usually requires a couple of heat cycles and going over with the 7/16 to get them settled.  After that, no issues.  My experience over the years is that if the header flange isn't substantial - like over 1/4" to 3/8" - you're going to have issues with bolts backing out.  Thinner flanges on lesser quality headers move around a lot.  Rear bolts on 302 with Hooker 1 5/8" pipes usually need the back bolt on each side and a couple of others hit with the 7/16 every so often.  Every so often, since 1974.