I've been running headers on SBC engines for most of my driving life, and when they blow a gasket, it's always on the #7 port.

Has anyone else had the same experience?

I've blown a couple on other ports, but 9 out of 10 times it's been on #7.

Seems like it would be a huge one if it's just a coincidence, but I can't think of any logical explanation for it.

The header gaskets blow out becuase of the weld ring on the flange.

So why has it always been #7, no matter what set of headers I've run? I'm talking about at least a dozen different cars and probably two dozen different engines, and well over two dozen different sets of headers.

Does every header manufacturer make the rearmost weld-ring on the driver's side defective?

They ALL make there headers the same. with exception to a few custom mfg's that are not worried about production time...as much.

I cant tell you why its number 7 for you. I dont know anyone having number 7 blow out alot, if much at all.

Are you using cheap-o gaskets instead of the metal backed fel-pro/victor gaskets?

#7 is back near the firewall, and reaching around the hood hinges, etc makes it harder to reach back and tighten the bolts...

don't know, but sounds good to me :D

Seems like #7 on a BBC or SBC is the hottest cyl by EGT temp senders. That can be why. One cylender that runs a little lean.

I got 2 words for you and this will save you from having to ever replace a header gasket again


LOCK WASHERS!

not sure if you run them but those little mr gasket lock washers for header bolts work magic, back in high school I would change header gaskets weekly, kept a spare set with a 7/16 wrench behind my seat and had frequently pulled over to swap gaskets while out driving or crusing. Then one day I installed the washers and never touched the gaskets again, even after hosing the engine down and getting the cheap gaskets wet I never blew them out.

Give that a try, monkey 'em down good with some new gaskets, go out get it hot, then retorque and you're set!


Oh yeah, and take a 11MM wrench and cut it in half, fits perfectly with no slack and by cutting in half it will let you get the full grip on the bolt, sometimes I'll even stick a box end over the nub and use that for leverage.

I've tried all the high-dollar header gaskets. Found the cheap ones still last longest. Believe me, I've been doing this all my life. I've tried 'em all.

I get many thousands of miles out of a header gasket, but when it finally goes, it's almost always on #7. This week's failed gasket was on there for about 15 months and probably 24,000 miles.

Oh well, just one of life's mysteries I guess.

And I use the allen/standard header bolts with the locking ring. It's a breeze to tighen them down with an allen wrench. Only a few require a 7/16" wrench, and I use a crow's foot socket on those.

I've never had the number 7 blow out first. Mine always seem to be between numbers 3&5 and 4&6. Dont really know why, mabey its the gaskets, mabey its the headers. It gets realy anoying though. Just hope they last longer when i put new ones on.
chris

Although I haven't tried it, a friend of mine has excellent luck with high temp permatex silicon without gaskets. he puts a good bead on and installs the headers without gaskets and he uses a dab on the bolt threads as a locktight. Lets them setup overnight and they don't leak ever. :confused:

Cylinders 7 and 5 fire next to each other, and this is always the hottest spot in the cylinder head.
Anyone for the 4/7 swap?

UDHarold

I always use drilled head bolts and saftey wire them, never have a problem with gaskets or loose bolts, I also cut the flanges when I install them. Harold, what is the deal with the 4/7 swap? I have heard of the cams for the swapped firing order and wondered what the advantages are.

I put the layered aluminum type (Percy's) I think.....they are the absolute best.....if the bolts loosen , you just tighten them up and the gaskets seal again perfectly........try them....
Ken
graemlins/thumbsup.gif http://www.chevelles.com/showroom/SS396Convert/side4.JPG
http://www.chevelles.com/showroom/SS396Convert/nova.jpg

I've used the basic aluminum type found in rebuilder sets without problems if I give the bolts a turn now and then. The safety wire deal mentioned is a simple idea I never thought of using. Thanks

Engine torqueing probably could cause some distortion in #7 & #8 as they are the first
tubes to absorb any flexing in your exhaust. IE...engine/headers torque
over but the rest of the exhaust system tends to want to stay stationary.

Emil Dusek
71 Chevelle SS-502
6.68@102mph 1/8 NA

I think you're onto something there, Emil. Between that and the fact that the collector flange is known to bump sometimes on rough ranch roads, overly aggressive speed bumps, etc. That would explain a lot.

Combine that with #7 running hotter because it may be a bit more lean than other cylinders due to fuel distribution issues with a carb, especially with the front barrels of the carb feeding 90% of the fuel.

I think we may be getting somewhere with this.

Oh!!!!! and by the way.......#7 is the one that loosens first...........
Ken graemlins/waving.gif

I had problems before I started putting the red hi temp sealant (which isn't all that high temp)on both sides of my gaskets, and let them dry thourghly. When I have to take a header off, it's no big deal either because most of it is stuck to the gasket, and whats left on the head will rub off with a finger. The stuff does not like oil though, so the head surface, and header durface need to be clean. But this is me, and some folks won't like the idea, but i have no leaks at the head. i do blow collector gaskets sometimes, maybe once in the last several years.