Hey guys I've got an 87 305 with Hedman shortys on it, about 4 years old. I recently had them off for the first time and upon reinstall had some leakage. So I pulled them off again and replaced the new gaskets with the copper crush type. The leak remained and I actually isolated to the flange between hole 3 and 5 using a piece of rubber hose. This time I decided to get some cheap, thick paper gaskets and red rtv both sides, which is what I initially did when they were new, with good results. But before the install I read here and other places that people have had good results, after trying several types of gaskets, with cutting the flanges out so each primary has it's own independent flange (except for the middle primaries which would share a flange). Being handy with an angle grinder I decided to give this a go and ten minutes later I'm watching paint dry. Anyway fast forward to tonight and I'm working on passenger side install (the easy side) and I've got all my bolts in except for the inside one on firing order hole number 2. After fighting with it for awhile I decide to take it back off. Using a straight edge against the other three primaries it seems the number 2 hole primary is tweaked like a 32nd of an inch, and when I compare the holes with my old copper gaskets the hole that was giving me trouble is out like an 8th of an inch, maybe a touch over a 16th. So I check the drivers side header and have the same issue, same primary, same hole. So my first thought for a quick fix would be to egg that hole out with a drill bit, except the hole is already really close to the primary. Hammering on the flange doesn't seem to be a good idea at the moment and according to the straight edge it is tweaked so little I think it would tighten down flat if I had a way to get the bolt started. If I start that bolt first then the other 5 are off. Thoughts? And has anyone ever run into this before? Thought cutting the flanges would be a good idea but I guess it was not?????
baker440ex
Get out your big prybar, and force it into alignment enough to get the last bolt in.
If your lucky, with use and heat and vibration the pipe will take a new "set" and not be as bad the next time it's off.
Part of your problem is stress that was in the original fit-up and welding from Hedman, that the 1-piece flange kept at bay. When you cut it loose you released that captive force and it sprung to it's current position.
Headers made with separate flanges from the get-go are not so bad for this situation.
If your lucky, with use and heat and vibration the pipe will take a new "set" and not be as bad the next time it's off.
Part of your problem is stress that was in the original fit-up and welding from Hedman, that the 1-piece flange kept at bay. When you cut it loose you released that captive force and it sprung to it's current position.
Headers made with separate flanges from the get-go are not so bad for this situation.
A common problem when cutting the flanges. Headers have a lot of build stress in them as they age this eventually works out and they settle down. Now you've got a problem that is only solved by stretching and twisting the offending tube. A manifold stretcher might work if the tube doesn't also need to twist. If it also needs to twist you might need to fabricate a horse that duplicates the exhaust mount as it is on the head from at least 3/8ths steel plate. This needs to be clamped to something that is sturdy enough to let you apply enough force to realign the offending header tube to where it can be bolted to the horse. You could do this using a head if your comfortable putting that kind of force against a cylinder head. Heating the tube may make this easier.
Bogie
Bogie
I would buy a pair of 3/8 thick header flanges that match your heads and lay them down against your headers then after enough material was removed to where they were flat I would weld the 3/8 flange to your headers flange to save these.
Normally a machine shop can mill them down if the flange is thick enough. If it is not then you(or they) can weld the thick 3/8 flange on there and have them mill that down so it is true.
I stopped using factory made headers years ago. Good chance you can flow just as well with aftermarket cast exhaust manifolds and never think about exhaust leaking again.
You will not have any of the runners blocking the plugs with manifolds also which is a major WTF moment that has me shaking my head with many aftermarket made header setups.
I have a set of headmans right now sitting in the sand for this exact reason. If I cant read my plugs without pulling the headers I won't replace them as regularly as I normally would and that leads to the engine running worse.
Do yourself a favor and pull the engine(and trans if need be) and bolt the headers on with the thing in the air if possible at all then slide it back in if they will fit in between the rails. You will have better access to the bolts and be able to torque everything proper.
If you cant pull the entire thing sometimes you can move the engine forward or transmission back a inch or so which lets you lift the engine up off the mounts and slide it forward a few inches which makes a world of difference in reaching those bolts.
Oh and buy new hardware. I cant stress that enough. Clean up your threads and install new bolts. Those old bolts have several heat cycles and are stretched or worn. New junk will tighten better to proper torque and hold tight once a few heat cycles have passed. Breaking a bolt off in a head because it was worn and you did not want to drive down the road for new (equally strong or better) bolts can turn a easy job into a nightmare.
Normally a machine shop can mill them down if the flange is thick enough. If it is not then you(or they) can weld the thick 3/8 flange on there and have them mill that down so it is true.
I stopped using factory made headers years ago. Good chance you can flow just as well with aftermarket cast exhaust manifolds and never think about exhaust leaking again.
You will not have any of the runners blocking the plugs with manifolds also which is a major WTF moment that has me shaking my head with many aftermarket made header setups.
I have a set of headmans right now sitting in the sand for this exact reason. If I cant read my plugs without pulling the headers I won't replace them as regularly as I normally would and that leads to the engine running worse.
Do yourself a favor and pull the engine(and trans if need be) and bolt the headers on with the thing in the air if possible at all then slide it back in if they will fit in between the rails. You will have better access to the bolts and be able to torque everything proper.
If you cant pull the entire thing sometimes you can move the engine forward or transmission back a inch or so which lets you lift the engine up off the mounts and slide it forward a few inches which makes a world of difference in reaching those bolts.
Oh and buy new hardware. I cant stress that enough. Clean up your threads and install new bolts. Those old bolts have several heat cycles and are stretched or worn. New junk will tighten better to proper torque and hold tight once a few heat cycles have passed. Breaking a bolt off in a head because it was worn and you did not want to drive down the road for new (equally strong or better) bolts can turn a easy job into a nightmare.
I'm pretty much anti-header on street cars after fighting with too many of them. I'm running ram horns on my SBC and am pretty happy with it.
I had a set of headers from headman once that was a full length set of v8 headers swap for a chevy s10 and the headers on both sides came apart in pieces and the middle two cylinder flanges were not fitted to the other parts of the headers and when I first ran them I had no problems at first but thanks to GM not being so smart as to have two exhaust runners side by side on there small blocks that makes for a very easy area to get warped quite easy. For about a year they were ok until I got a leak. I tried the copper gaskets and other types and even doubled gaskets and I even had the old pry bar and chisel out as well and had everything possible done and no matter what once they warped there was no fixing the things and the fit together type deal does not work good on that type of setup.
I had to go to just a deal with the single flange but I ended up having to go with shorty headers after that. Hope you can work it out. A lot of times when the flanges are messed up its almost impossible to get them straight again.
I had to go to just a deal with the single flange but I ended up having to go with shorty headers after that. Hope you can work it out. A lot of times when the flanges are messed up its almost impossible to get them straight again.
Another problem with separating the flanges is each of the primaries pipes expand and contract differently as the headers heat up and cool down... The one piece flange controlled that, as well...
Sometimes you can get better applied force with these: SB Chevy Stainless Steel Exhaust Header Stud Kit 1 1/2" Long NEW | eBay Cheap enough to give it a try.
I've done that before too.
What I did was use the gasket as a templet and had a buddy with a lazer jet cut a new flange. Clamped it all together and welded it back together. This was in a mud truck so the extra 3/8 wasn't a problem.
What I did was use the gasket as a templet and had a buddy with a lazer jet cut a new flange. Clamped it all together and welded it back together. This was in a mud truck so the extra 3/8 wasn't a problem.
Couple tricks for PITA bolts in tight quarters.
Here is a old trick I found that works great for getting that hard to reach bolt tight with exhaust header or cast.
You only need 3/4 of an inch between the firewall and exhaust for this to work.
If you don't have that good chance you can get it via BFH without to much messing around or modifying anything.
Most of the times I have the 3/4 of a inch. But do not have 1 1/2"-2" to get a ratchet in there.
Here is what I do that works.
You take a (grade 8 or 10 preferred)bolt with full threads that when threaded into the head will be 3/8 away from the firewall/frame/etc. You then thread a bolt onto those threads all the way till it is almost touching the bottom of the bolt head. You then find a bolt that will fit inside the recess of the header flange or cast area that is larger on the inside then the bolt to serve as a "spacer" and slide over the threads.
Your "spacer" should be tall enough so that you can get a wrench on both the bolt and nut without the wrench hitting the manifold/header.
You slide the bolt into your header/cast manifold and slap a piece of tape onto it to hold it while letting it slide back 1/2".
Tighten down your center bolts snug then remove the tape on the rear bolt and with a wrench tighten the large bolt down till it bottoms out then back it out 1/8".
Now tighten your Nut with a wrench that was almost threaded all the way up to the head while holding the Bolt in place. The bolt is just serving as a stud here.
When the headers heat up you can easily go back with a wrench(or both) and tighten down the bolt.
Removing that hard to reach bolt is where this shines. You back the nut loose until it hits the bottom of the bolts head then slide a second wrench on. Now you have a double nut with 1/2" head to remove that bolt using 2 wrenches from the head. After a bit of penetrating oil one good wack from a 3lb hammer will loosen it to where you can remove the bolt that would have been a nightmare otherwise.
In some cases you may need to modify(bend) a wrench so that it can turn 1/4 to 1/2 a turn around items. But generally you can get a straight wrench in there most of the time.
Next trick involves copper coat.
This is what I use;
https://www.summitracing.com/parts/...se1-_-sce-gaskets&gclid=EAIaIQobChMI77DVqr-t1QIVAYNpCh2PVQawEAQYASABEgLMcPD_BwE
You shoot copper coat onto the head and header or exhaust manifold(being careful not to spray the sides of the header/exhaust manifold) and wait till it is tacky around 10-20 minutes in most cases. While your waiting install 2 studs in the center to hold the gasket. Bolts(long enough to clear the header flange/manifold) with the heads cut off will work. You are not tightening these just using them to hold the header/gasket up temporally.
Put the gasket onto the head pressing it against the tacky copper coat and aligning the holes. If done correctly the thing should stick and you will not even need the studs. But the studs help if your impatient and want to avoid the gasket laying in the dirt.
Install your headers/exhaust manifold over the studs. Remove one stud and replace it with a bolt installing it loosely then remove the other stud and replace it with a bolt. Then do your others and torque the thing down.
Heat up the engine 3 or so times letting it cool completely each time during a afternoon to melt the copper coat, tighten the bolts and your golden. On cast manifolds your done on headers you may need t tighten them a few more times.
Even on 3 or 4 piece gaskets the copper coat trick works as long as you make sure the copper coat is tacky enough to hold the gasket against the head.
In tight areas where you can not use studs you apply the gasket over the tacky copper coat align the holes and wait. Check the holes over the next 10 minutes pressing the gasket against the head from time to time. It will hold the gasket in place allowing you to slide the header/manifold with copper coat sprayed on the flange up to the head and hit the gasket a couple times without knocking it loose.
This works with felt and cork gaskets best. But I have done it with metal gaskets using studs multiple times and even without studs a couple of times being careful not to hit the gasket.
Here is a old trick I found that works great for getting that hard to reach bolt tight with exhaust header or cast.
You only need 3/4 of an inch between the firewall and exhaust for this to work.
If you don't have that good chance you can get it via BFH without to much messing around or modifying anything.
Most of the times I have the 3/4 of a inch. But do not have 1 1/2"-2" to get a ratchet in there.
Here is what I do that works.
You take a (grade 8 or 10 preferred)bolt with full threads that when threaded into the head will be 3/8 away from the firewall/frame/etc. You then thread a bolt onto those threads all the way till it is almost touching the bottom of the bolt head. You then find a bolt that will fit inside the recess of the header flange or cast area that is larger on the inside then the bolt to serve as a "spacer" and slide over the threads.
Your "spacer" should be tall enough so that you can get a wrench on both the bolt and nut without the wrench hitting the manifold/header.
You slide the bolt into your header/cast manifold and slap a piece of tape onto it to hold it while letting it slide back 1/2".
Tighten down your center bolts snug then remove the tape on the rear bolt and with a wrench tighten the large bolt down till it bottoms out then back it out 1/8".
Now tighten your Nut with a wrench that was almost threaded all the way up to the head while holding the Bolt in place. The bolt is just serving as a stud here.
When the headers heat up you can easily go back with a wrench(or both) and tighten down the bolt.
Removing that hard to reach bolt is where this shines. You back the nut loose until it hits the bottom of the bolts head then slide a second wrench on. Now you have a double nut with 1/2" head to remove that bolt using 2 wrenches from the head. After a bit of penetrating oil one good wack from a 3lb hammer will loosen it to where you can remove the bolt that would have been a nightmare otherwise.
In some cases you may need to modify(bend) a wrench so that it can turn 1/4 to 1/2 a turn around items. But generally you can get a straight wrench in there most of the time.
Next trick involves copper coat.
This is what I use;
https://www.summitracing.com/parts/...se1-_-sce-gaskets&gclid=EAIaIQobChMI77DVqr-t1QIVAYNpCh2PVQawEAQYASABEgLMcPD_BwE
You shoot copper coat onto the head and header or exhaust manifold(being careful not to spray the sides of the header/exhaust manifold) and wait till it is tacky around 10-20 minutes in most cases. While your waiting install 2 studs in the center to hold the gasket. Bolts(long enough to clear the header flange/manifold) with the heads cut off will work. You are not tightening these just using them to hold the header/gasket up temporally.
Put the gasket onto the head pressing it against the tacky copper coat and aligning the holes. If done correctly the thing should stick and you will not even need the studs. But the studs help if your impatient and want to avoid the gasket laying in the dirt.
Install your headers/exhaust manifold over the studs. Remove one stud and replace it with a bolt installing it loosely then remove the other stud and replace it with a bolt. Then do your others and torque the thing down.
Heat up the engine 3 or so times letting it cool completely each time during a afternoon to melt the copper coat, tighten the bolts and your golden. On cast manifolds your done on headers you may need t tighten them a few more times.
Even on 3 or 4 piece gaskets the copper coat trick works as long as you make sure the copper coat is tacky enough to hold the gasket against the head.
In tight areas where you can not use studs you apply the gasket over the tacky copper coat align the holes and wait. Check the holes over the next 10 minutes pressing the gasket against the head from time to time. It will hold the gasket in place allowing you to slide the header/manifold with copper coat sprayed on the flange up to the head and hit the gasket a couple times without knocking it loose.
This works with felt and cork gaskets best. But I have done it with metal gaskets using studs multiple times and even without studs a couple of times being careful not to hit the gasket.
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