Options for '69 OE sidepipe mufflers
C6 the C5 of tomorrow
Joined: Nov 2000
Posts: 6,665
Likes: 2
From: Twin Cities Minnesota
I think I amthe only one putting the headmans down.
I put them down due to the experience I had with them as so thoughtfully re-posted by the kid above.
I'll bet money the flow worse than block huggers and slow down your vette compared to block huggers or ram horns.
I put them down due to the experience I had with them as so thoughtfully re-posted by the kid above.
I'll bet money the flow worse than block huggers and slow down your vette compared to block huggers or ram horns.
Racer
Joined: Nov 2007
Posts: 279
Likes: 0
From: Forrest City Ar
The thing about the hedman for factory side pipes is They are 1 5\8 which is small if you are producing higher HP and they have a short & small collector. This is base on Vizards theory's read "Exhast Science Demistfied. from Super Chevy. If you have Hedman's and they work for you great but if you have a hotter engine and are looking to tune your exhast you may want to do something else. This applies for factory side pipes only. Other systems ie: under car have plenty of choices with headers.
Thread Starter
Racer
Joined: Jun 2005
Posts: 409
Likes: 13
From: Lavonia Georgia
"
They epitomise every possibly thing you can do wrong with a header.
*The o-ring seals work very poorly.
*The primary length is too short to be of value.
*The difference in Primary length is almost as much as the shortest tube. This makes the engine very hard to tune as some clyinders are lean while the others are rich.
It's all about tuning, not performance.
the headmans are something to be concerned about...
I've had them. The engine was untuneable. when some clyinders were rich others were lean. It was impossible to get close."
They epitomise every possibly thing you can do wrong with a header.
*The o-ring seals work very poorly.
*The primary length is too short to be of value.
*The difference in Primary length is almost as much as the shortest tube. This makes the engine very hard to tune as some clyinders are lean while the others are rich.
It's all about tuning, not performance.
the headmans are something to be concerned about...
I've had them. The engine was untuneable. when some clyinders were rich others were lean. It was impossible to get close."
Were you able to test the mixture for each cylinder at idle versus under load and at different RPMS? I guess if you had an O2 bung in each tube you could do it easily, but it would look like a Frankenheader
. So how do you figure individual cylinder flow for a header like this? Let me know because I'd like to figure out the tune on mine too as long as I don't have to spend huge $$$.
Thread Starter
Racer
Joined: Jun 2005
Posts: 409
Likes: 13
From: Lavonia Georgia
a 4" round muffler will not fit under the stock side exhaust covers...they touch the insulators on the inside. I know this, because I tried it. I am running 3.5" glasspacks turned backwards (for better flow) with 2.5" pipe running off the hedman side exhaust headers. I agree, the hedman headers suck ***. I am actually in the process of redoing this whole exhaust setup...first off, getting rid of the headers, and go from there.
C6 the C5 of tomorrow
Joined: Nov 2000
Posts: 6,665
Likes: 2
From: Twin Cities Minnesota
By reading the plugs at WOT and using a vacuum gauge at idle.
I can only infer the issue at idle, but it manifests itself by the vacuum and idle not changing as the idle screws are changed right up untill the engine dies.
With better headers you can see the vacuum change as you adjust the idle mixture screws.
BTW, this whole rich /lean thing isn't my idea, I didn't invent it.
I can only infer the issue at idle, but it manifests itself by the vacuum and idle not changing as the idle screws are changed right up untill the engine dies.
With better headers you can see the vacuum change as you adjust the idle mixture screws.
BTW, this whole rich /lean thing isn't my idea, I didn't invent it.
I'm curious how you went about determining you had some cylinders lean and some rich? I remember an old piece of Sun diagnostic equipment way back when Moses was a boy (I'm not quite that old, but you get the picture) called a cylinder balance test but I was of a single digit age and didn't really understand what it did. I've always thought it was just an ignition strength test, but maybe not.
Were you able to test the mixture for each cylinder at idle versus under load and at different RPMS? I guess if you had an O2 bung in each tube you could do it easily, but it would look like a Frankenheader . So how do you figure individual cylinder flow for a header like this? Let me know because I'd like to figure out the tune on mine too as long as I don't have to spend huge $$$.
Were you able to test the mixture for each cylinder at idle versus under load and at different RPMS? I guess if you had an O2 bung in each tube you could do it easily, but it would look like a Frankenheader
. So how do you figure individual cylinder flow for a header like this? Let me know because I'd like to figure out the tune on mine too as long as I don't have to spend huge $$$.
Team Owner
Joined: Feb 2003
Posts: 30,183
Likes: 313
From: Lake Norman NC
The quality of the hedman headers is enough to say they are terrible. The flanges are very thin, I had to indent the sides of the primary tubes just to get a bolt on. They leaked very bad, until i found some very expensive gaskets with header studs.
Thread Starter
Racer
Joined: Jun 2005
Posts: 409
Likes: 13
From: Lavonia Georgia
How many pulls do you have to do on a new set of plugs before you can reliably read them? Is one enough or do you run them thru several pulls?
Is there any chance that low RPM/idle from startup to when you actually start the pull will affect the read or will the pull burn them in regardless of what happens at idle?
Is there any chance that low RPM/idle from startup to when you actually start the pull will affect the read or will the pull burn them in regardless of what happens at idle?
C6 the C5 of tomorrow
Joined: Nov 2000
Posts: 6,665
Likes: 2
From: Twin Cities Minnesota
How many pulls do you have to do on a new set of plugs before you can reliably read them? Is one enough or do you run them thru several pulls?
Is there any chance that low RPM/idle from startup to when you actually start the pull will affect the read or will the pull burn them in regardless of what happens at idle?
Is there any chance that low RPM/idle from startup to when you actually start the pull will affect the read or will the pull burn them in regardless of what happens at idle?
New plugs, make your WOT run and shut the car down.
Pull the plugs right there ( usually at the big end of the track )
The WOT run will burn off any idle mess.
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