1 7/8 inch headers

[kornball426]

Big flow sbc heads can see up to a 10 hp & 7-12 ft/lb increase from headers with larger than 1- 5/8" primaries. (depending on cam, carb, etc.) Buying a set of steel headers in 1-3/4" or 1-7/8" and having them powder coated is an option. The powder coat process heats the item coated to over 400 degrees during the process, so exhaust heat should not be a problem. I bought a powder coat outfit and built an oven a couple of months ago. I have a set of headers I want to coat to see what happens. Once done, I will bolt them onto a stroker I am going to put in my 79 Bo. I am not anticipating any issues.

Exhaust manifolds can easily get literally glowing red hot... Much much hotter than 400 degrees, I think regular powder coating would burn right off an exhaust header or manifold. Or do they sell a special high temperature powder coating?

I saw a magazine test of ceramic coated vs. raw steel headers where their only concern was how hot they got according to an infrared thermometer during a Dyno run, they were each measured immediately after the pull was made, then again with a 1 minute cool down. The raw steel hit almost 900 degrees and had cooled down to around 500 after one minute, coated hit just a few degrees below 300 and cooled to less than 200 a minute later. However the internal heat of the pipes I'm sure was wicked hot, the ceramic just insulates the pipes basically.

 

[fleming442]

Ceramic coating requires fitment, then coating. Once it's coated, any dings, nicks, or scratches show up as rust.

 

[kornball426]

Ceramic coating requires fitment, then coating. Once it's coated, any dings, nicks, or scratches show up as rust.

Well in a perfect world an application specific header should fit without having to dent them for fitment. I know that often times that's not how it goes and you end up having to do a bit of blunt force massaging to get headers to fit. However I'm waiting to hear back from the tech people at Doug's headers to see if their 1 3/4 ceramic headers are right for my application in terms of port match, but going from a thread I found on here from someone who bought the headers I'm currently considering (p/n D336 1 3/4 headers) they fit quite well, hard to install (been there done that) but required no dents to fit, however a small amount of material needs to be ground off the rear edge of the passenger side upper control arm for clearance of one of the primaries.

Unfortunately after that on the street, rock chips and speed bump scrapes and whatever else are just inevitable eventually. I assume places where the ceramic gets scratched off can be touched up with a shot of high temp paint once in a while to help slow down the rust. I don't know about that for sure though, I've never bought coated headers before.

 

[bracketchev1221]

Well in a perfect world an application specific header should fit without having to dent them for fitment. I know that often times that's not how it goes and you end up having to do a bit of blunt force massaging to get headers to fit. However I'm waiting to hear back from the tech people at Doug's headers to see if their 1 3/4 ceramic headers are right for my application in terms of port match, but going from a thread I found on here from someone who bought the headers I'm currently considering (p/n D336 1 3/4 headers) they fit quite well, hard to install (been there done that) but required no dents to fit, however a small amount of material needs to be ground off the rear edge of the passenger side upper control arm for clearance of one of the primaries.

Unfortunately after that on the street, rock chips and speed bump scrapes and whatever else are just inevitable eventually. I assume places where the ceramic gets scratched off can be touched up with a shot of high temp paint once in a while to help slow down the rust. I don't know about that for sure though, I've never bought coated headers before.

Yup in a perfect world everything fits and there is the perfect header for every application. But in the real world there isn't. So you make consolations and do your best to fit everything you have to deal with. And if that means losing 5 hp having to use a smaller header to fit ac, then that is what you have to do. I want to put a big block in my 80, but I want to keep the ac in my car too. So if that means the headers are small and the valve covers have to be short to fit, then that is what I have to do.

 

[kornball426]

Yup in a perfect world everything fits and there is the perfect header for every application. But in the real world there isn't. So you make consolations and do your best to fit everything you have to deal with. And if that means losing 5 hp having to use a smaller header to fit ac, then that is what you have to do. I want to put a big block in my 80, but I want to keep the ac in my car too. So if that means the headers are small and the valve covers have to be short to fit, then that is what I have to do.

I did acknowledge that it is not a perfect world... Haha.

I have reason to be hopeful the headers I'm looking at will fit without having to dent them for clearance since someone else on this forum installed the same headers and had no problem. The only fitment issue they had was they needed shorty spark plugs, but they had angle plug heads, and I have straight plug heads, so even that may not be an issue hopefully, fingers crossed.

Like I said getting every single last possible horsepower is NOT my goal... I just don't want to bolt on headers that are really not at all suited for the heads themselves. If using a 1 3/4 primary instead of 1 7/8 loses a few horsepower at 5000+ rpm, but otherwise don't physically block the port off like those 1 5/8 headers would, I don't really care in exchange for a bit easier packaging, cost, and availability. I just don't see it as acceptable to put a literal dam in your exhaust immediately at the exit of the port.

 

[bracketchev1221]

I did acknowledge that it is not a perfect world... Haha.

I have reason to be hopeful the headers I'm looking at will fit without having to dent them for clearance since someone else on this forum installed the same headers and had no problem. The only fitment issue they had was they needed shorty spark plugs, but they had angle plug heads, and I have straight plug heads, so even that may not be an issue hopefully, fingers crossed.

Like I said getting every single last possible horsepower is NOT my goal... I just don't want to bolt on headers that are really not at all suited for the heads themselves. If using a 1 3/4 primary instead of 1 7/8 loses a few horsepower at 5000+ rpm, but otherwise don't physically block the port off like those 1 5/8 headers would, I don't really care in exchange for a bit easier packaging, cost, and availability. I just don't see it as acceptable to put a literal dam in your exhaust immediately at the exit of the port.

The straight plugs will help you too. When I was a kid, I was in the race car phase where I did everything I thought that was going to get me every hp and the headaches it caused were not worth it. Just like big headers, angle plug heads, and any other flavor of the month. On the street you couldn't tell the difference. Then I built a dedicated race car and found even there that all the dyno work and tinkering on stuff some of it that showed promise on the dyno really showed nothing at the track. That was when I started going for function and reality. It was all wasting money and time that I did not have to do nothing. My car ran 9.0's for 4 years trying to get that 8.99 but only could get to 9.03. But I did not want to change any of the body panels to fiberglass and I did not want a giant forward facing hoodscoop on the car. I wanted a steel body, glass window, factory dash car with a 4" cowl hood to do it. Because the car looked like it shouldn't go that fast. Finally I re built the engine 17 cu in bigger and tried some other stuff and made another 70 hp and put the car in to the 8.80's at 151 weighing in at 3200 lbs with me in it. Today, I want my AC on, my power brakes to work and not idle at 1600 rpm. I want to be able to drive it and not need constant maintenance. Because if it needs work, I won't drive it.

 

[lilbowtie]

Kinda curious on the rest of your build is cause that's a lot of cylinder head for a street car. Once you go over 1 3/4 in headers fitment and interference come into play. I thought I need more header on mine (little over 500HP) and went to a 1 3/4 stepped to 1 7/8 header and got 0 gain. The Sonoma has around 600HP and I run 1 3/4 headers on it. Don't be afraid to do a little matching on the flange.

 

[kornball426]

Kinda curious on the rest of your build is cause that's a lot of cylinder head for a street car. Once you go over 1 3/4 in headers fitment and interference come into play. I thought I need more header on mine (little over 500HP) and went to a 1 3/4 stepped to 1 7/8 header and got 0 gain. The Sonoma has around 600HP and I run 1 3/4 headers on it. Don't be afraid to do a little matching on the flange.

Car is a work in progress, I drive it a few times a week it's currently stock.

I've got this 406 I got for a pretty good deal so I'm going to use it.

I have a GN rear for it, in the process of refreshing, going to stay with the 3.42's unless there's some very good reason not to. Installing a hydroboost brake system since I bought it for my T Type and ended up selling the car. Suspension, and wheels and tires will be upgraded although I am unsure of how far to go with it, I'm not into autocross or anything, if I was I have other cars better suited anyway, but I do want to make sure the thing isn't a complete death trap the handling of the car really isn't all that bad stock, but I think it would be deadly with like 3x the power. Was thinking rear solid lower arms, adjustable uppers. Taller ball joints in the front all new poly bushings. Body mount bushings were done, I'd like to box the frame but I also don't want to take the body off and I don't have a lift, doing it on jack stands underneath would really suck. Trans will be a 4L80e I'm thinking like 2600-2800 stall converter with lockup. Not probably ideal for best performance on the strip, more stall would probably be better, but I don't really care it's probably going to be too fast on the street regardless haha. I'd prefer more streetable manners than peak launch power that street tires are not going to be able to hook anyway.

I'm a little worried the engine is a bit much for the street like you said. I hope it's not lazy and weak in the lower to mid RPM's and just a screamer. I'm seeing similarly put together 406's in the range of 530-580 horsepower. The cam is really the only unknown with the engine, it's a big solid flat tappet, but I have yet to pull the timing cover and sprocket to find out what exactly it is.

 

[fleming442]

I'm a little worried the engine is a bit much for the street

Unpossible!

 

[kornball426]

Don't be afraid to do a little matching on the flange.

And as for that, yeah I was already thinking if the 1 3/4 opening is still slightly undersize I can go at it with a die grinder a little bit to open it up. The opening on that 1 5/8 set is hopelessly small, if you opened up the flange enough that it wouldn't interfere with the port opening you'd be through the pipe.