1972 C20 4-speed Header/Manifold Question

[ItWillBeSlow]

Currently "freshening" up the engine bay and the eye-sore rusty headers have to go.

1972 350ci 4-Speed 2wd C20

The truck has a set of 20 year old rusty headers that don't fit great. Headers were dented up during install and still make contact with clutch z-bar.

I am trying to determine if there is a good mid-level quality header out there that will fit this truck. I don't see a lot of people with this exact combo discussing headers.

I will also consider rams horns if there is a good aftermarket alternative. I see Jegs has sets for $180-270 depending on finish. This truck is a stock build and I just want them to look better. I prefer the header look but not if I have to modify them to fit or take a quality risk.

Also, can both options be installed without removing the heads while the engine is in the truck?

Please share any opinion or experience!

[mattfranklin]

Nice discussion of ram's horn manifolds here: http://67-72chevytrucks.com/vboard/s...d.php?t=620829

[ItWillBeSlow]

Originally Posted by mattfranklin

Nice discussion of ram's horn manifolds here: http://67-72chevytrucks.com/vboard/s...d.php?t=620829

That's a great thread, thanks for posting. Seems like the masses generally lean toward manifolds for a stock application and that's where I am leaning as well.

Also wondering how long the ceramic coating generally lasts on these things. I like the silver coated.

[AcampoDave]

I think the longevity of ceramic depends on the outfit who does it. The local machine shop guy sent a a pair out for me to get a black ceramic ( this was a long time ago) and the durability was very poor. They burned to a powdery silver looking color in the middle and just continued to deteriorate from there. At least now a person can research these outfits on the internet and get reviews.
If your looking to make 'em silver on a low budget, Rustoleum cold galvanizing compound in a spray can lasts a really long time.

I think part of the reason my ceramic didn't hold up well (way back when) was because I really didn't understand how to properly set up a distributor. There is a good chance my motor was running with insufficient advance likely caused by wornout junkyard HEI. Perhaps, the elevated exhaust temps associated with that were just too much for it. Good thing the internet came along and some of you (ahem) senior street rodders were able to school me on how to properly set up a SBC distributor.

[ItWillBeSlow]

After looking at the most popular options available (summit, speedway, JEGS, etc), it seems the 2.5" straight down manifold is the most widely available.

The outlet points straight down at the front cross member and it doesn't look like there is very much clearance.

Does anyone know if there are fitment issues with the straight outlet manifolds?

I haven't seen any angled back that have a coating anywhere, only raw.

Thanks

[AcampoDave]

I did the straight down 2.5's on a '61 Apache. It was tight, but the muffler guy made it happen.

[ItWillBeSlow]

I bought the JEGS 2.5 manifolds and mocked them up last night. They look very nice.

Clearance looks tight on that crossmember. Id guess the bottom flange is about 5" off that crossmember and will require a very tight radius at the reducer to bolt onto the flange.

Truck won't go to the exhaust guy for a while. If anyone has similar straight down 2.5" manifolds please share your experience.

[mattfranklin]

That looks really nice. Is that chrome or some kind of matte nickel?
I wound up getting a Dorman 674-504 for my driver side. My truck is a '70 2wd with a 350.

Originally Posted by ItWillBeSlow

I bought the JEGS 2.5 manifolds and mocked them up last night. They look very nice.

Clearance looks tight on that crossmember. Id guess the bottom flange is about 5" off that crossmember and will require a very tight radius at the reducer to bolt onto the flange.

Truck won't go to the exhaust guy for a while. If anyone has similar straight down 2.5" manifolds please share your experience.

[gmc684x4]

I have really good fitment with headman and hooked headers headman does answer fitment questions quite well before you buy

[truckster]

I used 2.5 rams horn manifolds and tied into the existing exhaust where the header collector was. I used 2.5 inch steel tube from Summit and welded it up myself. It was a pretty easy fit, but I did have to cut and weld the tube at one point to change the angle of a bend.

[ItWillBeSlow]

Originally Posted by mattfranklin

That looks really nice. Is that chrome or some kind of matte nickel?
I wound up getting a Dorman 674-504 for my driver side. My truck is a '70 with a 350.

Mine are silver ceramic coated from JEGS. They seems to be the JEGS equivalent to yours, without the accessory ear at the back.

Did you have any clearance issues with the crossmember with your pipe?

[ItWillBeSlow]

Originally Posted by truckster

I used 2.5 rams horn manifolds and tied into the existing exhaust where the header collector was. I used 2.5 inch steel tube from Summit and welded it up myself. It was a pretty easy fit, but I did have to cut and weld the tube at one point to change the angle of a bend.

Thanks for the feedback. That's a ~90 degree angle you had to make with the pipe you bought. Can you give some more detail on how you did this? If I could do something similar, I could salvage most of my exhaust.

[truckster]

This is the part I used. I had to do some digging in my email, because I started building this in 2016... It was Speedway, not Summit.

https://www.speedwaymotors.com/Tight...Query=91013385

In the picture you can see where I had to cut and rotate the tube to line it up with the collector flange. I looked through my build pictures and this is the only one I have of the exhaust, but if you need more I can get some for you on Monday.

[ItWillBeSlow]

Originally Posted by truckster

This is the part I used. I had to do some digging in my email, because I started building this in 2016... It was Speedway, not Summit.

https://www.speedwaymotors.com/Tight...Query=91013385

In the picture you can see where I had to cut and rotate the tube to line it up with the collector flange. I looked through my build pictures and this is the only one I have of the exhaust, but if you need more I can get some for you on Monday.

Thanks for the pic. How much of the "vertical" section of pipe did you have to cut to make this fit? Best I can tell there's 4-5" of available clearance from the crossmember below the manifold outlet, which means I'd think you'd have to cut and weld the flange on right at the start of the 90 in that pipe.

If you can get another photo or two without much trouble I would appreciate it.

[truckster]

I'll be under it tomorrow. I didn't cut any of the vertical portion, but it's pretty close to the front driveshaft. I'll get some pics for you.

[truckster]

OK, here we go. I crawled under there and there was interference with the front driveshaft. I took out 1.5" and everything clears nicely now. The first picture is of it laid out to be cut, and the second is with it welded up and bolted in. Of course, if you do the same thing, you can just cut the 1.5" off the top before you weld on the flange. That's on the passenger side - on the driver's side I didn't have to cut any length.

[ItWillBeSlow]

Thanks for posting those. I cant say for sure, but I think a key difference here is my truck is 2WD, and I have less clearance to the engine cross member than yours (or difference crossmember altogether?). It still seems that I could make that pipe work, but I think i would have to cut it even closer to the 90 than you did, maybe right at the radius, approximately.

[truckster]

I didn't realize you were working on a 2WD - that's what happens when I don't read carefully before I post. It's completely different. I may be wrong, but I think the passenger side exhaust manifold on the 2WD is angled toward the back. Still, you should be able to do something. I did it this way mostly because I didn't want to have to tow it to a muffler shop or drive it with an open manifold. There are kits out there that have various angles of bends, and I'll bet you can find something that will work.

[mattfranklin]

I'm appreciating the discussion because I also want to run the straight dump Vette style 2 1/2" manifolds. I also want to avoid a trip to the muffler shop with open manifold. I have a MIG and I'm not afraid to use it. ;-)

Although I am hesitant to cut and chop and mess with exhaust fitment, truckster's posts give me hope.

Because the ~1" stagger of the cylinder banks, the passenger side is ok and the driver's side catches the rear of the 2wd crossmember.

We're in the same boat so I'll try to post as I get into mine unless you post yours first. Then I'll learn from and follow you.