Block hugger headers for 455 Olds in GMC truck...??

[OldBlueDually]

As the title says, I am not not sure where I should go, or what style of block hugger headers to look for to use on my 455 in my 76 GMC (1-ton crew).

On set I found (Sanderson) looked really nice, but they dump straight down in the center and the cross-member of the truck I feel would be in the way.

I do NOT want to use the long tube style headers on this truck because I am placing a set of exhaust cutouts on it right after the headers to put pipes out behind the front tires. If you ask why: Because I want to

Have any suggestions? Thanks!!

 

[79K15 HIghSierra]

I tried fitting side huggers from summit on the 350 in my ‘79 k15 and they didn’t work, hitting on the drivers side and rubbing on passenger.

 

[Matt69olds]

What do the headers hit? If block hugger headers fit in a car, I would think there would be plenty of room in a square body.

 

[78C10BigTen]

I can honestly say i have long tubes on my 2wd square and they were second hand from.... god knows where! Only thing i dont like is they arent tucked up above the frame and the collector angle is more twords the ground. BUT they were free so... Also i can say they do not hit anything on the truck.

 

[OldBlueDually]

What do the headers hit? If block hugger headers fit in a car, I would think there would be plenty of room in a square body.

I actually do not have any, my concern was about the headers hitting the crossmember, or not having enough space for a bend in a 3" pipe for the collector....I suppose what I could do is buy some and see if they fit, and if they do not fit be sure I can return them..??

 

[78C10BigTen]

I actually do not have any, my concern was about the headers hitting the crossmember, or not having enough space for a bend in a 3" pipe for the collector....I suppose what I could do is buy some and see if they fit, and if they do not fit be sure I can return them..??

Wrap them in plastic so you dont ding or scar them....

 

[OldBlueDually]

Wrap them in plastic so you dont ding or scar them....

Good idea, I was hoping to find something like the below for this Olds engine...no luck though. All I can find for these is for 307 to 403 Olds...

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[OldBlueDually]

Here are the ones I can find...but have the concern about hitting the crossmember.

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[Ricko1966]

That pic looks like you could measure using center to center of the end exhaust ports the drop is about 2/3rds of the length and centered below the center ports.A little work with the tape measure and a little math this should be NBD

 

[OldBlueDually]

That pic looks like you could measure using center to center of the end exhaust ports the drop is about 2/3rds of the length and centered below the center ports.A little work with the tape measure and a little math this should be NBD

True. I have scaled many-a things at work doing this same thing. Never thought of doing that.....then again I don't like to think if I don't have to

I do like the style of the first set of headers though, wish I could find them for this 455. In this case however, beggers cannot be choosers....

 

[86K2500]

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You could try either of these. Never mind the listing saying for small block Olds. The exhaust flange is exactly the same. Only difference is big block Olds (400-455) is wider and taller deck.....
Years ago I had a set of headers in a ‘80 C-10 with a 455 Olds but they were a mismatched set because one would interfere with the A/C box and the other with the frame rail. Don’t remember what brand those were.

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[Matt69olds]

The bolt pattern is the same, but the port size are different between some small block and big block Olds. However, I’m pretty sure the difference is with the smaller small block. I pretty sure the 330,350,403 small blocks used the same size exhaust gaskets as the big block stuff. The 260 and 307 used smaller exhaust ports, with the same bolt pattern.


There are venders that make reproduction manifolds that copy the desirable W/Z manifolds used on the 442 and Hurst Olds. I think the reproduction manifolds have larger 2 1/2 inch outlets over the factory 2 1/4.

If you decide to get a pair of reproduction manifolds, I’d definitely throughly clean them and coat them with some heat resistant POR-15 or some other coating to protect them.

If I remember correctly, there is also a casting for the early cars that are visually identical, but don’t have a divider between the center exhaust ports.

There have been numerous dyno tests done between the good early manifolds and headers. The headers constantly show a 20-25 hp increase over manifolds. I’m guessing shorty headers would be a much smaller improvement. Of course, those dyno test never mention what the rest of the exhaust consists of! Are the manifolds choked with the factory restrictive exhaust pipes, compared to open headers?

 

[Ricko1966]

That's why I didn't pipe up.I know 330. 350
455. Are the same I think, but do not know 307 is different. I hate it when people post I think this or that, because inevitably somebody finds out the hard way that , I think isn't the same as I know.

 

[OldBlueDually]

Thanks guys, I will have to keep that in mind!! That I feel would make it easier to run the exhaust I want.

These exhaust mainfolds on there originally had a crossover pipe and exited out the one manifold to the exhaust system.

 

[Matt69olds]

That's why I didn't pipe up.I know 330. 350
455. Are the same I think, but do not know 307 is different. I hate it when people post I think this or that, because inevitably somebody finds out the hard way that , I think isn't the same as I know.

I learned along time ago that no matter what you know, someone somewhere knows more.

I KNOW for a fact that I have a bunch of exhaust gaskets in my extra Olds parts tote with different size exhaust ports. I also KNOW that I have a stack of exhaust manifolds with different size ports. I looked thru all of them last year when I replaced the rotten exhaust on dads 455 powered GMC. When I swapped in the 455 years ago I used the diesel manifolds that were on it, simply to keep the cost down. I figured if all the exhaust needed to be replaced, might as well install the proper manifolds.