Technical Building headers - Buick Straight 8

I have the intake pieces for my Straight 8 roughed in, and am getting ready to start on the headers. Do any of you have suppliers of reasonably priced 4-into-1 collectors, for 1.5 inch OD tubing? I've found a couple suppliers but the prices seem really high. For what they want for a pair of collectors I could buy a set of cheap headers and cut the collectors off for re-use. Or if any of you have a set of trashed headers, put a hacksaw to 'em and PM me. Here's some pics of the intake bits. Initially I'll be using a pair of 40mm Keihin CV carbs with bores just over 1.5 inches. Not much carburetor, just a bit more than the stock 263 had on it. Intake tubes are 16 gauge mandrel bent 1.5" OD. Not sure if I'll run a balance tube between the two intake manifolds, or just make sure the carbs and linkage are balanced. I've got a lot of experience balancing 4-carb motorcycle engines, so I'm not too concerned about that.

 

Cooool. Way way more cool than the usual sbc that gets swapped into these all to often.

Sent from my SM-T805Y using The H.A.M.B. mobile app

 

One of the best sources I found for header pieces and design knowledge is Schoenfeld http://www.schoenfeldheaders.com/ He does a lot of circle track stuff and knows his stuff. -EM

 

Thanks earlymopar, I'll give them a call.

 

Once you get going are you going to build the headers 180 degrees? I did that years ago and what a Bad Ass sound. I had always wanted to do that but on most V-8 street cars they set to low to do it and be cost effective. The strait 8 was a walk in the park plus He could say it was for the added H.P.
The Wizzard

 

A pair of formed tube collectors are cheap, the fabbed tubular ones can get pricey.
Jegs has a pretty good supply of new header parts at cheap prices $34 for the pair.
Would not mess with cutting up a used set and trying to weld on rust

 

Try Cone engineering, you'll get a HAMB discount. I've used them several times (close enough to me to drive to pick up parts).

http://www.coneeng.com/

 

It will be interesting to see how the CV's work out.

 

Bob,
I made fixture for holding 1 1/2" stubs to fabricate some slip on collectors. The material I used was 16 ga. 304 stainless. I haven't seen it kicking around here lately. But if I come across it, I'll let you know. I could send it to you and you could send it back when you are through.

Bruce

 

I just bought a mandrel bent header kit from Speedway. They have a few different ones. A lot cheaper then anyone else I could find. I also bought a couple of extra mandrel bent pipes for cheap. To make my headers for my coupe.

Pat

 

I've been kicking the 180 degree design around, but only for the look and bragging. This isn't going to be a hard core motor at all. Dimitri Elgin ground the cam for me a few years ago, and just added a little lift and duration. I cut .050 off the deck and the head to bump the compression. Other than the intake and exhaust I'm building, the only other modification is the plumbing for an external oil filter. I did have to do some carving on the pistons for valve clearance due to the cuts on the head and deck.

I'm trying them primarily because they are fresh rebuilt and were sitting on the shelf. They are very easy to tune, and may work out OK. If they don't, I've got SU and Weber DCOE options that will both work without having to do a lot of metal work on the intakes. Any input on using a balance tube between the two?

I appreciate the offer Bruce! The pricing from some of the vendors suggested above looks a lot better than what I original was looking at, so I will likely just go with a pair of formed collectors. But if you do find that fixture, I'd like to see a picture of it.

 

Not too hard to make, or make a hammer form


Crappy Better Best

 

By 180 degrees do you mean firing right ,left, right, left,++++ ?

Thanks.
Ben

 

[QUOTE="Ebbsspeed, I cut .050 off the deck and the head.
Each or combined?

 

The are several sets on EBAY for $30 or so.

 

I think someone needs to post the aforementioned 180 degree header on the straight 8.

 

My concern would be for intake pulse phasing.

Much the same as exhaust pulse phasing for scavenging purposes, the intakes are pulling in pulses.

If you can figure out how to make a phase-correct intake (unless you have), you can be assured that each carburetor has the same quantity of pulses, and at the same phasing. You would not want one carburetor doing more work that the other one.

Correct me if I am wrong, but the firing order is 1-6-2-5-8-3-7-4. That will remain the same, but used a reference for when the intake pulses happen.

"Convenience plumbing" of the runners would likely be:

Carb 1: 1-2-3-4
Carb 2: 5-6-7-8

That would be:
1 Carb 1
6 Carb 2
2 Carb 1
5 Carb 2
8 Carb 2
3 Carb 1
7 Carb 2
4 Carb 1

If you look near the middle, the intake pulses are out-of-phase. There are two stacked sequential pulses, back-to-back. It is not a problem with a plenum manifold, or an IR manifold, but it could be on a dual carburetor manifold.

The only way to balance this out perfectly would be to work the manifold so that the intake pulses alternate, or use a crossover that is at least the size of a single runner, which is still a compromise.

I have been trying to figure out for some time a runner configuration that won't stack sequential pulses, but I am falling asleep wile writing this. I will re-visit it in the morning.

I think you need this:

Carb 1: 1-2-7-8
Carb 2: 3-4-5-6

1 Carb 1
6 Carb 2
2 Carb 1
5 Carb 2
8 Carb 1
3 Carb 2
7 Carb 1
4 Carb 2

 

And now I looked at the port configuration, and it would appear that this is impossible on this engine.

Crossover/balance tube it is.

 

I looked at the firing order at length, and it is possible if I had the front and back intake ports (cylinders 1-2-7-8) on one carb and the center two intake ports (3-4-5-6) on another, but it would be an absolute bundle of snakes to approach getting the intake runners near the same length. I did consider making the center intake runners short and the outside ones long as that would be the easiest way to even out the intake pulses, and wondered if that might actually flatten the torque curve. Overall it would be lower, but the long tubes would have a good ram effect at the lower RPM range, and the short ones would be better on the high end. After all was said and done, I went for pure aesthetics.

 

What if you did 4 carbs?

 

4 Carb 1
1 Carb 1
6 carb 2
2 carb 1
5 carb 2
8 carb 2

1&4 would be longest runners on carb 1
5&8 would be longest runners on carb 2

 

I have a couple of 263s and a couple of older 248s, and have given some thought to this problem as well. It may be worth noting that Buick tackled this issue by designing an intake manifold that does (appear to) group the cylinders served 1-2-7-8 and 2-3-4-5 and feeds them with a single 2 barrel carb (exception is the Compound Carbs of '41/'42).

That is accomplished by not using a plenum manifold, but rather two intake runners, each fed by one barrel of the two barrel carb. Each runner feeds four cylinders via 2 intake ports and is done in the same manner with the Compound Carbs as well. A year or two ago I chose to replace the old malfunctioning Stromberg on my '38 with a small base 2GC Rochester from a Buick 300 V8. I used a common 3 bolt to 4 bolt aluminum adapter to mount the the newer carb. However, that created a mini plenum because the adapter was undivided internally. To retain the original Buick divided intake tract, I fabbed an insert for the adapter. Whether or not that was overkill, the Rochester conversion works very well.

My point is, you (Ebbspeed) were right on track with your short/long runners configuration. But I suppose the question is, how much gain in volume/flow is possible when emulating the factory solution, vs the short runners you are using that create 'competition' for the intake charge pointed out by Gimpy? The Buick straight 8 intake ports are all siamese which (based on Gimpy's first grouping) means that 5 and 8 would be fed by separate branches of the manifold, even though by the same carb. Would that not somewhat reduce the intake pulse conflict?

Ray

 

When I made my first post, I hadn't looked at the picture well well enough to realize that the intake ports are siamese.

I will bang my head against the desk some more, and see if anything useful comes out. At the very least, you can have the fun of watching me flail.

The ports appear to break down to:

Group 1: Ports 1 and 2, Carb 1
Group 2: Ports 3 and 4, Carb 1
Group 3: Ports 5 and 6, Carb 2
Group 4: Ports 7 and 8, Carb 2

That would be, based on firing order and runner group:

1 Group 1, Carb 1
6 Group 3, Carb 2
2 Group 1, Carb 1
5 Group 3, Carb 2
8 Group 4, Carb 2
3 Group 2, Carb 1
7 Group 4, Carb 2
4 Group 2, Carb 1

There is still a stacked pulse pair in the middle of the firing order, but they are in different runners.

I wonder if just tucking a small crossover tube, under the exhaust, connecting say Group 2 and Group 3 would flatten this out.

As in:
1 Group 1, Carb 1
6 Group 3, Carb 2
2 Group 1, Carb 1
5 Group 3, Carb 2 - partial pull from carbs 1 and 2
8 Group 4, Carb 2
3 Group 2, Carb 1
7 Group 4, Carb 2
4 Group 2, Carb 1

Then again, I do wonder if we are hashing it out over 10-12lb.-ft. that may or may not appear at a particular RPM that may or may not be useful to how the engine will be used.

 

You still get 4&1 with stacked pulse too the next round of the firing order

 

If Group 2 (contains Cylinder 4) and Group 3 (Contains Cylinder 5) are connected with a crossover, that would fit my plan (I just did not reflect it):

1 Group 1, Carb 1
6 Group 3, Carb 2
2 Group 1, Carb 1
5 Group 3, Carb 2 - partial pull from carbs 1 and 2
8 Group 4, Carb 2
3 Group 2, Carb 1
7 Group 4, Carb 2
4 Group 2, Carb 1 - partial pull from carbs 1 and 2

Both of those partial pulls are separated by the same number of full pulls in the firing order, too.

For a better textual visual (remember, timing is a repeating loop, and the start point is arbitrary):

4 Group 2, Carb 1 - partial pull from carbs 1 and 2
1 Group 1, Carb 1
6 Group 3, Carb 2
2 Group 1, Carb 1
5 Group 3, Carb 2 - partial pull from carbs 1 and 2
8 Group 4, Carb 2
3 Group 2, Carb 1
7 Group 4, Carb 2

 

For header parts I like Columbia River Mandrel Bends, look under merge collectors.
http://www.mandrelbends.com/

 

Not using motorcycle carbs but I run into this same problem withe the GMC 6. I used a 1/2" diameter tube approximately 3/4" below the carb plates and found all idling and lower throttle response problems were gone. Having 4 cylinders of vacuum pulses is a lot better than 2 even if they are not even. A friend built a pretty large displacement early Chevrolet 6 with 3 S&S Super G's and it really performed. He also used a balance tube. There is a gentleman in San Dimas Ca. that really knows Keihin CV carbs called Killer Products and made my Harley perform better than new. What your doing is neat and please keep us informed. Thanks.

 

I looked at that as well, and have a matched quartet of 40mm Mikunis that would work well. And the intake runners would simply be four straight tubes. It would solve some problems, but multiply the carb synchronization issues.

 

Syncing 4 carbs on equal runners is gonna be easier than syncing 2 with multiple length runners and asymmetrical pulses.

 

Truth.