I'm making up a set of headers for my 283 Chevy in the style of the old Belonds that were typical of 303 Olds where the center two ports were siamesed. In other words you end up with two small end primarys and a double wide center that serves two cylinders. My question is...... Is there any problem with doing this such as the inversion problem on flatties? Will it sound like a six like tri-Y headers do? Anything else I'm doing wrong this time? I'm sure there must be a reason you don't see this done.
Definitely not an expert, but I'll take a stab at it ... I don't think there will be a reversion problem as the exhaust ports are separated within the head. A flathead merges them together inside the block which is why adding a port divider helps them. If you look at a set of ramshorn manifolds, the centre two ports are not separated for very long inside the manifold so what you are proposing is not really very different from that. It won't be as efficient as a tuned set of headers, which is probably why you don't see it done. It will still probably be more efficient than a log style manifold would be, so if you like the way it looks, go for it and post some pics!
I was thinking of separating the ports in the center for a short distance anyway. The headers I'm looking at are as in frame #5 of the following thread... http://www.jalopyjournal.com/forum/showthread.php?t=308206&highlight=303+belond+headers Cool eh? And super easy to build. I'm using a flat flange plate like the old Hedmans for added wierdness also easier to seal. I usually use 3/8" x 1 3/4" cold rolled for the flat flanges. I'm planning on 1 3/4" on the front and rear ports and 2" on the center. Anybody have a set of origionals and know what O.D. the tubes were?
Hey Koz, It shouldn't be a problem. Cast manfolds just dump into a log. At higher RPMs it may matter more. I'd put a divider in that center pipe for an inch or two just to satisfy myself though. #5 and # 7 fire cylinders just a quarter turn from each other and exhaust ports do flow better with atleast acouple inches of tubing on them. So what if it sounds different... Smokey You don't see it much cause the chevy ports are further apart than Olds and Pontiacs.
MGs have two exhaust valves on one center port and they don't connect the header tubes until the collector. The header on the left of pic. http://www.mossmotors.com/Shop/ViewProducts.aspx?PlateIndexID=29810
This is definitly not a quest for maximum power. I'll have enough juice in that 283 to destroy my '39 style trans, (fuse?), in a heartbeat. I just want something different than the usual rams horns or, yuck, tight tucks. Plus, I can build them cheap, under a hundred bucks for everything. I'm shooting for a 1955-1957 time period on my coupe and these fit right in there.
I doubt you will be able to notice any loss of power compared to a 4 tube header in a Conservative street driven car. I don't think it will sound like a Chevy six with a split manifold. I'm trying to find out how to make a V6 sound like that and I don't think it will.
I know that straight six sound well. One of the best sounding engines I ever heard was a GMC straight six in a boat. Unbelievable!
Koz, I never heard that boat but you never heard my 302 powered '32 Ford five window. If anyone knows how to make a V6 sound like a straight six, please post
What kind of headers did you run on the 302 Rich, straight pipes? Do you have a picture of the 302 headers? If you have a picture of the headers and you know the firing order, can't you make some headers for the V6 that mimics the firing order and header arrangement. make a really quiet exhaust and then get a really load sound system with a speaker by the tailpipe,and play a 302 running while you drive
153624- A split exhaust on a straight 6 will normaly fire equally one in front then one in the rear and so forth. So does a V6. Left bank, right bank and so forth.So why do they sound so different?
A lot of headers built in the sixties for engines with that port arrangement (Chev, Buick, Olds, Cad, and Pontiac) were commonly built with one tube for the center port(s) to make it easier to fit them in chassis of that era. With the exception of Hedman's TriYs for 61 to 64s, it was almost impossible to get over the counter headers built any other way if you had a full size 60's Pontiac for instance.
So there are two Siamesed exhaust ports? That's what is looks like in this video. What were the headers like on your 302? Seems like if you figured out where the exhaust was routrd and when the cylinders were firing you could figure out how one might do it, but it would probably be a very odd looking set of exhaust headers and probably challenging to build and fit under the hood of a Bantam. Here the vid link http://youtu.be/ZZRhCtnDtGM
Rich it has to do with firing order and tyeing the same cylinders that are tied on the inline or the V-6 you have even fire and odd fire so you would need to overcome that also. If you go with the firing order and tyeing the same cylinders together as would be tied together on the inline according to the order that they fire in you should effectively be able to get the same sound or close to it. it may be a little off because of the swept volume per cylinder. My mom had a '66 Buick Special with a V-6 that when we split the exhaust sounded a lot like an inline. I am not real familiar with the Buick V6 so I can't tell you if it is odd or even fire. Back to the original question if you are building your headers for looks and not for performance you are whistling in the wind. Reversion may be a real problem with the Chevy 8 as opposed to the olds 8. They have a different firing order. The Chevy being 18436572 and the olds being 18736542. What you could do if it is looks that you are after it would be a simple task to build your headers with the center tubes touching than weld a piece of sheet metal on the top and bottom of them to make them appear to be one large tube as opposed to 2 separate and smaller tubes.
Since there weren't too many 283's in '55 or '56, you might need to shoot for the '57 and later, time period.
The firing order on a Chevy 6 or a GMC or any other inline six I have ever laid hands on is 153624. So if you split a stock manifold to make it a dual pipe car you fire in the front half then the rear half and then the front and then the rear and again. The V6 firing order I am familiar with and is pretty universal is 142536 which is first cylinder on the left then first on the right then second on the left and then second on the right and again for the last two cylinders. So with either engine you are evenly alternating between exhaust manifolds. So they should sound alike. They don't to me.
V6s came odd and even fire, I dont really know what that means as I have not played with them much, my assumption is that it is a firing order thing. My moms Buick sounded like a piper cub taking off which is what an inline with splits sounds like to me. Let me see if I can find the firing order for the '66 Buick. The Buick is an odd fire, the engine fires 165432. Maybe you need to connect the two manifolds. Most of the splits that I have seen over the years have not been divided in the middle, they just have a second flange welded on them. I'm just throwin stuff out here you realize that right?
The early V6s were just V8s missing a pair of rear cylinders. Pretty crude as there wasn't anything taken into account for the missing two cylinders. On a 90* engine you basically are missing two throws and the engine will shake your fillings with the firing order changing from 90* to 150*. In '77 Buick fixed the issue by split pinning the V6 crank 30*. This allowed the engine to have the cylinders fire every 120* thus even firing of the 90* Buick V6 was born. Prior to this, as seen on the dist cap, the firing was 1--6-5--4-3--2. With the even fire the order was 1_4_5_6_3_2, and the dist caps posts were evenly spaced.
Mike taking an engine and removing a couple of cylinders has never really worked out well. Lost of different companies have tried it with little success. my moms Buick ran out alright, it really ran well when we stuffed the 401 in it. I guess that is really off topic isn't it.
Porknbeaner, I'm already goint to split them inside with a divider welded between the ports. It just seems weird to me that nobody else has done this on here. I thought everything was done at least once and there was a tech on it. (Only kidding!) I'll post up when I get them done as I think the early Belonds were some of the coolist looking headers around. I don't really care if it sounds like an Olds, just so it doesn't sound like a six. Hey, I've thrown a lot more work than this away!
V-6 engines can have 3 configurations, ODD FIRE, EVEN FIRE, and SEMI-EVEN FIRING orders. The crankshaft rod journal throws are different on each also. A common crankpin, and 2 versions of offset pins.
And to say that cutting 2 cylinders off a V8 has not been successful is to ignore the millions of Buick and Chevy 90 degree V6 engines running around every where. Even Indy when the rules allowed American engines. Maynard V6 (Buick) sat on the pole.
The Jalopy Journal
