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Hi all.
How is the B18 dual downdraft exhaust manifold (individual unit, not one-piece-intake-exhaust) different from the B20 dual downdraft exhaust manifold (individual unit, not one-piece-intake-exhaust)? Are they the same in terms of flow diameter and performance, or are they different?
Ry
PDX
'63 544
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B18B Rally Pack Amazon Headers
I was looking for small bore 4-2-1 heades which I remember seeing somewhere in Sweden & found these 3-2-1 Amazon headers being reproduced at www.timosmotor.com in Sweden.
The ONLY decent headers I have seen in the USA are Bob Griffiths ITB headers or Jere Stahl's.
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I have an original set of these in the garage. The centre outlet being made into a single "box always intrigued me. Comments are made that it can't be as good as a pair of seperate tubes but Volvo generally knew what they were doing. Do YOU like it Paul?
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Can you measure the length down the centreline to the beginning of the 2-1 joint please, particularly the 2-3 cylinders.
For mild to medium motors including those with twin DCOEs, i.e. - cam is up to 240°@.050", 0.300" lobe lift, the stock manifold is OK, these B18B Historik headers are better & 4-2-1 1.5"-1.75"-2" are best. I then like the 2" section to dump into a 2.5" after about 3 feet, 2.5" muffler after that.
The Swedes just go bigger & bigger with their 4-2-1 headers & I don't know why? Likewise the VPD copies are too big, really only suited for a supercharged motor.
If you have a strong motor with a big cam, 4-1 is the best choice.
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I'm afraid it's stashed away in a garage that is hard to get into at the moment. I think I have a photo somewhere. I'll see if I can find it and put it up on Imgur or somewhere, then post a link. You'll have to extrapolate a measurement from that. A quick look found one on a RHD red 142S without the carbs on so it might be possible to make a guess at the measurement. I do have one of the exhaust on the ground by itself which may or may not be be more useful.
https://i.postimg.cc/prx7LptK/142-S-1970-Factory-build-with-box-type-header.jpg
This one apparently a build for a Australian customer. It might have been mentioned here somewhere?
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That is one of George Minassian's cars, about 80 miles from me.
http://www.volvo1800-120parts.com.au/volvo142Srally.htm
http://www.georgeminassian.com.au/
Where did you find that pic?
It is a historic car, he bought it in the original mustard colour, overhauled it & changed it to red.
The top half of the Amazon headers are what they appear to be, a light, sheetmetal replica of the stock exhaust manifold, but the bottom section is longer, but still 1.75"OD/1.625"ID. I think they would total 36" from the 2-3 valves to 2-1 joint.
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Picture off the net and might have come from Georges site?
They are I think shown in the R-Sport Tuning guides.
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no text.
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All of the dual downdraft exhaust manifolds, even the ones combined with intakes,
are pretty much the same. The later models MIGHT be a little freer flowing but NOT MUCH!
--
George Downs Bartlesville, Oklahoma
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Well there was never a b18 dual downdraft exhaust that was a stand alone... If you car has one, some PO grabbed it off a b20 and put it on a b18.
But as George said, the flow is about the same. I personally think that the later b20 stand alone manifolds are a bit thicker (in the crotch area) than the early dual manifolds (intake/exhaust with two pipes out) as they don't seem to crack as often in there. But I have one of the early duals cut apart (to run one of the alumn. intakes) on my own 1800. Careful of the offset to the washer seats when you get mixing and matching different manifolds. I have cleaned my own up with a 1" end mill and a Bridgeport, so I don't have half washers or anything like that.
I've got some manifolds about if you decide you want them and I'm not far away...
Chris
Scappoose Oregon
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Folks,
I have a what I believe is an original unmodified dual port header / manifold: https://www.ebay.com/itm/193886354052
It has B18 written on it in paint pencil.
Can anyone shed some light on which models / years this may have been OEM?
Many thanks!
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That manifold is a modified B18 manifold. In its original form, it would have had the intake manifold attached such that exhaust and intake were a single piece. I think it's a 1967 piece - later manifolds were also combined intake/exhaust, but there were additional butterflies in the exhaust which hampered performance.
Unfortunately, the 1967 manifold is both the most rare and - according to many enthusiasts - the best original piece to use with SU carbs.
A brand new exhaust manifold costs about the same as the asking price for this one.
Cameron
Portland
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"That manifold is a modified B18 manifold. In its original form, it would have had the intake manifold attached such that exhaust and intake were a single piece. I think it's a 1967 piece - later manifolds were also combined intake/exhaust, but there were additional butterflies in the exhaust which hampered performance.
Unfortunately, the 1967 manifold is both the most rare and - according to many enthusiasts - the best original piece to use with SU carbs."
I thought about those in manifold throttles, they are the same size as what's in the SU's & it did meet emission standards. I always wondered would the butterflies closed improve fuel economy? Cold air & fuel gives more power, but, cruising down the highway with very little throttle a gasoline engine would like to be fed warm, vaporised fuel, that's why most every road car has the injectors aimed at the hot intake valves. Outright performance needs injectors mounted further back in the runner so the fuel goes in atomized.
Rarity: It's the opposite way around here. I only have one of the manifolds with emission throttles. It came in the 1st of the B20 142's here & the throttle shafts were flogged out in car with not much more than 100,000 miles. It got swapped out asap along with the emmision needles in the SU's.
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Mark;
It may say B18 on it, and that's what the seller may have taken it off, because it is a favorite when combined with other intake arrangements, but that is a 4 into 2 Manifold, originally from an injected B20.
See also: https://www.sw-em.com/manifolding_notes.htm#factory_manifolds
Cheers
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It looks more like one of the one piece combined intake and exhaust manifolds after someone crudely cut away the intake portion.
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Cameron;
I didn't look at all the pix on the epay offering, but after seeing the remains of the Intake joint on the fifth picture, I must agree of course...
...for the (right hefty!) $320 he wants, he could have at least spent some time with a grinder cleaning the area up...
Cheers
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If this one is worth $320, maybe we should rethink how we go about our livelihood!
Best regards, Ron -
Cameron
Portland
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Agreed. Ludicrous price too.
$320 for this and $150 for what looks to be a correct 1800 boot rack in decent condition from the same vendor. Makes no sense.
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Chris, thank you for the generous offer. It appears that I'm good on manifolds for now, but I'll keep you in mind for the future if my dual downdraft exhaust ever starts leaking at the Y. It is fairly well pitted, but I'm going to have it cleaned up and coated with ceramic anyway. The aluminum intake looks great were it not for a crushed shoulder where a misfit washer tragically interfaced with a bolt stud. My plan for that is a visit to the machine shop. :-)
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Chris wrote: "Well there was never a b18 dual downdraft exhaust that was a stand alone... If you car has one, some PO grabbed it off a b20 and put it on a b18."
I'm not too sure of that. With Volvo it is pretty hard to definitively say "never". I bought a bunch of stuff from a guy whose roommate totaled his 68 142 on the Bridge of the Americas in Panama. Among that stuff were the manifolds, aluminum intake and cast iron dual downdraft exhaust. No evidence that they were not original. It had a very late B18 engine with the alternator ear as well as generator mount boltholes. Then there are at least a couple of 164s in Europe with triple side-draft carbs, and one of the owners informed me that the car was provided new that way. It was a 69 and had 3 Z-S 175CD2 carbs. You can see a pic of it on the German 164 club website.
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George Downs Bartlesville, Oklahoma
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Thanks guys, for the information. Very interesting and very helpful. Although I don't think the PO installed a later model manifold, I'll never really know. It sounds like I'll be using the aluminum intake and cast exhaust from the B18 on the B20 since they both already fit together just fine. Now on to the Z Therapy carb mods...
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Hey Ry -
Not sure about the manifold question but have lost your phone number. Please give a call if you're still interested in some 544 parts.
Or, if you've lost my number as well, drop me a note
volvorelix yahoo
Sorry about that.
Cameron
Rose City
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Thanks Cameron. I'll call you soon.
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