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tips, technology, tools and techniques related to vehicle driveline components

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Wilitrun
David M

(45 posts)

Registered:
10/21/2021 05:17PM

Main British Car:


300 exhaust port spacing?
Posted by: Wilitrun
Date: March 20, 2022 05:50PM

Hi, I'm wondering if anyone's done the measuring and comparing of exhaust port spacing with other popular engines.
This might allow me to modify a more readily available exhaust header by swapping over a custom cut flange plate.
I imagine it wouldn't be an issue so much for an equal-length chop-suey looking thing as you could just muscle them into position but something like a log manifold for a turbo with the right port spacing would be great. I'm aware someone's making a cast dual turbo manifold but they hang way out there and would hit my inner fenders for sure.
Just asking, maybe I'm blazing a trail here.


Roverbeam
Chad McNeely
N.E. MO
(38 posts)

Registered:
06/09/2021 06:03PM

Main British Car:
Alpine S4 Rover 4.0

Re: 300 exhaust port spacing?
Posted by: Roverbeam
Date: March 20, 2022 07:40PM

Here's my draft of a 300 exhaust flange, with existing and proposed port openings. I've 3d printed it and tested it against my own heads just to verify that the geometry would work. Note this pattern works with 10-bolt heads; for 14 bolts you need to lower the link bar about 1/2".
300 exhaust flange.jpg
flange check.jpg

There's a bunch of SBF flanges shown on this site, if you want to compare them to the rover/buick pattern:
[www.spdexhaust.com]



Edited 1 time(s). Last edit at 03/20/2022 07:42PM by Roverbeam.


mgb260
Jim Nichols
Sequim,WA
(2276 posts)

Registered:
02/29/2008 08:29PM

Main British Car:
1973 MGB roadster 260 Ford V8

Re: 300 exhaust port spacing?
Posted by: mgb260
Date: March 20, 2022 08:04PM

Only other motor is the Rover V8. The old Buick Nailhead is similar but larger.


MGBV8
Carl Floyd
Kingsport, TN
(4327 posts)

Registered:
10/23/2007 11:32PM

Main British Car:
1979 MGB Buick 215

authors avatar
Re: 300 exhaust port spacing?
Posted by: MGBV8
Date: March 21, 2022 08:41AM

For 14 bolt heads, omit the bottom row of head bolts. They just cause head gasket sealing issues anyway.


Wilitrun
David M

(45 posts)

Registered:
10/21/2021 05:17PM

Main British Car:


Re: 300 exhaust port spacing?
Posted by: Wilitrun
Date: March 21, 2022 01:16PM

Hey Chad,
That's outstanding information, thank you very much.
Looking at the staggered spacing it certainly would support Jim's report that 215/300/Rover would be the only ones identical.
From Kurt's article in the BV8 archive, I'm guessing the link bar has to either go down or be relieved to accommodate the lower sparkplugs and the dipstick tube on the Olds engine (not a problem I have).
This rules out adapting any short-runner log manifolds but it certainly seems that long runners could be bent to fit the port flange rendered above if someone wanted to use something already available.
Not sure that any of this helps my situation but it's certainly saved me a lot of potentially wasted research time. Cheers.


BlownMGB-V8
Jim Blackwood
9406 Gunpowder Rd., Florence, KY 41042
(6272 posts)

Registered:
10/23/2007 12:59PM

Main British Car:
1971 MGB Blown,Injected,Intercooled Buick 340/AA80E/JagIRS

authors avatar
Re: 300 exhaust port spacing?
Posted by: BlownMGB-V8
Date: March 21, 2022 01:42PM

It's also permissible to omit the straps between ports.

Jim


Wilitrun
David M

(45 posts)

Registered:
10/21/2021 05:17PM

Main British Car:


Re: 300 exhaust port spacing?
Posted by: Wilitrun
Date: March 21, 2022 01:57PM

Hey Jim,
For sure, and Kurt did mention that in the article about flexing being a problem with aluminum heads due to the different expansion coefficient but this won't be a consideration with the iron marine heads I'm running. So no straps is definitely an option here. Cheers.



MGBV8
Carl Floyd
Kingsport, TN
(4327 posts)

Registered:
10/23/2007 11:32PM

Main British Car:
1979 MGB Buick 215

authors avatar
Re: 300 exhaust port spacing?
Posted by: MGBV8
Date: March 21, 2022 03:12PM

"From Kurt's article in the BV8 archive, I'm guessing the link bar has to either go down or be relieved to accommodate the lower sparkplugs and the dipstick tube on the Olds engine (not a problem I have)."

Chad's will work for the 215/Rover V8/300.

Back in the day the 215/Rover headers had individual flanges after heat cycles if they needed to come off they were very difficult to reinstall. Dan Lagrou designed a header with them all connected. The bar comes off the side of the end ports & angles down to go under the center two ports.

215 Header800x600.jpg


MGBV8
Carl Floyd
Kingsport, TN
(4327 posts)

Registered:
10/23/2007 11:32PM

Main British Car:
1979 MGB Buick 215

authors avatar
Re: 300 exhaust port spacing?
Posted by: MGBV8
Date: March 21, 2022 03:18PM

"Kurt did mention that in the article about flexing being a problem with aluminum heads due to the different expansion coefficient but this won't be a consideration with the iron marine heads I'm running. So no straps is definitely an option here."

Don't count on it.

We had an expensive header on our TR6 race car (iron block & head 6 cyl). We were using pry bars to reinstall it. Took three people.


BlownMGB-V8
Jim Blackwood
9406 Gunpowder Rd., Florence, KY 41042
(6272 posts)

Registered:
10/23/2007 12:59PM

Main British Car:
1971 MGB Blown,Injected,Intercooled Buick 340/AA80E/JagIRS

authors avatar
Re: 300 exhaust port spacing?
Posted by: BlownMGB-V8
Date: March 21, 2022 04:51PM

Interesting. I cut the straps off mine for the Olds 215 and it's never been a problem. But then I guess 32" tubes would have a bit more give. For sure, don't pressure wash the engine hot.

Jim


Airwreckc
Eric Cumming
RTP, North Carolina
(152 posts)

Registered:
05/28/2020 10:10AM

Main British Car:
1972 MGB-GT (working on a Sebring project) Buick 300-4 V8

Re: 300 exhaust port spacing?
Posted by: Airwreckc
Date: March 21, 2022 09:11PM

In case you don't want to go to the trouble, here's a source for flanges: [www.headersbyed.com]


Roverbeam
Chad McNeely
N.E. MO
(38 posts)

Registered:
06/09/2021 06:03PM

Main British Car:
Alpine S4 Rover 4.0

Re: 300 exhaust port spacing?
Posted by: Roverbeam
Date: March 22, 2022 10:14AM

I never saw that resource, Eric - thanks for sharing it!

I think Art mentioned a few weeks ago the idea of using pre-made headers for engines with nearly equal-distant exhaust ports (like the SBF), cutting off the Ford flange and 'adjusting' the tubes to fit the Rover/Buick pattern. This isn't exactly what David seems to need for his turbo or short tube needs (if I understand right?), but his question wasn't too far away from Art's solution, and something I was looking at recently.

Looking at 'Headers by Ed' offerings, for the plain flanges for my heads they want $147; with my drawing at an online water jet company (I use sendcutsend; there are others) the pair of flanges in 1/4" mild steel is $48 with free shipping. Unless I use Ed's $314 "finished" flanges with the 2" long rectangle-to round tubes attached, I have to come up with a way to blend the sbf tubes to the rectangle ports of the Buick using fairly ordinary garage tools - heat and a peening hammer, most likely - and maybe some kind of fabricated male buck to jamb into the round tube end.


Airwreckc
Eric Cumming
RTP, North Carolina
(152 posts)

Registered:
05/28/2020 10:10AM

Main British Car:
1972 MGB-GT (working on a Sebring project) Buick 300-4 V8

Re: 300 exhaust port spacing?
Posted by: Airwreckc
Date: March 22, 2022 02:34PM

Chad, I agree that it probably will cost less for you--but some people might not want to go that route. In any case, if you decide to make the flanges, I'd love to have a pair for my 300. Any thought to doing some for others?


Roverbeam
Chad McNeely
N.E. MO
(38 posts)

Registered:
06/09/2021 06:03PM

Main British Car:
Alpine S4 Rover 4.0

Re: 300 exhaust port spacing?
Posted by: Roverbeam
Date: March 22, 2022 03:25PM

Happy to share my drawing file with anyone, or if you want a different port dimension I can incorporate that instead - mine is set up for 1 5/8" header pipe. From there, anybody can get their own flanges cut from the water jet guys.


MGBV8
Carl Floyd
Kingsport, TN
(4327 posts)

Registered:
10/23/2007 11:32PM

Main British Car:
1979 MGB Buick 215

authors avatar
Re: 300 exhaust port spacing?
Posted by: MGBV8
Date: March 22, 2022 04:07PM

Port layout & distance.

[victorylibrary.com]



Airwreckc
Eric Cumming
RTP, North Carolina
(152 posts)

Registered:
05/28/2020 10:10AM

Main British Car:
1972 MGB-GT (working on a Sebring project) Buick 300-4 V8

Re: 300 exhaust port spacing?
Posted by: Airwreckc
Date: March 23, 2022 12:31PM

Chad,

I'd love to have a copy of your file. That's the size pipe I would use, too, Thanks much!


Roverbeam
Chad McNeely
N.E. MO
(38 posts)

Registered:
06/09/2021 06:03PM

Main British Car:
Alpine S4 Rover 4.0

Re: 300 exhaust port spacing?
Posted by: Roverbeam
Date: March 23, 2022 04:49PM

I've put the .eps file on Dropbox.

To use, create an account with sendcutsend.com, and follow the instructions. The file is in inches when it asks. I selected 1/4" mild steel for mine, but other materials and thicknesses are available. (Not shilling for this water jet company, they're just the one I've used and am familiar with).

[www.dropbox.com]

I have a set of later v6 gaskets coming in the next few days, to see how their port size compares - one of the tips I saw at the 'Headers by Ed' link posted above.



Edited 1 time(s). Last edit at 03/23/2022 04:51PM by Roverbeam.


Airwreckc
Eric Cumming
RTP, North Carolina
(152 posts)

Registered:
05/28/2020 10:10AM

Main British Car:
1972 MGB-GT (working on a Sebring project) Buick 300-4 V8

Re: 300 exhaust port spacing?
Posted by: Airwreckc
Date: March 24, 2022 05:58PM

Chad, thanks much. Quick question--my 300 has the aluminum heads. Does your design retain the straps and, more importantly, will it actually work on the 300 aluminum heads?


Roverbeam
Chad McNeely
N.E. MO
(38 posts)

Registered:
06/09/2021 06:03PM

Main British Car:
Alpine S4 Rover 4.0

Re: 300 exhaust port spacing?
Posted by: Roverbeam
Date: March 24, 2022 08:52PM

My heads are the aluminum 300’s too. The 3d printed version shown above is being tested against the aluminum head. I enlarged the ports slightly (.050 all around) from the drawing/3d print above, to allow for the header tube thickness and still retain the desired finished port size. I also added some tolerance to the bolt hole diameters, since I previously wanted the 3d print to be close to zero to reveal any errors. Otherwise the .eps (Illustrator) file is exactly what’s shown above, with the straps.

I have some eBay sbf headers coming, some bigger v6 gaskets coming, and when I get my block back from the machinist I’ll start mocking this all up. So, ‘does it work’ isn’t guaranteed, but this is what I’m going to be using. Early adopters beware!


mgb260
Jim Nichols
Sequim,WA
(2276 posts)

Registered:
02/29/2008 08:29PM

Main British Car:
1973 MGB roadster 260 Ford V8

Re: 300 exhaust port spacing?
Posted by: mgb260
Date: March 24, 2022 10:06PM

Chad, are you using the Mustang tri-y headers? I already proved they will fit the Alpine/Tiger. You have to cut the rib below the brace on the Alpine to match the Tiger.

[forum.sunbeamalpine.org]



Edited 1 time(s). Last edit at 03/24/2022 10:07PM by mgb260.
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