Olds 350 exhaust manifold questions
July 28th, 2015, 04:18 AM
#1
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Join Date: Jul 2015
Posts: 16
Olds 350 exhaust manifold questions
Hello
I had old rusty headers with bunch of holes and found used exhaust manifold which is in much better shape. It needs to be cleaned but it is only option for me in Finland for now.
I have no experience with these manifolds. I am not sure if these are the stock exhaust manifolds.
Passenger side: 398704 RH 02 L
Driver: 22503678 7
Questions:
1- Is it OK to somehow block the crossover exit from passenger side and connect both exhaust manifolds to the exhaust pipes?
2- Do I need flange rings? I cannot seem to find any suitable size.
3-Do I need gaskets between the manifold and engine?
I apologize for my approximate english.
I had old rusty headers with bunch of holes and found used exhaust manifold which is in much better shape. It needs to be cleaned but it is only option for me in Finland for now.
I have no experience with these manifolds. I am not sure if these are the stock exhaust manifolds.
Passenger side: 398704 RH 02 L
Driver: 22503678 7
Questions:
1- Is it OK to somehow block the crossover exit from passenger side and connect both exhaust manifolds to the exhaust pipes?
2- Do I need flange rings? I cannot seem to find any suitable size.
3-Do I need gaskets between the manifold and engine?
I apologize for my approximate english.
Last edited by oldsdale; July 28th, 2015 at 06:31 AM.
July 28th, 2015, 05:02 AM
#2
Registered User
Join Date: Feb 2013
Posts: 37
Hi Oldsdale,
I don't know the casting numbers and don't have my car handy to check, but those look like the manifolds on my stock 350.
Answers to your quesions:
1. Yes, you can block it. On my car someone welded it up, and it looks like they cut a block of plate and welded it in place, so now it has true dual exhaust pipes.
2. You need what I call "donut" ring gaskets at the outlets of the manifolds where the pipes connect. I lived in Norway for 4 years and found these at a Swedish store called Biltema, I don't know if you have those in Finland. I was also able to get them at an exhaust repair facility but they might be more expensive.
3. I would use a gasket, I believe they are called for by the manufacturer, but I am relatively new to Oldsmobiles so I could be wrong. The experts will chime in, I'm sure.
Having lived in Scandinavia and worked on an old car (1970 Mercury Cougar) I can tell you that Summit Racing will ship to Norway, you might try them, they also sell a LOT of stock parts, like the rings and gaskets.
summitracing.com
Good luck
Jeff
I don't know the casting numbers and don't have my car handy to check, but those look like the manifolds on my stock 350.
Answers to your quesions:
1. Yes, you can block it. On my car someone welded it up, and it looks like they cut a block of plate and welded it in place, so now it has true dual exhaust pipes.
2. You need what I call "donut" ring gaskets at the outlets of the manifolds where the pipes connect. I lived in Norway for 4 years and found these at a Swedish store called Biltema, I don't know if you have those in Finland. I was also able to get them at an exhaust repair facility but they might be more expensive.
3. I would use a gasket, I believe they are called for by the manufacturer, but I am relatively new to Oldsmobiles so I could be wrong. The experts will chime in, I'm sure.
Having lived in Scandinavia and worked on an old car (1970 Mercury Cougar) I can tell you that Summit Racing will ship to Norway, you might try them, they also sell a LOT of stock parts, like the rings and gaskets.
summitracing.com
Good luck
Jeff
July 28th, 2015, 06:08 AM
#3
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Thread Starter
Join Date: Jul 2015
Posts: 16
Thank you for the fast reply.
driver side outlet is 5 cm (1.9685 inch)
passenger side outlet 5.4 cm (2.12598 inch)
Online part stores cannot find donut gaskets with these sizes. I am not sure if I'm searching it correctly.
And there is no single store or repair shop willing to help me in Finland
(note: Finnish Biltema doesn't have either)
driver side outlet is 5 cm (1.9685 inch)
passenger side outlet 5.4 cm (2.12598 inch)
Online part stores cannot find donut gaskets with these sizes. I am not sure if I'm searching it correctly.
And there is no single store or repair shop willing to help me in Finland
(note: Finnish Biltema doesn't have either)
July 28th, 2015, 06:11 AM
#4
72 Olds CS
Join Date: Jun 2011
Posts: 6,657
http://www.ebay.com/itm/1968-72-Olds...d65f4a&vxp=mtr
heres the block off plate for the manifold, on my car someone took a section of pipe and welded it shut at one end wasnt pretty but does the same thing
most olds didnt use a gasket between the engine and manifold, unless the surface dictates the need for one ie pitted
no donut gaskets there is a flanged end that fits on there, supercars has them im sure others do
http://www.supercarsunlimited.com/Ex...nges-i198.aspx
heres the block off plate for the manifold, on my car someone took a section of pipe and welded it shut at one end wasnt pretty but does the same thing
most olds didnt use a gasket between the engine and manifold, unless the surface dictates the need for one ie pitted
no donut gaskets there is a flanged end that fits on there, supercars has them im sure others do
http://www.supercarsunlimited.com/Ex...nges-i198.aspx
July 28th, 2015, 06:20 AM
#5
Registered User
Thread Starter
Join Date: Jul 2015
Posts: 16
http://www.ebay.com/itm/1968-72-Olds...d65f4a&vxp=mtr
heres the block off plate for the manifold, on my car someone took a section of pipe and welded it shut at one end wasnt pretty but does the same thing
most olds didnt use a gasket between the engine and manifold, unless the surface dictates the need for one ie pitted
no donut gaskets there is a flanged end that fits on there, supercars has them im sure others do
http://www.supercarsunlimited.com/Ex...nges-i198.aspx
heres the block off plate for the manifold, on my car someone took a section of pipe and welded it shut at one end wasnt pretty but does the same thing
most olds didnt use a gasket between the engine and manifold, unless the surface dictates the need for one ie pitted
no donut gaskets there is a flanged end that fits on there, supercars has them im sure others do
http://www.supercarsunlimited.com/Ex...nges-i198.aspx
July 28th, 2015, 06:55 AM
#6
Old(s) Fart
Join Date: Mar 2007
Location: Northern VA
Posts: 47,366
398704 is the very common small block RH manifold used from the mid-60s to the mid-70. 22503678 is from an early 1980s 307. It will work for your application. As noted, if the flanges are flat and not pitted, no gasket is needed. Same for the donut gaskets at he outlets. You will likely need longer bolts for these manifolds, as headers have thinner flanges.
August 4th, 2015, 11:13 AM
#9
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Join Date: Jul 2015
Posts: 16
Thank you all for the ideas. I found an exhaust repair shop and it took some time to find suitable sizes.
Also, I could barely find bolts and nuts in imperial size but they were too long. I used some redneck engineering.
I also used exhaust paste for outlets.
Also, I could barely find bolts and nuts in imperial size but they were too long. I used some redneck engineering.
I also used exhaust paste for outlets.
Last edited by oldsdale; August 4th, 2015 at 11:22 AM.
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