| Author |  Topic  | |
andydeans3
V4 Guru
United Kingdom
2016 Posts |  Posted - 31 Oct 2018 : 21:22:55  
| I recently helped a chap across in Edinburgh to change his clutch.
On his exhaust manifolds, the lower fixing was an allen head cap screw, instead of studs with nuts.
This made life so easy in terms of removing the engine. No wrestling with exhaust end pipes, trying to get them past the lower exhaust studs. Also easy to screw and unscrew with an 8 mm allen key in a socket.
I'd like to do the same on my car, so my question is, given the temperature these bolts will see, what material should they be made of?
Wouldn't want them getting seized in the cylinder head, because they're the wrong material.
Stainless? High Tensile steel, brass? something else?
I'll be at the NEC on Friday 9th/10th November, so would hope to find something there.
Andy
1978 LHD SAAB 96
1978 MGB Roadster
2008 LHD "Classic" Renault Twingo
1991 Nissan Figaro |
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melle
V4 Guru
United Kingdom
3833 Posts | Posted - 31 Oct 2018 : 21:56:46
| I use 304 (A2) or 316 (A4) stainless threaded rod, whatever I have at hand. 316 has a higher tensile strength, but 304 handles heat better. To be honest, I'm not too fussed about it, mild steel will do as well. I dislike the idea of using bolts for this application, I prefer studs with copper exhaust nuts with a 14mm spanner width.
www.saabv4.com |
Edited by - melle on 01 Nov 2018 08:12:18 |  |
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RhysN
V4 Fanatic
United Kingdom
411 Posts | Posted - 01 Nov 2018 : 07:46:18
| | Melle, a question. Copper or brass exhaust nuts? | |
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melle
V4 Guru
United Kingdom
3833 Posts | Posted - 01 Nov 2018 : 08:27:05
| I've never used brass nuts for the exhaust. I don't think it matters much to be honest. Do you? I've also used copper plated (in below pic) and plain stainless nuts in the past, worked fine as well.
What I do think is much more important than stud/ bolt material, and often overlooked I believe, is that the gasket surfaces on the block and the "collars" must be dead flat for a good seal. I file them until they're acceptable and then lap them with (block) or on (collars) something flat, like a piece of thick glass, with valve grinding paste. I use copper gaskets; pattern on my website: http://www.saabv4.com/index.php/engine-gaskets/exhaust/
www.saabv4.com | |
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andydeans3
V4 Guru
United Kingdom
2016 Posts | Posted - 01 Nov 2018 : 08:55:22
| Melle.
Thanks for your thoughts.
Problem with nuts is that you can't get a socket or ring spanner on them, because of the restricted space.
When we took my engine out, to change it, back in 2014, we had to seriously heat the nuts in order to remove them. Lucky we were at John Wyatt's place and had access to an acetylene torch.
With a cap head allen bolt, this problem disappears of getting a socket on the head disappears.
Anyway, you'd go for 304 stainless.
I'll see what I can find at the autojumble at the NEC next week.
Andy
1978 LHD SAAB 96
1978 MGB Roadster
2008 LHD "Classic" Renault Twingo
1991 Nissan Figaro | |
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melle
V4 Guru
United Kingdom
3833 Posts | Posted - 01 Nov 2018 : 09:00:42
| Standard nuts are 17mm spanner width, the ones I use are 14mm; works fine with a Jetex exhaust. Also, stainless/ brass/ copper nuts don't freeze onto the studs. 304/ A2 stainless is what they sell in B&Q, or otherwise I guess eBay will be much cheaper than anyone at the NEC!
www.saabv4.com | |
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RhysN
V4 Fanatic
United Kingdom
411 Posts | Posted - 01 Nov 2018 : 14:18:26
| | Clear now, thanks. I had never come across copper nuts. Brass for exhaust I knew about, and I am learning about copper plated nuts (again never come across them before). | |
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andydeans3
V4 Guru
United Kingdom
2016 Posts | Posted - 01 Nov 2018 : 23:46:54
| Melle
Yep, they are normally 17 mm, so there is no room around then for a ring, or socket to go on. I have made things a little easier on my car, by using 15 mm long nuts, on the studs. Still like the idea of allen head screws, at least on the bottom. The thread is M8 I think.
I'll find S/S ones I think.
Andy
1978 LHD SAAB 96
1978 MGB Roadster
2008 LHD "Classic" Renault Twingo
1991 Nissan Figaro | |
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melle
V4 Guru
United Kingdom
3833 Posts | |
Borstlap
V4 Fanatic
Norway
334 Posts | Posted - 02 Nov 2018 : 15:46:34
| I use extension nuts that I tapered on one side. Keeps a Highgate exhaust (which is wider than a Jetex) in place. Snug at the underside but it works. Use a dab of exhaust cement beteween all the mating surfaces and everything seals beautifully.
Alex | |
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Woody
V4 Guru
United Kingdom
2764 Posts | Posted - 02 Nov 2018 : 18:33:13
| I use stainless Allen bolts instead of studs. Studs/nuts were not compatible with the original Grp 2 rally exhaust.
The SSR exhaust came with Allen bolts for head and connections.
I got stainless equivalents when fitting the stainless copy of the rally exhaust. Also used brass nuts for the connection bolts underneath. | |
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Doive
V4 Fan
United Kingdom
160 Posts | Posted - 05 Nov 2018 : 00:56:48
| When replacing ours with a Jetex, two of the studs came out with the nuts seized to them. A good smear of exhaust paste sealed everything perfectly. Were I doing it again, I'd definitely look at stainless allen bolts.
1970 95 V4 van
1972 Sonett 3
1973 95 V4 estate | |
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andydeans3
V4 Guru
United Kingdom
2016 Posts | Posted - 05 Nov 2018 : 14:20:27
| Yep, I'm going to get some stainless allen head cap screws, at least for the bottom connections, that foul the exhaust, when removing the engine.
1978 LHD SAAB 96
1978 MGB Roadster
2008 LHD "Classic" Renault Twingo
1991 Nissan Figaro | |
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| | Topic | |
Exhaust Manifold studs/bolts.
