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HQ/J/X/Z V8 Exhaust help needed..
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RdS Offline
#1 Posted : Monday, 30 November 2009 5:56:06 AM(UTC)
RdS

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hey everyone..!
need a little help with the exhaust on my HJ. dont know enough about what im doing; so itd be great if people could point me in the right direction!

My HJ ive been rebuilding over the last few years needs an exhaust. ill eventually get a nice one made up, but bit hard until the cars drivable, and a stock one for going through rego would make it a bit easier. so i have a full stock single system i pulled off a HZ V8.
looks like this:

hopefully its clear in my fairly dodgy drawing, but the exhaust piping seals up against the manifolds with a series of chamfers.
on the drivers side there is an extra piece sandwitched in.. with a buttefly in the centre that spins. it has a spring and weighted piece on the end.
in the pic in the top corner; the first bit is the back of the manifold with the studs coming out, then the butterfly piece, then the start of the exhaust pipe itself, and then the plate bit on the exhaust that pulls the lot together.
the PROBLEM im having is when trying to get my car running today, it was very bloody noisy! the manifolds are tight against the block with a new gasket (i cant see a ploblem there), so im assuming its coming from where the manifolds meet the exhuast.


questions:
- where the exhaust meets the manifolds, is there meant to be gaskets or some sort of gasket glue/seal? the chamfers on the seperate pieces seem to seal up pretty nicely, but im not sure..

- with the exhaust all bolted up tight, the perpendicular part of the exhaust (next to the red squiggle in the picture) is pressed up against the back of the sump.
is there a difference between the sumps on the HJ and HZ, is it bent, or am i just bolting it up wrong?

- what is the buttefly incert piece (with the red arrow pointing at it) for?? it looks VERY restrictive to just 4cyl for no reasons i can see.

hope thats simple to understand. ive over-complicated a simple question for sure!
cheers.



4/76 HJ monaroGTS
4/76 HJ monaroGTS
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AGRO Offline
#2 Posted : Monday, 30 November 2009 8:24:38 AM(UTC)
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From my understanding this is for pollution.
What happens "in theory" is the butterfly will be closed when cold.It then redirects the exhaust gas back through the inlet manifold (in has a passage leading under the carby) and out the passengers side exhaust.

When the spring on the end of the butterfly heats up,(therefore causing the spring to lose tension), the weight causes the butterfly to open and let the exhaust flow as per normal.

P.S. dont use a pre pollution manifold on a pollution motor as it pressurises the sump and blows the dipstick out.

75 HJ Sandman Pano
78 HZ BO6 Pano
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74HJLS Offline
#3 Posted : Monday, 30 November 2009 8:24:06 PM(UTC)
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That butterfly is for the HZ, dont use it on the HJ. You may need a spacer to replace it though. You could remove the butterfly plate out of it then put it back in, sealing up any holes.

Cheers,
Pete.
Old Holdens never die, they just go faster.
Cheers,
Pete.
Old Holdens never die, they just go faster.
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RdS Offline
#4 Posted : Monday, 30 November 2009 10:08:56 PM(UTC)
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^ thanks. ill just knock the butterfly out of it if i use it.
quote:
Originally posted by AGRO
P.S. dont use a pre pollution manifold on a pollution motor as it pressurises the sump and blows the dipstick out.


you meant that the other way round yeah? as in "dont use a pollution manifold on a pre-pollution motor". if thats true i should just pull the lot off now. :(

Edited by user Monday, 30 November 2009 10:12:16 PM(UTC)  | Reason: Not specified

4/76 HJ monaroGTS
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AGRO Offline
#5 Posted : Tuesday, 1 December 2009 5:04:24 AM(UTC)
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If you use a pollution manifold on pre pollution heads i imagine therell be no drama. But as the pollution heads have an extra hole in them, when the exhaust gasses go thru the extra hole, it then gets forced into the motor.

Im sure someone would have pics of what im talking about.

75 HJ Sandman Pano
78 HZ BO6 Pano
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RdS Offline
#6 Posted : Tuesday, 1 December 2009 7:39:10 AM(UTC)
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i think im okay then???
im using polution manifolds (HZ) on pre-polution heads (HJ) here. so no dramas? :S

only other basic questions again though:
- Do i use a glue/sealant inbetween the joins of the manifold-to-exhuast?
- and is there a difference in manifolds/exhaust on the HJ
and HZ, or am i just not alligning the whole exhaust properly?

cheers for the help sofar.

4/76 HJ monaroGTS
4/76 HJ monaroGTS
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RdS Offline
#7 Posted : Thursday, 3 December 2009 11:49:41 PM(UTC)
RdS

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quote:
Originally posted by RdS
only other basic questions again though:
- Do i use a glue/sealant inbetween the joins of the manifold-to-exhuast?
- and is there a difference in manifolds/exhaust on the HJ and HZ, or am i just not alligning the whole exhaust properly?


any ideas for these anyone? wanna know if its worth having a crack this weekend at getting this exhaust back on... :)

4/76 HJ monaroGTS
4/76 HJ monaroGTS
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jim Offline
#8 Posted : Friday, 4 December 2009 1:34:38 AM(UTC)
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I use maniseal if I use anything,I cant see any gaskets in the ones I have here where they join onto the exhaust flange but they are a really
neat fit,if you take out the butterfly joint it will hit the sump for sure,better off leaving that in for now,and no difference in sumps that I know of,P.S Dissmantle the thing and check for holes and ill fitting connections ,thats your best bet....jim

Jim in Adelaide...Hindsight is bad vision!

Edited by user Friday, 4 December 2009 1:47:44 AM(UTC)  | Reason: Not specified

Jim in Adelaide..
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Dr Terry Offline
#9 Posted : Friday, 4 December 2009 7:12:17 PM(UTC)
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Hi RdS.

Ive been looking at this post for a number of days wondering how to answer it, so here goes.

Firstly the butterfly valve in the RH-side exhaust manifold, should only be used with HX onwards heads & inlet manifold. What is happening now is that with the butterfly closed (cold) the exhaust from the four RH-side cylinders has nowhere to go & is forcing itself out of any available passage (or leak) under pressure.

What AGRO said about not using pollution heads with an early manifold, was correct but he was referring to the INLET manifold, but that didnt solve your problem because you werent talking about the inlet manifold.

The only 2 ways to solve your problem is to remove the butterfly flap but retain the shaft, otherwise you will have created some more exhaust leaks. The correct method would be to toss the butterfly assembly altogether & obtain the correct RH-side engine pipe which is a bit longer (by the thickness of the butterfly assembly to be exact).

As a sealant I use a product called Mani-Seal but it must be used sparingly. If you lay it on too thick, you are simply creating more future possible leaks.

Dr Terry

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There are only 3 types of people in the world.
1. Those who make things happen.
2. Those who watch things happen.
3. Those who wonder what happened.
If at first you don't succeed, just call it Version 1.0
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Sandman Offline
#10 Posted : Thursday, 10 December 2009 5:14:56 AM(UTC)
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Maniseal is good on a pretty tight joint, although it goes hard eventually and can crack out if the flanges/whatever arent machined well.
I have used Copper Silastic with fairly good success, as it stays flexible. But it still wont fill a bigger gap. I dont use any gasket on my extractors, only this silastic, to head as the heads have been ported quite a bit and theres not much sealing area on the exhaust ports.
On my skiboat I used some other stuff that I got from mates exhaust shop, its silver and very tacky/gooey, but worked very well. Also stays flexible.

With the spacer and butterfly, you can take out the butterfly and shaft, then tap some 1/8th bsp threads in were the shaft was and fit brass plugs.
Then use the spacer with no restrictions in it.
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