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Tips

Installing the manifolds

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bigjones

bigjones

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(This relates to my Midget, but the same applies to TR3's)

The intake and exhaust manifolds bolt to the head. The manifolds are also bolted together.

Now, when assembling, what comes first, bolting them together or bolting them to the head?

Seems there are various ways of doing this;
1. Bolt them together and bolt assembly to head.
2. Bolt manifolds to head and then bolt together.
3. Bolt exhaust manifold to head, bolt manifolds together, then bolt intake to head.

What is the correct procedure? Also, why are they bolted together?

Cheers!
 
The TR3 workshop manual says to assemble the two manifolds leaving the nuts finger-tight, fit the assembly to the head, then tighten the two nuts. Makes sense to me.

They are bolted together in order to supply some heat to the intake manifold, which helps prevent fuel from condensing (under certain conditions) and then being sucked in all at once when the throttles are opened suddenly.

But I disconnected mine many years ago, and have never had a problem.
 
Thanks for that information Randall.

The reason I ask is that I've just replaced the head gasket and although I was careful in installing a new manifold gasket, I seem to have an exhaust leak there. I did forget to re-install the single bolt that connects the two manifolds so I was thinking that may have something to do with it but now it seems that is a red herring.

I'll put in another gasket following the method you mention from the TR3 manual.

Cheers!
 
While it's apart, check the surfaces for flatness. An ordinary carpenter's square will do; or I like to actually rub a machinist's file (which is not tapered as ordinary files are) lightly over the surface to pick up any high spots. If the manifold faces are significantly distorted, you may need to have them machined flat.

Also check that the nuts spin easily all the way down the threads. If not, best to change that stud. New lockwashers, of course.

Don't know if this would apply to your Midget or not, but on the TR3 I find it helps to add a heavy flat washer on the outermost studs (the ones without a bridge piece to bear on both manifolds).

Also wouldn't hurt to do a 'dry' fitting without the gasket, to check for any interference. On the TR, if the head has been milled, the exhaust will sometimes hang up on the edge of the cylinder block, just enough to encourage a leak.

Good luck!
 
Wow! Some good advice there, many thanks.
I did indeed have the head skimmed so I will definitely do a dry run first.

Cheers!
 
TR3driver said:
...While it's apart, check the surfaces for flatness...
Click to expand...
Looks like Randall nailed it:
ManifoldGap.jpg


The new gasket is 44 thou - is it worth trying or should I just pull the manifold and take it to the machine shop for skimming?

Here's the gasket that came out:
BlownGasket1.jpg


BlownGasket2.jpg


BlownGasket3.jpg


Cheers
 
Good catch.

Personally, I would have it machined flat.

Cheers,
M. Pied Lourd
 
Maybe I'm missing something ... you just tried a new gasket, which promptly failed, and you've found a huge low spot that matches exactly with the gasket failure.

Why are you asking us ?

badhairday-x.jpg
 
TR3driver said:
Why are you asking us ?
Click to expand...

Hope springs eternal.

Someone might have replied "Well, there's a bit of a gap but that is what gaskets are for, and 44 is bigger than 28. There is no need to unbolt the manifold from the downpipe, snapping off a stud in the process, trudging to the machine shop in the snow, and then waiting for the flange gasket to arrive from Moss, etc. Just bolt it up and Bob's your uncle".

That's what I was hoping for.
 
bigjones said:
Someone might have replied "Well, there's a bit of a gap but that is what gaskets are for, and 44 is bigger than 28.
Click to expand...
Well, someone still might. But that was my smart-alec way of saying I agree with Pied. No offense intended.

billthecat.gif
 
It goes back to the old saying that applies to how we fix things. "Just because you can do something, doesn't necessarily mean that you should do something".

I agree with Randall and Pied and I mean no offense either. It will never be right until you correct the gap issue.
 
Adrian, It would be a little bit difficult to fixture on my mill... but we could true up those surfaces at my house if you want to. Of course... that means taking the exhaust manifold off completely. I'm out of town today but can look at the manifold tomorrow (Sunday). Remember that I also have one of those extra manifold gaskets.
 
Doug that is mighty kind of you - let's set something up when I get the thing out the car - see the new thread over in the Spridgets forum.

Cheers!
 
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