34 replies to this topic

[stuart bowes]

I think the point he was making is that the flanges where you bolt through can be different thicknesses when comparing exhaust and inlet, when they're separate parts

 

so what is tight for one part actually isn't pressing down on the adjacent part 

 

exaggerated for effect;

 

 

so you either machine the thicker part down to match the thinner part, or perhaps use some kind of shim?   I've only seem pictures of them being different i've not dealt with it myself

 

saying that from the one picture we've seen it's not really conclusive if that's the case or if it's just muck pouring down from the obvious gasket leak

Edited by stuart bowes, 06 November 2023 - 10:06 PM.

[gazza82]

You need to check the manifold flanges for the inlet and exhaust are the same thickness, unless you are using a combined manifold.

The truth is that the exhaust and intake manifold are independent and made of different materials, but if they are well tightened to the cylinder head, there should not be any leaks.

Some inlet and exhaust manifolds are made with different thickness of mounting flange so if they are offset the thick mounting washer doesn't sit flat and one of the manifolds does not seal properly.

Edited by gazza82, 06 November 2023 - 11:17 PM.

[Lplus]

I think the point he was making is that the flanges where you bolt through can be different thicknesses when comparing exhaust and inlet, when they're separate parts

 

so what is tight for one part actually isn't pressing down on the adjacent part 

 

exaggerated for effect;

 

 

so you either machine the thicker part down to match the thinner part, or perhaps use some kind of shim?   I've only seem pictures of them being different i've not dealt with it myself

 

saying that from the one picture we've seen it's not really conclusive if that's the case or if it's just muck pouring down from the obvious gasket leak

Thanks for the diagram.  I've noticed it on all the exhaust/inlet manifold flanges I've seen in the last few years.  Various methods work - grind down the thicker flange, weld up the thinner flange and grind off (steel obvs), file down half the thick washer, tack weld thin shim to half the thick washer...  A very slightly thicker inlet flange helps to prevent air leaks and support the carbs properly, but I'm talking no more than 10 thou or so.

 

It's usually the exhaust manifold flange that is thinner.

Edited by Lplus, 07 November 2023 - 08:56 AM.

[PACINO]

I think the point he was making is that the flanges where you bolt through can be different thicknesses when comparing exhaust and inlet, when they're separate parts
 
so what is tight for one part actually isn't pressing down on the adjacent part 
 
exaggerated for effect;
 

 
so you either machine the thicker part down to match the thinner part, or perhaps use some kind of shim?   I've only seem pictures of them being different i've not dealt with it myself
 
saying that from the one picture we've seen it's not really conclusive if that's the case or if it's just muck pouring down from the obvious gasket leak

Lovely Stuart. Fantastic answer.

[PACINO]

You need to check the manifold flanges for the inlet and exhaust are the same thickness, unless you are using a combined manifold.

The truth is that the exhaust and intake manifold are independent and made of different materials, but if they are well tightened to the cylinder head, there should not be any leaks.

Some inlet and exhaust manifolds are made with different thickness of mounting flange so if they are offset the thick mounting washer doesn't sit flat and one of the manifolds does not seal properly.

Cheers Gazza!