Inlet Manifold

[stag-phil]

Hi All

I am looking for some advice or hopefully re-assurance.

I have discovered water in the ‘V’ and although I cannot tell were the water is coming from I suspect it is from the inlet manifold.

What I have discovered is that the inlet manifold is not perfectly true, when it is offered up to the heads there is a slight rock.

I don’t know if that is usual and when torqued down it is ok or whether I should have the manifold skimmed assuming that is possible.

Firstly, is it normal that the manifold will warp slightly but will seal when bolted to the heads?

Assuming not, what is the procedure for having the manifold skimmed?

Working on the basis that the machine shop has never skimmed a Triumph Stag inlet manifold before is there any information I should give them to ensure that they do not make the situation worse? For example, both sides of the manifold have to have the same amount skimmed off and the amount of skimming needs to be minimal?

I would imagine if I have the manifold skimmed that I will need thicker gaskets, is there a recommended supplier, or in the case of having to make my own to a given thickness, where is the best place to buy good quality gasket paper which would be suitable for the job?

Finally, the easiest solution may be a second-hand inlet manifold, in which case does anyone have one or know where I can get one that is ‘true’.

Thanks.

Phil

[jleyton]

If it 'rocks' I'd check to see if it is bottoming out on the block. If so then you can cure this by removing some aluminium from the bottom of the manifold with a 'ba**ard' file - a very coarse one.

Cheers

Julian

[stag-phil]

Thanks Julian

I have put a straight edge between the two sets of ports on each side of the inlet manifold and on one side it is not true.

I don't know bolting it to the head will pull it true or if the gaskets will take up the difference or it will leak again.

When I took the manifold off some of the bolts were not very tight but I dont want to assume that was the cause of the leak without getting some advice on how 'true' the manifold should be.

Given the number of people using K Seal to cure the leaks in the 'V' area I do wonder if it is normal.

Phil

[Goldstar]

Phil if your heads have been skimmed at some point and the inlet manifold hasn't that could be making the situation worse as it will not sit true. Sounds like thee is some warping by your straight edge test? I assume a machine shop can true up the warp and then match the other side to make it square (not sure if that's how they do it but you get me drift). Otherwise I've got one you can acquire

Cheers

Paul

[flying farmer]

Unfortunately a machine shop will not know where the manifold needs skimming as much depends on how the heads have been skimmed in the past.

The best thing you can do is get a long coarse file (make sure it doesn't have a bend in it) and carefully file out the worst of the warp. The file really needs to be long enough to bridge the front and rear inlet ports as it reduces the chance of error.

If the manifold then sits flat without gaskets, use feeler gauges under the manifold face to make sure it is touching the heads top and bottom.

The first Stag engine I built blew the inlet gaskets twice before I realised the manifold was touching the top of the ports but was leaving the waterway with insufficient clamping pressure to prevent the gasket blowing out.

There is usually plenty of metal to be removed, just go carefully and keep checking.

Neil

[Kevin Garrod]

I had mine skimmed at a machine shop, it cost about £35 cash IIRC

[Richard G]

Had similar issues, but have changed engine now. I bought a set of skimmed heads with an inlet manifold skimmed to suit, the V angle changes with the skim.(so I am told)

I have a spare Mk2 inlet manifold if you want to borrow it and try. I have not done any measuring on it.
Water in the V seems a common issue. Mine now does not get water in the V , only after its been stopped for some time, no idea why (even after I have depressurised it) Decided life is too short... etc.

Let me know if you want to borrow.

RG

Hi All

I am looking for some advice or hopefully re-assurance.

I have discovered water in the ‘V’ and although I cannot tell were the water is coming from I suspect it is from the inlet manifold.

What I have discovered is that the inlet manifold is not perfectly true, when it is offered up to the heads there is a slight rock.

I don’t know if that is usual and when torqued down it is ok or whether I should have the manifold skimmed assuming that is possible.

Firstly, is it normal that the manifold will warp slightly but will seal when bolted to the heads?

Assuming not, what is the procedure for having the manifold skimmed?

Working on the basis that the machine shop has never skimmed a Triumph Stag inlet manifold before is there any information I should give them to ensure that they do not make the situation worse? For example, both sides of the manifold have to have the same amount skimmed off and the amount of skimming needs to be minimal?

I would imagine if I have the manifold skimmed that I will need thicker gaskets, is there a recommended supplier, or in the case of having to make my own to a given thickness, where is the best place to buy good quality gasket paper which would be suitable for the job?

Finally, the easiest solution may be a second-hand inlet manifold, in which case does anyone have one or know where I can get one that is ‘true’.

Thanks.

Phil

[stag-phil]

Thanks Richard that is a very kind offer.

I have taken up Paul’s (Goldstar) offer of a replacement manifold so I should be sorted.

On the basis that my manifold is warped and there was a few bolts that were not as tight as they should be I think I am better off fitting another manifold rather than trying to skim or file my manifold.

I did think of trying Neil’s (Flying farmer) suggestion and file the warp out but I could see myself making the situation worse. Great idea if you know what you are doing.

If I had a local machine shop that had skimmed inlet manifolds before I would feel a bit more confident. But, I want to avoid the situation were too much is skimmed off and then I am into making thicker gaskets to compensate.

Sometime ago there was talk of remanufacturing the cylinder heads, I wonder if the water in the ‘V’ problem would have been addressed with the new heads.

All a bit of a nightmare not to mention the two bolts that snapped off when I was trying to remove the manifold.
Here is a tip, if you are looking at buying a Stag have a look at the manifold bolts to see if each bolt has a washer. Quite a few of mine were missing and I suspect a previous owner had removed them in order to screw the bolts into fresh thread and therefore make them tighter in order to stop the ‘V’ leak.

Phil

[Ian F]

Phil

Standard repair tool for working on the inlet manifold is a helicoil kit. Many members helicoil them anyway as a precaution!
I have to admit I recently refitted my inlet manifold for the same reason ( water in the vee) but all threads were good, new gaskets, including water pump cover gasket, appears to have cured it. So I left well alone. Ian F

[edd]

Being able to file isn't a diy operation either. At college our first lesson was making a cube using a file using blue on all surfaces. It cleared out about a third of the lads on the course all of them moaning this is taking ages. Like Niel says some files have a curve and aren't totally flat. I seem to remember semi circle files are usually flat on the flat side. Skilled use of a scraper comes in handy too.
Edd

[stag8manod]

Hi Phil, A suggestion, perhaps the heads were tightened down not parallel to the manifold. When I refitted my heads I temporarily refitted the manifold and nipped its bolts up before torqueing heads down to ensure both faces were as parallel as they could be. After all torqued down, removed the manifold fitted the gaskets and tightened the manifold down. As a precaution I also Heli-coiled all the threads in the heads.
Cheers Ian A

[stag-phil]

Thanks Ian

Unless there was something physically wrong with the heads or the block I can’t see how the heads could be incorrectly fitted.

I am not an engineer but to me there is not enough ‘meet’ around the water galleries and steel bolts into alloy over time is likely to cause problems with corrosion and damaged threads.

Some of the threads have already been Heli-coiled and the rest I have chased out and appear to be ok.

When I was checking the threads I noticed that one of the Heli-coils fitted by a previous owner still had the tang. This could well be part of the problem which caused the leak, the bolt could have bottomed out on the tang.

While I am waiting to get the inlet manifold sorted I am listening to everyone’s advice (thanks Ian F) about Heli-coiling all of the threads.

Also, I have ordered a set of stainless steel bolts. Two of the original bolts broke when I was removing the manifold but we won’t go there.

Although I don’t think the water pump was leaking have sent that to EJ Wards to be rebuilt with upgraded seals.
Because it appears to be a common problem once it is all back together I will probably check and re-tighten the bolts a number of times.

Phil

[Staggard]

I think what Ian A is saying is that there is enough movement in the stud/bolt holes to allow the heads to move longitudinal ( hope that's the right word) so the gap between the heads could be narrower at the back than the front or visa versa. So the mating faces for the manifold are not parallel with each other.

[edd]

Hi Phil, A suggestion, perhaps the heads were tightened down not parallel to the manifold. When I refitted my heads I temporarily refitted the manifold and nipped its bolts up before torqueing heads down to ensure both faces were as parallel as they could be. After all torqued down, removed the manifold fitted the gaskets and tightened the manifold down. As a precaution I also Heli-coiled all the threads in the heads.
Cheers Ian A

And "that's the way to do it" stag heads are without dowels so a very small amount of play can be made to your advantage.

[stag-phil]

Ahh, I see.

That probably explains why some people have to lever the inlet the inlet manifold into position or open up the holes in the manifold to get the bolts to line up.

When the time comes to remove the heads I will remember that.
Thanks All.

Phil