Manifold gaskets

[Toltec]

We find the manifold gaskets start to blow with monotonous regularity and I was wondering if any of you had an idea how to fix the issue. We have tried two types of gasket, one is made up of three layers of metal which span two ports, the other is two thin metal sheets sandwiching some dark material and each port uses a separate gasket.

The other thing of note is that the opening in the gaskets is rather smaller than the ports one edge is about 4mm out. It could be that these are just standard 3.9 rover gakets and something more exotic is needed.

So any ideas?

[Barkychoc]

I've bought the 'high performance' ones from Real Steel and cannot honestly comment on them long term but so far they are not blowing.
They are an odd material - a cream coloured gasket thats really quite smooth with metal reinforcing under the surface - you can see it at the edge of the gasket.

Part number AZ830 quoted as HD for tubular manifolds.

[Toltec]

Sounds like they may work better, what happens with the sandwich ones we use is the material just gets blown/eaten out from between the metal faces so perhaps these are made of sterner stuff. Having checked the web site I would certainly hope so at the price.

[adam quantrill]

Perhaps you need to tighten the bolts better? I do them up, then run on idle for a few minutes, nip them up again hot, then again when cold, and again a week later.

I also use a bit of that white exhaust paste on the gaskets. I use my cars a lot and never have any problems. The gaskets are standard wire reinforced ones.

[pwd95]

I had this exact same problem recently. I used 2 sets of these.....

http://cgi.ebay.co.uk/Rover-V8-Competition-Exhaust...


double them up & they'll seal.

[TVRleigh_BBWR]

Half the problem is the mating surface of the manifolds, 90% of the time one or two will not have a complete surface,
I had to re-build mine up with weld then grinded flat, after this I never had a problem. esp as going though the history every service and reports of blowing exhaust, also a few thread in the head was damaged due to over tightening.
RPI also do a good gasket with large ports. I've even re-used them on the racer without any problems. I think they was about £15 a set though. I think ACT sell a large port ones also.

[Barkychoc]

Toltec said:

Sounds like they may work better, what happens with the sandwich ones we use is the material just gets blown/eaten out from between the metal faces so perhaps these are made of sterner stuff. Having checked the web site I would certainly hope so at the price.

I thought that but the price is for a full set - so not expensive at all.

[Toltec]

Thanks for the suggestions, hopefully one of those at least will do the trick.

[TVRleigh_BBWR]

Toltec said:

Thanks for the suggestions, hopefully one of those at least will do the trick.

As said before would be a good idea to take them off and make sure you have a good surface on the manifold. no gasket will work unless you have a complete surface.

[Toltec]

TVRleigh_BBWR said:

Toltec said:

Thanks for the suggestions, hopefully one of those at least will do the trick.

As said before would be a good idea to take them off and make sure you have a good surface on the manifold. no gasket will work unless you have a complete surface.

Sorry for the tardy response, it has been a busy week.

I thought of that last time the gaskets were changed, but did not have the time to unbolt the engine etc. and lift it to get the manifold off given we have never tried it before. They looked OK when we had the engine out a few years ago and I checked them with a straight edge.

Ideally they need matching to the engine ports and both sides ground flat I suppose.

[Toltec]

Got around to measuring the gasket/port apertures

Standard gasket is 24x34mm

Ports between 27x39 and 28x40 so 29 to 37% larger

Fitting the right gaskets might be worth a few bhp I guess

[C O Jones]

I bought a sheet of copper (3mm thick?) and made a set of gaskets by hand to fit, took about an afternoon.

Russ

[Toltec]

Called in at V8 conversions, a company that puts RV8s into MGs, he recommended some Buick performance gaskets as he had gone through the same loop a long time ago. As it turns out they are the ones Barkychoc describes above, same part number etc.

The apertures are too small, however rather than try to cut away the extra material the chap suggested that the gasket not clamped between the faces would just burn away. Given that is what happened to the material in the standard gaskets then that sounds reasonable.

[ed_crouch]

Got mine off the 'bay. 25 quid for 2 engine sets, and they are top quality. I too had to build the manifold faces up with weld and the file them flat again. Long job, but it worked a treat.

You DO need big bore gaskets for anything other than a 350i - the ports are enlarged, and having a sharp edged gasket throttling the exhaust ports is not going to do the power any good.


EDIT: yep I bought them from the place Wyn alludes to - use assembly paste (sparingly so you dont get great gobs of it blocking the port when it oozes on assembly) having rebuilt the manifold faces, and you're sorted. Stainless bolts are nice too, but dont go for the ARP ones cos you cant get an open ended spanner on them cos theyre Bi-hex, and you'll need to be able to use the open ended spanner on some of the bolts to get them nipped up. Good old TVR manifolds - bds.

Edited by ed_crouch on Saturday 10th July 22:37

[wooly350i]

Remember though when nipping up the bolts that they are going into aluminium and a bit of heavy overtightening will strip the threads if ya not carefull!