splitting inlet manifold gasket

Seight-V8 · Post by **Seight-V8** » Sun Apr 05, 2009 6:35 pm

hiya all,

I need to lose at least 7mm from my inlet manifold gasket to make the ports and bolt holes line up.

This must be because my heads have been over skimmed.

Have split an old inlet gasket from hole to hole along its length, and now have a 7mm overlap.

But how to join it back together and get it to seal correctly???

anyone done this before that can help.

cheers

scott

ChrisJC · Post by **ChrisJC** » Sun Apr 05, 2009 8:16 pm

7mm eh?, that's a fair bit.

I did this once with a tin gasket. I just drilled & rivetted the join, using shed loads of instant gasket in the join. It worked OK.

Don't forget that the inlet manifold will need machining too.

Chris.

Post by **katanaman** » Sun Apr 05, 2009 9:28 pm

I use 2 inlet gaskets and overlap them and pop rivet them together with some silicon between them. I don't think you will have enough material to get a seal just cutting and overlapping one gasket.

ppyvabw · Post by **ppyvabw** » Sun Apr 05, 2009 10:15 pm

Could make one maybe?

CastleMGBV8 · Post by **CastleMGBV8** » Mon Apr 06, 2009 8:52 am

Scott,

Just to clarify,

1. 10 or 14 bolt heads

2 comp or tin head gaskets.

3 comp or tin valley gasket.

Appreciate the haeds have been modified and skimmed but you should not be having that much of a problem.

Are you saying you are trying to make the valley gasket port sizes match the head sizes, the gasket port sizes are usually quite a lot larger than the ports in the heads and you need not worry abouth that.

Is the gasket sitting too high and the holes in the gasket not lining up with the bolt holes in the heads?

Are you trying to use the neoprene seals at each end of the block if so remove them and see how the gasket sits in relation to the heads, if ok as it should be, then just seal the gasket to the block with some blue hylomar and put a blob of HT silicone in the 4 notches at the position where the heads mate with at each end of the block.

My engine had 40 thou of both the heads and the decks for a total of 80 thou and had no problem getting the comp gasket to fit correctly, however you will probably need to modify the inlet manifold as the bolt holes will not line up.

What size are the inlet ports in your heads? if they have not been taken out to gasket size you can probably elongate the holes in the manifold so it can sit a little higher, the important thing is to get the roof of the port runners in the manifold and the heads to line up, as this is more important than the floors of the runners and ports.

Kevin.

Seight-V8 · Post by **Seight-V8** » Sun Apr 12, 2009 9:14 am

sorry about the wait for the reply, been busy on other things.

I have 4.6 heads, 10 bolt style with composite inlet & head gaskets.

The problem i have is the when i lay the inlet gasket on the rubber end seals and heads, the whole of the ports & bolt holes in the gasket dont match the heads.

The port sizes and holes match size for size, just not lined up.

So i split and old gasket, when i line all the ports up on both sides, i have a 7mm gasket overlap where i split it.

I can get away with losing a fair bit if i remove the rubber end seals.

Just worried about either way.

Still need to get my inlet manifold machined, i recon i need to loose at least the thickness of the composite inlet gasket (about 1.25-1.5mm).

Then the manifold should bolt up ok.

Looks like best option is no rubber ends seals at the moment.

scott

CastleMGBV8 · Post by **CastleMGBV8** » Sun Apr 12, 2009 12:00 pm

Scott,
Deleting the rubber seals is a lot simpler than cutting and shutting valley gaskets, and is the usual thing to do if any machining has been done to heads, decks or both as in my case.

kevin.

mgbv8 · Post by **mgbv8** » Sun Apr 12, 2009 10:18 pm

Scott
Ditch the rubber seals and get yourself a tin of "Right Stuff" sealant to use on the front and rear. I got mine from Real Steel. It aint cheap at approx £18 for a 7oz tin, but it will be plenty to do what you need with lots left over for other uses.

Perry

Darkspeed · Post by **Darkspeed** » Thu Apr 16, 2009 1:37 pm

Surely rather than cutting and riveting two gaskets it would be easier just to put a fold or a hump in the centre and then crimp the end at the valley clamps.

A ---^--- sort of affair

Andrew

topcatcustom · Post by **topcatcustom** » Thu Apr 16, 2009 2:51 pm

Or if you have cut them and not enough overlap to join them together- cut the spare 7mm off so they butt together put an inch wide strip of thin ally or something over the joint and seal and join both sides. Wouldn't be much work at all and they will butt up perfectly thus sealing with no probs at the ends.

Seight-V8 · Post by **Seight-V8** » Fri Apr 17, 2009 4:53 pm

thanks all,

best option looking at the problem is for me to just remove the end seals.

At least everything then lines up pretty good.

Spoke to v8D today, and manifold & trumpet base off on monday for porting & machining.

Getting at least gasket thickness (1.50mm) taken off the manifold mating surfaces.

This should allow me to get it bolted up.

Hopefully another problem solved.

cheers

scott

CastleMGBV8 · Post by **CastleMGBV8** » Sun Apr 19, 2009 5:55 pm

Scott,

Did V8D give you any idea what they would have machined off the head faces as this will give an indication of how much need to came off the manifold faces or did they recommend 1.5mm (60thou.) from each manifold face?

I've got an EFI manifold that need the same treatment and have forgotten what is normally done, ie if a combination of 80 thou came of the the heads and decks what needs to come off each manifold face?

Kevin

Seight-V8 · Post by **Seight-V8** » Wed Apr 22, 2009 8:56 pm

kevin,

i had already worked out that if i fitted the manifold without a gasket the manifold would bolt up ok.

So i measured the inlet gasket thickness as 1.25mm.

So i presume if i take a min of 1.25mm from the inlet faces, when i put the manifold back with a gasket it would fit.

V8D said that 0.060 to 0.80ins removal was normal....but i thought this might be way too much.

i recon my heads are 1mm (0.040ins) over machined in height.

Unless they know a formula for working the corerct amount out.

There looks to be enought play between the hole & the bolt, so i went to 1.5mm hoping this would be enough.

scott