18 replies to this topic

[BigEnd]

Does anone have some ideas on what I can try next to stop air leaks on the inlet manifold?

I have recently rebuilt my HIF44 and had the new needle and mixture set up on a rolling road and all is good, my problem is with tickover and trying to find a balence between the car cutting out when I pull up at junctions or idling at 1900 rpm.

I've changed the manifold gasket as advised by the rolling road guy and it has helped but not solved the problem completely. If I spray carb cleaner around the inlet manifold when the car is running, the revs pick up indictating I still have a leak. Any suggestions or advice are appreciated

[Wil_h]

It sounds like your manifold won't bolt up flat because it's fouling something.

[RobG295]

Has it got a servo take off, that could be were its leaking from?? If it has, also check the gromet on the servo that the pipe sits in and the pipe, as if theres a split in either of these it will cause a leak.

[GraemeC]

Is this an alloy inlet manifold with LCB combination? If so are the flanges the same thickness and therefore nipping down evenly under the thick washers?

If the flanges are uneven it is very difficult to get them to tighten up properly. Some people use/make stepped washers but these may only reduce the effect rather than cure it if they are not accurately made.

[BigEnd]

It sounds like your manifold won't bolt up flat because it's fouling something.

I've had a good look around and there is nothing fouling the inlet to the cylinderhead. The leaks are not obvious which is whats irritating me

Has it got a servo take off, that could be were its leaking from?? If it has, also check the gromet on the servo that the pipe sits in and the pipe, as if theres a split in either of these it will cause a leak.

My car doesn't run a servo so I assume one of the blanking bolts (there are 2, one big brass one on top and one small one to the right) has stopped the feed. I've checked both of these and they are fine.

Is this an alloy inlet manifold with LCB combination? If so are the flanges the same thickness and therefore nipping down evenly under the thick washers?

If the flanges are uneven it is very difficult to get them to tighten up properly. Some people use/make stepped washers but these may only reduce the effect rather than cure it if they are not accurately made.

The car runs an alloy inlet and LCB. The thickness of the flanges seem to be very close but I guess even a slight difference will reduce the clamping force, I'll give it a check.

Thanks for the suggestions guys, I'll let you know how it goes

[minipac]

It sounds like your manifold won't bolt up flat because it's fouling something.

I've had a good look around and there is nothing fouling the inlet to the cylinderhead. The leaks are not obvious which is whats irritating me

Has it got a servo take off, that could be were its leaking from?? If it has, also check the gromet on the servo that the pipe sits in and the pipe, as if theres a split in either of these it will cause a leak.

My car doesn't run a servo so I assume one of the blanking bolts (there are 2, one big brass one on top and one small one to the right) has stopped the feed. I've checked both of these and they are fine.

Is this an alloy inlet manifold with LCB combination? If so are the flanges the same thickness and therefore nipping down evenly under the thick washers?

If the flanges are uneven it is very difficult to get them to tighten up properly. Some people use/make stepped washers but these may only reduce the effect rather than cure it if they are not accurately made.

The car runs an alloy inlet and LCB. The thickness of the flanges seem to be very close but I guess even a slight difference will reduce the clamping force, I'll give it a check.

Thanks for the suggestions guys, I'll let you know how it goes

hi mate do a search for a 12g297 this is a locating ring used with heated manifolds to give a better seal I think it can only be used with the 12g202 12g295 (small bore heads) or the bigger 1275 heads not to sure. but it does help to seal the heated manifolds to the heads

hope this helps

[BigEnd]

Cheers Minipac. Just ordered 2 rings for the princely sum of £3.40 inc. delivery. These sound like just the thing to stop my leaks. I'll let you know if they work

[mini_turbo_pete]

What make is your inlet manifold??

I have found in the past certain inlet manifolds will only fit over certain LCB's as they foul slightly on the centre branch, this hold the manifold up slightly, check to make sure you have clearance between the inlet and LCB.

[nomininolife]

I have a similar problem on one of ours, it appears that the heat sink/spacer has gone porous.


David

[BigEnd]

So I got these in the post to try and solve the leak problem....



And while they fit into the head or the manifold nice and snug



There is no way I can get the inlet back on the head with the rings in place. The fit is so tight on the individual items, that ANY mis-alignment between the ports of the manifold and the cylinder head means they won't go together.

In the end I refitted the inlet with the rocker cover removed and no rings in place. I did this because there looked like a bit of interferance between the two. I'm please to say this has definately improved the situation to a degree. I'll see how things progress on the drive up to Malvern next weekend.....

Thanks for all the help nd suggestions guys (and Minipac, if you have any tips on fitting those rings....I'm all ears )

[minipac]

So I got these in the post to try and solve the leak problem....



And while they fit into the head or the manifold nice and snug



There is no way I can get the inlet back on the head with the rings in place. The fit is so tight on the individual items, that ANY mis-alignment between the ports of the manifold and the cylinder head means they won't go together.

In the end I refitted the inlet with the rocker cover removed and no rings in place. I did this because there looked like a bit of interferance between the two. I'm please to say this has definately improved the situation to a degree. I'll see how things progress on the drive up to Malvern next weekend.....

Thanks for all the help nd suggestions guys (and Minipac, if you have any tips on fitting those rings....I'm all ears )

hi mate there should be a recess in your inlet manifold to take the other half of the ring some after market inlets didnt put these in. but i fitted mine with a little help from a rubber mallet just to tap them in place.

[minipac]

It sounds like your manifold won't bolt up flat because it's fouling something.

I've had a good look around and there is nothing fouling the inlet to the cylinderhead. The leaks are not obvious which is whats irritating me

Has it got a servo take off, that could be were its leaking from?? If it has, also check the gromet on the servo that the pipe sits in and the pipe, as if theres a split in either of these it will cause a leak.

My car doesn't run a servo so I assume one of the blanking bolts (there are 2, one big brass one on top and one small one to the right) has stopped the feed. I've checked both of these and they are fine.

Is this an alloy inlet manifold with LCB combination? If so are the flanges the same thickness and therefore nipping down evenly under the thick washers?

If the flanges are uneven it is very difficult to get them to tighten up properly. Some people use/make stepped washers but these may only reduce the effect rather than cure it if they are not accurately made.

The car runs an alloy inlet and LCB. The thickness of the flanges seem to be very close but I guess even a slight difference will reduce the clamping force, I'll give it a check.

Thanks for the suggestions guys, I'll let you know how it goes

hi mate do a search for a 12g297 this is a locating ring used with heated manifolds to give a better seal I think it can only be used with the 12g202 12g295 (small bore heads) or the bigger 1275 heads not to sure. but it does help to seal the heated manifolds to the heads

hope this helps

hi mate took some photo hope you can see what I mean from pic as cameras is playing up

[BigEnd]

Hi mate,

Thanks for getting back. Here is a piccy of the inlet manifold. The inserts fitted fine but just wouldn't go together with the 'head....even with a bit of 'fettling' with the FBH

[partsguy1]

Are you sure that those extra alignment pins are not the problem. Try using the rings without the pins.
Terry

[minipac]

Are you sure that those extra alignment pins are not the problem. Try using the rings without the pins.
Terry

i would have to agree with partsquy1 i think its the extra locating pins what are the problem