Intake manifold gasket - metalic or paper?/ Vacuum leak?

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sima112
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Intake manifold gasket - metalic or paper?/ Vacuum leak?

Post by sima112 » 16th September 2020 - 7:07pm

Hi guys,

Im trying to locate an intake vacuum leak. I have a hissing sound from left carburetor and also a vacuum gauge shows intake or heat riser leak or late valve timing. As i just checked valves (0.006inch/0.15mm) im pretty sure timing is ok. Ive tried spraying carburetor cleaning aerosol around all gaskets carburetor and balance pipes without any results. So im changing gaskets between carburetor and intake manifold and intake manifold to head. Which gasket should i get for the manifold/head? The original is metal but i saw selling paper one too.
Which one seals better? You experience and opinions please. Also any additional tips for vacuum leak tracking.
Next i will replace the boots on balancing pipes and carburetor is the last.

Thank you and good day Sima

Ps. advance vacuum in distributor works fine, no leaks there and hose is new
Last edited by sima112 on 20th September 2020 - 7:15am, edited 2 times in total.

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broady_6
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Re: Intake manifold gasket - metalic or paper?

Post by broady_6 » 16th September 2020 - 9:12pm

Heat riser? Which car is this on?

The metal gaskets work perfectly well on new stuff, or faces which have been machined. But for manifolds which have seen a few years work they will have distored slightly and a thicker paper gasket will do a much better job of sealing the less than flat face. So id use that if were talking about old parts.

Hope ths helps.
The sultan of swing

sima112
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Joined: 15th April 2016 - 6:17pm

Re: Intake manifold gasket - metalic or paper?

Post by sima112 » 17th September 2020 - 3:11am

Excellent, thank you.
I not very familiar what heat riser is but i think this car doesn't have it. Its '71 type 3 Squareback.
Im sorry for the confusion, it is written on the display of vacuum gauge i have:
"Late valve timing or leak or intake manifold or heat riser"
Thanks again for your advice. Seems logical to me

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broady_6
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Re: Intake manifold gasket - metalic or paper?

Post by broady_6 » 17th September 2020 - 8:46am

I know what a heat riser is. I was questioning "do you have one? I wonder what car this is?" but now youve said a 71 fasty then its as I thought. You dont have a heat riser. So you can forget about it.

What makes you think you have a vacuum leak other than the hissing?
The sultan of swing

sima112
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Joined: 15th April 2016 - 6:17pm

Re: Intake manifold gasket - metalic or paper?

Post by sima112 » 20th September 2020 - 7:14am

When i connect vacuum gauge into hose from carburetor to distributor (at distributor end), the gauge shows 22 hg, (on the gauge is written: late valve timing or vacuum leak at intake manifold or heat riser) normal reading should be 45-55hg.

The first impulse for searching was that the car was always driving purely before heating up. Also the rpm are a bit higher. I have to wait a bit when cold to get it going or its struggle need a lot of pumping gas pedal. Once warm up drives well, however id still expect more power.

I replaced gaskets in both carbs at the base, between carb and intake and now intake and head, didnt improve a bit.
I tried cabr cleaner aerosol again and only place where, i guess, could be a bit of difference is in top carb seals. So im searching for kit or gasket paper and again a hassle here in Colombia.

I will go to check emissions soo and it will show something. Still when I checked spark plugs they were a bit black, not much but if i understand well it shows more richer than leaner running engine. Which should be running with a vacuum leak.

Thank you Sima

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broady_6
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Re: Intake manifold gasket - metalic or paper?/ Vacuum leak?

Post by broady_6 » 20th September 2020 - 7:24am

As a general rule, an air leak in the intake will cus the care to stall at idle. So with you saying that it has a high idle makes me think its not a leak in the intake.

Could it be that the carbs are out of balance and one is sucking much harder than the other? Or have any of the rubber joiners on the balance pipe split?

Gaskets are easy though, I stock these.

viewtopic.php?f=9&p=70275#p70275
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sima112
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Re: Intake manifold gasket - metalic or paper?/ Vacuum leak?

Post by sima112 » 20th September 2020 - 6:39pm

It is quite possible, i have never done it before but i will study and try out some maintenance. Carbs on the car are Solex brosol 32-34 pdsit 2 and 3. They need some cleaning as well. The rubber joins looks ok spraying carb cleaner over them didnt do anything. I already looking for replacement to be sure. However looks like carburetor job first. Looking at the pictures of your gaskets ive already replaced n 1,3 and 4 , looks the same, I need the top if its the same. I thing a postage from Uk would have been ridiculous, but still its a possibility if other options fails. I think i must be able to find a material for these here.

Thank you for the info on vacuum leaks
Sima

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broady_6
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Re: Intake manifold gasket - metalic or paper?/ Vacuum leak?

Post by broady_6 » 20th September 2020 - 8:20pm

Just had a quick look, postage to columbia is £2.50 for the two top gaskets.
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sima112
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Re: Intake manifold gasket - metalic or paper?/ Vacuum leak?

Post by sima112 » 22nd September 2020 - 5:41pm

Thank you so much for helping me with this, Broady. I will open one of the carbs and check the gasket, if they are alike. I can also compere it with the original German 32's. to be sure they will fit.
I read that the kits for 32 and 23/34 are not interchangeable, but the gasket still might fit alright.
It will take a few days as I'm extremely busy right now.
Thanks again Sima

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broady_6
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Re: Intake manifold gasket - metalic or paper?/ Vacuum leak?

Post by broady_6 » 11th October 2020 - 5:38pm

:thumbsup:
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