1974 Radio Ignition Noise

[Arminho]

I have a 74 911 2.7L. I get considerable ignition interference with the Blaupunkt Frankfurt radio, which has been verified to work. New center dash speaker is installed.

Did model year 74 come with the radio suppressor condensor part# 91161890300
I see a couple on Ebay for sale.

[75 911s]

Yep, my 75 has one. Is your Faraday cage still intact? That is to say, are the ground wires still attached to the rear metal decklid? Was a plastic decklid put in place? Do you have the grounded ignition wires?

[speedster911]

Originally Posted by Arminho

I have a 74 911 2.7L. I get considerable ignition interference with the Blaupunkt Frankfurt radio, which has been verified to work. New center dash speaker is installed.

Did model year 74 come with the radio suppressor condensor part# 91161890300
I see a couple on Ebay for sale.

yes, but not from the factory... at least not an the majority of the 74s. There were two styles I believe. There is a technical document on this and most were installed by dealers. Mine was mounted on the coil bracket on a 74.

[Arminho]

Originally Posted by 75 911s

Yep, my 75 has one. Is your Faraday cage still intact? That is to say, are the ground wires still attached to the rear metal decklid? Was a plastic decklid put in place? Do you have the grounded ignition wires?

I'll check on this. I definitely don't have a plastic decklid .

Originally Posted by speedster911

yes, but not from the factory... at least not an the majority of the 74s. There were two styles I believe. There is a technical document on this and most were installed by dealers. Mine was mounted on the coil bracket on a 74.

Gotcha, any idea where I can find the technical bulletin or document?

Planning on buying the 75+ radio suppressor and gonna try to make it work.

[Arminho]

Originally Posted by 75 911s

Yep, my 75 has one. Is your Faraday cage still intact? That is to say, are the ground wires still attached to the rear metal decklid? Was a plastic decklid put in place? Do you have the grounded ignition wires?

Ground wires are still attached to the metal decklid.
Here’s what it looks like:





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[Walter_Middie]

Number 7 is a "Radio Noise Suppressor".

[gomezoneill]

Not to break balls but you're still using a radio?

[75 911s]

Both suppressors are visible in your picture. Ensure they are connected to the voltage regulator back there. Looks like they are. Perhaps the power on the radio was tapped into the wrong lead under the dash.

[Arminho]

Originally Posted by gomezoneill

Not to break balls but you're still using a radio?

We have gone through quite a bit of work to get everything looking and working as it did originally back in 74. I found the original 73 BP Frankfurt radio and I'm picky. Why have something if it doesn't work well? Same goes for my seatbelt sensors, windshield wiper nozzles, etc... But I get it. I did sneak a bluetooth chip into the DIN slot on the back of the Frankfurt radio so at least I can stream

[Arminho]

Originally Posted by 75 911s

Both suppressors are visible in your picture. Ensure they are connected to the voltage regulator back there. Looks like they are. Perhaps the power on the radio was tapped into the wrong lead under the dash.

Hmmm could be. There was a previous Pioneer headunit in there. I'll try to check it out.

Armin

[Alfasrule]

https://www.amazon.com/Isolator-Suppressor-Amplifier-Equalizer-Subwoofer/dp/B07S8VKG99/ref=sr_1_1_sspa?dchild=1&keywords=Car+Radio+Power+filter&qid=1617223805&sr=8-1-spons&psc=1&spLa=ZW5jcnlwdGVkUXVhbGlmaWVyPUEzOTNXNkJGWEJFMUFJJ mVuY3J5cHRlZElkPUEwMjAzMTEwMzg1SFY2TTcwOEozVSZlbmN yeXB0ZWRBZElkPUEwMDMzODk1UVlVR0kwWVpMVk1QJndpZGdld E5hbWU9c3BfYXRmJmFjdGlvbj1jbGlja1JlZGlyZWN0JmRvTm9 0TG9nQ2xpY2s9dHJ1ZQ==

Get one of these.

[E Sully]

I don't know if it was used on 1974, but along with the regulator capacitors this radio noise suppressor was installed on my 1973. In post 4 it was used in place of part#3, RPM sensor, that was no longer needed. https://www.ebay.com/itm/Porsche-911-Distributor-Condenser-nos-new-old-stock-radio-suppress-91161890300-/373018598227

[Arminho]

Originally Posted by E Sully

I don't know if it was used on 1974, but along with the regulator capacitors this radio noise suppressor was installed on my 1973. In post 4 it was used in place of part#3, RPM sensor, that was no longer needed. https://www.ebay.com/itm/Porsche-911-Distributor-Condenser-nos-new-old-stock-radio-suppress-91161890300-/373018598227

Oddly enough, I purchased this same exact condenser from this Ebay user 2 weeks ago, and received a random Magnetti Marelli condensator for a Fiat 125! I've sent the return back and bought another one from a different seller, and will try to install as soon as it arrives.