Jrtaylor9

I’m back. The car runs amazing; truly amazing for a 1965 911. Everything “checks out” mechanically, it’s not alternator, belts, nada. It even has dynomat already in the back. However, this high pitched wail resonance sound is still there and it’s not as I have experienced hearing early 2.0 swb cars in my past. I’ve had a couple of people suggest it could be a result of swapping oem for ssi stainless header/heat-exchanger. On one hand I want to try it given I’ve heard that suggestion 2x now. On the other hand, don’t a LOT of people replace oem header/heat-exchanger with ssi stainless setup? And if so, I can’t imagine anyone not complaining about what I’m hearing. The oem soundtrack is there, it’s just accented/over-shadowed by a foreign wail that doesn’t belong. I know people often make old cars work because they find the balance between ideal and reality. This one is a head scratcher for me and it is the only thing short of this car being all I could ever want for in a swb 911; my dream absent this odd soundtrack addition!

Jrtaylor9

Heat exchanger check is next on the list. Seems to be the consensus for what to try next.

theiceman

can you post a sound clip at all ?

i have SSi , and yes they have a drone , especially when matched with a 2-1 muffler as required, but i would not consider it a howl by any means.

Jrtaylor9

There are a couple of clips at the beginning of the thread. The motor and entire drive train have been totally rebuilt and the car runs amazingly well; so we are confident it’s not an internal issue. I’ve gotten a couple of opinions from independent sources that sometimes the vibration from heat exchangers and shroud can create the high pitch resonance “wail” I’m hearing. Fingers crossed because otherwise I’m beyond pleased with how it runs.

theiceman

oh yeah i remember this now ...

doesnt sound like anything to do with exhaust to me ... mechanics stethoscope doesnt help ?

budge96

An engine builder I know pretty well recently showed me an oil passage tube that runs along the path of the cam rockers that once clogged if not cleared or replaced will cause a valve train whine like nun other ..
I was basically unaware this channel existed , my friend was replacing one on a 3.2 but apparently it exists on earlier valve train cam towers as well .. just a suggestion …
Bert

Jrtaylor9

I appreciate all of the suggestions and hope one of them does the trick. Keep them coming. I’ll report back when I find this gremlin.

Mark Salvetti

You haven't mentioned whether you've looked at the induction? Have you tried running without the air cleaners? I'm just wondering if there is something weird going on in there. Since you can reproduce the sound by reving at a standstill, I would poke around the intake components with an automotive stethoscope.

And yeah, we need to see some photos of the car and engine.

Mark

Jrtaylor9

Pics coming. Thanks for all the ideas to investigate.