1986 302 EFI upper plenum and throttle body

[ReneH]

Hi, cause I'm still having these noise with my stock intake on my 302/347 stroker, I suspect the plenum and/or the throttle body as source of this noise.

So I'm searching for an aftermarket plenum with according throttle body for the 1986 302 intake mainfold.

Maybe one of you have something in stock.
Thanks for your offers.

[Gary Lewis]

You could do this in two steps.  Like replace the throttle body and then the upper plenum if the throttle body didn't help.

I'm running a BBK throttle body on Big Blue.  Mainly I wanted the bearings on the ends of the throttle shaft instead of the shaft running in the casting like Ford did.  My reasoning was that as the casting wears the throttle blades will hit differently and cause differences in the idle and running.  But as I think about it now the computer adjusts the amount of air going in to give the same idle speed, so maybe it isn't an issue?

As for the plenum, I'm going to use Trick Flow upper and lower plenums on Dad's 400.  They are made to look like yours with the comb-over, but fit the Cleveland instead of the Windsor.  Supposed to be of high quality, but I don't have them yet.

[ReneH]

Thanks Gary for the information.

As I have already cleared all reachable sharp edges in the plenum and also the throttle body...it's a bit better since doing this.

Using the BBK body will bind me to the stock plenum, as far as I know...

I've found other plenum for single 75mm throttle bodies...may this be an alternative?

On the other hand, I'll try to save some money by now. I've invested about 17,000 Euro for the truck and another 11,000 for all the repairs and customisation...

That's why I asked here for some used parts...

[Gary Lewis]

I understand the investment.  Trust me.  I don't want to know how much I've sunk in either of my trucks - but I pretty well know.  

As for the BBK throttle body, I understand what you are saying.  You might find a used plenum that takes a different size, so you don't want to go that way.  Makes sense to me.

Hope you find something used.  Unfortunately I don't have anything at all.

[ReneH]

Hmm...the whistling sound of the intake is really very annoying while driving. It changes from this high frequency sound at low speed and rpm to a much deeper sound when driving a constant speed about over 50 miles and accelerating carefully...

I have read that some similar sound also can occur with aftermarket plenum and throttle bodys:

"Okay, so i re-read your post and if you didnt mess with the intake manifold or throttle body then it is without a doubt your cold air intake. By switching to a high performance intake you are by default removing the factory air silencer. This is a part that keeps the incoming air from whistling. A lot of people that i have talked to like the little noise it makes, it kind of reminds them they have a little extra something under the hood. I hope this helps!"

This was a post from 2011 about a 302 EFI Mustang BOSS with aftermarket intake.
This makes me think about that a new plenum and TB may won't solve my problem. Maybe it's the best to add the old filter box and check if the sound will go away...or to add some "diffusor" or additional in-line filter inside my intake-pipe-system...

[Gary Lewis]

I know about annoying sounds when you are driving since I just went through that with Big Blue's air conditioning.

But I think you are right - go back to the original filter box and air inlet plumbing and see if that makes a difference.  Lots cheaper and easier than a new plenum and/or throttle body, and from that post it sounds like it make be the culprit.

[Damon Hart]

I have used plenum and throttle body.

[Damon Hart]

[ReneH]

Hi!

Thanks for the offer...but this is the same stock plenum and TB as I have...I think this won't solve my problem...