[TB1]

I’ve got a quick question. In the pic I have installed a 5/16” bolt into the hole in #8 runner that was a major vacuum leak. Was this used as a vacuum port originally? I had the manifold CNC ported by SD Performance (full meal deal) so maybe it broke through. Either way just curious as it’s plugged now and the car runs way better....... can’t believe I didn’t find this sooner!
thanks
Trevor.


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[b-man]

Originally used to bolt down the rear leg of the A/C compressor support bracket.

Definitely not a vacuum port, at least not until the porting work was performed.

[steve25]

Also it's a blind hole so you do not have to worry about it sucking vacuum unless someone gasket matched that runner in too deep and too tall.

Putting a Allen set bolt in there will help it to not attract as much attention to its non use if that's what your looking for?

[Formulas]

Don't know how long your bolt is but you don't want it sticking down into the runner.

Measure hole depth real good on short side cut to fit install with sealer

Next time you have intake off you could install a set screw deep with loctite and then grind off protrusion in the port to match
.or use all thread flush the top and in the port

[TB1]

Thanks for the replies, I'm going to pull out the ugly bolt today and use a set screw type plug with some sealer. The current bolt is only in about 3/8-1/2" just enough that it stopped the vacuum leak when I found it yesterday and not far enough to enter the intake port.

[Tom Vaught]

All above replies fit the typical "what is going on here".

Factory might have drilled the hole a bit too deep.
Leak IF the heads were ported so now that hole is a vacuum leak
Poor fastener choice by someone.
Sealer used on the threads required.

Sometimes you see valve cover bolt holes that go into the intake ports.
I have always used longer Allen Head Set Screws and loctited them in place.
Maybe not stock but allows thick valve cover gaskets and aluminum valve covers, (and no vacuum leaks).

Tom V.

[78w72]

thats a common issue with the SD CNC porting of factory intakes. dave told me about that when mine was done, surprised he didnt mention it on yours if it broke through. very easy to put a bolt or set screw with sealer in there.

[Scott Thelander]

howz your heater workin ?

heater hose looks a little choked off

allen head bolt ?? no visual attraction ? hmmmmm

[TB1]

Originally Posted by 78w72

thats a common issue with the SD CNC porting of factory intakes. dave told me about that when mine was done, surprised he didnt mention it on yours if it broke through. very easy to put a bolt or set screw with sealer in there.

The intake was a last minute thing as I was on my way to pick up my engine from Dave and I came across a factory manifold for cheap so he ported one he had a day before I showed up and we swapped cores. He didn't mention anything but it was a rushed thing. Either way no big deal except it took me awhile to stumble across it.

I took a 5/16" bolt and cut it off to about 1/2" put some sealant on it and will call it a permanent fix. Car drove good before but much better now its only got maybe a couple hundred miles on it and still working out some bugs overall and making the winter to do list, Like the kinked heater core hose.

[78w72]

gotcha.

you will love the intake, daves testing showed it almost as good as a port matched RPM. i wanted to run the RPM but due to hood clearance issues i had to find another option & the SD ported factory intake was the best option using a q-jet.

[grandam1979]

We had Dave do two intakes both came back with a bolt installed before porting.