One Piece Intake Manifold Plug

[6daytonas]

Blew the plug out of my one piece and left it on the side of the road somewhere. My manuals don't reference the plug anywhere. Searches here haven't turned up much. Anybody have any luck finding a suitable replacement? I'm hoping something exists without having to resort to a new manifold...

[contraption22]

Have you measured the ID of the hole with a dial caliper?

[6daytonas]

Looks to be 2.25". Pretty big hole...

[contraption22]

If you get an exact measurement, you might be able to get a plug for it somewhere, like a local engine builder or something.

[BadAssPerformance]

+1, they make all sizes. Any good engine shop or even a Napa or local auot sto4re that does machine work would have it

[6daytonas]

Yup - Just went to NAPA. All good...

[Directconnection]

seal it with some sort of epoxy or something on the outside, too... (JB weld type)

[moparman76_69]

Question is why did you blow it out? I think its designed to pop out if there is too much pressure in the plenum or in the case of a backfire.

[turbovanman²]

I would say its there for a backfire.

[86Shelby]

It's just a simple core plug nothing more nothing less...there was a lot of sand inside when they were cast...

[moparman76_69]

I would think it would be smaller if it was a core plug. You don't need a 2.25 hole to empty the sand out.

[86Shelby]

Why would the engineers put a safety valve type of plug in the intake when the electronics will simply act like the engine is at WOT if it pops out?

[shadow88]

Why would the engineers put a safety valve type of plug in the intake when the electronics will simply act like the engine is at WOT if it pops out?

Factory electronics don't go to an uncontrolled WOT when there's a huge vacuum leak. Ask a guy who's removed his intake manifold with nitrous and drove home a couple times how I know

I'm sure it's just a core plug, not a precaution.

[contraption22]

I beleive mine was replaced with an aluminum plug and welded in place.

[6daytonas]

I just think it was a case of 23 years of service. Car didn't backfire when it popped out. I was starting to go up a hill at about 35 mph - was maybe around 3 or 4 psi... Computer did a nice job of preventing any over-revving. I popped it into neutral because I didn't know what happened. The car revved to 3800 rpm and dropped. On its way back up to 3800, I cut the ignition and coasted into a parking lot, expecting the worst. I run the car to 12.5 psi occasionally, but nothing severe. The engine is a rebuild and the head was new when I bought the car - I do think the car was raced prior to my ownership, so chances are good the manifold saw some hard days in the past. Either way - plug seems to be holding fine now.

[Reeves]

I beleive mine was replaced with an aluminum plug and welded in place.

Do you know where you got the aluminum plug? Or did you make one?

I'm thinking of making one.

[contraption22]

Just made one.

It was about 15 years ago lol

[Reeves]

Yeah, took a spare intake and knocked out the plug. Hole is just about exactly 2.25" and plug is slightly bigger for tight fit. Think I'll make a bolt in plug and put it in with RTV. No time to remove head to weld it in. Or may put an O-ring seal on it if I get time.

[sdac guy]

I'm not really sure if it is on this site or if it was the other one before this site happened, but there was a discussion about the "cone" that Ed Peters used to sell to go in that hole. The cone shape pointed into the manifold and was supposed to dampen pulsing of the airflow (or something like that) in the plenum.

Barry

[Reeves]

I'm not really sure if it is on this site or if it was the other one before this site happened, but there was a discussion about the "cone" that Ed Peters used to sell to go in that hole. The cone shape pointed into the manifold and was supposed to dampen pulsing of the airflow (or something like that) in the plenum.

Barry

Hmmm....dont' remember that one.