I bought one used awhile back and decided to install this w/ the Z tube and K&N all at once. Got it all done fairly quick w/o problems I thought. Started it and immediately there was a LOUD whistle. I noticed that the plenum "rocked" back/forth on the lower. But I thought I could torque it down and seal it. I ended up loosening and retorquing everything again. Tried a different order. Same thing. It was pretty late so I didn't really try to source the leak that long. I tried to run my hand along the outer edge of the plenum to see if I could feel a vacuum leak but a quick check didn't find anything.

I ended up putting the stocker back on. I note this one didn't "rock" back/forth and even though I just basicly threw it back on (it was 1:30am now), the car started/ran fine w/o any "whistle" leaks.

Is it common to have a slightly warped plenum? Is there some special method of installing this thing? I was careful not to pinch the oil filler flap and made sure all the hoses/clamps were secure.

Any help would be great. A quick search of "whistle" or "crawford" didn't reveal much. But I've read something about this before.

Jeff

 

did u install the shims inside the plenum?

 

There are no shims with the Crawford Plenum.

 

Jeff,

Which Crawford Plenum do you have? Since the Crawford V-5 and cast plenum only uses two long center bolts, is it safe to say that you installed the four short "plug bolts"? How about the seal washers under the head of the two long bolts?

If your plenum is slightly warped you might try adding a second gasket and carefully re-torquing all the bolts to 9-10 ft-lbs (108-120 in-lbs) after a few thermal cycles.


DaveO

 

Jeff,

Crawford did have problems with the earlier plenums warping because of the cutting and welding done the plenum. That has always been a downside. I'm uncertain what the V5 plenum looks like though. Is it still a cut up OEM plenum or is it a completely new cast unit? Like DaveO said, you could use an additional gasket. It may work, it may not. The fact that the gaps sound fairly significant makes me think getting a good seal could be a problem.

 

Dave and Dave thanks for the replies. It's the welded up Crawford. I did install the 4 "plug" bolts w/ loctite. And I made sure to use the teflon washers on the two center bolts. I put the plenum on my concrete floor for a rough flatness check. This thing is way warped. If I put the back end down, the front has a good 1/8" gap. That's a big gap to have to crank down on. I'm sure I was way over the oem torque specs on the outside brass bolts. I was thinking maybe a 2nd gasket with two lines of permatex or something but this thing might be too warped to work with. Maybe if someone bolted this thing down on a jig and heated it up you could work it flat. I'm pretty disappointed. I have a PM to the original owner to get his opinion. I wonder if I should call Crawford? I thought of shaving it but, that would defeat the purpose of this thing.

 

Which one?

 

I would give it back to the guy you bought it from and ask for a refund.

 

Dave O. The one on the right. Mine powder coated shiny black.

 

Jeff if you have any problems with the orginal owner, you can always send it to me and I'll machine it flat again for you. If you want.......... I'll polish the inside for you too. For a fee of course. Let me know.

 

At first thought that seems like a good idea. But IMHO, having to shave enough to get a 1/8" warp flat again is defeating the original purpose of the plenum in the 1st place. Also that much material is going make the bolt flanges dangerously thin?

 

I just went downstairs and measured my flange and it measures .580" to .600". I hear you but I wouldn't machine the whole .125(1/8th) away. As for being afraid to machine away material from this part, the only problem would be the reduction in volume. I'll leave it up to you, but my offer still stands.

 

It might not be that the Plenum is warped...

Check the two long centerbolts of the plenum with a straight edge... (mine had a slight issues that's easily fixed)

Simple check... take out a straight edge, run it around all the sides to check that it's flat (with respect to the 2 centerbolts). Check to see that the two inner centerbolts of the plenum are cleared/flat. That is most likely the issue of the "rocking" that you are seeing.

I got my plenum a couple of months ago, and the 2 centerbolts were "slightly" long just as you mentioned (veryminor... 1/32"). I'm guessing this is from the "welding" of the 2 centerbolts to the cast plenum.

This is a Q.A. issue from Crawfordz... I'm sure the 2 long centerbolts were perfect when they made it, but after welding, you could be 1/32" off and you would get the rocking... and potentially leading to leaks or worst yet, cracking of the plenum down the road for someone that doesn't know better and just torque it down.

I just busted out an air compressor and "milled" it down to make it flush in <2min. (A simple straight edge will tell you where you need to be). No problems since day1. If you don't have the tools, you can try slowing sanding it with different grits of sandpaper.

Hope this info helps.

 

Great suggestion! And I'll try to see if it can be "milled" down.

I had to think about this for min. I thought you originally meant the actual bolts. But realized you mean the 2 center bolt mounting bores.

That would make alot of sense as the "rocking" seems to be right in the middle.

I hope!

 

Just from your description, that seems like the issue I had with the "rocking". I just hope for those who bought it as a bolt on mod too "literally" take it as a bolt on and torque it down without checking.

Just be careful NOT to over-mill it as that would cause the inverse problem...

Go slowly, lil by lil...

Good luck, and hope the suggestion helps you out.