fnbrowning

For those of use that have a “ticking” noise associated with LT headers, the A.I.R. Pipe Restrictor Plate Mod has been suggested.

Forum posts at several sites claim that the constant fluttering of these check valves will eventually burn them up. Forum posters say that putting some restrictor plates in the air pipe flange seems to dampen the pulse that causes the fluttering, yet they still allow enough air flow so that the A.I.R. system can function normally, therefore it won't cause a "Service Engine Soon" light. These restrictors can be easily made using some sheet metal, some tin snips, a 3/16" drill bit for the restriction.

Okay, serious question here: Where does this information come from?
I did some work on the phone, I called two sponsers, and guys at Magnuson Products, Inc, Edelbrock Inc, and Dynatech Inc, and no-one has heard of the check valves in the A.I.R. system fluttering.
Is there an authoritative source for this mod? Or are the LS1 F-body sites quoting each other in round-robin fashion?
Wouldn't be the first time a "mod" was "all the rage" and then was discredited later!

Who first posted it and how did they arrive at the conclusion? For instance, how was the 3/16" drill bit for the restriction arrived at, experimentation? On what grounds did someone decide that 3/16 allowed the correct amount of air to the converters?

Please don’t take these questions out of context. But before another person does the A.I.R. Pipe Restrictor Plate Mod it would be nice to get some background.

WILWAXU

iTrader: (6)

Umm.. not sure about any rage... but it worked for my car(s).

First drive after header install, my SS rattled like someone hid a baby rattler under the hood. I installed the plates the next morning, noise went away.

I made my plates using the directions here: http://riptide63.homestead.com/restrictor.html

Not all headers or cars need this mod. Only ones that rattle the check valves after install.

LMAO.. how many sets of LS1 headers do you think the guy on the other end of the phone has actually install himself? I'm betting less than one watching someone else doesn't count

Camaro SS 2002

[QUOTE=WILWAXU]Not all headers or cars need this mod. Only ones that rattle the check valves after install.[QUOTE]

If I decided to !AIR, would the check valves no longer be an issue whatsoever?

fnbrowning

Yes, I've seen this page, along with another. They both have good directions.

But as I've said previously, Who first posted it and how did they arrive at the conclusion? For instance, how was the 3/16" drill bit for the restriction arrived at, experimentation? On what grounds did someone decide that 3/16 {0.1875"} allowed the correct amount of air to the converters?
Which type of converter? Stock or high flow?

jimmyblue

iTrader: (11)

I did this mod w/ 1/8" holes and it eventually
set an AIR SES code. But my checkvalves
were not rattling either (shown by the lack
of improvement, from restrictors). So I went
back to the stock gaskets.

Camaro SS 2002

Do you have LT's, I don't see them in your sig?

slik98z

it works. you don't get performance from it, but it DOES get rid of the ticking. You will set off the SES light. Easily removed via Edit, Predator i believe or when you go to get your tune (which we all "should" with long tubes anyhow) they can remove it then.

I'm kind of stumped why you ask this question

Camaro SS 2002

The restrictor mod didn't get rid of my ticking, and I have NO exhaust leaks.

WILWAXU

iTrader: (6)

The check valves are part of what you take off when you remove the AIR system.

Not sure what it matters.. but, if I remember right, it was trial and error deal. This mod started back when there was only one long tube header on the market for our cars...

As I said previously.. It varies from car to car. If the suggested hole size doesn't work for you, try a different size. This isn't rocket science.

Me too..

2002 Trans Am

Trial and error.....its basically how everything else gets invented

slik98z

some it doesnt work for. sometimes by the time people have gotten aroudn to doing this mod, their check valves have already started to burn up. If you really wish to keep them, try a slightly smaller hole in the restrictor plate, and replace teh check valves. but imo might as well remove it. that will definately get rid of teh ticking. also have you checked your pullies? i browse the newbie section as i had an issue with squeeks and ticks, and it took replacing a few pullies and the belt and that took care of it. most likely its the check valves.

T

Camaro SS 2002

I checked my check valves before I did the restrictor mod and they were still good. Im going to pull the AIR pump fuse and put in some block off plates, if the ticking is still there then I know its not the AIR system.

fnbrowning

You are both stumped why I ask this question? I'll tell you!

Because I was trained as an aerospace machinist, and it was drummed into our brains that you don't make a change to a mechanical system without knowing the consequences.

Because some of the trendy modifications or practices posted on LS1 sites once talked up like “the greatest thing” are found later to be useless or downright wrong. For instance, you may or may not be aware, an incredible debate once raged at LS1.com over the aftermarket vs stock vs ported MAF question. Some will remember the "Mass Airflow Sensor Scam" as a point of reference.

Because even if it isn’t “rocket science” I care about my car, and my engine in particular. It’s a state-of-the-art mechanical system controlled by a sophisticated, electronic management system. It’s a high $$ investment, and there’s nothing wrong with trying to get all the angles covered before a change is made.

WEASEL

If you don't want any performance part related problems, then don't mod your car.

No matter how careful, how well thought out, how much research and planning goes into modifying your vehicle, there will inevitably be problems that you can't foresee. There's no problem at all in asking or planning but like others have said, what may work flawlessly on my car may work like crap on yours.

Fortunately, there are lots of people out there willing to experiment, intelligently or not, to find a solution for problems. Then you have the early adopters and then shortly thereafter the masses will follow. You will always have some though, that things don't work for and shortly after that, a second or better solution comes around.

You kinda got put potential risk into categories like "big risk", little risk" or "no risk" and decide how comfortable you are with your decisions........and of course, how expensive your screw up might be.

blu98ta

iTrader: (4)

I think I have narrowed down this sound to the front of the motor, specifically the belt tensioner. Does that sound like it could be where the noise is coming from or is it really the check valves? I need help too. Let me know what to do.

highgear

My check valves started to tick at about 20K miles. The crappy factory plastic clamps were not holding a good clamp. I changed over to the good 'ol screw clamps and no more clicking. No, I don't have LT's. They will tick anyway; if you don't have a good seal on the hose.