Who has the correct/best fitting PCV and PCV Grommet - Kirban or Highway Stars???

[Darkstar72]

I got my intake off last night going through and sealing up top - intake manifold gaskets, valve cover gaskets, turbo drain gasket, etc.

Since I don't want to do this job again any time soon I am replacing the PCV grommet and PCV while I have it all out on the bench. I see conflicting information from Kirbans' measurements on the opening versus the sizes mentioned on Highway Stars.

Per Kirban site on grommet - "This replacement PCV valve grommet also had the wrong size relief. It measured only .175 instead of .230 in the original. The center hole measurement was .440 instead of .495."

Per Highway Stars - "This grommet was engineered to original GM blueprints and features the correct .485" hole diameter for the proper seating and sealing of the PCV valve."

Looking for anyone that can give some insight into this. Anyone have experience with either grommet to truly say which one will work the best? The cost of the part is obviously not an issue from wherever I may get it from as these are not expensive parts, but I HATE doing the same job twice. TIA.

 

[GNRick]

If I had to choose I would go with Kirban's, as Richard Clark designed it.

 

[1986 Buick GX1]

And pick up RJC's PCV valve from Kirban's as well.

http://www.kirbanperformance.com/product/43836/REPLACEMENT+HEAVY-DUTY+PCV+VALVE+#7302.html

 

[Thumper]

Highway stars has the better/ correct pcv grommet. I own both and have installed both and nos4gn has beat out kirban on this product.

 

[Dennis Kirban]

kirban 2 cents worth

I not seen the others but its true RC Richard Clark had it made and that is where I get it from. If a better one exists I extremely doubt it. RC is pretty darn thorough.....

denniskirban@yahoo.com

 

[Darkstar72]

Highway stars has the better/ correct pcv grommet. I own both and have installed both and nos4gn has beat out kirban on this product.

Thank you! That’s exactly what I was hopin that someone had tried both to compare. I appreciate it.

 

[SGRIM]

Please remember to support the vendors that support the board! When you buy tell them you are a TurboBuick.com member!

 

[Thumper]

I decided to go out to my inventory of pcv grommets ( approximately 15 ) take some pictures and measure the differences. I realized the Kirban grommet I have is the older version, not the RC version. I have placed an order with Kirban this morning for his newest available offerings. Once I have them in my hands I will post pics and measurements of the old oem one, the gm replacement, the dorman help section, Kirbans (RC), and highway stars for comparisons. In all reality they are all useable, some may just be a better fit than others.

Thanks
Bill

 

[Darkstar72]

I decided to go out to my inventory of pcv grommets ( approximately 15 ) take some pictures and measure the differences. I realized the Kirban grommet I have is the older version, not the RC version. I have placed an order with Kirban this morning for his newest available offerings. Once I have them in my hands I will post pics and measurements of the old oem one, the gm replacement, the dorman help section, Kirbans (RC), and highway stars for comparisons. In all reality they are all useable, some may just be a better fit than others.

Thanks
Bill

That would be amazing and I'm sure would benefit so many others when deciding what is needed when taking on the super fun task of replacing one.

 

[A2000RICH]

Here is the truth. Either will work just fine. Since the early 90's every vendor (even GM dealers) sold the wrong grommet for the vin 7 motor. After an exaustive search I decided to have a correct grommet made since it appeared no one even was aware that everything available was simply wrong. A search of this site over ten years ago will prove this. An ex employee of a GM dealer that worked for G-body parts for several years disputed me and I posted pictures and part numbers to prove him wrong. He finally admitted that I was right. I was first to make the correct part since everyone was selling the wrong part. Several years after I did Highway stars also repopped the part. Either of the parts from Kirban or HW will work just fine since the differences are very minor- only thousands of an inch. Glen makes his parts from the original mold dimensions and I made mine from actual NOS parts from the late 80's. Since I have more molding experience than Glenn (owning 23 molding machines made by Netstal and Sumitomo) I realized there was a shrinkage factor that needed to be compensated for since the material was a rubber compound. Thats why my parts are EXACTLY LIKE THE ORIGINALS not the mold dimensions. But it is a minor point since either will work just fine since they are so similar. For some strange reason Glenn has always had a rather strong dislike for me and I have never understood why. But if you ever have a doubt about anything I do remember the extensive experience I have in the mechanical and electronic fields as well as my dedication to the turbo regals in general. Shortly after I introduced the Z Plus product Glenn got on a radio pod cast and dissed it. Now the market is flooded with similar ZDDP products from nearly every oil company. Anyone remember the Powermaster that Glenn was going to market 4 years ago. He teamed up with a rather well known company to have them made in the far east. After none of the prototypes worked correctly finally the brake company sent a sample directly to me for evaluation. How about this-----they copied it and completely left out the check valve! These guys didn't even understand the basic functioning of how the thing even worked. And they even claimed to have put samples out in the field for testing! Put simply sometimes it takes hands on experience to fully understand the manufacture of parts! Experience in sales and marketing doesn't always make the grade.

 

[salvageV6]

I'd use the Dorman one in the Help section before I had to pick a side...

 

[Wknight13]

This post came at a good time as I am deleting an existing cheap catch can setup and going back to straight PCV. Just started the research and done already, now to order. Thanks for the info guys.

 

[Thumper]

Ok now, wow. Back to facts and measurements.

Pcv valve grommets used from my inventory, along with Richard Clark's version purchased from Kirban Performance.

Dorman part number 42056
GM replacement 1381487
Highway Stars, reproduction with GM part number 1254119
30 year old original, part number 1254119
Richard Clark reproduction

All parts measured on the same day, same temperature and with the same calipers. Also measured by the same person ( ME ).

My nomeclature for the following measurements:
ID is the inside diameter that the pcv valve is inserted into
OD is the entire outside top in which you see when installed in intake, not really needed, but...
Relief width This is the part that mates up to the intake hole thickness
Relief diameter This is the part that mates to the intake hole diameter
Relief diameter with pcv valve installed This shows the growth of grommet when valve is installed and will also help to understand sealing expansion/tension.
Seal tightness This shows how much growth/ compression each combination of grommet and pcv valve can grow due to design.
Grommet thickness Thickness of grommet from top face to bottom face

The pcv valve measured is a new, nos, GM part number CV893C ( 25095468 ).
Measurements from the valve are throat diameter, which fits the ID of the grommet, and throat length which is the measurement from the flat bottom of the valve body to the flare of the bottom throat tube.

The last item measured was a used original intake manifold. I measured the pcv valve hole diameter and thickness of the intake at the hole. This will mate with the Relief width and diameter of the grommet.

Ok , here are the measurements:
The pcv valve throats diameter is .505
The pcv valve throat length is .495
The pcv valve hole in intake diameter is .930
The intake thickness at pcv grommet hole is .200

Keep in mind that all new grommets were soft and pliable, the original was very brittle and deformed from 30 years of exposure to heat, oil and other elements.

I went as far as destroying 4 of the grommets to show all the differences between them, cutting in half the original, RC's, HW's and the Dorman.
I found that the original had a sealing surface against the throat of the pcv valve of .374
RC's had a sealing surface of .310
highway stars had a sealing surface of .370


RC summed it up, only a few thousands difference between the best two options. They all will work, but RC's and Highway stars are the most correct fitting and sealing, you cannot go wrong with either or. Both are excellent products.

I do have an unanswered question with this testing, RC's grommet seams to be a different rubber compound and feel, almost like polyurethane qualities compared to the others that have the usual rubber soft feel. This made the grommet just a touch harder to install into the intake hole as flexibility was reduced. This is also why in the measurement of the relief od with valve installed has a minimal growth/expansion.

Highway stars has a more pliable rubber feel, so installing while the intake on engine was easier due to being more flexible.
Highway stars also has the original part number on the grommet for the concours style restorations.

I have posted FACTS and measurements. I am truly being unbiased, as I really don't care whose names are attached here. I only care about the product quality and fitment to help fellow board members make the best informed purchase for their purpose.

Here are many pics.

 

[Thumper]

A few more pics

 

[Darkstar72]

Wow. I think this should just about answer all questions EVER regarding the PCV grommet...LOL.

I honestly didn’t think that the very slight difference would impact its functionality. I wasn’t trying to stir up any grommet controversy but it’s geat to get the truth behind the numbers.

Also...I have the intake on the bench now and I have no idea how would one accomplish this job on car. The old one may very well have been the original as well because that thing was rock hard.

 

[A2000RICH]

A few more pics
View attachment 318358 View attachment 318359 View attachment 318360 View attachment 318361 View attachment 318362 View attachment 318363 View attachment 318364

As you can see the replacement GM part and Dorman does not even resemble the original GM part shape or dimensions. They don't match the shape of the pcv valve at all. The area where the original was undercut was the entire reason I chose to reproduce the part to begin with.This undercut bottom served to "lock" the pcv in and prevented it from backing out. The Dorman and replacement GM parts tended to squeeze the pcv out under conditions where the material was hot and there was excess crankcase pressure. Yes mine are made from a different material since I didn't care about cost, only about long term performance. And yes they are a little more difficult to install unless you preheat them before you try to install them which is what I recommend. I can install them in a car in about 30 seconds. Perhaps I will do a video?

 

[seedling]

WOW!! Holy smokes Batman! If I could get this kind of analysis on my investments then I might actually be able to retire one day! LOL!!!!

ADMIN - Someone should make this a sticky!!!!

 

[greeneyegi]

Without reading all of this what is the final answer?

 

[GNRick]

Without reading all of this what is the final answer?

Kirban's or Highway Stars, both will work.