Need Help with Grommet

[schovil69]

Originally Posted by dmjlambert

When I search online that part appears to be for 8 cylinder big block engines and 6 cylinder engines, not for small block 8 cylinder. Try the part numbers I gave in post 15, your local parts store or Chevrolet dealership if you have one nearby should be able to get them for you.

Originally Posted by dmjlambert

Breather/flame arrester grommet GM# 14091870 Dorman 42052

That's good to know. I have a 454 block fresh from the machine shop on the stand I'm just getting started on. I will use the 42323 with those valve covers.

The dimensions for Dorman 42052 are,
Inside Diameter: 0.728"
Outside Diameter: 1.204"

The dimensions for Dorman 42323 are,
Inside Diameter: 0.718"
Outside Diameter: 1.403"

I think what has been most confusing for me with this is I didn't realize the advertised outside diameters are not the outside diameter of the grommet groove that sits in the hole of the valve cover. The advertised outside diameter is referencing the outermost diameter of the grommet. So, when I saw post 15 and looked up the number only to find a grommet with the same outside diameter as what I already had, I just ignored it. Unbeknownst to me, though, is what I just stated. That being, my measured-in-the-groove outside diameter was being compared to the overall outermost diameter of the grommet in my mind.

Knowing what I do about the 42323 with its measured-in-the-groove outside diameter at 1.2" and its advertised outside diameter of 1.4", I would suggest the 42052 with its advertised outside diameter of 1.2" will be spot on for my application in a 0.9" valve cover hole expecting its measured-in-the-groove outside diameter to be approximately 1.0".


Thank you dmjlambert for directing me to have another look, don't think I would have connected all the dots if you hadn't.

Thank you to all you guys as well for helping me figure out this issue. I'm still in disbelief that a guy who builds engines with his eyes closed had such a difficult time with the lowly grommet.

[dmjlambert]

I had a heck of a time figuring out the grommet, and parts store guys and even speed shops were useless. The best they could do is suggest I buy a breather from the chrome-gets-you-home section of their store and throw away the breather and keep the grommet that comes in the package. I don't know why the outside diameter is even given as a dimension for these grommets, nobody on Earth would care about that. We need the inside-the-groove or fits-hole-size diameter.