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+--- Thread: Bulkhead hole diameter (/showthread.php?tid=8923)
Bulkhead hole diameter - Steve Bryant - 06-10-2023
Hi all. My firewall / bulkhead does not have the hole drilled for the vacuum pipe to go through. Anyone know the proper diameter the hole should be WITHOUT the grommet in it?
Thanks,
Stephen
BULKHEAD HOLE 1.jpg (Size: 131.8 KB / Downloads: 427)
BULKHEAD HOLE 2.jpg (Size: 137.27 KB / Downloads: 426)
RE: Bulkhead hole diameter - Duncan Grimmond - 06-10-2023
Measure the pipe for the right size of grommet and drill a hole to match the grommet?
RE: Bulkhead hole diameter - Steve Bryant - 06-10-2023
Duncan, there is no pipe at present, so was wondering what the original factory diameter was.
Thanks,
Stephen
RE: Bulkhead hole diameter - Howard Wright - 06-10-2023
Hi Steve
The pipe on my car is about 1/4” (it’s squishy rubber so difficult to measure exactly). It is reproduction bought from one of our Cherished suppliers.
Hope that helps
Cheers
Howard
RE: Bulkhead hole diameter - Tony Griffiths - 08-10-2023
As grommets now all seem to be metric you'd be better off - as others have said - finding some that look to be correct and drilling according to the dimensions of the chosen one (I'd recommend experimenting first on a piece of suitable scrap metal sheet). BTW, the hole would originally have used not a rubber grommet, but one of the rather lovely, two-part, screw-together, nickel-plated metal type. Very similar ones can still be obtained with a search on eBay turning up more than one supplier. Unfortunately, the gap between the two halves of these is greater than the thickness of the bulkhead metal - hence they either need turning down (tricky) or a small washer found or made (very tricky) to compensate.
RE: Bulkhead hole diameter - Steve Bryant - 08-10-2023
Thanks Tony. From what I can see and extrapolate from photos the hole would appear to be 1/2" diameter. I'll turn something up on the lathe to do the job.
Stephen
RE: Bulkhead hole diameter - Parazine - 08-10-2023
I made some up during lockdown for the Top Hat restoration:
DSC_1055s.JPG (Size: 67.75 KB / Downloads: 157)
RE: Bulkhead hole diameter - Chris Garner - 09-10-2023
Steve. I think you'll find the diameter is 7/16". I can let you have a brass grommet FOC if it helps.
Parazine. I had a batch made some time back but mine were not as long as yours and closer to the original pattern. I didn't take the risk to Ni plate as I worried about the threads and whether the two halves would screw together after the plate.
RE: Bulkhead hole diameter - Steve Bryant - 09-10-2023
Hi Chris, thanks for the information and your generous offer. I'll go with 7/16" and open it up to 1/2" if need be. I need to turn up a batch of brass grommets anyway for the wiring when the time comes.
Cheers,
Stephen