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How To Modify Dcoe Phenolic Insulators?


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Based on 2002FAQ discussions and other research I decided to hard mount my 45 Weber DCOE's on the intake manifolds using phenolic (aka Bakalite) insulating spacers sandwiched between pairs of base gaskets.

I ordered four 2002ti Insulators (13110639028) from BMW but did not account for the fact that these have 40mm ID openings, while I need 45mm ID openings to avoid flow constriction. The BMW insulators are about 1/4" thick, black on the mating surfaces and brown on the inside.

1. Are 45mm DCOE phenolic insulators available? If so, what is the part number and likely suppliers?

2. How can I open up my 40mm spacers to 45mm? From what I read, Bakalite and other phenolic materials are brittle, and the dust from cutting them may be hazardous. People generally mill phenolic materials with high RPM and low feed rates to avoid overheating, and sometimes use a soapy water bath to minimize dust.

Which of the following might worK?

[a] Bimetalic hole saw in a drill press (I have one that is just under 45mm)

High speed carbide burr in an air powered cutoff tool. I would make a metal template with the hole saw as a guide, but this method would throw a lot of dust.


[c] Cylindrical milling bit in a drill press  (I have an X-Y cross-slide vise to move the workpiece)


[d] Hand shaped with the curved side of a metal file. This would be very labor-intensive and fairly dusty.

[e] other?

Thanks in advance,
Fred '74tii (engine project #1) & '69 DCOE (engine project #2)

Edited by FB73tii
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thats awesome ! i sanded them for a 40dcoe app, they do have a small bit o casting/molding bugger on them.

If i had 45's i think i would try a back to back chamfer(in<>out) just to see if it worked before i blew them out to a full 45mm

edit 3 time.... ^_^  a unibit can accomplish the chamfer

Edited by ndog
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