Unfortunately a disclaimer of this nature is necessary due to the fact that we are delaing with a fuel delivery source and this information is sent out over the internet with little or no control. For these same reasons I will not be a part to any recommendations
to modify a fuel pump (or in this instance, any recommendations
to modify a carb), I hope everyone can understand the need for the following disclaimer becuase it is there for a reason, and that is to provide notice this is a potentially dangerous or costly thing to do, and if you elect to do so you proceed at your own risk.
The following photos and text documentation is provided in the best of faith and to provide information to my fellow boating enthusiasts.
This procedure may not be in conformance with USCG laws or safety regulations, so this information is NOT a recommendation or suggestion, it is only a documentation regarding what I did with my carb for my own personal use. Since there is NO assurance the actual carb body I drilled into is the same as the one someone else may have, and no assurance the manufacturer did not change the internal or external casting, neither I, the Chris-Craft Commander Forum, Inc., nor anyone directly or indirectly associated with this forum shall assume any liability for carb damage, any consequential damage and/or claim in the event someone takes this information and elects to proceed on their own by drilling into a carb.
Since I have a couple 1409 Edelbrock carbs and may be going for more in the future, I decided I would drill and tap one for a proper PCV installation just to see how it was done, and to also document it so other people here on THE FORUM could use it as a reference. Photo below is compliments of TS Clymer, showing the standard method of hooking from the valve cover mounted PCV valve with a copper tube to the carb.
If the PCV system is not working on these motors you will get a real stench on board, and the fumes will build up inside the sump, making acid and potentially being explosive in the event there is a fuel leak.
The standard Carter AFB carb as provided on the 427 engines has a fitting tapped into the aft side of the carb which is intended to hook up to the PCV system. The photo above shows the fitting as installed in a Carter AFB marine 625 cfm carb.
The Edelbrock #1409 marine 600 cfm carb is a clone of the original AFB and although not identical, it is nearly identical but with some improvements. The carb is not drilled for the PCV system so we have to do that ourselves if we are going to hook things up properly and control fumes, oder and run the system as intended by Chris Craft.
The 1409 has a nice dimple on the front where you can drill. I called Edelbrock and the tech guy was rather set in reciting the company position like a recording machine, saying they tested the carb without the PCV system and it was therefore only certified with the EPA yadda yadda, and he did not want to hear anything about the merits of controlling the odor and fumes that come from a crankcase. He was of absolutely no assistance in helping, yet Edelbrock cast in a dimple where we are given the big hint and a wink to drill for the PCV system.
So I decided to remove the old fitting from the old Carter and drill a new hole so the original fitting could be reinstalled. Here are the drill and the tap that I used to do this.
First thing I did was to tape up all the openings in the 1409 that might get bits of metal from drilling and tapping, then I went right to the drill press and gently started drilling deeper and deeper into the carb body until the hole penetrated into the chamber Edelbrock has also left us for this very operation.
Once the hole was opened up and viewed from the underside of the carb and from the backside, I used some WD40 which serves as a very nice cutting oil for aluminum and ran the tap inside gently screwing it in, and backing it out, then in a little deeper, until the new threads were cut nicely.
The new fitting was tested for a fit, the tap was run again just to remove any additional loose material, a vacuum hose was hooked up from a shop vac to get any filings, and in went the fitting just like the original AFB.
The 1409 was put back on the intake manifold and is now ready to receive the original PCV system hook up.
In the thread that follows we'll take a look at the underside and note why we did not elect to drill the spacer or use a tap somewhere in the intake manifold (that would potentially cause a lean condition in one cylinder).