283F & 327F Engines : Distributor Cap Modification Kit Development Project

Transcription

1 283F & 327F Engines : Distributor Cap Modification Kit Development Project By Dick Morland Chris Craft offered the "F" series engines (283 F & 327 F) in Commanders from 23' to 35'. There are a lot of these engines out there, and they have a problem. Most of these engines were equipped with IBM Prestolite 4115 distributors. Unfortunately these distributors use a "flat cap type" distributor cap which is no longer in production and is virtually impossible to find. I had rebuilt a couple of these distributors for a friend back in 2009 and at that time I could not find the proper cap. It was still listed in some marine supplies and places like NAPA, but they did not fit. The original cap was a higher than normal flat cap which had been problematic in the past, just as the Mallory flat cap on 427's is problematic. Club member & friend Tim Gressett has a 31 Commander with these flat caps and he has been fighting this problem for a number of years. He also owns an elderly 79 Chrysler Cordoba with a V-8 engine, and noticed that the stack cap (wires coming out of cap vertically) on his Chrysler had almost the same weird external "key" type of cap orientation as his 327's. He subsequently purchased a cap for his car and found that he had to do some filing on the external cap locator key to make it fit his boat distributor. After filing on the cap, it indeed sat on and oriented to the correct position on the boats distributor. There was a problem with the boat distributor's hold down clips which were way too long to hold down the Chrysler cap. Tim used a couple of small "rubber spacers" he found in a hardware store to act as a standoff for a hose clamp he tightened on to the upper portion of the cap for the distributor clips to hook on and exert a locking downward force. Next came the rotor. The Chrysler rotor would not fit the distributor shaft, but fortunately the original boat rotor (AL-159) is still available from a number of sources. Unfortunately, while it fits the distributor shaft, the arm is too long and strikes the cap's internal brass terminals. Tim had to shorten the brass tip of the rotor by 1/4", and also the much thicker & wider phenolic support under the rotor tip had to be ground back 1/4" also. When installed on his port engine it fired right up, and at the time of this writing has about 10 hours of trouble free running in Florida's sunny & humid conditions. Tim contacted me with this story and asked if we should post this information on the club's forum. I asked him to send me what he had so I could evaluate from a members standpoint who did not have the shop facilities Tim & I have, and thus might have a hard time executing the necessary modifications. I had seen prior pictures, but when Tim shipped me the real McCoy, I realized it was a rough prototype that would be hard to duplicate for some of our members with these affected "F" engines. How could I simplify and make this cap conversion easier to execute?? Just about this time I noticed something very interesting on our forum. Texas member Chris Hebert was having a whole bunch of engine troubles with one of the 327F engines in his boat and had published a picture showing the distributor. Holy Bat Guano!! This distributor does not have the original flat cap. It has a nice looking stack cap instead. I contacted Chris for some pictures with more detail, which he provided. Now I noticed the clips on the distributor appeared to be somewhat shorter than normal. The distributor cap clips on the Prestolite 4115 distributors are about 2" long and almost impossible to change without major surgery. Chris's clips appeared noticeably shorter. After some back & forth with Chris on where this distributor & cap came from (PO had purchased distributor with cap on ebay) we came to the conclusion that Prestolite made this basic marine distributor for a number of manufacturers, as indeed further research confirmed. Chris then came up with a stack cap number and rotor number for a cap that looked like it would fit on the 327F Prestolite. These were Sierra for the cap, Sierra for the rotor. I found that Amazon was one source for this cap & rotor which came in a tune up kit. With bated breath I ordered two of the tune up kits. Two days later after I opened the box I found the cap & rotor did indeed fit the 327F distributor, but the hold down clips were way too long and looked very difficult to change, even if one did find some shorter clips. Time for some shop time to see if I could come up with some spacers that the longer clips could grab on to and exert downward pressure. A couple of hours later I had a rough prototype fashioned with just a vise, hacksaw, & file. It looked like it would work, so next I actually drew it up with dimensions & angles and everything else

2 needed for a machine shop to produce. I do have a pretty well-equipped shop, so I machined 4 spacers that met the B/P specifications and glued them to a couple of the Sierra caps I had purchased. I had also added a notch in the spacer for a cable tie for extra insurance if the glue joint failed. The first glue joint was with a 2 part epoxy Gorilla Glue product. This one went to Tim and now has 5 operating hours on and is doing fine. The second one I did was for the friend who loaned me the 4115 distributor for this project, Dave DiSesa. On this one I used JB Weld, another 2 part epoxy. This one was a high heat, automotive/marine product and I think it will hold just fine. As a bit of humor, yesterday I came across a small tube of 5200 Sealant / Adhesive in my shop. I was thinking about all of the club members who have bemoaned trying to disassemble something that had been bedded down with this stuff :-) Might be just the thing for this project! The following pictures tell the story. DC & DC1, DC2, & DC2A show where Tim started and the final product on one of his engines. The cap filing required for this type of cap modification is not bad, but the tough part is the required shortening of both the rotor bronze finger and the phenolic rotor body itself. DC

3 DC1 DC2

4 DC 2A

5 DC3 is the picture of Chris Hebert's engine which got me thinking there was a stack cap out there that might be a better way to solve the OEM cap unavailability. DC3

6 DC4, DC5, & DC6 show my first hand made rough prototype. Although hard to see, there is a different angle on each end of the spacer, along with very narrow flat ledges. DC4 DC5

7 DC6

8 DC7 through DC11 show the adhesive installation of two machined spacers I had made. These are much more precise than the first hacksaw & file prototype At this point I had already added a slot for a cable tie to retain the spacer in the remote event the adhesive joint failed for any reason. DC7

9 DC8 DC9

10 DC 10 The hose clamp shown in DC10 is merely to put a small amount of clamping pressure on the adhesive joint while the adhesive dries & cures.

11 DC11 is the finished, modified cap. DC11

12 DC12 shows the finished product on the distributor itself. DC12 For members interested in this project, you must purchase a cap & rotor for each engine. I recommend a Google search for the cap to find the various online sources. I purchased the cap shown in these instructions from Wholesale Marine. There are many other sources available, but the prices vary substantially. The Sierra numbers also cross reference to Echlin AL 168 for the cap and AL 125 for the rotor. You may also be able to find these numbers at automotive stores such as NAPA, but again, prices vary wildly! My industry mole told me all the caps on the market come from Sierra, but some retailers rebrand them and use their numbering. A little keyboard research can save you a lot of money on these purchases.

13 DC13 shows our current stock of 40 pieces which were made at a real machine shop. DC 13 Modification Kit $15.00 for US Orders Modification Kit $25.00 for International Orders Includes 2 spacers, a cable tie, installation instructions, and S & H Modification kit does not include cap & rotor. These must be acquired separately by purchaser. Each kit modifies one distributor.