Twin Plug Engine Tin

Fast Corners · 03-05-2008, 12:39 PM

I know that people have to have dealt with this issue. I searched the BBS but couldn't find any hits.

I have twin plugged my 2.4 Ltr MFI engine and I'm in the final phases of assembling the motor. I fit the left rear engine tin (901 106 081 03) over the left cam shaft and bolted it in place. I then noticed that the tin does not leave enough room for the #3 exhaust side spark plug connector to get past it. Basically I'm left with a 1/2 moon shaped area (due to the partial hole machined in the lower valve cover)

Unless someone has a better Idea, I'm going to get a wooden dowel and a mallet and coax the sheet metal into a conical shape that will accept the spark plug connector. Other than that I suppose that I could cut a new piece of sheet steel shape it and then have it welded in place. This is probably my best bet since the sealing of the connector boot would be better. I just wish I had thought about this before I had the tins freshly powder-coated.

If anyone has tackled this and has pictures or suggestions, they would be appreciated.

FC

RLJ · RLJ's Garage

This is one way of doing it. The plug wires will need to be assembled on one end or the other "after" the wire is pushed through the rubber gromet. This way the wire is not rubbing against the motor or sharp tin edges.

Randy Jones
1971 911 "Iris"

Fast Corners · 03-05-2008, 01:37 PM

Randy,

Thanks for the quick reply. That looks like a nice clean installatioin. I'm not planning on running the front or side tins. The one in question is part of the air deflection tin on the back left side of the motor.

FC

RLJ · RLJ's Garage

Here is another picture from the bottom. This is on the driver side (left) and shows the back of the engine. All six of the holes are in the side sheet metal.

I'm not an expert on this matter but some where in my memory bank I believe I was told to use all of the engine sheet metal, it will help with cooling ande keep out exhaust heat.

Good luck,
~Randy Jones
1971 911 "Iris"

len911 · 03-05-2008, 04:31 PM

I have mine going between the sheetmetal and the rubber seal... Lou

eapcpa · 03-05-2008, 07:33 PM

I had the same issue some time back. Here is how Henry dealt with it.MFI twin plug tin mods Cyl #3
I ended up bending a piece of sheetmetal into a cone shape and cutting the left rear tin and welding the cone shaped piece in. I also had to notch the MFI belt cover to clear the newly formed tin. I too discoverd this after powdercoating. Don't have pics of mine finished but might be able to post some tomorrow evening.

schnellmann · 03-05-2008, 07:48 PM

I simply got a 1 1/8" hole saw and cut one hole on each side of the tins. Then I went to the hardware store and purchased 2 rubber grommets of the same size and popped them in the holes.

Then I fed each of the 3 (assembled) lower plug wires through the new holes one at a time. By the time the 3rd wire end is through, the hole is basically full of the grommet and wires.

Ta da...

Easy and looks neat/clean too. Sorry, no pics handy.

Fast Corners · 03-06-2008, 06:44 AM

Ed,

Thanks for the link. That is what I'm talking about. I think that I'm going to go your rout too. I figure that I can get a thin wall tube (possibly wiring conduit) and cutting it to the required cone shape. This may save some time with the forming process of a flat piece of sheet metal. If not that will be my second step. I figure that I will weld that piece on and have it re-powder-coated. Should only be about $25 bucks or so to have that done...lesson learned.

I know that porsche always used the full engine tin (er fiberglass) on their motors. I would bet that it does help cooling. I may add the rest at a later date. Just want to get the car back out on the track soon. After that, there is always time for improvement & tweaks.

Thanks to all for the help and suggestions.