3.3SS rebuild finally underway..........

[fred cook]

Originally Posted by KTL

XDi will take some work with your CIS in terms of spark plug wire routing and the wire lengths.

The DFU (coil board/Direct Fire Unit) platform that Clewett makes is very nice when you've got carbs or throttle bodies, which allows the area between the throttles to be very open. Platform mounts on standoffs that screw into the engine case breather cover studs.

Yep, I'm working on the DFU location "issue" right now. My plan is to put a "shelf" behind the CIS and mount the DFUs lying flat so that the wires plug in towards the ground rather than being mounted vertically. I will have to make certain that I know which wire goes into which socket since the unit on the right side will be completely hidden. I am backdating the heat so at least the old heater motor and hoses won't be in the way on the left side. I thought about stacking the DFUs on the left side, but the length of the plug wires might be an issue. Thanks for the heads up!

[fred cook]

Had to stop and clean up the shop! Just could not take it anymore! Straightened out the work benches a bit, washed and put up tools and mopped the floor. Now, at least, I don't have to worry (as much) about dirt finding it's way into the engine!

[Flat6Heaven]

Looks like a great place to work!

Have you kept count of the hours it's taken you thus far?

Ben.

[fred cook]

Originally Posted by Flat6Heaven

Looks like a great place to work!

Have you kept count of the hours it's taken you thus far?

Ben.

I started this project on May 1st and probably have spent about 80 hours on it over the last 3 weeks. Of course, that does not include the time spent over the last 4-5 years gathering parts like heads, cylinder kit, pistons, etc. Before I pulled the engine I had about 90% of the bits and pieces on hand to do the rebuild. I did not want to get into the middle of the job and find that some part was a long lead time item! Thanks for following along!

[Flat6Heaven]

Thank you for all the details!

Does the new tinware fit the Nickies well?

[fred cook]

Spent some time building a bracket to mount the DFUs (Direct Fire Units). Wound up using two pieces of steel angle, one turned up and one down. I left the back panel solid to prevent the DFUs from coming in contact with the engine compartment sound insulation. I cut out most of the front flange, leaving only 3 tabs for mounting purposes. Pictures.





The right DFU will be completely hidden behind the CIS system, so I will need to know which plug wire goes where before installing the engine. The left DFU should be visible as I am backdating the heat and eliminating the large blower motor that mounts on the left side. Will probably use some clip on plug wire labels to help keep things sorted out.

I also installed a couple more of the Electromotive XDi/Clewett Engineering parts on the engine, the distributor hole plug and the sensor mount. Will check the end cover plate tomorrow to see if any "adjustments are required.

[KTL]

Nice job making a mount. Be sure to get your boards grounded well. They technically ground themselves to the mount but it's always a good idea to put an extra ground strap from the mount to the chassis, in addition to the already-present ground wires on the boards themselves.

[fred cook]

Built a mounting bracket for the ignition control box and installed it (and the box) on the relay panel on the left side of the engine compartment.





The mounting bracket started as a flat piece of 26 gauge sheet metal. I drew the design on graph paper, cut it out and taped it on the metal. Then I used an awl to scratch the design onto the metal and cut it out with shears. Then, I used a couple of blocks of wood and two C clamps to hold the metal while I bent it into shape. Once done, a little work with a file and grindstone and some black paint finished it up. It is built on a slope so that the control dials on the front of the box may be seen more easily. Started in on the wiring, but so far have only plugged in the DFUs to the master plug and finished plugging the DFU wires into the master plug. Will need to get a relay so that I can switch off the power to the DFUs so that the engine will stop running! More later.

[KTL]

Did you get your XDi as a new kit or secondhand? Reason I ask is because I got mine in pieces. Rounded up some parts I needed (additional DFU + DFU harness) to suit my needs for twin plug. However since I got it used, I didn't get any main power relays with the XDi ECU main harness.

Do you know what size relay is needed for each power feed from the battery? Instruction manual doesn't indicate relay capacity.......

Thanks and keep up the good work!

[Oheggem]

I think the xdi unit is really recommended to be mounted out of the engine bay. This is ofcourse a choice but i followed this advice and fitted it inside the cabin under the drivers seat. Don`t want that unit to go bad.

Anyway the rest is looking great.

[Oheggem]

KTL: Check out page 22 / chapter 4.4 in the xdi manual. Think that`s what you`re looking for?

[fred cook]

Originally Posted by Oheggem

I think the xdi unit is really recommended to be mounted out of the engine bay. This is ofcourse a choice but i followed this advice and fitted it inside the cabin under the drivers seat. Don`t want that unit to go bad.

Anyway the rest is looking great.

Don't fault you one bit for your mounting selection! However, with as much air as the engine fan pulls into the engine compartment, I am willing to take a chance on locating the control box there. I considered locating it under a seat, but accessing it to make timing adjustments could be difficult. I considered mounting it vertically behind the passenger seat but finally decided to try to keep everything in one spot. I might have regrets later on, I guess only time will tell!

[fred cook]

KTL,

See if this is what you are looking for! Generally speaking, you can expect a power draw of about 1 amp per 1000 rpm. So, if you spin your engine to 7K, you would need at least 7 amps (per DFU). Hope this helps.

[fred cook]

Originally Posted by KTL

Did you get your XDi as a new kit or secondhand? Reason I ask is because I got mine in pieces. Rounded up some parts I needed (additional DFU + DFU harness) to suit my needs for twin plug. However since I got it used, I didn't get any main power relays with the XDi ECU main harness.

Do you know what size relay is needed for each power feed from the battery? Instruction manual doesn't indicate relay capacity.......

Thanks and keep up the good work!

Kevin,

I bought my set new. However, it did not come with the necessary relays. I will get a couple from my local NAPA dealer. They carry (at least) 1 that is equipped with a diode to prevent a power surge when the power is turned off.

[KTL]

Fred,

I read that page a number of times and, duh, didn't pick up on the fact that it says right there peak current is 10 amps for the power supply. Not to mention the fuse size is 10 amps. DUH....... Thanks for the advice and keep up the good work.


Agreed on the ECU location. Engine bay not ideal but considering the 911 engine bay gets some airflow, not the worst location. Need to have the ECU in a suitable location to make your adjustments while checking with the timing light. Otherwise you keep going back and forth to engine bay and inside car to make adjustments.

Another thing to consider is the older HPV systems with the electronics integrated into each board live in the engine bay quite well. I would venture to guess that the XDi ECU is at least as durable as the old HPV DFU? Total assumption on my part.

[Lapkritis]

Should be fine; if worried you could put some reflective heat shield on it such as the self-adhesive gold stuff used on frames near turbo chargers and down pipes.

[fred cook]

Originally Posted by KTL

Fred,

I read that page a number of times and, duh, didn't pick up on the fact that it says right there peak current is 10 amps for the power supply. Not to mention the fuse size is 10 amps. DUH....... Thanks for the advice and keep up the good work.


Agreed on the ECU location. Engine bay not ideal but considering the 911 engine bay gets some airflow, not the worst location. Need to have the ECU in a suitable location to make your adjustments while checking with the timing light. Otherwise you keep going back and forth to engine bay and inside car to make adjustments.

Another thing to consider is the older HPV systems with the electronics integrated into each board live in the engine bay quite well. I would venture to guess that the XDi ECU is at least as durable as the old HPV DFU? Total assumption on my part.

After re-reading the installation info and thinking about the control box location overnight, I decided to move it into the cabin. Yeah, yeah, I know, I'm a wimp, flip-flopper, etc. Anyway, got it installed in the cabin against the rear of the footwell. I did get to use the base that I made so that was not a waste of time! The wiring runs out the bottom of the control box, thru the bulkhead, follows an original wiring harness up to the right side of the engine compartment and then runs across the engine compartment to the left side. Had to extend a couple of wires, but nothing serious. Still have to mount the two relays and wire them up.

[fred cook]

Installed the two relays that power the XDi system, made up all the connections and added a couple of extra tie wraps here and there. Then, I went back thru the XDi installation book and checked off each item that was completed. Theoretically, all I have left to do is (once the engine is installed) plug in the switched power lead and the lead for the tachometer and connect the crank sensor to the master harness! I've got the DFUs grounded a couple of ways and have the main ground from the control box set up to ground both to the chassis and engine. I even used my V/O meter to check the ground resistance both at the point of ground and across the engine compartment at another ground point. If this sucker doesn't work, it won't be because of a bad ground! I'm at a bit of a halt on the engine as I am waiting on the delivery of a couple of 23mm piston wrist pin circlips. I managed to bend the last one to go in, so I can't button up that side of the engine until I get the clip and get it installed. So, since I am caught up on the wiring job and stalled on the engine, I'm taking the afternoon off to go see a movie! Y'all enjoy your Memorial Day weekend and remember those whose sacrifices have made it possible.

Later,

[fred cook]

Went to see the new Star Trek movie. Very well done, should be well liked by all of the Trekies out there! Great scenes and some very cool stunts!

When I got back to the house, I went out to the shop and took a good look at the CIS system (removed as a unit). After pulling out my books on CIS injection, I believe that I can "simplify" the system somewhat. I'll keep the WUR, AAR and the various electrical bits, but will remove the two AAVs and their associated complex plumbing. What previously filled up the area under the intake runners will now simply be a couple of vacuum hoses. The support bracket for the heater/defrost blower motor will be trimmed up to get rid of un-needed portions and a couple of previously used, but now un-necessary brackets will be removed. The remaining pieces will be transferred onto an early, large port SC airbox with it's large port runners (36mm vs 28mm). This will eliminate a number of potential vacuum leak points as well as making it easier to deal with once on the engine and in the car. More on this later along with some pictures.

[fred cook]

After lunch, I spent some time working on the CIS system that will be going on this engine. First, I spent some time matching the intake runner to the head port size. The head ports are about 3mm larger than the intake runner inside diameter so I used the good ole Dremel tool to bevel the inside edges of the pipes. It is important to have a smooth transition from the intake runner to the head port so that the air flow will stay in a laminar flow. Having an abrupt change in diameter with a "ledge" will cause non laminar flow to develop which interferes with the max amount of air/fuel the engine can be fed.

Original pipe diameter showing how much material needs to be removed.


Pipe with opening beveled to match the cylinder head opening.


The next problem to resolve will be the phenolic spacers. The notch for the fuel injector extends too far and leaves an open space that the intake runner can't cover.

Not sure how I will overcome this, but right now I am considering making my own spacers, probably from aluminum. The phenolic plastic would be easier, but not sure that I can source that material.



Also, I am working on the CIS unit, trying to strip it down to a good fighting weight. So far, I have removed the AAVs and a bunch of vacuum piping. I will keep the WUR, the AAR, the cold start valve, the fuel pump safety switch and the throttle position sensor. It is going to look pretty naked, but I don't see any reason the "lightweight" version won't work. If there are any running issues, I'll find a fix.

Now, on to supper!