I Must be Nuts to Undertake This!

Ok so here we go. Rusty’s old motor was pulled. Fairly easy to do now that I’ve done it a few times. Drain fluids, disconnect fuel and oil lines, remove radiator, unplug emissions (injector) harness at the ECU and pull it through, remove intake filter, AFM, and hose, unplug engine (ignition) harness, unbolt the engine from the tranny and motor mounts and out it comes. Simple.

After 122,000 miles the poor S4 motor expires and is extricated form the car.


First up was getting the injectors cleaned and serviced. These I pulled off the S5 eBay motor. Due to a compatibility issue with the plug shape from the 460cc red S4 (‘88) injectors and the emissions harness I had to use the 460cc red S5 (‘91) injectors. I decided to give WitchHunter a shot. There were getting good reviews and were cheap - $60 for cleaning, servicing, and flow testing for all 4 injectors including the return shipping. This included new pintle caps, new “O” rings, new insulators, and new screens and all injectors were flow matched. I shipped them on a Monday and had them back the following Saturday (and this was East coast to West coast!). They looked great. Money well spent.

Before (nasty, rusty, crusty, YECH!) and after (cleaned and serviced) fuel injectors.

The new injectors installed. Note the one piece primary rail and fuel pulsation dampener. Also the rails from the S5 are now stamped steel versus the machined aluminum from the S4.


After removing the S5 manifolds from the eBay motor they were in dire need of a good cleaning. A friend ran through their shop steam cleaner and they looked better afterwards. I also hosed down the inside of the intake runners liberally with carb and choke cleaner. All the old gasket material was scraped off the three parts of the intake manifold assembly and I began the task of capping and plugging holes. First up was installing the ACV block off plate - 3 10mm bolts - done. Next was the 5/6 port sleeves. Actuators were removed and the studs taken out of the manifold. I pulled the sleeves out of the lower intake manifold (LIM). NASTY!. The sleeve actuator shafts in the LIM were jammed in place. The 5/6 ports were not working on this car for sure. So jammed that when trying to twist them out one snapped off! Out came the punch and they were hammered out. Similar the shaft sleeves were hammered out of the LIM also. I then dropped a bolt into each of the two holes and sealed them in place with some JB weld. Done. The VDI actuator was removed and the VDI sleeve was wire tied in the open position. Done.

The sleeve actuator bushings hammered out of the manifold [left]
one of the plugged actuator holes (left arrow) and ACV blockoff plate installed (right arrow)[right]


I had planned on simplifying the vacuum system on Rusty but never got to it. Now with the S5 top end all in pieces and the vacuum spider out lets break out the dremel and start cutting. Items that can go - 2 solenoids controlling the ACV (Secondary Air Injection System), 6PI solenoid (6 Port Induction) controlling the 5/6 port actuators, and the control solenoid working the VDI. The only remaining solenoid should be the pressure regulator control (PRC) solenoid to assist with hot starts, and even that is debatable if it’s needed or not. With the 4 extra control soleniods removed it was just a matter of chasing all the hard lines and removing any lines that weren’t needed anymore. Any questionable lines were saved and capped and any unused vacuum sources from the manifold were also capped. The PCV valve and fuel purge solenoid and lines were left in place. And while I was at it I replaced all the fuel lines with new hose and did the same for the remaining vacuum lines.

The targeted areas (red arrows) solenoid rack, oil injector spider, and ACV spider [left] Picture from grungy eBay motor - NOT the new motor.
Plugged oil injector holes (red arrows), three of the remaining vacuum lines or fuel atomization, fuel pressure regulator, and PCV (yellow arrows)[right]


My desire was to maintain a functional oil metering system, but alas it was not to be. I found this out the hard way. In the beginning I had a set of OMP lines from the eBay S5 block. A set of broken lines - one line was missing and entire section. So I would either have to replace the line or...make my own. Discovered on the RX7lcub forum was an excellent posting on how to make you own lines. I can take NO credit for this information. But it is good information. All the materials to rebuild the lines can be sourced from MSC Direct. I ordered:

1) Tubing: MSC # 48701031 available in 10' lengths. 1/8 x 3/16 (CTL) Teflon PFA - Industrial. Translucent. 1/8" I.D., 3/16" O.D.
$1.51 per foot x 10' = $15.10

PFA Characteristics
• Excellent abrasion & temperature-resistance
• Low coefficient of friction for ease of flow• UV & Gamma radiation stable, chemically inert
• Thermally superior to most plastics
• Outstanding chemical & electrical properties
• Durometer=shore D 55±5
• Temperature range: -320°F to +500°F

2) Clamps: MSC # 48547962. Two-Ear Clamps
Type: 2-Ear, Nominal Size: 1/4, Inner Width of Ear: 0.118 In., Thickness: 0.0276 In., Width: 0.236 In., Material: Stainless Steel
$.33 ea. x 12 = $4.00

The original OMP lines one of which was broken one the car before removal [left]
materials for the new lines and the removed and cleaned banjo bolts from the old lines [right]

So with these materials in hand I did as the originator indicated: RX7Club Link [note: link may not last] and made some new lines. I wire-wheeled all the old banjo bolts and fittings and did the same for the oil injectors themselves. All were cleaned with carb cleaner to degum the insides and they look almost as good as new. Happy with my new lines and fresh hardware I installed the newly refurbished OMP system, pump included. Routing the lines without kinking them was a little tricky as I made them a tad too long but they fit fine. I had originally left the vacuum line nipples that feed the oil injector nozzles in place during my vacuum spider simplification. With this taken care of I moved onto the water pump and water pump housing issue.

The new OMP lines and cleaned and refitted original banjo fittings

Routed new OMP lines.


The red arrows indicate the fundametal differences between what are seemingly interchangeable parts - NOT!

There is a marked difference in the way the cooling system, namely the radiators, are setup between S4 and S5 cars. In Rusty I have a nice Fluidyne aluminum race radiator....for an S4. See, on an S4 water pump housing the discharge nozzle feeds to a 2 bolt thermostat housing. The thermostat having a gasketed flange. And the t’stat housing having a “radiator” cap at the highest point. The S5 thermostat housing has no radiator cap, as it has been moved to the radiator, and the t’stat housing is a 3 bolt flange with rubber ‘O” ring instead of a gasket. Given my S4 radiator does not have the S5 style radiator cap arrangement I needed to maintain my S4 water pump housing and t’stat housing. No problem...should bolt right up...and it did. (Be sure to use the shims on the one water pump housing bolt between housing and block -lest you crack the water pump housing! - the shim is to compensate for the thickness of the gasket on the other parts of the housing to block interface) This was also good as my S4 t’stat housing is aluminum and had the fitting for my water temp gauge, the S5 neck is some kind of crap plastic. BUT, two problems arose. The first being the S4 and S5 water pumps are also different meaning I couldn’t use the brand new pump that came with the reman motor...damn. All but one of the bolt holes lines up. I’d have to reuse my old pump. The second problem, and this one really pissed me off, the angle of the lower radiator return fitting on the water pump housing was different. The S5 is angled up about ˝ inch to clear the electrical OMP (The S4 has a smaller mechanical OMP). This meant my S4 housing would not work with the S5 electrical OMP. The answer, ditch the OMP system altogether and run straight premix fuel like all the other racers. And all that work refurbishing the OMP lines was for nought. So the OMP was removed and a block of plate I fabbed up bolted in it’s place, the OMP lines and injectors were removed and bolts installed in place of the oil injectors (see pic above). It certainly is cleaner looking, the only issue being the OMP has to remain connected to the electrical harness or else the ECU throws the car into “limp mode.”

Interference of pump housing to OMP. The solution - REMOVE THE OMP and BLOCK IT OFF!

SO with all the above done, the upgrades and improvements are complete and all was assembled together. Now gaskets were used everywhere, new vacuum lines installed, extra vacuum nipples capped, and fuel lines connected. With the long block essentailly complete the assembly was dropped into the car ready for wiring. ULP!

The completed S5 shortblock and it's new home. (Alternator missing)

That's enough for now. Tomorrow on "As the Rotor Turns" - OIL!.

Chapter I: To Begin the Hooptie to Hotrod Saga: Part 1 of the First 16 Installments
Chapter II: The Saga Continues beginning with Part 17 through 21, A Good Rear End: Part 17
Chapter III: Picking up the Pieces. Part 23 (clutch, adjustable proportioning valve + more)
Chapter III: Shift Mad Quick, Yo! Part 24
Chapter III: Getting a License - Racing School No. 2, Part 25
Chapter III: The S5 Decision, Part 26
Chapter III: Oil System Upgrades, Part 28
Chapter III: More Suspension Improvements? Part 29



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This page last updated June 10, 2006

Disclaimer: All images contained on this page are the sole property of C. Regan.