2nd gen RX-7 / Chevy V-8...

The purpose of these instructions is not so much to insult anyones’ mechanical abilities, but more to lay down the necessary tasks in an orderly fashion, to hopefully minimize the time and effort required to pull off a successful conversion.
Often times projects such as this are undertaken without a full understanding of what is involved. Hopefully, this summary of the steps necessary will provide individuals with the insight necessary to evaluate their own abilities, and help them come up with accurate estimates for both time and cost .

Many, if not most of the steps described here, are the same regardless of the engine choice. Injected engines such as the LT1 / LS1 will differ mostly with regards to electrical connections and fuel system plumbing. The main mechanical components and basic proceedures are generally the same.

Additions and corrections to this page are encouraged, and will hopefully result in an evolutionary process that will eventually include EVERY detail required, right down to the wrench type, sizes, torque specifications and parts required to carry out each individual step.

Please send your suggestions to grannys@sos.net

...Realistic Expectations...

Effects On Maintenence & Reliability...
...If you already own a 2nd gen RX-7, then you already know about the rotary’s maintenance requirements, have probably heard stories about dealer service departments that lack proper training on rotary engines, and chances are, your beautiful RX-7 is probably on it’s 2nd or 3rd engine by now. These cars have not been sold in the US for over 8 years now, and replacement parts are getting scarce.
The Chevy engine, on the other hand, is perhaps the most common engine on the planet. Most any person with automotive experience has worked on one, and a well factory trained network of technicians exist from coast to coast. The modern Chevy engine routinely goes 100k between tune-ups, and replacement parts are among the cheapest and most common.

Effects On Performance...
...As you might suspect, the switch to a V-8 powerplant has an effect on performance too. The additional low-end torque makes the RX-7 very easy to drive, and is available throughout the RPM range. No longer will you have to excessively slip the clutch at a stop light to keep from killing the engine. No longer do you have to downshift, wait for your RPMs to come up (or boost to build) to pass a car. No longer will you live in constant fear of the dreaded carbon lock. With the V-8, your power is always available.
If and when it comes time for an upgrade, things can really get interesting. Simple $100. modifications can result in 15-20hp increases, while spending a mere $4-5000. can get you up to around 500hp level. We are seeing low to mid 13 second 1/4mi times from mild smog legal engines with around 300-325hp, which is better than the high 13 second times that were possible with the 3rd gen RX-7’s stock twin turbo rotary engine.

Effects On Weight, Balance, and Handling...
...This is where you probably expected there to be a downside. People have probably told you that your handling and perfect weight distribution will be ruined with the addition of that big, heavy, american V-8. Just ask yourself if any of those so-called experts you have been talking to have any actual experience with piston-powered RX-7s. We’ve got the numbers to prove all those bystanders and spectators are just that....bystanders and spectators.
Here are some real numbers from a typical 2nd gen RX-7 converted to Chevy power:
The example car is an ‘86, which was not lightened in any way. The car was converted using a ZZ-4 crate engine & T-5 transmission. It has a full stock interior, as well as the stock air conditioning and power steering. The stock RX-7 cooling system was re-located but retained, as was the stock RX-7’s engine oil cooler. The battery was relocated to rear area just in front of the tail lites. With a full tank of fuel, the balance is close to 50/50, 1535 lbs front / 1545 lbs rear, for a total of 3080 lbs (including the 200lb driver). Subtract the weight of the 200lb driver, and the total weight is 2880, 235lbs heavier than the RX-7's 2645 stock weight, and only slightly less than the later Turbo II's stock weight of 3003lbs.

Skills Required...
...If you have a good grasp of things mechanical, do all your own automotive maintenance, have a good selection of tools and know how to use them, you are probably qualified to perform this swap.

Estimating Time For Completion...
...We do not include the pre-conversion preparations in our estimates, as these are things that can be scheduled and carried out by the owner as time & budget permit.
...We have broken the conversion process down into smaller steps below (under “the actual conversion”). This allows the person actually doing the conversion to estimate the time he should allow depending on his abilities and resources.

Considerations...

Selling Your Stock Engine/Turbos/Trans...
...If your engine/turbos/transmission are in running condition, the best time to secure a buyer is while they are still in use, where the running condition can be easily verified by the prospective buyer. This way, there is no question about the compression, boost pattern, seal condition, etc. There are many more RX-7’s than there are available running engines, so a good engine can demand a premium price. This can go a long way to help defray the cost of your V-8 conversion.

Tools Required...

...Both Metric & inch sized hand tools
...Floor Jack
...Engine Hoist
...A minimum of (4) Jack Stands
...Drain Buckets & Floor Dry
...Coolant storage Buckets
...Penetrating Oil
...Tags (for labeling parts & wires)
...12v Test Lite / Volt-Ohm Meter
...Fender Covers
...Drop Light
...RX-7 Shop Manual
...Small Storage Boxes (for bolts & small parts)
...Wiring Terminal End Assortment & Crimping Pliers
...Wire (misc colors for extending harnesses)
...Wire (for temporary support of misc. components)

Parts Included In Our Deluxe Kit w/ AC & Power Steering...

...V-8 Basic Kit instructions
...Engine Cradle & installation hardware
...Transmission crossmember
...Engine & transmission rubber mounts
...Modified Oil Pan
...Custom aluminum radiator and bolt-in bracket set
...Aluminum wa

...Additional Parts Recommended...

Complete engine including...
......Starter
Complete transmission assy. including ....
......Clutch disc / pressure plate / throwout bearing
......Bellhousing / flywheel / output yoke
......Shifter / knob
(2) Motor mounts
(1) Transmission mount
Temp sender adapter bushing
Alternator relocation kit
PS pump bracket
Speedometer interface
Tachometer interface
Cooling fan thermostat & relay
S-10 clutch master / slave set w/ plumbing
Block Hugger type header set (optional)
Transmission output shaft yoke
Front U-joint
Front tube weld yoke
Optima style dry cell battery
Battery box/hold down
Battery cable & ends
Upper radiator hose & clamps
Lower radiator hose & clamps
Heater hose & clamps
Heater hose restrictor fitting
Oil cooler adapter, hoses, & fittings
Drop base air cleaner
Throttle cable
Engine Oil & Tune-Up Supplies
Transmission Gear Oil
Brake Fluid (for clutch hyd. system)

...Recommended Work Area...

...The bare minimum should include a level, dry cement or asphalt surface to provide firm and safe support for your jack stands, as well as to ease the rolling around of the engine hoist and floor jack.

...Engine Preparations...

...To minimize the down-time required to complete the conversion, the new engine should be prepped & detailed in advance.

Removing Un-needed Parts & Accessories...
...Remove the alternator and stock motor mounts. After you’re done, now would be a good time to pressure wash the engine, before it gets “too” exposed.
...Remove the stock exhaust manifolds. Use a 6 point socket, and be careful not to break any bolts.
...Remove the distributor & intake manifold.
...Remove the oil pan.

Preventive Maintenance...
...If there is any PM to be done on your new engine, now is the time to do it. Replace any leaking seals or gaskets. If you want to install a new timing chain, oil pump, etc, it will never be easier than now.

Modifing, Checking, & Re-installing The Oil Pan...

Installing The Oil Cooler Adapter...

...Transmission Preparations...

Prevenitive Maintenence...

Joining The Engine / Transmission...

...Pre-conversion Last Minute Preparations...

Draining / Evacuating Your AC System...
...While your RX-7 is still mobile is the best time to have your AC system properly evacuated by a professional. Not only is it illegal to release your refrigerant into the atmosphere, it is also bad to expose the inside of your AC components to the outside moisture laden air. A pro will be able to evacuate and seal your system, and at the same time he can recover and save your rare and valuable R-12 for re-use later.

Pressure Washing The Engine Compartment...
...On your way back from the AC shop, it’s a good idea to stop by the car wash and give the underhood area a good, thorough pressure washing. You would be surprised at how much easier and more enjoyable the job will be when you can actually see what you’re working on.


...Finally, The Actual Conversion...

Jacking & Supporting Your RX-7...
...Be very careful when jacking up and supporting your RX-7. The Mazda engineers went to great lengths to build these cars as lightweight as practically possible, and that meant using much thinner metals than you may be accustomed to. The sheetmetal “frame rails” under these cars are made from around 18 ga. sheetmetal, about as thick as your average oil pan. A bend or kink can significantly weaken their stiffness. As they are easily damaged and repair is difficult, it is much better to avoid damage in the first place.

Fender Covers...
...Now is a good time to get these out, before you do any damage. Thick blankets can also be used, and will prevent any paint damage should a wrench or socket be dropped on the fenders or nose area.

What To Squirt W/ Penetrating Oil...
...First thing after the car is safely in the air & properly supported, be sure to hit all the bolts/nuts in the following :
...Exhaust manifold studs/nuts
...All other exhaust bolts/nuts
...Engine subframe bolts/nuts
...Upper front strut tower bearing plate nuts
...Lower control arm inner pivot bolts/nuts
...Steering rack to subframe bolts/nuts
...Rear driveline to pinion flange bolts/nuts
...A little squirt now can save a lot of busted knuckles and cussing later.

Disconnecting The Battery...
...12mm wrench
...It’s best to do this step now, before you melt any wrenches or damage any electrical components. You might as well remove it now too.

Draining Your Cooling System...
...Be sure to drain both the radiator and engine. Catch the coolant in drain pans, not only to save it or dispose of it properly, but to keep the work area neat & clean. Antifreeze does not evaporate very fast, and can hang around for several days if not cleaned up. This can expose both your and the neighborhood’s kids & pets to a toxic substance.

Removing Your Hood...
...Blankets or protective pads
...12mm socket & ratchet
...Marking paint or scribe
...Place blankets or pads on the cowl area of the body and fenders. This will protect your body and paint from accidental contact from the hood as it is being un-bolted and removed.
...Scribe or paint alignment marks around the heads of the hood bolts before removal, as this helps make proper re-installation and alignment much easier.
...Disconnect any wiring harness or hoses that will interfere with the hood removal.
...Have an assistant support the weight of the hood as you remove the bolts. Be very careful to avoid damage to the hood or body if the hood suddenly comes loose as the bolts are removed.
...Remove the hood, being careful to place it in a safe place, and protect the areas that contact the ground from paint chips or other damage. Be sure to thread the bolts back into their holes in the hood, so these special bolts won’t get mis-placed.

Shifter & Boot Removal...
...Phillips & regular screwdrivers
...10mm socket , ratchet, & 6”extension
...Clean rag
...While you are still nice and clean, now is a good time to get things ready inside. Remove any screws in the plastic trim around the boot, then carefully pry the plastic cover off to reveal the inner rubber boot and attaching screws. After the screws are removed and the rubber boot carefully pried loose and pulled up, the (4) shifter retaining plate screws can be removed with the 10mm socket, ratchet, and extension. Have a rag handy as the shifter pulls free, so that the oily bottom of the shifter’s inner workings can be wrapped to prevent dripping oil on your nice clean carpets & interior.

Remove The Seats...

Disconnect The Throttle Cable...
...The throttle cable should be dis-connected from the throttle pedal, so thet the cable will be free to removed from the engine compartment side of the firewall.

Disconnect The Clutch Master Cylinder...
...Needle Nose Pliers
...Again, while you are inside the car and relatively clean, it’s a good time to go up under the dash to dis-connect the clutch master cylinder’s pushrod clevise from the brake pedal. Simple removal of the pin is all that’s required.

Tagging The Electrical System...
...Tags (or masking tape) & a Marking Pen
...The connectors of primary importance are the following:
...Starter

...Alternator

...Water Temp Sender

...Oil Pressure Sender

...Oil Level Sensor

...AC Compressor Clutch

...Coolant Level Sensor

...Cooling Fans

Misc Underbody & Exhaust Removal...
...12mm socket
...10mm socket
...First thing to remove is the (3) aluminum crossbraces (12mm socket) attached across the bottom of the transmission tunnel, and the shields (10mm socket) attached to them.
...Disconnect the harness to the oxygen sensor, as well as the ground strap to the catalytic converter.
...Disconnect the harness connectors attached to the transmisson for the reverse lights & gear position sensors. Automatic equipped cars will also have cooling lines, as well as undercar shift linkage to remove.
...All the exhaust system can be removed between the Turbos and the rear axle. The bolts/nuts are often very difficult to remove, so be sure to use 6 point sockets and wrenches to reduce the possibility of rounding off the hex. The penetrating oil applied earlier will greatly reduce the risk, but a little extra caution should still be exercised.
...After all the bolts are removed, the pipes can be pulled from their rubber hangers. A little twisting and tugging is all it takes to pull the rubber over the expanded head of it’s mounting stud.

Prepping The Engine/Trans For Removal...
...Before the driveline is removed, be sure to drain the oil from the engine & transmission. This will prevent a big mess later when the engine/trans are pulled as a unit.
...Remove the driveline.
...Remove the underbody cover from under the radiator/oil cooler.
...Remove the engine’s oil cooler lines.
...Remove the lower radiator hose.
...Remove the nuts & washers from the engine mounts at the subframe.

Removing The Power Plant Frame (PPF)...
...Support the rear of the transmission with a floor jack.
...There are (4) vertical studs & nuts (22mm socket / 6”extension) that attach the PPF to the transmission, and (4) vertical studs & nuts (22mm socket / 6” extension) as well as (1) horizontal bolt (22mm socket) attaching the PPF to the rear differential housing. Before removing any of these bolts altogether, they should all be “broken loose” first, as they are very tight.
...Remove the (4) bolts that attach the PPF to the transmission. When the last bolt is removed, the front of the PPF can be lowered to relieve the weight of the nose of the differential.
...Remove the horizontal bolt from the lower right side of the PPF’s rear attachment points.
...Now the rear (4) vertical nuts can be removed. The PPF can now be lowered and removed.
...Of the (4) vertical studs that held the PPF to the rear differential, loosen the front upper pressed-in stud, using moderate blows from a hammer to the smaller pilot portion of the threaded end. Remove and save the stud for later use. The rear upper stud can be left in place. The (2) lower studs are threaded into the bottom of the differential housing. Thread (2) of the nuts onto one of the studs, with the large flat areas of the nuts facing each other. Tighten the nuts against each other using (2) 22mm wrenches, with enough force so that the studs can be removed from the differential housing by using a wrench on the upper nut, and turning the stud out. Repeat for removal of the other lower stud.

Removing The Engine/Trans...
...Follow the proceedures set forth in the RX-7’s shop manual.

What To Save Off Of The Engine/Trans...
...You will want to remove the following for re-use later:
...Temp sender
...Oil pressure sender
...PS pump (dis-connect the hoses at the steering rack)

Removing Un-needed Underhood Wiring & Misc...
...The entire ECU and ECU/engine harness can be removed. Be sure not to disturb the wiring for the wipers, cruise control, and ABS systems.

Steering Rack Preparations...
...Remove the shield over the steering column u-joint.
...Remove the bolts that secure the intermediate steering shaft between the column and rack.
...Remove the (4) bolts (14mm socket w/6” extension) that attach the steering rack to the engine subframe. The rack can now be pulled loose, moved forward, and temporarily supported out of the way by hanging it with wire.

Removing The Stock Rotary Engine Subframe...
...Remove the front wheels & tires.
...Support the lower control arm at it’s inner end with a floor jack.
...Remove the lower control arm’s inner pivot bolts, both front and rear.
...Lower the control arm from the subframe.
...Support the lower control arm with blocks.
...Repeat for the other side.
...Support the subframe with a floor jack.
...Remove the (6) nuts & bolts attaching the subframe to the RX-7’s chassis.
...Carefully lower, remove the subframe. It will not be re-used.

Pre-Assembly Cleaning / Detailing Of The Engine Compartment...
...Now’s the time to clean all those areas you couldn’t get to with the pressure washer earlier. Most any cleaner/de-greaser can be used. We use a product like Simple Green, applied by spraying, followed up with scrubbing with a nylon bristle brush, wiped off with rags. This won’t take long if you did a good job with the pressure washer earlier.


...V-8 Subframe Installation...

Install the new subframe, re-using the origional bolts. Be sure to torque all (6) bolts & nuts to origional specifications.

Installing The Steering Rack...
...Temporarily place the rack in position, while carefully aligning & inserting the steering column’s intermediate shaft into the rack’s input shaft/u-joint.
...When the intermediate shaft is in place, install the rack onto the new subframe, using the origional bolts (14mm socket w/6”extension), torquing them to origional specifications.

Re-Assembling The Front Suspension...
...Reverse of dis-assembly.


...Engine / Transmission Installation...

Pre-Installation Cleaning / Detailing...
...This is probably your last chance to easily detail those places remote and inaccessible, so take a quick look around before it’s too late.

Rigging Engine/Trans For Installation...
...For installation, the engine/trans should be rigged so that they naturally hang level, or slightly tail down.

Dropping the Engine / Transmission into Position...
...Because of the engine’s close proximity to the firewall, it is easier to install the rubber engine mounts after the engine is in position over the new subframe.
...Carefully lower the engine/trans into the engine bay.
...Slip the rubber engine mount pads into place. Install and tighten the (3) bolts attaching each mount to the engine first, then line up and install the long bolts and nuts that pin the mount to the new subframe.
...After the engine/trans are in their approximate position, support the transmission, with a floor jack or jackstand, with the output shaft centerline about 6-1/4” below the top of the transmission tunnel.
...Remove the engine hoist and chains.


...Torque Arm, Anchor & Transmission Crossmember Installation...

Torque Arm Anchor Bracket Installation...
...The anchor bracket bolts onto the side of the T-56, on the left side just below the shifter.

...Torque Arm Installation...

Installing Torque Arm / Differential Adapter Brackets...
...The torque arm differential adapter brackets bolt onto the existing differential studs (formerly used to attach the PPF), using the origional RX-7 hardware. The lower bracket can be identified by it’s use of (2) vertical bolt holes, and an additional horizontal bolt hole, for a total of (3) attaching holes. The upper bracket has only the (2) vertical bolts.

Installing / Pre-Adjusting The Torque Arm...
...The rod ends in the rear of the torque arm come installed and pre-adjusted for proper pinion angle.
...The rod end on the front of the torque arm should be adjusted at the time of installation, to a length that allows easy assembly of the eye bolt into the torque arm anchor bracket attached to the left side of the transmission.

Transmission Crossmember Installation...
...Remove the plastic shield that covers the fuel lines on the left side/bottom of the floor pan, where they pass by the rear of the transmission.
...Install and loosely bolt the rubber transmission mount pad onto the transmission.
...The new transmission crossmember is properly located for installation by attaching it to the holes in the transmission tunnel formerly used for the forward aluminum crossbrace. Loosely install the (4) bolts in the existing holes in the floor pan.
...Loosely bolt the crossmember onto the rubber trans mount pad.
...Tighten all the installed trans mount and crossmember bolts.
...Using a 7/16” drill bit, drill holes in the floor pan thru the (6) holes in the ends of the trans crossmember (3 holes on each end).
...Install the supplied bolt plates from the top side of the floor pan, thru the new drilled holes.
...From the bottom side of the floor pan, bolt the trans crossmember onto the bolt plate studs, using the washers and nuts supplied. Tighten the bolts.
...Remove the floor jack (or jack stand) from under the transmission. The engine/trans should now be resting on it’s own mounts, and supported by the chassis.

...Checking Drivetrain Alignment...

...The properly installed Chevy engine is centered in the car. The RX-7’s rear differential’s pinion flange is offset 3/4” to the right or center. This is normal. The engine/trans and the rear diff’s pinion centerline should be parallel, but NOT concentric. If the centerlines were concentric (exactly lined up with each other), the u-joints would fail prematurely as they need at least slight internal movement to lube properly.

...Connecting The Reverse Lite Switch...

...Driveline Modification...

Determining Proper Length...
...The transmission’s output shaft yoke should be fully into the installed transmission’s tailhousing, the pulled back out approximatly 3/4”. A measurement is then taken from the flat surface of the pinion flange on the rear differential, to the center of the u-joint bearing bore of the output shaft yoke. This measurement should be around 33-1/4”.

Driveline Modification Choices...
...A local shop should be able to properly modify your RX-7’s driveshaft. $100. seems to be the going rate. If it costs more than $150. for the modification and balancing, I’d look for another shop.

Driveline Installation & Clearances To Check...
...The assembled driveline can be installed. The (4) pinion flange bolts should be torqued to 43 ft/lbs. At least 3/8” of clearance should exist between all parts of the driveline / torque arm / transmission tunnel.

...Exhaust Manifold / Headers / Exhaust Installation...

What Are The Choices?...
Here’s a rundown on what we know to fit...
...Stock LT1 cast iron manifolds.
...”Block Hugger” style header sets (these are typically the same pipe right & left, and exit at the oil pan level in the center of the block).
...Crossover pipe...at present, your exhaust shop will have to fabricate this one. Due to the tight clearances under the car, the left side exhaust will need to be routed under the engine in the space between the oil pan sump and the engine’s subframe. A size for these pipes of 2-1/2” o.d. is recommended. They should be “Y” together on the right side into a single 3-1/2” o.d. exhaust pipe traveling on the right side of the transmission, to a 3-1/2” hi-flo cat converter located under the transmission tunnel below the driveline/torque arm. This routing provides maximum ground clearance, and takes advantage of the RX-7’s existing heat shielding and cat converter overtemp sensors.

...Throttle Cable...

Adapting The Chevy's Cable...

...Clutch Master / Slave Cylinder Installation...

Clutch Master Cylinder...
...We recommend using a clutch master cylinder from a ‘88-’92 full size GM pickup with a 5spd transmission. The bolt patterns are slightly different, but it will easily bolt directly onto the RX-7’s firewall with no cutting or drilling.

Slave Cylinder...
...You can use the stock plastic T-56 slave cylinder, but the inlet fitting will have to be modified by drilling it out and tapping it for 1/8” NPT pipe threads. This in turn allows using commonly available fittings and hoses to plumb the slave to the new clutch master cylinder. An optional route would be to use an S-10 5spd slave cylinder (GM PN# 15616089), which is steel and uses normal flare fittings. Be sure to install the slave with the inlet fitting pointing upward.

Hose Routing & Bleeding...
...Route the hose between the clutch master cylinder and slave without any high spots in the line to trap pockets of air. This will get you a self bleeding clutch, as any air bubbles will be free to travel directly from the slave to the master cylinder un-impeded using only gravity, freeing you from normal under the car clutch bleeding hassles.

...Oil Cooler Plumbing...

Types Of Hoses & Fittings...

Adapter Fittings For Your RX-7's Oil Cooler...

Routing / Supporting The Hoses...

Installing The RX-7's Oil Pressure Gauge Sending Unit...

...Accessory Drive Mounting / Pulleys...

Proper Heater Core Plumbing / Fittings...

Accessory Drive Pulley Choices & Installation...


...Electrical System Modifications...

ECU / PCM Transplant...the RX-7's B1-01 ECU connectors...
...These (4) connectors are located behind the right side kick panel in the passenger compartment. They were formerly arranged in a row along the front side of the RX-7's ECU, which is now removed. The wire locations and color code are shown in the illustrations below. The yellow highlighted wire locations are the ones that we will be either modifing or connecting to the LT1's PCM. The IDs of the highlited wire locations are listed below the illustrations. The non-highlited wires are no longer needed, and we will not be connecting them to anything.