• Click Here for a PDF Version of This FAQ page: 81-85 12A Shutter Valve The 81-85 12A RX-7’s have a valve that opens on deceleration (by vacuum and a solenoid and the Throttle Position Sensor)  to lean the mixture out for emissions. They LOVE to go bad ! We have heard of MANY unnecessary carb […]

  • PDF Version of this Post. Easier to read! 81-95 Short Shifter Installation Please – this is an EASY job! We do them in well under 10 minutes (yes, we have done a bunch, but they actually take us less than 5 minutes). It will take you longer than that to read this page, read the instructions, and […]

  • The 6-port non-turbo engines (made from ’84-’92) are a totally different story for porting. The front and rear side housings have the auxiliary ports in them, and the center housing has very small ports. Additionally, there is not a lot of casting thickness behind the upper part of the center port. This means if you […]

  • The antenna mast on 86-92 cars likes to break off, or break internally. Normally, as long as you can hear the antenna motor running when you turn the stereo on and off, all that needs replacing is the mast. The following instructions are for coupes, but the convertibles are basically the same – just somewhat […]

  • This one is a little hard to explain — bottom line is MAZDA changed things and never told anybody + did/does not always supply the correct parts !! — in addition to that, if you purchase a NEW front side housing for your 86-88, it will PROBABLY come with the 89-92 casting style! What you […]

  • These bushings wear out somewhat frequently. Replacement is not hard, and only requires a few tools. Symptoms are simply a very sloppy shift lever. “Top” bushing set — #17-481B-M508 for 79-95 This is the infamous “bottom” set, that contains the bushing Mazda (according to them) swears does not exist. #17-481A-M501 for 84-95 These are the parts from […]

  • Main Bearings For 93-95 Twin Turbo, 3-Rotor, and RX8 Part Number Color Code Bearing Thickness 10-E040-NF01 Yellow 1.980mm = .07795″ 10-E050-NF01 Green 1.983mm = .07807″ 10-E060-NF01 Brown 1.986mm = .07819″ 10-E070-NF01 Black 1.989mm = .07831″ 10-E080-NF01 Blue 1.992mm = .07846″ 10-E220-NF01 Yellow 1.988mm = .07827″ 10-E230-NF01 Green 1.991mm = .07839″ 10-E240-NF01 Brown 1.994mm = .07850″ […]

  • Bridge porting just requires a LOT more grinding than street porting. We do the initial cut for the extra port on the mill, but it can be done with a hand drill. You just need enough to get the rotary files in there and start grinding. These sample images are of a “J Bridge”. As […]

  • Mazda, for some unexplained reason, made changing 86-92 front wheel bearings “impossible” and they only offer the complete front hubs, with new bearings, for an outrageous price. The bearings ARE changeable, although extra work is required, and we DO sell the bearings. Inner bearing is part number B001-33-047 Outer bearing is number 1391-33-075-MV Seal is part number FB01-33-065A […]

  • More images will be added periodically as we have time, and need to do them. This center housing is an 86-88 Turbo that we cut away to check the casting thickness around the port. It shows quite well why there is not much porting that can be done on these housings. The 6-port 84-92 engines have […]

  • If you have an 86-92 non-turbo engine, please refer to our: Porting 6-Port Exhaust (why not to) FAQ    Exhaust Templates are available in our Tools Section. They come with the actual port shape scribed on them. You have to cut/grind the port into the template, following the scribed lines.    These are two examples of […]

  • Be sure to review our video and read all the steps before removing your flywheel. Improper tools and techniques may cause damage to your flywheel (or to yourself).   To remove the flywheel, you must first remove the flywheel nut. If you do not have a 2 1/8″ socket and impact gun available, you will probably […]

  • ANYONE changing a front pulley, or loosening the front eccentric shaft bolt for ANY reason!, needs to be aware of what can go wrong with the torrington thrust bearings inside the front cover/front of engine!! Before we wade through this FAQ, the way to prevent the problem from happening in the first place is to, (BEFORE! you loosen the […]

  • The “number on engine side” is shown here. Although you can’t really see it, the number is toward the top of each of the “engine side” images (for those that have a number). Year/Engine Clutch Side Engine Side Number on Engine Side Weight (lbs) 79-80 12A None 30# 74-78 13B No image yet None 31? […]

  • We consider there to be four “types” of rotor housings: 1) New – require only quick inspection to be sure there was no bad casting or shipping damage and they are ready for assembly or porting. 2) Used in EXCELLENT Condition – very rare to find, require lots of cleaning and inspection. 3) Used, not […]

  • Identifying rear counterweights is not an easy task. There are very few features that differentiate the various counterweights from one another. The best way to insure that you know which counterweight you are dealing with is to scribe, or otherwise permanently mark the counterweight as soon as you take it off the motor. This only […]

  • Dont know which short shifter to buy for your 1st gen transmission? No Problem! The 81-83 transmissions have the “lower bushing” cast into the tower, so it doesn’t use two bushings like all the others. See the pictures below for a comparison. 81-83 with cast bushing in the tower, highlighted with red. All other transmissions […]

  • Intake Templates are available in our Tools Section. They come with the actual port shape scribed on them. You have to cut/grind the port into the template, following the scribed lines. The one pictured is for bridgeport intake. These are various intake templates we use in our porting. We prefer using Dykem Layout Fluid to allow […]

  • August 2000 The Mazdatrix drag car was built mainly for advertising purposes (and we will continue with it). However, our true interests have always been in road racing. After being “involved” with drag racing for two years now, the owner (Dave Lemon), has decided it is just not exciting enough to ONLY do. He “started” […]

  • We have used the Miata box in our race cars with great success, and it is not bad for a cheap close ratio box. We have actually found these ratios to be better than the high $$ MazdaSpeed ones for our Buttonwillow track out here – it’s the box we put in our EP car […]

  • There ARE limits of how much you can boost any engine. This is assuming the fuel mixture is correct (this alone can cost a few engines to find out), the octane is high enough, nothing else has changed, etc. etc. What we are talking about here is the physical / design / metallurgy limits of […]

  • In a Rotary engine, the port timing is equivalent to a camshaft in a piston engine. The higher the top of the port, the later the intake or exhaust is closing, and the longer the duration. On the exhaust port, the lower the bottom is, the sooner the port opens, and the longer the duration […]

  • The 86-92 non-turbo rotor housings have a “splitter” (also called a “diffuser”) in the middle of the exhaust port. These are part of the casting of the sleeve insert, and are VERY hard metal. We do not do any porting on these rotor housings! If we are assembling a “ported” 86-92 6-port engine, we use […]

  • The 86-92 RX7’s have “rear steer”. For those of you not familiar with this, it is a combination of rear suspension geometry, and compliant bushings that “make” the rear of the car steer into the turn. This is accomplished by making the rear of the car steer to the outside of the corner, which then […]

  • This chart is included in our Website for reference purposes. The weights listed are for production, unmodified rotors. Engine Year Compression Weight (Grams) Weight (Pounds) 12A 76-82 9.4 4603 10.15 12A 83-85 9.4 4353 9.60 13B 74-78 9.2 5253 11.58 13B 84-85 9.4 5253 11.58 13B N/T 86-88 9.4 4553 10.04 13B Turbo 86-88 8.5 […]

  • This is just a sample of a typical side housing as it comes out of an engine. The greatest wear is usually opposite the intake port – in the area of where the lines in the image are converging. This is a close up of the above shot. The depth of the vertical wear groove […]

  • Metric to LBS/INCH KG/MM LBS/INCH 4 225 5 281 6 337 7 393 8 450 9 506 10 564 11 620 12 674 14 787 16 899 18 1012 20 1124 22 1238 24 1348

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