"A company named 'Scarab' made the first popular V-8 conversion kits for the Datsun Z. Scarab is now out of business. Hooker Headers still sells Scarab-style motor mounts, transmission cross-members and headers. Other companies sell more complete kits which are similar to the original Scarab." "The Scarab was a well designed and very thorough conversion and most kits are still based on the Scarab. However, since the Scarab conversions were first developed, many parts have become available that make for a better and less costly conversion. Some Chevrolet items to come out in the 1980's which make for a better, easier and less costly conversion are: 1. Factor Chevrolet aluminum heads for under $600/pair. 2. Hydraulic clutch release for Corvettes and Camaros (1984 and newer cars). 3. 5-speed overdrive transmissions for Camaros (1983 and newer). 4. 4-speed manual transmissions with electric overdrive (1984-1988 Corvettes). 5. Automatic transmissions with overdrive (1982 and newer cars). 6. Light-weight cast iron flywheels (1983-1986 Camaros with the high output L-69 engine)." [From "Datsun Z V-8 Conversion Manual," Mike Knell, (c) 1990 by Jaguars That Run, P.O. Box 66, Livermore, CA 94550. JTR offers a conversion kit claimed to improve upon the Scarab, largely by setting the engine back.] Scarab was a small company located in California's Silicon Valley who did these conversions for customers on *their* cars or on cars they purchased on the used market for a re-work (in which case, they did sell some "turn-key" cars). Brian Morrow, the owner of the co. is still around but what he's doing these days, who knows? They were one of the first companies doing this and offered the conversion in "kit" form for the do-it yourselfer. The ultimate setup available from Scarab Engineering was the turbo 5.7 liter Chevy setup. All of their literature featured this one car, based on a '75-6 280 body with a complete body kit very similar looking to the Jim Cook Racing California Z kit. It was retina-burning red and showed very well at local car shows. Real Scarabs had scarabs on the side vent trim (behind the rearmost side windows). Scarabs were not sold through Datsun dealers. Scarab is no longer in business as far as I know. (rumors that smog certification of their cars in California was a big sting to the co.) There is a road test of a Scarab Z in the January 1978 issue of Road and Track.
One area of debate regarding V8 conversions concerns which engine to use. Its probably no surprise the the main battle comes down to whether to put in a Ford or Chevy. Of course there are those who argue that one doesn't need a V8, a turbo is the way to go, but that can remain the subject of a different FAQ. My personal experience has been with a Chevy conversion, so much of this FAQ will have a slant (at least for now) in that direction. I welcome any inputs from those who have experience with Ford conversions. All the kits and plans I have seen have been for Chevy conversions, but I have heard of many Ford conversions as well. Another option is to install a Buick Grand National turbo motor. Claims are that the GN engine makes as much power as a built small-block but is much lighter. The swap provides for a relatively empty engine compartment! It appears that a small block Ford motor is a better fit because the distributor is in the front (won't hit the hood latch) and because it is a bit lighter. The guys with the Fords said that they had to do no suspension mods while most of the Chevy guys had to add at least a larger swaybar and usually stronger springs. The Ford motor is slightly more expensive to build than the Chevy. The Chevy installation (set-back) deals with the distributor/hood latch problem by removing the stock hood catch on the fire wall and replacing it with a fabricated one that can be unbolted if the distributor needs to be pulled. The Ford V8 would not require this mod.
A complete conversion manual is available from a company called "Jags That Run". This book covers, in detail, most of the aspects of putting a Small Block Chevy V8 into the Datsun Z. The book does not get into bolt A in Hole B, wire C to terminal D for the common sense items. Measured drawings are given for the motor mount brackets, which you may order pre fabricated from JTR. If you have seen the "standard" Scarab type Z V8 installation, this differs in that they recommend using their brackets to drop the engine one inch, and move it up to four inches rearward. Per JTR, this compensates for the additional weight, restoring "near" original front/rear weight distribution. They also shift the engine to the passenger side slightly (don't recall how much), to help clear the steering shaft, and the small bonus of balancing left/right weight distribution. The brackets should be really easy to fabricate. The book covers adjustments and modifications required to retain the stock tach (much appreciated). Basic wiring changes are given, mostly based on 240Z wiring. There is a section on how to get your new toy smogged in CA, yes, legally. Some suspension mods are also listed, not necessarily required for the V8, but helpful. Overall, I am very happy with the book. Don't expect a hardcover, jacketed book for your coffee table, the book is paper bound. V8 Conversion Book Address: Datsun Z V-8 Conversion Manual Jaguars That Run P.O. Box 66 Livermore, CA 94550 ($39.95) -- Hooker Headers sells motor mounts, transmission mount and headers for putting a SB Chevy and TH350 into the Z. This installation is similar to the original "Scarab" design. (Hooker PN) (Cost *) Front Frame Mounts 12651 $85.88 Tranny mount 12652 (70-72) $51.56 12653 (73-78) $72.75 Headers 2147 $235.88 * These are costs that are listed in Performance Automotive Wholesale, Inc 1990 catalog. Phone is (818) 998-6000 . -- "Motorsport Engineering" sells a V8 conversion kit. This company is, if I remember correctly, run by a former Motorsport Auto person. This is a fairly complete kit, consisting of the following: 1) Four-row, cross-flow radiator that uses the stock mounts. 2) Fan shroud. 3) Radiator hoses, clamps, and in-line filler. 4) Engine and trans mounts. 5) Floor-mounted auto trans shifter. 6) driveshaft w/replaceable U-joints. 7) Block-Hugger headers. 8) Electric fuel pump. 9) Stock fuel pump block off plate. 10) Throttle cable. 11) Kick down cable. 12) Speedo cable. 13) Hood latch and bracket. 14) Easy to Understand installation manual. This appears to be a very complete kit, and costs $2,335.00, plus UPS shipping. This kit uses a set back engine position, similar to the one recommended from Jaguars That Run, although the engine mount adapters are different. Motorsport Engineering A division of Silverado Industries Inc. 12510 Gayle Lane Nevada City, CA 95959 (916) 274-2331 --
The R200 differential used on 280Z's should be adequate for most V8 applications. The R180 used in the 240Z and 260Z is not quite as strong, but many conversions have run them without any failures. If you want, earlier R180's can be easily replaced with an R200. Its pretty much a bolt in swap. Some of the more exotic setups have used rear ends out of Corvettes and Jags, but this shouldn't be necessary. There was also a writeup done some time ago in Hot Rod magazine. It was spread out over 4 (??) issues. Their conversion included replacing the R180/R200 with a Ford 9 inch rear and the obvious solid axle. If I remember correctly, at the end of the section were several sources for parts and plans et al. The drive shaft, for the Chevy conversion, is basically a shortened Chevy shaft with a special adapter flange that goes from the Chevy U-joint to the Datsun differential. (NEAPCO 2-2-899-1 about $20) you end up with a nice stout drive shaft with GM U-joints on both ends. The most common tranny for the Chevy conversion is the TH350, but the 700R4 tranny is becoming more popular. The lockup torque converter and the overdrive will gain you a significant mileage boost. Various manual trannys have been used. The clutch hookup is simplified by using the hydraulics from a Camaro.
For the "Scarab" setup, Hooker sells a special header that will fit the Z. (see Kits/Plans above) For the set-back conversion, use "Block Hugger" or "Street Rod" headers. These are available from Hooker as well as other manufacturers. The old "Rams Horn" style manifolds can also be made to work, but may require a little machining to tuck them in a little closer to the block in order to clear the steering shaft. Some type of heat shield or header wrap is recommended, especially on the passenger side where the wiring harness, fuel line and brake line get real close to the exhaust. The rest of the system can be set up to suit the needs of the individual. Its a pretty tight fit for dual 2-1/2" but it can be done, pipes run up under the center hump near the drive shaft. (I ran dual 2" on mine) Others have opted for a single 3" which fits a little easier, especially in the rear where trying to fit 2 mufflers is a little difficult.
Most of the electrical connections for the conversion are pretty straight forward. Use the Delco internally regulated alternator and get rid of the external regulator and associated wiring. One subject that has seen some discussion in the mailing list concerns using the stock Tachometer Datsun Z Tach adjustment: There is an adjustment screw on rear of the tach, reachable through a small hole, sometimes covered with electrical tape. Per the V8 conversion manual, the ignition must be off while making adjustments. The pot in the Z tach varies the pulse width of the multivibrator that drives the meter movement. The meter movement integrates the pulse train to provide the RPM indication. The multivibrator cleans up the incoming signal and makes it independent of the width of the incoming pulse. The pot thus DOES calibrate the span of the instrument.
For the cooling system one can use a 3-row radiator from a Camaro (early 70s?) that has been modified by removing the outlet side tank (the one with the filler cap and tranny oil cooler) and replacing it with another inlet tank that is flipped over. This makes it narrow enough to fit. An in-line filler cap is added to the upper radiator hose and a separate oil cooler is mounted in front of the radiator. Use the overflow tank from a Monte Carlo and mount it on the inside fender, drivers side. Use a fan shroud from a '73 (or so) Nova and an aftermarket flex fan. The single biggest thing you can do for Z car cooling is to properly duct and shroud the fan. Other suggestions to improve cooling have been: - aftermarket 4-core radiators - using electric fans - electric fan from a Nissan Sentra mounted in front of the radiator and the stock fan in the rear. - having the hood louvered similarly to the later model turbos - ventilation holes between the engine compartment and the cowl.
One FAQ concerns the added weight of placing a V8 into the Z. The weight increase is marginal (160 lbs more) with a slight shift of center-of-gravity to the rear, (for the set-back design) Stock suspension should be adequate but, of course, could be improved with performance springs, shocks, anti-sway bars, etc. Numerous things can be done to decrease the additional weight. This is standard "Hot Rodding" fare : Aluminum heads Aluminum Intake Aluminum water pump, radiator, pulleys ... Headers Move the Battery to the back. Alloy wheels The list goes on, all it takes is $$$ If you can afford it, you might want to look at one of the competition aluminum, iron sleeved blocks. Brodix makes one. That should make the weight about even.
A lot of people who have done the V8 conversion have found that they need to do some level of modification to stiffen the chassis. The following is a list modifications that have been suggested on the net. The book " How to Hotrod an Race Your Datsun" by Bob Waar, has some additional useful information and pictures regarding Chassis and suspension mods that might be applicable to a V8 Z. - Make a "torque tube" which will bolt to the back of the tranny and the front of the diff case. This should eliminate the torquing of the body shell due to engine torque, since the reaction torque to the driveshaft will go through this torque-tube instead of the body between the motor and diff mounts. Make it out of two 3" aluminum channels, one for each side of the diff case. - Replace the frame rails in the engine compartment with 2.5" square steel tubing, .095" thick wall. - Remove outer rocker panels and put 2x3 tubing in there, then replace the rocker panel. - Put the tube to the inside of the rocker box, in the passenger compartment. This would have same advantage as above alternative, but you would give up the dead pedal and seatbelt retractors. - Add an 8-point roll cage. This would mean getting tubing bent somewhere. This looks like money and possibly fitting problems. One could buy a bolt- together cage but its' expensive ($700). - If you look at the Bob Sharp prepared 240s from the 70's they added a tube from the front end of the rocker panel through the inner fenderwell to the top of the strut. I always thought that this would add some strength and not be that hard to do. It looked like they used some 1.5" tubing, and it all fit nicely under the fender. - Add a stiffening rod between the 2 front strut towers, Simply bolt to the existing strut attachment points. With the V-8 conversion, you won't need one that hinges for easy access to the valve cover like is used with the Datsun engines. - Add an after market roll bar. Bolt in versions are available from Motorsports Auto, Phone (800) 633-6331 - Add a stiffening rod between the 2 rear strut towers. - Take a piece of 4" wide channel and put it over the existing hat-section sheetmetal "frame rail". Then put a piece of flat 1/4" steel on the floor board over on top of the frame rail and channel and bolt through the channel, floor, old "frame rail", and flat steel piece. Weld the ends of the channel to the front frame rails and rear subframe piece that the diff mount and control arm crossmember bolts to. Weld 1/4" flat steel, positioned vertically to tie the vertical sides of the front (engine compartment) frame rails to the channel.
Emission requirements vary from state to state, but I believe for most of those that require testing, their laws are patterned in some form after California's laws. (I am familiar with Washington's requirements because I live there) Mike Knell's manual has a chapter consisting of several pages that describes the requirements for Cal legalization. In a nutshell, it states that the engine going into the car must be the same year or newer than the car, and that all pollution control devices must remain with the engine ie EGR, Air Cleaner, Charcoal canister, etc. One exception is the catalytic converter. The car only needs to have a cat if it was originally equipped with one. The car then needs to be inspected at a special "referee" station, and if it passes both visual and emissions tests a special sticker is placed inside the door jam. In Washington State, the requirements are not as strict. For pre 1980 cars, there is no visual inspection, so the car simply has to pass the emission requirements for it's year model independent of whats under the hood.