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................................-- Swapping a Small Block Chevy --
..............................................-- Into a 1973 Datsun Z --
Shawn Begay who is a friend of mine asked if I would help him put a 1975 Z motor into his 1973 Datsun Z. The '75 was the first year for the injection motor for the Z car. I looked at the wiring mess and fuel system mess and started to try and convince him to put a 305 small block Chevy I had in the car instead. After some time the '75 motor was in and some of the fuel system was switched over, but we still had the daunting task of the computer, wiring and fuel injection ahead of us. Finally the decision was made to pull the '75 motor out and put the sbc motor in.This isn't exactly a how-to-do it page, but what is here would probably help you get the job done. The pictures are not necessarily in order and to prove that we will start with the exhaust, so the engine/trans is in during this process.
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A friend, Jim Rivers of Phoenix, had given me some street rod block huggers a few years ago and I passed them on to Shawn. This car is low and not much room under if for an exhaust system, especially dual exhausts. The only mufflers that would really work were straight through ones and Shaun got 4 of those (2 long ones and 2 shorter ones). The drive-shaft sits pretty high in the tunnel and doesn't go up and down since the car has IRS. We started by using a piece of strap to tack the mufflers close together and then put them up in the tunnel as much as possible. Then we work forward to the headers one side at a time. We did this together on one side then Shawn copied that side and cut and fit the pieces for the other side and I would tack them together. He did over 90% of the work here. I gave some guidance and was the welder and fabricated a few things, but he came up with some good ideas when we were stuck a couple times.
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Here you can see the ends of the longer mufflers and the shorter ones behind them. A lot of effort went into tucking the exhaust up as close to the car as possible. Mandrel bends were cut and used along with some straight pipe. First it was all tacked together and hangers tacked on.
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The left arrow points to a couple pieces of temporary straps that located the pipes until they were all welded together. The stock exhaust opening in the body was to narrow for two pipes and the pipes have to both come out this side due to the gas tank to the right. The body (roll pan) was cut and moved over. It will have to be finished later. I couldn't believe how thin the metal is on this car. I'll bet it is 22 or 23 gauge. Hard to weld.
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After the exhaust was tacked together it was taken down and finish welded. The pipe and bends are aluminized. A cross over ( "H" pipe) was put in right in front of the mufflers.
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You can also see the hangers that were used. There were two more ahead of the mufflers that aren't shown. The complete exhaust comes down as one piece. It sounds real good, not loud, but you hear it and on the road at speed you don't hear it.
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This is looking forward out of the engine compartment (no engine). Shawn had this one electric fan, but I questioned it's effectiveness so it was mounted in front of the radiator as a "pusher" and might be manually operated via a switch. To the right is the transmission cooler.
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Looking at the pusher fan and trans cooler from the front of the car.
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The engine sat too close to the Z radiator and was too high to use the stock mechanical fan. Both fans are Deral Electric fans, but this is their better one and has about twice the output of the other one that we are using as a pusher. Obviously this is set up to run as a puller. This fan operates automatically off an adjustable thermostat that could also run the pusher, but we will probably wire the pusher on a manual switch.
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A lot of effort went into building a good shroud. Shawn brought this piece of aluminum from work and we used the plasma cutter to cut the center out and it was bent over at the top and bottom so that it would fit flush to the radiator and assured the fan would be pulling all of the air through the radiator. It was held on by screws on the sides and I welded tabs on the bottom. Shawn also had a larger bottom outlet soldered over the smaller 1 1/4 inch one that was on the radiator. This helped when it came time to find radiator hoses. They are hoses from a mid '70's chevy Camaro top and bottom.
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The top left arrow points to an external transmission filter. The transmission fluid goes to the filter then the cooler then back to the 200R4 transmission. The top right arrow points to the starter cable. A Ford type starter relay was installed up on the firewall. That allow just one cable to the starter and a jumper then on the starter from the cable to the solenoid. The other two arrows point to the motor mounts.
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Two plates were cut from strap and drilled with 4 holes to match stock chevy motor mounts. The right one on the passenger side was welded directly to the stock Z pedestal for the Z motor mount. The left one used most of the stock pedestal, but vertical pieces were added to it to get the motor where we wanted (better seen in the picture before this one). The arrow points to the steering shaft that dictated where we placed the motor to some degree. We had to cut the left side engine mount, the part that bolts to the block, some to clear the header on that side.
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We spent a lot of time getting the motor/trans where they were parallel to the centerline of the drive shaft and at an equal angle to the pinion. Since the pinion doesn't go up and down with the IRS we set the motor/trans so that there was about 1 degree difference in the angle of the engine/trans and the pinion. I saw where this was important on two piece drive-shafts where the front one is fixed when I put a sbc into a Ford pickup with a two piece drive-shaft. This is suppose to help the bearings in the U-Joints rotate some. We spent a lot of time on this process dropping plumb lines to the floor and such so that the U-joints will last.
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Here the motor is going in for the final time. We had it in once to tack the motor mounts in, build the exhaust, take care of the cooling system and run the plumbing and wiring. Then we pulled it to do the finish welding and Shaun put on a 4 barrel manifold he bought used and some nicer valve covers and a Q-jet that our friend Phil donated to the project. This is a 305 with about 135,000 miles on it, so it is a little tired and of course leaks oil and has a little valve seal smoke. Shawn hopes to build a 350 in the future and it will bolt right in and replace this motor.
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This is the transmission mount we made. The upper two arrows point to were it bolts into the stock Z transmission mounts on the unibody car. The center arrow is for the bolt on the back of the transmission output shaft housing. The two outer bottom arrows point to hangers used to hold the exhaust on.
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Here the transmission mount is in place. The transmission is a 4 speed overdrive 200R4 that my friend Hooley gave me a few years ago when my transmission blew up in Oklahoma on a trip east. It came out of the car that the 305 came from, which was in fact not a Chevy, but a 1978 Buick. Shawn got an after-market ratchet shifter that controls the transmission. Care was taken to properly hook up the TV cable from the transmission to the Q-jet for the proper geometry with a bracket that was made for it. This is important if you want the 200R4 (or a 700R4) to last. The info is elsewhere on my site ( HERE ).
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A view looking towards the rear of the car. The top arrow is pointing to the 200R4 and the bottom arrow is pointing to the drive shaft. It is only about 26 inches long. We sent the Z drive-shaft along with the GM drive shaft over to Drive Line Service Co in Grand Junction, CO where they made us a new drive shaft with a GM front and Z rear.
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Looking forward from the back of the car.
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The exhaust was painted with a hi-temp flat black paint to make it less noticeable under the car, although you would have to be laying on the ground to see it. We also hope it helps with slowing rust where the welds are.
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Shawn will get some tips that will be welded to the pipes in the back and also finish the body work on the roll-pan.
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As mentioned the hoses (bottom left arrow) are Camaro top and bottom. The bottom right arrow points to the block hugger headers that will get some stainless paint from Eastwood. The top left arrow points to the starter solenoid. The top right points to the hood latch. We cut the angled support for it off thinking we needed the clearance for the distributor, but didn't, so Shawn had to put in a new support not shown.
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The small block really looks like it belongs in one of these cars.
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Finally it was finished to where we pushed it outside to adjust the carb and burn the paint off the headers.
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Before our test ride Shawn topped off the transmission. While the motor/trans was out I put a TCI converter lockup kit in the transmission. I also had to make a mount on the carb for the TV cable and get the geometry right on it.
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We took a ride in the car and I adjusted the TV cable. Even with the tired motor the car runs good. Shawn says it is a lot faster than before. With the overdrive and q-jet I have a feeling it might get close to 25 mpg.
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The car is pretty straight and just has a little rust. Shawn hopes to do some body work and light customizing to it in the future and spray a different color on it.
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