Alexp521 Posted January 31, 2021 Report Share Posted January 31, 2021 Need a little help what radiator to run on the swap and will the oem ac system work on the 521 I have a complet doner truck it is carburated I have engine trans mounts doing a complet new wiring kit 1 Quote Link to comment
datzenmike Posted January 31, 2021 Report Share Posted January 31, 2021 The Z24 will not bolt properly top your 521 4 speed. If you swap the Z24 transmission in it more likely that it's longer and the front half of the two piece drive shaft will need to be shortened. Some 720 transmission are the same length as your 4 speed, lets hope this is so. In either case the transmission mount will need to be shortened to move it back to fit the Z24 5 speed. Probably you can use the 521 rad.... for now, but keep an eye out for a 620 L20B rad. The top inlet is on the opposite side from the Z series so an elbow and extra clamps used. The Z24 block is 1.5 inches taller that the L16 but the head and valve cover may be thinner and off set this. Put the L16 oil pan and pick up tube on the Z24. Putting the 720 air conditioning into the 521 would be quite the under taking. The 720 draws it's air in from the far right of the cowl and down into the fan box. From there into the air conditioner and from there into the heater assembly, more or less in the middle of the dash undersides. It's tight even in the much wider 720. The 521 draws it's air from directly above the heater in the middle of the cowl and the glove box would be totally in the way. Probably you can use the 521 rad.... for now, but keep an eye out for a 620 L20B rad. The top inlet is on the opposite side from the Z series so an elbow and extra clamps used. The electric fuel pump would need to be installed. The 521 coil and ballast removed and the Z dual coils replace them. Swap the 720 throttle cable in to reach the new carburetor location. Join the Z down pipe to the 521 exhaust. I had a Z24 in my 620 for a while.... lots of torque. 1 Quote Link to comment
Charlie69 Posted January 31, 2021 Report Share Posted January 31, 2021 If you go through my 66 520 thread I have fit a 85 720 heater, AC, and blower boxes into my 66 520. It took a lot of modification to get it to work on my 66. The 521 engine compartment is about 5" longer than the 520. Quote Link to comment
datzenmike Posted January 31, 2021 Report Share Posted January 31, 2021 I put the 720 fan and heater into my 620. It did not have A/C but there was a tube to direct the air from the fan box to the heater where it would go. It was an insane amount of work. The wiper had to be re-located in the air plenum and a new air inlet for the new fan location. 1 Quote Link to comment
Alexp521 Posted January 31, 2021 Author Report Share Posted January 31, 2021 So swap the oil pan use the 521 radiator was going to use electric fan dnt know what brand to buy use coils from the 720 as well as throttle cAble fuel pump. Can I just use the radiator from the 720 1 Quote Link to comment
datzenmike Posted January 31, 2021 Report Share Posted January 31, 2021 No way that will fit between the head lights. The L16 rad will work but not if worked moderately hard. Perhaps a custom L20B rad. 1 Quote Link to comment
Alexp521 Posted January 31, 2021 Author Report Share Posted January 31, 2021 On the ac is ther a alternative othe than the oem 720 like on my 57 Chevy pickup I bought a kit that would bolt up so have you heard anything like this for the 521 1 Quote Link to comment
datzenmike Posted January 31, 2021 Report Share Posted January 31, 2021 A kit is somewhat a custom install where the 720 is taking something and making the truck fit it. I think a kit would be easier. 2 Quote Link to comment
Alexp521 Posted January 31, 2021 Author Report Share Posted January 31, 2021 Okay and where can I get a custom radadiator 1 Quote Link to comment
datzenmike Posted January 31, 2021 Report Share Posted January 31, 2021 Ask on here. Summit? Rock auto? I think they are all aluminum now. Ask also if a 620 L20B rad will fit the 521 just to be safe. There was a three core 620 rad option I think.... I had one once. 1 Quote Link to comment
Alexp521 Posted January 31, 2021 Author Report Share Posted January 31, 2021 Okay thanks for info I’ll update pics as some as engine is out 1 Quote Link to comment
Alexp521 Posted January 31, 2021 Author Report Share Posted January 31, 2021 They have asked me for the complete ac system what dose something like that run so I can give them a price if I’m not going to use it 1 Quote Link to comment
Stoffregen Motorsports Posted January 31, 2021 Report Share Posted January 31, 2021 1 hour ago, datzenmike said: A kit is somewhat a custom install where the 720 is taking something and making the truck fit it. I think a kit would be easier. Aftermarket kits are somewhat less than high quality crap. You get what you pay for. The nicest kits I have seen (planning on using one in a Jeepster Commando soon) come from Restomod Air - https://www.restomodair.com/shopproducts/cyclone-ultra-compact-custom-air-conditioning-kit/ I would still use the compressor and bracket that came with the motor, but the custom interior box may be easier to fit. 2 Quote Link to comment
wayno Posted February 2, 2021 Report Share Posted February 2, 2021 I actually used the stock L16 521 radiator in the one I built. 2 Quote Link to comment
Stoffregen Motorsports Posted February 2, 2021 Report Share Posted February 2, 2021 Wayno! You're back! 1 Quote Link to comment
Alexp521 Posted February 2, 2021 Author Report Share Posted February 2, 2021 So this is where I’m at for now have a box for a engine 1 1 Quote Link to comment
Alexp521 Posted February 2, 2021 Author Report Share Posted February 2, 2021 What fan are u running on it wayno 1 Quote Link to comment
wayno Posted February 3, 2021 Report Share Posted February 3, 2021 I believe I used the stock Z24 720 fan, but I had/have a lot of fans with different offsets, maybe that was a diesel fan. 1 Quote Link to comment
Alexp521 Posted February 3, 2021 Author Report Share Posted February 3, 2021 That will work will try it and see if it won’t affect any thing I’ll run with it but if not I’ll have to go electric So far I but disk brakes New wheels and tires new brake master and proportion valve brake Lines 1 Quote Link to comment
wayno Posted February 3, 2021 Report Share Posted February 3, 2021 My goal is always to use stock fans, I have been left on the side of a dirt road leading up to the top of a hanggliding hill more than once from a failure of an electric fan, I have never been left on a road because of a stock fan failure. I do not think I had to modify that fan for it to work, but I have had to trim the fan on my Datsun 521 diesel truck because it was hitting the upper radiator hose, when I put a Volvo wagon radiator in it 8 years later I replaced that trimmed plastic fan blade with a stock plastic fan blade assembly, like I said I may have replaced the stock Z24 fan assembly with a diesel fan assembly because they are very low profile as the diesel engine is longer than the Z block engines, but they did not make the engine compartment longer in the 720. 2 Quote Link to comment
datzenmike Posted February 3, 2021 Report Share Posted February 3, 2021 I have two and electric hardly run at all where mechanical run all the time and when not needed.. 1 Quote Link to comment
Alexp521 Posted February 3, 2021 Author Report Share Posted February 3, 2021 (edited) Dose the fan clutch change or the whole assembly with the fan of the 720 diesel one Edited February 3, 2021 by Alexp521 Quote Link to comment
Alexp521 Posted February 3, 2021 Author Report Share Posted February 3, 2021 Will I have to swap the pumpkin in the rear end from the 720 over to the 521 Quote Link to comment
Stoffregen Motorsports Posted February 3, 2021 Report Share Posted February 3, 2021 Mechanical clutch fans are always better if you can get them to fit. They pull more CFM than any similarly sized electric fan and they don't really rob you of HP unless they are engaged. There is a minimum required clearance from the fan to the radiator core though. 5/8" is usually enough. Any closer and you run the risk of the fan getting pulled into the core when it's pulling air, or when the motor mounts shift. Quote Link to comment
mainer311 Posted February 3, 2021 Report Share Posted February 3, 2021 20 hours ago, Alexp521 said: So this is where I’m at for now have a box for a engine You know, cats love boxes. If a cat jumped in there you’d have 1 pussy power. 1 Quote Link to comment
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