Nissan 720 Z24 Guidance

[DesertSport]

I'm the pround new owner of a 86 nissan 720, reg cab, 4x4, with a california napz z24. I have been researching this truck for the past two weeks. I'm having a few engine questions, and was hoping some of you guys can point me in the right direction.

 

Im going to get a weber carb. But was looking to get a performance cam.

 

Here are some of the cams I found. Does anyone have any experience with them. The truck will be a crawler, bobbed and dove tailed. So im really looking for low end torque. I was going to get a webber 23/36 but read on a forum If i get a different cam I could get a 38, and gain so more power. I know the engine is not a power house, just looking for a little more torque the what they came with stock. I would be very happy with 200 ftlb at low rpms.

 

http://www.importperformanceparts.net/imports/webcam-nissan.html

 

http://www.sfxperformance.com/parts/COM881196.htm

 

http://www.compperformancegroupstores.com/store/merchant.mvc?Screen=PROD&Store_Code=CC&Product_Code=88-123-6&Category_Code=Z2024

 

Aside from the carb, I have about 600 to put in to the engine. I have not torn it apart yet, but has extremly poor compression, starts hard, and has no power at all. 240k on the odo. So a full rebuild is in order. Can anyone recommend a full rebuild kit. I dont want to piece togeather everything I need. With that budget what parts can you recemend.

 

Headers and exhaust. Ive been reading the headers and exhaust dont really add to much power, for the price and was looking for some opinions on that.

 

Lastly the head. What options do I really have. Ive read about the ka24## heads. But came to the conclusion that I will have to go efi, and there is some fab work needed, and the power is going to be mostly high end. which i dont really need. Maybe some one can enlighten me? Again its going to be a cralwer, Im looking for performance at 1-5 MPH. I have a ton more question's that I just cant remember. And plan on starting with in 3 weeks. So im just trying to get a good solid plan fo the engine, befor I start buying parts.

 

Also if anyone has any home brew ideas or plans, im welder, junkyard, and fab friendly.

 

Thanks in adance for any help....

[datzenmike]

You want 0-5 mph power/torque?

 

Stick with stock and forget the cam. At low speed there is lots of time for complete cylinder filling so you will be making all the torque you can. Cams always move the power and torque upward in the rev range anyway. Take a good look at the Z24 specs vs. the L series. You'll see that the L series has lifts of over 0.500". Why doesn't the Z? Because the valves will touch. Power is made in the head and depends on how much air can be drawn into and out of it. Next it has to rev higher. The Z head isn't suited for this. Valve lift is limited. Valve springs are not strong enough for revving. The ports are badly designed and breathing is like sucking air through a straw. But for what it was designed, low speed power/torque, it does a very good job. 134 ft lbs @ 2,800 RPM. Almost the same as the KA and about 1,000 RPMs lower.

 

You want crawl power?

 

Find an '81-'83 4X4 and swap the diffs into yours. These early 4wds. had 4.375 ratio... yours is a pathetic 4.11. This will increase the bottom end way more than any cam change.

 

The Z24 has a very 'restrictive' carb and owners rave about the 32/36 Weber. Be sure to spend the money and get the Weber replacement for your exact model. This will give the best results and will pass Kalifornia emissions. The 38 Weber is way too big and the motor will fall on it's face at anything under 3,000 if you step on it too fast.

 

Get the widest tires you can without increasing the height which will reduce the overall gear ratio.

 

Forget the header. Expensive and sexy but more like a high maintainance g/f. Their gain (if any) is at high RPMs and indeed can reduce bottom end torque.

 

 

$600 will get you started towards a rebuild if it does not need over size pistons and resultant over bore machine costs... and if you do all the disassembly/assembly work.

[DesertSport]

You want 0-5 mph power/torque?

 

Stick with stock and forget the cam. At low speed there is lots of time for complete cylinder filling so you will be making all the torque you can. Cams always move the power and torque upward in the rev range anyway. Take a good look at the Z24 specs vs. the L series. You'll see that the L series has lifts of over 0.500". Why doesn't the Z? Because the valves will touch. Power is made in the head and depends on how much air can be drawn into and out of it. Next it has to rev higher. The Z head isn't suited for this. Valve lift is limited. Valve springs are not strong enough for revving. The ports are badly designed and breathing is like sucking air through a straw. But for what it was designed, low speed power/torque, it does a very good job. 134 ft lbs @ 2,800 RPM. Almost the same as the KA and about 1,000 RPMs lower.

 

You want crawl power?

 

Find an '81-'83 4X4 and swap the diffs into yours. These early 4wds. had 4.375 ratio... yours is a pathetic 4.11. This will increase the bottom end way more than any cam change.

 

The Z24 has a very 'restrictive' carb and owners rave about the 32/36 Weber. Be sure to spend the money and get the Weber replacement for your exact model. This will give the best results and will pass Kalifornia emissions. The 38 Weber is way too big and the motor will fall on it's face at anything under 3,000 if you step on it too fast.

 

Get the widest tires you can without increasing the height which will reduce the overall gear ratio.

 

Forget the header. Expensive and sexy but more like a high maintainance g/f. Their gain (if any) is at high RPMs and indeed can reduce bottom end torque.

 

 

$600 will get you started towards a rebuild if it does not need over size pistons and resultant over bore machine costs... and if you do all the disassembly/assembly work.

 

 

Im allready ahead of you on the axles. Just purchased a 60 44 combo that will be going in shortly. I didnt see to much after market support as far as axles. and looking at the rear axle on mine, i dont think it could handle to much larger of a tire. And tires are going to be big. 37 or 38s....

 

So a recap of what I read was - Forget the cam, Its going to make higher rpm torque, same with the header. And the 32/36 should suit my needs perfect. Thanks. I do appreciate the info. I hate putting money into cars expecting one thing and getting another. the header and cam info just saved me 4-500.

 

Ive been looking at redline weber, and used, but wanted to make sure im getting the right kit... Is that a good company. Can you rememend one. Any other engine tips tricks would be great

 

Thanks,

 

Regards

 

Chris

[datzenmike]

Im allready ahead of you on the axles. Just purchased a 60 44 combo that will be going in shortly. I didnt see to much after market support as far as axles. and looking at the rear axle on mine, i dont think it could handle to much larger of a tire. And tires are going to be big. 37 or 38s....

 

So a recap of what I read was - Forget the cam, Its going to make higher rpm torque, same with the header. And the 32/36 should suit my needs perfect. Thanks. I do appreciate the info. I hate putting money into cars expecting one thing and getting another. the header and cam info just saved me 4-500.

 

Ive been looking at redline weber, and used, but wanted to make sure im getting the right kit... Is that a good company. Can you rememend one. Any other engine tips tricks would be great

 

Thanks,

 

Regards

 

Chris

 

Geez 38s, you'll need gear ratios of 5.00 or higher for the diffs. The stock 720 trans case reduces about 2 to 1.

 

For Webers see Jim Hilton in Vancouver BC.

[DesertSport]

Geez 38s, you'll need gear ratios of 5.00 or higher for the diffs. The stock 720 trans case reduces about 2 to 1.

 

For Webers see Jim Hilton in Vancouver BC.

 

Yea, I have a set of 5.38's to go in them. Looking for lockers now. hopefully can find a detroit and arb used. Id be happy to find one used, but will probibly have to go new. dosent matter I dont have the money for them now. But am always looking.

 

Is jim hilton a member on this board. or possibly a website.

 

I found a doubler kit tx10 to d300. Just above i think 4.78 to 1 gear reduction

 

Any essential reading I can and should be doing on theses. Also maybe you can help me. There is a little box under my seat. It only has one light and no switches to put into diog mode. I dont know what its for , but the truck wont run with it unplugged. Whats it for what does it do. Thanks.

[datzenmike]

It's a rudimentary ECU that uses input from an O2 sensor in the exhaust, temp sender, clutch and tranny switches, throttle valve switch, ignition coil, manifold vacuum switch to regulate the air/fuel mixture by constantly adjusting the electric solenoid in the main jet. Somewhat like fuel injection but uses a carb. Overly complicated and while good for economy not a ball of fire on the road. I don't think there is a fault storage retrieval built into them. They are notorious for wires breaking internally at the 6 pin round connector at the carb. I forgot you are in the emissions capital of the US so Weber may not have an emissions compliant replacement carb for you... well that's street legal.

 

All I have for Jim is http://www.overseas-auto.com He is also at The Realm as bigjim5551212

 

He sells Redline Weber carbs