The little truck that just doesn't cut it.

[DanielC]

I notices you listed Yosemite as a location. What altitude do you drive your truck at?

I have ran my Datsun 521 over Tioga pass, both ways. Especially climbing the 8% grade from Nevada, that has a bottom at 7,000 feet, any engine you put in a Datsun is going to seem gutless.

You lose 3% of your horsepower every 1000 feet you are above sea level. You have a heavy truck. You have an oversize tire diameter. All this works against you.

It sounds to me like you need a lot lower axle ratios in your truck, 4.88 maybe?

 

I was at an off road Jeep specialty shop, getting some parts for a CJ2A I was working on. In the shop, there was a newer Jeep on on the rack, both differentials out of it, and oversized tires by it. They were swapping in a 5.xx ring and pinion, both axles. I believe the Jeep on the rack had a V-8 in it.

[datzenmike]

 

if the truck has an H-190 you could also try some lower gears from a 620 or 521, with and without the 31's.

 

If the 620/521 gears feel better to you, get an R-180 for the front to match the new rear gears

 

 

 

The '74 620 with automatic had 4.625 rear gears. For a front R-180 with 4.625, try the WD21 Pathfinder. Only the Z24i equipped with standard tranny had them.

[ggzilla]

Also remember to let it shift down when pulling hills. Keeping it in top gear on hills is not how Datsuns are designed.

[datsun mechanic]

I have a 1980 Datsun 720 4WD king cab pickup (the year that still has DATSUN in big raised letters on the tailgate)

 

When I bought it, it had a L-20B engine in it with a 5 speed trans and 4.375 ring and pinion, (front and rear) 31x10.5 tires, and stock Hitachi carb.

 

This thing weighs 4,060 pounds empty, hard to believe but two different Cali certified weigh station scales say the same.

The engine ran well but the truck drove like a overloaded mule having to downshift to third to get up a grade.

 

Rebuilt the L-20B, put a Weber carb on it and a low restriction muffler, guess what?

It still drove like a pig.

 

Acquired a good Z22 normally aspirated engine from a wrecked truck, put it in mine and the truck was just noticeably quicker but still a pig.

 

Took a rebuilt Z24 block and “Frankensteined” it by putting a fresh L20B head on it,

drilled the extra coolant passages in the block and head, lengthened the timing chain, pricey custom head gasket, all the good shit, machine shop work done by very reputable

shop, LOT’S OF MONEY in this build.

So now I have this engine that is 400cc’s larger than the stock engine, 10.5 to 1 compression ratio (wont run on regular gas)

After a long and careful break in the engine runs great but I still have to drop down to third gear to get this POS up a grade! Pulling a small single axle tent trailer is out of the question!

 

Guys, I love Datsuns, I have a 1974 B210 hatchback with the little stock A13 in it’s fun to drive actually “zippy”.

The 720 is great off road but even with the “L24B” in it it’s still a pig on the highway.

It has 4.375 gears which I would think should offset the use of 31” tires, but no.

 

The horsepower to weight ratio is about 0.0264

A Ford Escort has a horsepower to weight ratio of 0.045 WTF?

 

Part it out and try to recover some $$$ ?

Put a Chevy 4.3 v6 in it ?

Do something to increase power (something you good folks know about) ?

[datsun mechanic]

what you say involves only torque.....simple dependable torque comes from gears trans dif wheel tires

 

all i can offer is what i did for 77 620 L20 2wd to pull large overhead camper and 2 mtr cycle on trailer up and down moutain from riverside ca to mojave desert races for 14 yrs

 

4:88 gears retarded camshaft sprocket 20 50 engine oil 185 70 14 trailer type tires 1800 pistons

[HRH]

The '81 720 kingcab 4x4 I had with 30" mudders weighed 3600-3700 pounds empty, and it had significant rust. Probably enough for at least another 50 pounds. The hardbody weighs 4000 with me in it. Still, with all that extra torque and power, it should move right along. Did you check cam timing?

 

What carburetor are you running? A 32/36 is WAY TOO SMALL for an L24/20b combo if that's what you have on there. It just can't feed the beast. You'll need at least a 38/38, or better yet, SUs or sidedrafts, or better still, EFI.

[Guest kamakazi620]

http://www.hotrod.co...no_results.html

I say 4.3 also get a transfer case and 5 speed from a S10 or S10 blazer

[72240z]

Your just not going to be happy until you get someone to use one of those shitty 4.3's eh Kama? lmao

Drop one in your 620 you like it so much. :lol:

[Guest kamakazi620]

Your just not going to be happy until you get someone to use one of those shitty 4.3's eh Kama? lmao

Drop one in your 620 you like it so much. :lol:

Maybe I will an' smoke yer ass on da freeway at a stoplight anywhere basically!!!!!!

BTW they ain't shitty its a 350 chev -2 cylinders with bigger main bearings it's not MY fault everyone thats rebuilt one on this thread dosent know how to rebuild Chev motors they probably had a 2.8 an' thought it was a 4.3,ma parents have had 3 different chevs with the 4.3 an' loved each of 'em a '94 S10 blazer w/5speed (hauled ass) a '94 astro w/Vortec 4.3 and a '98 (not as fast as Vortec)

[Guest kamakazi620]

And as EVERYONE else said SOUNDS like Cam timing!!!! cuz ma dads 85 720 w/Z24 pulls damn good!!!,maybe yer just use to domestic V8 power???