32/36DGEV or 34DGEC carburetor for my 1981 Datsun 720 4x4?

[blondeham]

Hey guys, first timer on the forums here, I have a 1981 Datsun 720 4x4 with rebuilt engine and whatnot. I went offroading in the snow and my truck started bogging out. So, after having a professional figure out what the hell is wrong with it, he has determined that my carburetor is not working as it should. Fuel is there, just not being delivered properly. He had an aircompressor to shoot whatever junk might have gotten stuck in some air bleed tubes but I didn't want him to do an overhaul on the crappy carburetor for extra $$ so he told me the easiest and best thing to do is to get a new carburetor.

I am on the verge of purchasing a new weber carb either 32/36DGEV or the 34DGEC. I understand that the 34 is a little bit more performance with little decrease in fuel economy but I was wondering how well it would do at high altitudes. I live in Prescott, AZ which is 5000ft, I know other people on the forums here are probably higher altitude, and was wondering which one should I choose. I am kinda siding with the 34 because it is actually cheaper for some strange reason than the 32/36 by $20, woot. I emailed webercarbsdirect.com but they have not gotten back to me. Any feedback is appreciated.

I want to get this done before the car show my club is putting on. Whoever would like to participate in the show, whether its a car, truck, motorcycle, whatever, this show is gonna be a very decent size. It is taking place April 10th at the Embry-Riddle School in Prescott, AZ. Please call the number on the flyer or PM me to reserve a space

Here is a flyer if it works:http://clubs.pr.erau.edu/cma/i...9.jpgh ... /i...2.jpg

[PEZi]

well basically... the carb itself is not gonna be the issue at altitude.. it'll be how you jet it

i have a 38DGES at 6,500 ft. and it works fine

pick whatever you want really.... 34 has better low end... 32/36 has better economy

[blondeham]

sweet, thanks for your input. I've worked on cars and trucks before but when it gets to fuel issues, I'm left in a daze so, as long as its like a bolt on, hook it up, and fire it up kind of deal, then I'll get the 34 then. Just gotta adjust the mixture and it should be good.

I did see your thread about finding a 38 for like $100 but I couldn't find one about which one is better or if there were any issues between the two. I think if weber is making it, then they know what they're doing.

You can delete this tread if you want unless other people want to discuss it.

[PEZi]

i'm not sure what main jets come in the 34.... you may need to go leaner

my 38 has the correct size mains for my altitude... but i need a bigger air corrector as well as leaner idle jets

you may run into this as well... it WILL run as is... but to run right you may need to change it just a tad

[blondeham]

ill probably take it into a shop to have them look at it when I get it on. It can't be that hard to adjust the mixture. the jets and whatnot on the other hand, I'll definitely take it into a shop to see what they say.

I appreciate your input so much

I also ordered the 34 last night so its being shipped as we speak

[PEZi]

the mixture is VERY easy.... there are 2 screws, one on either side of the baseplate.... turning them right (tight) is lean and left (loose) is rich

[smileyhs]

I'm a FNG what up. Any ways I'm doing the same research and I have found many people are having problews with the 34 and rumors that it isn't even a weber. Not on datsun formums but other 4x4 forums. I think its the cheapest for a reason. Anyways on to my problem, I have a 1981 z22, I want the power gains of the 38 but I also don't want to have to deal with getting all sorts of bells and whisils to make it work right. Is the 32/36 easier to install and if not what is the best way to get my new 38 jetted correctly for the 4000 ft- 5000ft range with out having to send in for more jets. Also when I drove this baby home from boise it really struggled to get to 60 will either the 32/36 or the 38 let cruise at 75 with out dificulty or is that unrealistic.

Modified by smileyhs at 9:46 AM 4/3/2010
Modified by smileyhs at 9:51 AM 4/3/2010

[PEZi]

^ interesting you mention the 38

i have the 38... i live at 6,000 ft.... and it runs fine with the stock jets!

they are 145 mains which is perfect for the altitude with a larger air corrector.... the only other issue besides the bigger air corrector would be the idle jets... they are too rich stock... but simply turning in the baseplate screws will lean them out enough to make it idle properly

just don't forget a FPR!

[smileyhs]

Does your do fine at highway speeds, I was hoping to be able to drive on the highway at the speed limit, 75 up here is that to much to ask of the old datsun or will it not be a problem with a new carb. Also you may not know pezi720 but will the 32/36 let me drive at those speeds.

[flinterman2000]

Doing 75 with a 32/36 will burn some fuel. It will be possible with the right timing and the 32/36.

[PEZi]

^ what he said

i assume the 32/36 is fine at highway speeds to hit 75... hell my stock carb let me go 90 if i wanted (although mine is much lighter than yours)... to cruise at 75 you'll be opening both barrels tho... thus the excess burn

the 38 is overkill for highway use on my truck simply because of how light it is... on a 4x4 tho... it might be just right

[noface]

I just put a 32/36 on my boys truck.

Runs WAY better than the stock Hitachi.

At hwy/interstate speeds she's screamin at 75mph. Nearly to the floor. Tops out about 80mph on flat ground. That's all she's got.

This is a stock 1985 4x4 with regular tires, and stock gearing. Visited the family about an hours drive down the interstate for easter, going 75mph and still got 18mpg with it though...

I might try some bigger jets in the secondaries to see if it pulls a little better at hwy speeds.

The carb I put on is a used setup, I've never been inside it to see what jets it's got (likely with whatever they come with from Redline), so we'll see...

[flinterman2000]

If it screams and tops out at 80 and you have a 5 speed then its the gearing thats killing you. These trucks come with a 4.6 ratio in the diff. May be a 4.1 or 3.9 will help at highway speeds.

[[email protected]]

If it screams and tops out at 80 and you have a 5 speed then its the gearing thats killing you. These trucks come with a 4.6 ratio in the diff. May be a 4.1 or 3.9 will help at highway speeds.

A 4.60? Really? Not doubting you I just have no idea.

I just put a 32/36 on my boys truck.

Runs WAY better than the stock Hitachi.

At hwy/interstate speeds she's screamin at 75mph. Nearly to the floor. Tops out about 80mph on flat ground. That's all she's got.

This is a stock 1985 4x4 with regular tires, and stock gearing. Visited the family about an hours drive down the interstate for easter, going 75mph and still got 18mpg with it though...

I might try some bigger jets in the secondaries to see if it pulls a little better at hwy speeds.

The carb I put on is a used setup, I've never been inside it to see what jets it's got (likely with whatever they come with from Redline), so we'll see...

I have a 85 720 4x4. 32/36 stock jets, 5 speed, stock gears (I assume) 30x9x15 all terrian bfg's, timing set a 12 degrees initial. cruise 70 all day with ease on one barrel turning 3000 RPM. How can your truck be topped out?

Timing has a lot to do with it! My truck came with the 32/36 already installed and it was a dog. Keep an eye on the air filter that comes with the redline kit, mine came apart.

[PEZi]

If it screams and tops out at 80 and you have a 5 speed then its the gearing thats killing you. These trucks come with a 4.6 ratio in the diff. May be a 4.1 or 3.9 will help at highway speeds.

are you sure on this? i'm not all that positive on the 4x4's... but my 2wd ST only has a 3.7 rear diff

i know some of the older 620's and stuff had 4.67's but i wasn't aware that any of the 720's had such ridiculous gearing

[flinterman2000]

The manual I have covers the 720 with the J16, L18, Z22 and the SD22. These carry the H190A and C200 diffs. The ratios go from 4.111 to 4.625 for the L18 and Z22, and from 4.375 to 4.825 for the J16 and SD22.

[smileyhs]

Might be a dumb question but for higher highway speeds do you want to retard or advance the timing?

[[email protected]]

Might be a dumb question but for higher highway speeds do you want to retard or advance the timing?

timing doesnt really have anything to do with what speed you are running. more to do with engine speed, amount of fuel and engine load.

[blondeham]

well, an update on my long process.
Will have pictures up sooner or later.
I got a 34DGEC and installed it. Took off the old fuel supply line that went under the intake manifold. Used a brass T-connector for the supply and return fuel line. Started it up and it sounded much smoother and overall better even before tuning. I haven't tuned it yet because I ran into another problem... After the engine warms up for awhile and driving it around the block two times, theres a slight incline or a hill on one side of the block and it would bogg out, like fuel starvation, only going uphill but would work on level and downhill. There is more than half a tank of fuel in there and am hoping that it was the old fuel pump. So, i purchased a new fuel pump that outputs pressure between 4-7psi and the weber carb specifies 3.5psi so i gotta fuel pressure regulator to put on it later today. Hopefully it was the old fuel pump, but if its not, what else would it be???? I know it is not the carb or any of the fuel lines, I'm thinking its something with the tank. I notice that on this truck, the fuel tank will pressurize and I'm afraid that the pressure builds up so much that it vapor locks and, therefore, no fuel is delivered. I'll loosen the gas cap a little too and see if that's it. So, any ideas otherwise??

Thanks for your input!

[PEZi]

try out the FPR first... then try messing with timing....

if not one of those two things i'd be a little baffled as you shouldn't be getting vapor lock that easy

[blondeham]

well, i got everything hooked up and after warming it up and stuff it still did it. So, i took the fuel line hose off and turned the fuel pump on. I know the fuel pump was doing its job because i took the line off of it and it, literally, shot out fuel at an enormous rate, glad i got the FPR. I ended up geting a Mr. Gasket FPR, the Spector ones didn't seem to do the job and the Spector ones came with plastic nipples while the Mr. Gasket one came with brass nipples. I got the Mr. Gasket FPR at Checkers/ O Reily's FYI. So, the fuel pump was doing its job, but somewhere along the way, fuel wasn't getting to the carb. With the pump on, I pinched the return fuel line hose, and fuel immediately pumped back out of the tube. So then I bypassed the return fuel line hose and it worked great for about 20 minutes of going up and down steep hills around the neighborhood. At like the 4th hill, it bogged out like it did before . The only thing I can think of is that there is some sediment sloshing around, even after putting a fuel system cleaner in, in the fuel tank and occasionally blocks the tube. So, I'm gonna drain the fuel, drop the tank, flush it out, and try and see if I can see if there is anything in the tank. I am utterly confused and baffled by this whole situation and quite frustrated because a simple truck like this should not be doing problems like this.

I don't think timing is an issue because it will start right up when cold and will run for awhile, so the spark is there, it just needs fuel to make it goooooo

Thanks for your input BTW, any other ideas?

[PEZi]

i guess it is possible that you got an old tank that is clogging up your lines.... i dunno though

it just seems you have everything in order, but for some reason its just not working.... i'll see if i can think of anything else but try the tank cleaning

[flinterman2000]

Might be a dumb question but for higher highway speeds do you want to retard or advance the timing?

Advance is better. A retarded ignition causes the exhaust manifold and header to glow as fuel still burns when the valve opens and is expelled from the cylinder.

[flinterman2000]

i guess it is possible that you got an old tank that is clogging up your lines.... i dunno though

it just seems you have everything in order, but for some reason its just not working.... i'll see if i can think of anything else but try the tank cleaning

Had the same problem when I got my 720. Changed the pump, no help. When I got the tank cleaned it helped a lot. Also had a similar problem with the laurel I had but that was a surge tank problem which developed after I installed a RB20DET, cornering hard to the right.

[blondeham]

thanks for your input, I still got to find some time to do it and on a nice day (i don't have a garage but hopefully soon and I'm really hoping that draining and flushing it out with something will solve the problem. If the problem is too big, then I'm just gonna get a fuel cell that someone is selling on craigslist.

When it runs it sounds awesome and much smoother. I'll eventually get some pics up. Depending on money, I might do a suspension upgrade that is offered from 4x4parts.com. a 3 inch suspension lift is $260 and a 3 inch body lift is $180. I know bodylifts don't help in getting over stuff but mostly allows for larger size tires. Well, one problem at a time and the fuel tank is next. I'm gonna try and tackle it this week.

[blondeham]

well, another slow update. I dropped the tank and cleaned it out. There was plenty of fuel in there, and there was plenty of gunk in there as well. Now it runs awesome when it runs but I have run into another problem, as usual. My battery wasn't getting charged or something so I'll take it down to checkers to see what the problem is cause they do battery and alternator testing. They charged my battery and said it is a perfectly good battery. Also, I thought my trans case was leaking, and it probably is, out of the speedometer cable so I tried tightening it but it sheared the metal that the speedometer cable screws onto. SOAB. So, I've decided to be cheap about it and epoxy it back on because I am fed up with this thing and am going to sell it once I get it in somewhat tip top shape. If i had like $4K, I would totally put a V8 in it, lift it, put big tires on it and call it good, but I don't have that and I have my other priorities so this has to go unfortunately .