LZ Losing power and Overheating

[Stoffregen Motorsports]

I hope that's on a chassis dyno. Even if it's not, 145 lbs/torque at 2500 rpm is impressive. What's your engine combo? 6" rod, 2.2 crank, 89mm bore?

[68Datsun510]

I'd love to see what my engine does... though im sure 145lbs of torque isnt gonna be there :P

[metalmonkey47]

WOW. I need to get mine on the dyno. I don't feel very confident yet. I don't think I'm making that big of a difference in HP just yet. I've been reading up on the Dime Quarterly article about suggested jet sizes on the 32/36, but nothing seems to be too concrete. I'm seeing a lot of info suggesting that the emulsion tubes need to change as the air jets change, while it's suggested that the air jets increase at about the same interval as the mains. I think my 160 main's are still too small, but I haven't even opened the air jets yet. I think I'm going to open up the main primary to 170, and evaluate the air jets from there. I believe they're 65/60. That would mean I'd want to go to an 80/75?

 

Any suggestions on what I might look at increasing as far as the air jets go? This is getting a little too detailed for my noobish self to go without a second opinion.

[Z-train]

It is on a chassis dyno.

Z22 block

Z20 rods

custom slugs

U-67 un-ported

L-18 intake un-ported

32/36

Cam is from Rebello.

Distributor is mechanic with 17 intial.

factory airlceaner hosuing adapted to the Webber.

 

My point in posting this is that if i'm making this power then MM's 32/36 should support higher RPM's with proper tuning.

[metalmonkey47]

I don't think mines doing quite as well as yours right now, carb being the biggest issue at the moment. I was gonna open up the air jets today, but didn't find the right size bits, so I may go order new jets tonight or a re-jet kit. 

The truck stumbles SO bad when the secondary opens all the way for about a second or so and I'm hoping it has to do with jetting, because I've tried everything else. 

 

 

Video will be up in a second for you to see what I mean... 

 

 

http://www.youtube.com/watch?v=dNmP9mbeWEc&feature=youtu.be

[metalmonkey47]

For future reference, 

 

http://www.scuderiatopolino.com/TuningofWebercarburetorsrev2.pdf

 

 

^That is an awesome resource for understanding the importance of jetting. Def something I'm printing and putting in my Datsun handbook I'm making. 
 

 

 

My understanding is that an increase on the main jets would be considered to be .5 per step. So essentially my 140-160 jet was 4 steps. My air jets could not possibly be as small as I thought they were, probably thinking of the idle since redline weber starts at a 105 air jet and goes up from there.

 

The Air jet goes 20 per step, so maybe I need to asses my air jets and increase them about 1/2 step to a full step at a time. 

[Sealik]

For future reference, 

 

http://www.scuderiatopolino.com/TuningofWebercarburetorsrev2.pdf

 

 

^That is an awesome resource for understanding the importance of jetting. Def something I'm printing and putting in my Datsun handbook I'm making. 

 

 

 

My understanding is that an increase on the main jets would be considered to be .5 per step. So essentially my 140-160 jet was 4 steps. My air jets could not possibly be as small as I thought they were, probably thinking of the idle since redline weber starts at a 105 air jet and goes up from there.

 

The Air jet goes 20 per step, so maybe I need to asses my air jets and increase them about 1/2 step to a full step at a time. 

 

For future reference....

http://www.ebay.ca/itm/Innovate-LC1-Wideband-w-DB-Blue-Gauge-Kit-LC-1-o2-3795-/261225947537?pt=Motors_Car_Truck_Parts_Accessories&hash=item3cd247a191&vxp=mtr&_uhb=1

 

Might be shocked at the A/F ratio numbers you see

[Stupid_fast]

For future reference, 

 

http://www.scuderiatopolino.com/TuningofWebercarburetorsrev2.pdf

 

 

^That is an awesome resource for understanding the importance of jetting. Def something I'm printing and putting in my Datsun handbook I'm making. 

 

 

 

My understanding is that an increase on the main jets would be considered to be .5 per step. So essentially my 140-160 jet was 4 steps. My air jets could not possibly be as small as I thought they were, probably thinking of the idle since redline weber starts at a 105 air jet and goes up from there.

 

The Air jet goes 20 per step, so maybe I need to asses my air jets and increase them about 1/2 step to a full step at a time. 

 

That guide is different from every other resource I've read on 32/36 tuning.  Idle mix screw should be 1.5-2.5 turns out, it ran a ton better then when I was tuning to 2-3 turns out.

 

AFAIK 10 = 1 step up, 140 main -> 150 main = 1 step, .5's are just for fine tuning once its around the right setting.

Air jets 10 = 1 step...  BIGGER air jet = more lean at the top end.   

 

 

The video, that sounds just like a 32/36... Never runs right... its why I just replaced the carb.   Dude  it sounded like you were shifting at 3000rpm ... that's barely off the idle circuit. 

160/160 mains ?  can you tell if its a lean stumble(cuts out, then cuts in abruptly) or rich stumble(sputtering, bogging)?

[metalmonkey47]

Hmmmm...

 

I was shifting initially around 3-4K, I'm easy on the go since It's kinda loud and people were outside, didn't wanna scare them. Revved to about 5500 on the second shift pulling out. 

 

I opened the air jets from a 160-170 to a 170-200 and no change. I'm wondering if I leaned it up too far and still need to increase main jets another step or 2. 

 

It sounds like a lean stumble. If you abruptly open the secondary the truck chokes heavily and takes off with no warning. If I roll into the throttle It's okay and doesn't really stumble. I'm gonna go pull the plugs in a few minuets and go see how they look. 

[Stoffregen Motorsports]

It's a 32/36 DGV right? Do you know how old it is? Does it say 5A on the side near the other stamped in numbers?

[metalmonkey47]

Yessir! No clue how hold it is, it came from a junkyard. I replaced the gaskets, and accel pump and did a good cleaning. Been on there for almost 2 years now.Everything is okay now, power valve is working fine.

 

Only marking on the carb: 

 

 

 

 

 

Plugs don't look too bad:

 

 

[Sealik]

Plugs don't look too bad:

 

 

Looks like a rich mixture.

This was after idle...cruise or WOT????

[Stoffregen Motorsports]

Well it's hard to tell from the pic, but it doesn't look like a 5A.

 

Early DGV carbs had a single feed circuit to the emulsion tubes, the later carbs (5A) had a split system. In other words, when the throttle transitions from the primary to seconday circuit, the extra fuel needed to feed the secondary came from the primary emulsion tube area. This is the famous "bog" or delay between the primary and secondary. They fixed this when the 5A carb was introduced by giving each the primary and secondary their own fuel supply from the float bowl, eliminating the fuel starving caused by the transition.

 

If you got the carb from a junkyard, chances are it's an older carb. Get a newer carb and compare for yourself.

[68Datsun510]

My 5A works fine unless you stomp it at too low of RPM...

[620Turbo4X4]

I don't think mines doing quite as well as yours right now, carb being the biggest issue at the moment. I was gonna open up the air jets today, but didn't find the right size bits, so I may go order new jets tonight or a re-jet kit. 

The truck stumbles SO bad when the secondary opens all the way for about a second or so and I'm hoping it has to do with jetting, because I've tried everything else. 

 

 

Video will be up in a second for you to see what I mean... 

 

Are you still running the 160 thermostat?

 

My truck bogs like that when it's not fully warmed up. Try a 180 instead, so your not trying to tune a cold engine. (the raw fuel from the accelerator pump will atomize better at the higher temperature, and your forged pistons will like that much better too.)

 

Your plugs should be a light tan (preferred), to brown color. Not black. This will lead to plug fouling down the road. Try a BP8ES or B8ES like I originally suggested. Looks like the 9's are a bit too cold for it or you have gone too rich with the mixture. You should have easily caught up to that Toyota in front of you in the vid. Read my earlier post about the distributer mods I've done.  That helped my engine a bunch.

 

It also sounds too rich at light throttle. What idle jet do you have in the primary? My webber was originally a 60 and was fine at idle, but ran too rich at light throttle. I dropped it down to a 50 and opened up the screw a bit and it no longer "blubbers" at part throttle.

 

Good job with your engine. With a bit more tuning you'll have it nailed. :thumbup:

[Stoffregen Motorsports]

Honestly, that plug looks like one that has been fouled before. And maybe after it fouled, the A/F ratio was changed.

 

Once a plug has fouled or run way too rich, you can't really use it to tell you how your engine is running. The black never goes away. unless you bead blast it.

 

Also, looking at the tip of the plug is not how you do a thorough ID on mixture. You have to look deep into the plug, down the cone, to see how it's running. Sometimes even with a magnifying glass.

[budsaipan]

Do you have any specs for your motor? 

[metalmonkey47]

Are you still running the 160 thermostat?

 

My truck bogs like that when it's not fully warmed up. Try a 180 instead, so your not trying to tune a cold engine. (the raw fuel from the accelerator pump will atomize better at the higher temperature, and your forged pistons will like that much better too.)

 

Your plugs should be a light tan (preferred), to brown color. Not black. This will lead to plug fouling down the road. Try a BP8ES or B8ES like I originally suggested. Looks like the 9's are a bit too cold for it or you have gone too rich with the mixture. You should have easily caught up to that Toyota in front of you in the vid. Read my earlier post about the distributer mods I've done.  That helped my engine a bunch.

 

It also sounds too rich at light throttle. What idle jet do you have in the primary? My webber was originally a 60 and was fine at idle, but ran too rich at light throttle. I dropped it down to a 50 and opened up the screw a bit and it no longer "blubbers" at part throttle.

 

Good job with your engine. With a bit more tuning you'll have it nailed. :thumbup:

 

I'm running no t-stat right now :P I'm gonna toss a new stat in again sometime after my vacation and see how it goes. 

 

I'll go down a step tomorrow and see how it does with the plugs  :thumbup:

 

I'm not sure what size idle jets I have, but I really need to look. I'd like to say off of the top of my head that it's a 60, but I'm not 100% sure right now. 

 

Preciate the help  :thumbup:

 

Honestly, that plug looks like one that has been fouled before. And maybe after it fouled, the A/F ratio was changed.

 

Once a plug has fouled or run way too rich, you can't really use it to tell you how your engine is running. The black never goes away. unless you bead blast it.

 

Also, looking at the tip of the plug is not how you do a thorough ID on mixture. You have to look deep into the plug, down the cone, to see how it's running. Sometimes even with a magnifying glass.

 

It may be running a little rich. It still stumbles whenever I open the secondary after opening the air jets on the primary and switching the old primary to the secondary. When the secondary opens and it stumbles I actually feel sometimes like I'm LOSING power. it's a strange feeling. It's fine if I'm at high speeds and high RPM's pounding down the road. 

 

Do you have any specs for your motor? 

 

Z20E block 

Z22 Crank

86mm bore

Forged pistons w/ fully floating wrist pins

Z20 Long rods

A87 Peanut Head W/ ...

    -L28 Valves

    -1 5/8 intake ports

    -Racer Brown .475 Cam

    -C/R comes out around 9.4

Port matched intake manifold

Shorty Header

 

I'm sure I'm missing something.

 

EDIT: Just realized that's all in my original post. 

[budsaipan]

Are you pinging at all with that peanut head? 

[metalmonkey47]

not even the slightest. Ive run the timing every direction possible but it never pinged on 93 octane.

[budsaipan]

Awesome man.  :thumbup: Should check the dyno and see where you at once everything is running smoothly. 

[metalmonkey47]

Dyno will be done with new carbs! Don't want to dyno with this shitty 32/36

 

 

 

So I've run into a problem... The trucks been running strange the last 48 hours. a week ago I put on a new adapter to get rid of the tall home made POS that I had prior. Probably irrelevent but just putting it out there, Been running great for the last week but this morning it randomly started choking and missing. It fell flat on it's face for no reason and I don't know why. This afternoon it also did it. Now I just got home and it was at it's absolute worst. 

 

Dumped the clutch in the rain just playing with all my torque in the turn lane turning right, and when I straightened out and the tires finally grabbed it fell flat on it's face and ran out of power. Eventually it picked back up and it was okay. Turning left about 2 min later into my side street, it did it again. I can't seem to recall if when it did it the two times prior it was when cornering or not...But it seems that it's either a coincidence, or indication of the problem.

 

I'm wondering if maybe the float is stuck and the fuel is sloshing to the side in the float bowl and it chokes? I'd love to the the regular 'ol D-mike suggestion and drive it until it has the problem, and turn it off, coast to a safe place and open the float bowl but I never seem to be in the right place for that. 

[datzenmike]

Float may be too low and what little fuel there is, sloshes over and uncovers the jets and it runs out of gas. Check/set the float height.

 

Ha ha it's raining here today too! Goosed it coming off the lights and half way through first it broke loose and all the way through 2nd to 5K.

[metalmonkey47]

Got it. Again fuckin vacuum leaks! The carb adapter slipped a thread over a hairline crack on the side and one corner won't tighten.. im gonna JB weld the stud in place tonight and put it all back together. Off at 10: gonna be pretty much tearing the whole carb to pieces little by little. I pulled an idle jet out and it had shit in it. Again. After 2 days.

[datzenmike]

Check/replace the filter. The last two the element had fallen out and was loose inside.