Weber DCOE's installed | Initial impressions

[Leon]

I agree that 40s choked down to 33mm on a 3.1 motor is way too small, a rookie mistake, turning now into an epic mistake. Sad/Funny to witness.

Because he had them laying around. Yeah, but no. Doesnt change it for me.

 

Wow, and are you the God of Zs? Go back to Zcar.com.

[Gollum]

My initial impressions, this is gonna be a hell of a "project" with a lot more work to go!.  I was hoping I could get the carbs on the car for about $500.  I got the carbs, manifold, and linkage from the PO with the car...with all the other misc pieces and "while I'm at it" stuff...so far I'm about $1600 in!  A lot of the cost came from air horns and new main venturi's (carbs came with 30's), but there were a lot of little odds and ends that added up quick!  

 

 

I believe I got my carbs for $650 with everything, but after the rebuild, ITG filters, air horns, heat shield, I was at around $1500 also.

 

 

And people look at me like I'm crazy sometimes when I mention EFI as a "budget" solution compared to any form of triples... 

 

That said, I'm always happy to see another engine bay like this, even if it is sad/funny.

[T-Bone028]

Anywho, figured I show some pics of how I ran my throttle cable.  I wanted the least amount of permanent modification as possible, and I think I was able to accomplish it with a great pedal feel and smooth action/return without any binding.  

 

Parts list:

- Lokar 36in throttle cable, I used p/n: LOK-TC-1000U36 ($48 from Summitracing)

- Quick Disconnect Ball Joint Assembly 5/16-24 ($15 for 2 from Amazon.com)

- 5/16 (8mm) rod arm p/n: 99006.251 ($8 from pierce manifolds)

- DCOE bottom mount cable bracket, p/n: 40930 ($33 from Pierce Manifolds)

- DCOE external spring kit, p/n: LT5000 ($32 from Pierce Manifolds)

- 16" stainless steel linkage rod p/n: 36016 ($13 from piercemanifolds)

- 2 5/16 shaft collars p/n: 99024.350 ($13 from piercemanifolds)

- Last piece was the firewall bracket that replaced the bell crank.  I received it from HybridZ member Savage42 for $25.  This could probably be made for you DIY'ers.

 

Total cost: ~$187  I'm sure some of you more creative/thrifty folks have done something similar for a whole lot cheaper...but this was all readily available, off-the-shelf products delivered to my door.  

 

 

The Lokar throttle cable has one end with a ball and cup (1/4") that can be disconnected.  Unfortunately the cup is too small to fit over the datsun pivot ball.  So, I took the 5/16 quick disconnect ball joint and slid it over the lokar cable end, and bonded the two permanently in place with JB Weld.  I like the quick-disconnect because it takes me all of 30 seconds to completely disconnect my throttle cable to make adjustments.  Plus, I didnt have to crawl under the dash and modify the gas pedal at all.  The only other "modification" I had to do was trim the cable sheath 3" to give me more cable wire. Here's a pic of the cable (that shows both ends of the cable) and the quick disconnect ball joint before being JB welded together..

 

 

And here's a pic of it in place along with the firewall bracket from Savage42:

 

 

To connect the throttle cable to the carb/linkage, I used the DCOE bottom mount cable bracket from PierceManifolds, and a small L shaped bracket I had leftover from a universal choke cable to attach the other end of the lokar cable to the rod arm on the main linkage rod.

 

Here's a pic of the bottom mount from Pierce Mainfolds, and it attached to the center carb.

 

 

 

Lastly, the return spring is fitted to my 1st carb closest to the radiator...its the only return spring I'm running and with all the rods/arms attached to the carb/main linkage rod, all carbs return fully to the throttle stops.

 

 

Based on some other posts, seems like I'm of the lucky few that is able to run all three rod ends on my intake manifold (brand is Redline).  With my throttle cable rod arm mounted closely to the center rod end, I have good mechanical advantage and solid support to avoid bending the linkage rod. I've read some other experiences of folks only being able to run two rod ends due to uneven spacing and in some cases, the linkage rod flexing/being bent.  I believe a fix for some folks has been re-drilling the manifold to accept 3/8 rod ends and a beefy 3/8" rod. Or JB welding the center rod end mount, and re-drilling to be centered correctly. 

 

Hope this helps someone, it probably took me a solid few days of thinking about and finding all the parts online I would need to make everything work as I envisioned.  Now if only this weather would cooperate so I can continue tuning my rookie-mistake carbs!

[AZGhost623]

Man Im super interested in that throttle cable setup. I have been looking for a decent setup and a how to for some time. I may be asking you some questions later

[Heroez]

If he put as much time and effort into making some cash as he is the carbs, He would have the ITBs or whatever. It just seems like a waste of time, and materials to dedicate his resources to something subpar. Im not saying build a rocket. Im saying its not a well thought out plan. Planning is fundamental. Think about it. He is choking down a 3.1 stroker, limiting its effective power. Why? Because some old carbs sized for a 2.2-2.4 engine were laying around? That is a bad plan! Build a 3.1 stroker and not take advantage of it. Why bother. Who here would opt to put 40mm DCOEs choked to 33 on a 3.1 stroker? Not me. I would try and find a sucker that doesnt know 40s are too small, and sell them for whatever I could get. Spend my time making/saving money instead to purchase something optimal and/or in balance with the motor work.

[Heroez]

Wow, and are you the God of Zs? Go back to Zcar.com.

No Leon, you are. A lot of people including me look up to you and others here. Lets say I had a 3.0 turbo motor, MS2, ported head, cam, intercooler, 3 inch exhaust, OK? I had this t25 turbo charger laying around. So I start to install it. I would hope you or someone would say- Dude, that turbo is too small for the motor! What are you thinking? Before I got too involved in building in retarded performance. I like Tbones drive and passion, we all do. He is a good guy. Dont we owe him the truth? Even if its hard to listen to? I think he is in reach of something greater. That is my take on the thread. That is all, just saying. I may be a monster, but Im an honest one. Now let us all get back on topic aye?

[duragg]

You will learn a ton with the 40s and down the road you can apply that knowledge to some 45s when the budget is ready.

I have a big aftermarket vacuum resevoir kit which helps at idle, along with header wrap, blankets, shields and venting.

 

I have the double rubber o-ring anti vibe mounts and secretely hate them. Tried every o-ring, Thackery washers, the Pierce Manifold rubber washers, no washers. I've read many posts of racers that delete them. Since I am mostly done being a street car I may do this.

Edited May 19, 2013 by duragg

[T-Bone028]

Hey Heroez, I'm addressing you directly (again)...thanks for your opinion.  I'll make sure to run everything I do by you first, I'm just not good at planning things.  Wait...did I just make a plan?!?  Awesome!!!!

 

Moving on...I finished up my heatshield and put it on this morning.  I purchased the heat shield from ZCCJDM.com...its a nice piece, but being universal, it had to be modified to fit.  It took some time to trim the heatshield to fit my engine bay and I ended up having to use brackets to mount it to the intake manifold studs.  There just wasnt any way to get it securely in place with the existing mounting slots.  If I were better at planning, I probably could have just made the shield myself... but I'm relatively pleased with how it turned out.

 

Here's a pic from ZCCJDM's website...when I received it in the mail it looked nothing like the picture from zccjdm's website, it had a lot of additional material on top of the mounting holes and it would not fit as received due to clearance issues with the carburetor bodies.

 

 

Aside from trimming the excess material above the mounting slots, and adding brackets, I also had to trim part of the shield to clear my brake booster vacuum reservoir.  Here's a picture of the shield trimmed to fit, thermo-tec heat adhesive backed heat barrier applied (about $18 from summitracing), and brackets added.

 

 

And lastly, as mounted in the engine bay.

 

 

Weather still wont cooperate and its forecasted to rain the next 5 days...so once I get permission from Heroez and the weather clears up, I'll be able to road tune and try out different jets.

 

Moderators, please feel free to move this thread to the members project sub-forum if it makes more sense.  Heroez, that okay with you?

Edited May 19, 2013 by T-Bone028

[T-Bone028]

Oops, double post.

Edited May 19, 2013 by T-Bone028

[T-Bone028]

Hey duragg...good feedback.  I've heard mixed reviews on the anti-vibe mounts and o-rings.  Some say they're necessary, others say that they get vacuum leaks with them.  

 

If I notice heat-soak or noticeably inconsistent AFR's, I may switch out the paper gaskets to the anti-vibe mounts and get lower profile air cleaners.  Right now, my filter height is 3 1/2 inch...with a lower profile air cleaner, I would only have 3/4" space between the air horns and filter lids using a 2 1/2 inch height cleaner...that and they are around $45 a piece!  

 

Has anyone had any direct experience between using stack filters and a regular oval airfilter?  I've read the stack filters reduce the effectiveness of the lip/radius in the air horns and I worry about their filtration...they look pretty wicked though.  Regarding foam/ITG's...just dont love them, and I've read some experiences of their durability after a few years.  

[Gollum]

No Leon, you are. A lot of people including me look up to you and others here. Lets say I had a 3.0 turbo motor, MS2, ported head, cam, intercooler, 3 inch exhaust, OK? I had this t25 turbo charger laying around. So I start to install it. I would hope you or someone would say- Dude, that turbo is too small for the motor! What are you thinking? Before I got too involved in building in retarded performance. I like Tbones drive and passion, we all do. He is a good guy. Dont we owe him the truth? Even if its hard to listen to? I think he is in reach of something greater. That is my take on the thread. That is all, just saying. I may be a monster, but Im an honest one. Now let us all get back on topic aye?

 

In the end though, 75% of the money he's spending won't get re-spent should he decide to step up to 45's.

 

Believe it or not, many people on this board (Leon included I think) would rather spend MORE money on their car in order to have it DRIVEABLE between iterations rather than taking on more at once in order to save money.

 

T-Bone had these lying around, so he figured "what the heck?" and went at it. I admire that. I've got a P90 sitting around that I'd love to weld the chambers on... have I? Nope... What would it cost me? Almost nothing really, just time. I admire those that get out there and actually DO IT!

 

As to the turbo analogy, it's a fair analogy. But again, 75% or more of the time and energy will NOT be wasted. The things you do and learn about tuning a turbocharged motor are a higher priority than the actual horsepower you extract, and in the end a well set up T25 engine cam still make 250-275 to the wheels. Yes you can make more with a larger turbo and yes many of us do. Right now my turbo S30 is stuck in a garage due to not having a functional EFI. I'd rather be driving that car, even if it meant a few less horsepower, just to at least have it on the road.

 

So yes, I understand your point, but at the end of the day, horsepower isn't everything, even on HybridZ.

[ram75280z]

I really wasn't saying don't do it. Just saying that you're leaving a lot of power on the table if you keep the 40s on there. I only mention it because I have seen it soo many times. Many, many folks with 2.8s & stage 3 cams(and bigger) running around making around 200hp(at 5600rpm) & wondering why, because they have tripples. Yea, tripples with 32mm chokes, even some with 45s have 32mm chokes, in the name of low rpm power. They don't notice the dropoff to 4cyl power at 6500rpm, when they should be peaking around there, because their engine has that strong mid range & the dropoff is so progressive.

 

By all means have fun this summer, & I'm sure you will because you have great throttle response & more power. But, next winter, find someone who has a 2.4 or 2.6 & sell or trade them, knowing what you know now & learn this summer with what you have.

 

On a side note, CFM is important. But it really only affects power, an engine is setup to make, within the rpm range as I described in my previous post. You still need to have properly tuned intake runners. The beauty of the tripples is that you can do most of that by changing the choke size, given they're the right size to start with.

[T-Bone028]

For those following this thread (and I hope my experience thus far is interesting to you), I was able to do some tuning today.

 

But first...Ram, I agree, I could be leaving power on the table...but I also left some money in my pocket!  My primary cost on these specific 40 DCOE's, are the 33mm venturis, air horns, and filters.  Everything else, like Gollum mentioned previously, would have had to be purchased regardless (assuming I purchased used 45's).  Rebuild kits, additional linkage/throttle cable pieces, heat shield, manifold gasket, fuel hose/fittings, supplies, etc would still have been needed.  And different main venturis could be a cost if the set of 45's I hypothetically were to purchase werent already ideally sized.

 

However, what I really gained out of this project (aside from a LOT of fun) is experience.  I now have a far better understanding of the disassembly/assembly, various circuits, and tuning of a DCOE carb then I ever had reading the Weber carb books I've been casually scanning through for the past 3 years.   

 

And as you mentioned...the beauty of these DCOE's are their design.  I can always bump of the choke size with almost minimal work.  Lastly, regarding CFM's...what I posted was for all intents and purposes...100% arbitrary.  Numbers picked from obscurity over multiple years, unknown flow benches, and a whole lot of other variables.  But in the end, I now have 6 carbs with 33 mm venturis, instead of 2 carbs with 32 mm venturis.

 

On to my tuning experience this afternoon...I removed the air horns to make room for my sychrometer and measured their flow, and I changed my idle jet from 50F9 to 55F9.  They are now all about as close as I could get them without being drastically different from the number of turns out on the idle mixture screws.  I bench-set the idle speed screws prior to installing and dont plan on changing their position.

 

Idle speed now hovers between 1000-1100 RPM, and AFR at idle is 12.5 to 13.  Under load, AFR's up to about 2000-2500 RPM are in the 11's...however, I did not get the chance to get up to a real cruising speed (just running around at 30 mph on a short road less than a 1/4 mile from my home).  Hopefully, this weekend I can take her on the highway to get a better idea of AFR's at steady state cruising.

 

The real effect I noticed from the change of 50F9's to 55F9's, was the dreaded "bog" other people have experienced with triples.  When flooring the throttle with the 50F9's from about 10 mph, I would get a slight half-second bog before getting planted in my seat.  Now, with the change to 55F9's...the bog/hole/hesitation/what-ever-you-want-to-call-it, is effectively gone.  I'm sure if I were strapped to a dyno with every single measurement device known to man hooked up, there would be data that shows there is a bog.  But from a "seat of the pants" feel, there wasnt anything I could perceive...and somehow a grin ear-to-ear is permanently on my face.

 

Finally, I was able to look at my AFR's at full throttle at 6500-6700 RPM.  They climbed up to about an AFR of 13.8 at WOT.  I may change my air correction jets from 180 to 170 to see if I can richen it up on top.  From 2500-6000ish, AFR's are in the 12's at WOT...so according to the gauge, I probably dont need to change anything with the mains.  Will I change my mains to experiment?  In the words of Sarah Palin, you betcha!  

 

For those debating the move to triples, do it!  So far, they have been completely drivable on the street, 100% fun, and noticeably faster in comparison to my SU's (SU's were rebuilt by Ztherapy in 2002). Hope to give some more updates as I progress through this project/exercise. 

[Heroez]

The Weber bog. Small accelerator pumps. Overcome the track design to fit street driving. That is the other fun bit.

Edited May 20, 2013 by Heroez

[Leon]

No Leon, you are. A lot of people including me look up to you and others here. Lets say I had a 3.0 turbo motor, MS2, ported head, cam, intercooler, 3 inch exhaust, OK? I had this t25 turbo charger laying around. So I start to install it. I would hope you or someone would say- Dude, that turbo is too small for the motor! What are you thinking? Before I got too involved in building in retarded performance. I like Tbones drive and passion, we all do. He is a good guy. Dont we owe him the truth? Even if its hard to listen to? I think he is in reach of something greater. That is my take on the thread. That is all, just saying. I may be a monster, but Im an honest one. Now let us all get back on topic aye?

 

My entire point here is that I don't have a problem with the content of your message, but with your delivery. Condescension and trolling are best left at ZC.C.

 

I try to hold online conversations like I would face-to-face ones. If you walked up to a group of guys hovering around T-Bone's car and proceeded to say what you said in the manner you delivered it, you think that would go over well?

 

Gollum said it well, I'm in agreement with the "get the car working and enjoy it" philosophy. At that point, you'll learn strengths and weaknesses which will guide you into the proper direction. If/when T-Bone028 decides that his engine is under-performing and he is no longer having fun - which is the whole point since he's not building a top-tier race-car from which every .01hp must be extracted from - then will be the time to re-evaluate his plan.

 

For now, enjoy yourself, T-B. Triples are a ton of fun and the process of setting them up can be both very frustrating but very rewarding.

[Heroez]

Leon, well maybe I have a communication problem. I was in big brother mode I guess. If I saw that car with you guys around, with that set up, yeah, I likely would say something like- 'you know, those 40s are too small for that engine.' He would get that quite a bit actually. Dont you think? After his explanation I would probably go look at a different Z car, and stand around with some different guys.

[duragg]

Sounds like your tuning is coming along.

I found when I had a wideband that the nature of a "bog" was often not what it seemed.  What I thought was lean due to small accel jets was actually splashing the Wideband to sub-10 AFR.  And what I thought was too rich in progression and transition was actually lean from bad prog-port placement and long reach from prog to mains.    The wideband made it all painfully obvious and when the sensor finally died and the car was performing well enough I didn't replace the sensor for a while and lived quite peacefully in that region.

 

The Sidedraft Central forum and the FAQ (All who live for) should be read frequently as there are small gems inside all of that.

 

I did quite well with my 40s on 34 chokes and made fine power.  At one track I would max out 3rd gear at the end of the straight prior to braking.  Later I put on the 45s with 40 chokes and at the end of that same straight I was most of the way through 4th gear.  Measurable, yes.  Awe inspiring, not as much.

 

When my next head is done the 45s will be put to better use.  

 

Leon:  Thank you for putting it all in context with respect to conversing as if face to face and the Hybridz rules mention this in the last sentence.  Very well put.

Tom.

[steve260z]

T-Bone,

 

I'm about 1 week behind you. Waiting on a couple of linkage pieces. Anyway, I have a stroker as well. After weighing the differences between 40s and 45s I chose 40s. I've rejetting them and currently have 34mm chokes. Since I couldn't find any hard data regarding these two carbs on a stroker I went conservative thus guaranteeing good street performance verses a car that only performed between 4,500 and redline. Its a street car. Not a track car.

 

Interesting write here: Based on a 2.8 but still good and from a good source.:

http://datsunzgarage.com/weber/

 

I'll update my install within the week.

steve

[T-Bone028]

Nice Steve! Hope some of my posts gave you some ideas. When I selected 33 chokes, I looked at every single graph/table I could find and read countless posts. For my first iteration, I too was worried about selecting something too big and being disappointed with low-end grunt.

 

So I looked at some reviews of people running L28's with 32's and some people with 34's. I would say some folks pointed to the smaller side for the street. That's when I said eff the graphs amd split the difference between 32 and 34 to come to 33 for my starting point. Extremely scientific. As I continue to drive and tune, I'm going to keep my eye out for used jets/parts.

 

Good luck Steve, hope to read something from you soon!

[steve260z]

T-Bone,

 

Oh yea, you will. After wrestling out stuck pump jets, grinding down the intake manifold to fit next to the headers, ordering all new chokes, main jets, E Tubes, Idle Jets, exhaust jets, main jets and air correctors I've finally got the carbs on the car.

Not to mention soft mounts, T and deadhead fittings and billet linkage. I've now discovered I need left side throttle levers so those are coming thursday. But, without any throttle I've got the webers/car running at idle! Sounds great and idles well. I haven't messed with the timing yet. I just wanted to make sure my gaskets and hoses didn't have any leaks since I was making an order to Pierce anyway.

steve