R1 Carbs (lots of pics)

[Stupid_fast]

rich popping is/sounds sooo cool though

...as long as its not killing the F out of your gas mileage :)

Its only on deceleration in the idle circuit.  

 

 

It gets tiring when it pops loudly any time you engine brake.

[Dawa]

i hear ya. i dont engine brake very often, especially in my 620.

when i do, it pops like youre talking about (but im not runnin the r1 carbs yet)

[Stupid_fast]

@Dawa ... That 'usually' means the idle / low speed circuit is rich.  Try leaning it out a bit.  Better to have the motor running correctly IMO.

[Dawa]

i do appreciate it, however i am aware.

i replaced the 32/36 carb the truck came with a new one and tuned it

however

my stock 1.6 is slowly dying (major oil consumption, etc)

i have a rebuilt 2.0L waitin to go in i just gotta find the time :)

[Stupid_fast]

I'm going to try this solution to my lean surge/popping at cruise ... This may be the answer I was looking for. 

 

Also for the guys who have their needles thrown way off to get the cruise mixture correct... you're doing it wrong !!!

http://factorypro.com/tech/tech_tuning_procedures/tuning_pilot%20jet,%20affect%20of%20size%20on%20idle%20and%20cruise.html

 

 

 

 

 

Question:

Greg Johnson wrote:
 
> I have installed one of your 1.0 jet kits on my R6 and I am coming to the final parts of tuning it.

> It runs well and passes most of the tests as provided on your tuning guide. It does, however, appear to be lean low down, as there is a "hole" when cracking the throttle wide open at below 2500rpm and at high rpm/part throttle, it shows some surging. I have though set the fuel screws, so that it idles correctly and returns to the correct rpm, when the idle is set below 1000rpm and the throttle is blipped.

> To fix the lean patch, is it better to go the next step up in pilot jets, rather than adjust the fuel screw?
> Will upsizing the pilot jet, require re-adjustment of the fuel screw and thus negating some of or all of the gains made by the larger pilot jet?

> Thanks,
> Greg J


Answer:

Greg - Good diagnosis on the pilot jet size -

As far as the pilot... Look at it this way...

There are 4 outlet holes for the pilot mixture. ~3-4 at the butterfly and one "downstream" of that (for 75% of the idle mixture).

1 hole is controlled by the mixture screw and with the other 3 or 4, max flow is limited by the size of the pilot jet.

At idle, 1 hole (metered by the fuel screw) and 1 un metered hole are open.

At cruise, when the "butterfly" is just "cracked", all 3-4 unmetered holes + the 1 metered one are uncovered -

So.....

At cruise, you get those 3 unmetered holes + the metered hole... So, at least 75% of the fuel delivered at cruise is limited by the size of the pilot jet.

At idle, you get 100% of the trimmed 1  hole + a butterfly valve-trimmed amount of the other 3-4 metered holes.

Rule of thumb....
If you go 1 size larger or smaller on the size of the pilot jet, you will change the fuel screw ~1.5x richer or leaner to retain the original idle mixture -

Example:
You have a #40 pilot jet installed (with the proper main, needle height and fuel  level already done)  and to get best idle, you are 4.0 turns out (from lightly bottomed out).
Cruise seems lean....

So, I'd expect that I could richen the cruise with 1 size larger (42) pilot jet (size of pj is 75% of cruise mixture) and the "trim" the fuel screw "in" for best mixture for best idle (size of pilot is 25% of idle mixture).

To go back to ~ the same idle mixture, after going from 40 pj/4.0x to the 42........ try 2.5x

40 pj / 4.0x = our reference idle mixture
42 pj / 2.5x = ~ same idle mixture
38 pj /5.5x = ~ same idle mixture (this is a "stretch - after 4.5x, not much changes)

(Using another "rule of thumb", if you have the correct pilot jet, the fuel screw will end up at between 1.5x and 3.0x when set for best idle.)

Marc

 

[Dalesun]

Dont want to read thru this again to find it but has anyone been able to get a intake mani for the r1 carbs recently. I heard bogg brothers stopped making them. Is that true?

[Stupid_fast]

Dont want to read thru this again to find it but has anyone been able to get a intake mani for the r1 carbs recently. I heard bogg brothers stopped making them. Is that true?

then search through it.

 

Send an email to Steve and ask. 

boggbrothersltd@btconnect.com

[Dalesun]

then search through it.

 

Send an email to Steve and ask.

boggbrothersltd@btconnect.com

Thanks. Ill shoot him an email

[Stupid_fast]

What kind of fuel pump setups have been tested with these carbs ?? 

 

 

Anyone running an aftermarket fuel pump or even stock datsun pump on these?

 

Curious if anyone's tried a return line setup. 

 

 

Mine's just running a stock R1 pump, trying to find something to advise to my friend who is doing R1's on his KA.

[spudly13]

i ran a stock l series pump and it worked great

[DADZSUN]

Dalesun, with my Bogg-equipped KA24e almost ready to run, I'm done with my Bogg L20B intake manifold if you're interested.

 

Funny on the pilot jet info. I've finally figured late last year that my R1 L20B throttle sticking issues were related to the OEM R1 (.175) pilot jets being too small. For the larger KA24e I've gone up two sizes (.25mm increments) to a .225. I've also installed 21 mains, Bogg thought that might still be too small. We shall see in the next few weeks, I have a wide band O2 sensor to help.

 

I've also installed a set of DCOE velocity stacks (45mm). I had to machine down the carb mouth's lip a little but it's a perfect friction fit. All will fit under a deeper Pipercross filter. Pics to come.

[Stupid_fast]

How did you hold the velocity stacks on?  Mine have just rubber hose around them and its hardly ideal... they usually fall off when I pull the filter.

[DADZSUN]

These velocity stacks slide over the outside of the carb mouth (about 1cm). The velocity stack ID is not the same as the carb's ID, ~42mm

 

When I machined the outer lip on the carb mouth I made sure to leave enough material to make a tight friction fit with the velocity stack. Bogg said they use some kind of bonding compound as well. I also shaved the carb mouth's inside lip so that it has a smoother transition to the velocity stack's larger ID.

 

Bogg also said they've seen better airflow/hp on the dyno with these exact units. If I can squeeze another 5hp that is good for me, my primary interest is the sound.

[Kirden]

Wanted to stop by and let everyone know that Steve at bogg brothers contacted me back and they still make manifolds for the A-series datsun engines. Very decently priced as well. I'm pretty sure they still make the L-series design as well so be sure to contact him and double check prior to ordering your carbs.

[MantisX620]

So what happens with the PCV valve when adding these? I just bought the boggs manifold off Dadzsun. I know ill need to add a nipple to the manifold for the brake booster, but does the PCV port now just run to a catch can?

 

Thanks

MantisX

[Stupid_fast]

I run it open PCV. works fine. 

 

spits oil out the crank case at high RPM though. (above 6k) 

 

 

Set up a catch can and route the exit to air filter box so the majority of vapor gets sucked back into the engine.  

[MantisX620]

Thanks Stupid_Fast, will do.

 

For the guys that didnt hook up vacuum for your brake booster, how did they feel?

 

MantisX

[Stupid_fast]

remove the brake booster or run vacuum balance thingy across all four runners. 

[Dalesun]

They still do make the l series manifolds. Also have a bunch of the other parts to go with it like cables, air filters, connectors and I think jets. Just the manifols with shipping to Eugene, OR would be $410.00.

[MantisX620]

Hoping ratsun can help on this one. Took my r1 l20 on its maiden voyage and had to call a tow truck. I was driving along and it died on me. Would not start back up. Thought it might be flooded so I waited 20 mins and did the ole floor it and crank. No dice.

 

What do you guys think it could be? I'm still on points ignition. Could it not handle the R1s? The carbs have 1.8 main jets and I'm out 3 and a half on the idle mixture screws. I'm using the stock fuel pump. Engine is completely stock

 

Thanks

MantisX

[Dalesun]

As long as your points work. Dizzy doesnt know what carb is on there. Did you check for spark? Heard of people getting stranded with points cause the points go out. When I had points I always had two spare sets on me. See if it has spark. If the dizzy is the problem go ei. Hell go ei anyways. Way nicer to not have to worry about points. But find out your problem first.

[MantisX620]

Yep, I've confirmed the carbs aren't to blame here. I'm working through my electrical now as I was able to start it today. A 78 620 disti and box will be installed this week.

 

Thanks

MantisX

[Dalesun]

One of the best improvments you can do. There is a couple write ups on here that explain everything.

[Kirden]

I'll just drop these here as well...

 

 

R1 manifold for my oval port A15 from bogg brothers. Threaded bosses on the first and last runner to anchor the carbs for boost, r1 style connector ends, and shiney to boot! The section across the middle was for manufacturing only and will be removed prior to install.

[MantisX620]

Sweet!! Gonna have a build thread on the boost project?