R1 Carbs (lots of pics)

[VintageRice]

Spuddy?!?! What did you do to those poor carbs?!?

[datzenmike]

Intake plenum? That would be before the carbs correct? And open to the outside air. Vacuum is only on the engine side of the carb.

 

If a reading of only 10 " Hg is present, perhaps this carb is open too much and this cylinder doing all the work to keep the motor idling. In other words the carbs are not in sync. If all the carbs were adjusted so they are drawing the same amount of air through them, I bet the reading would go up. Try a different runner.

[Drummerboy4as]

My thinking was that the plenum might restrict airflow somewhat like a restrictor plate possibly causing the vacuum to increase. Just grabbing at straws.

 

The carbs are synced according to my empi syncing tool but I'll check again.

I'm getting 10hg off of 2 different runners. One with a 1/2" port for the brake booster and one with a 1/4" port. All the vacuum lines are clamped and I've checked multiple times for leaks at the head and the carb boots.

 

 

[spudly13]

Intake plenum? That would be before the carbs correct? And open to the outside air. Vacuum is only on the engine side of the carb.

 

If a reading of only 10 " Hg is present, perhaps this carb is open too much and this cylinder doing all the work to keep the motor idling. In other words the carbs are not in sync. If all the carbs were adjusted so they are drawing the same amount of air through them, I bet the reading would go up. Try a different runner.

 

I was thinking the same thing..

 

 

My thinking was that the plenum might restrict airflow somewhat like a restrictor plate possibly causing the vacuum to increase. Just grabbing at straws.

 

The carbs are synced according to my empi syncing tool but I'll check again.

I'm getting 10hg off of 2 different runners. One with a 1/2" port for the brake booster and one with a 1/4" port. All the vacuum lines are clamped and I've checked multiple times for leaks at the head and the carb boots.

 

I think someone said this, but couldnt timing/valve adjustment/and cam effect it vaccum?

[spudly13]

Spuddy?!?! What did you do to those poor carbs?!?

 

Well... i was taking them apart to swap jets and clean them out (i was worried they were plugged for some paranoied reason) and appearently when i put it back together i tightened the screw down to much and... snap! nothing a little jb weld couldnt fix lol

[datzenmike]

Cams with huge overlap... when intake and exhaust are open at the same time... act like a huge vacuum leak at low speeds and idle. Big cam V8s are still 15" maybe down to 12"?

[VintageRice]

R1` carb update.

 

Yesterday at a car gathering, a guy was chekin out my bay and grabbed my carbs and wiggled them and said"Man, I can't believe those are held on there with rubber hose!"

 

 

A while later I pulled out and the carbs fell off............yep...........in front of everyone...........

 

 

 

So, FYI, when carb boots are warm and covered in fuel inside, they get pretty slipery. Why covered in fuel you ask???

 

 

Well, when I got home(borrowed a crecent wrench to re-attach carbs) I was going to re-do the carb boots and adjust my air-fuel screws back down. I had them at 4 turns out to be on the "safe" side.

 

Well, don't turn them 4 turns out. Theres not enough spring pressure and they FALL OUT. Yes. Two of mine where GONE. No air fuel screws, so I was running beyond full rich on idle. That might explain the constant popping on decel.

 

 

So, once I order new screws, I'm going to set them at 3 turns out and see how she does. Also going to build some kind of bracket that holds the carbs against the motor. That way the only job the couplers have is to stay air tight, not support the weight of the carbs.

 

 

Just thought you all would like an update of my latest issues!!

[datzenmike]

Yes, it's all good info for the collective. One day I want to do this and don't want them falling off with the old lady in the car. :blush:

[spudly13]

im gunna go check my screws today....

[VintageRice]

Yes, it's all good info for the collective. One day I want to do this and don't want them falling off with the old lady in the car. :blush:

im gunna go check my screws today....

 

Both good plans.

[slingshot532]

I have been having the same problem with the carb couplers. The far back coupler keeps poping off where it conects to the carb. when that happens I start to get a poping random backfire.

 

As long as I can keep the carbs on the motor she runs great. I installed a choke cable so I can just jump in and start it. Befor I had to hold the "choke" open with a hose clamp, get the motor started and warmed up, remove the hose clamp, then get in and go.

 

I was going to ride my bike last weak and geting off the freeway I got stuck behind someone going slow. This other guy in newer BMW sped around me and got in the next lane. The slow person made it through the light so me and this BMW guy in a hury are at the light together. When we took off he pulled away quick so I floored it. we went left under the freeway and up a hill. I passed him so fast and kept going full speed up the hill. I don't think he was racing me but it felt so good to pull away from him like that.

 

This setup is so fun.

 

Rice, are you still thinking about getting that cam? I think a little moar top end would be nice.

[VintageRice]

Yeah the cam is still on the list for sure! I'd like the Nismo R4, cause its more of a NA cam I believe whereas the O&J is more aimed at the turbo side, but they are close in specs and the O&J is so much more affordable.

 

 

I was looking at my carbs tonight and it looks like building something to hold the carbs on wouldn't be too hard. I want to build some sort of bracket that will bear the weight of the carbs and pull them toward to motor. That way, the only job of the couplers is sealing airflow. Not holding the weight of the carbs too. Will keep you posted.

[spudly13]

I have been having the same problem with the carb couplers. The far back coupler keeps poping off where it conects to the carb. when that happens I start to get a poping random backfire.

 

Huh, i havent had this problem yet, what kind of clamps are you guys using?

[HudsonMC]

I was looking at my carbs tonight and it looks like building something to hold the carbs on wouldn't be too hard. I want to build some sort of bracket that will bear the weight of the carbs and pull them toward to motor. That way, the only job of the couplers is sealing airflow. Not holding the weight of the carbs too. Will keep you posted.

 

Where are you going to mount the bracket on the carbs? There doesn't seem to be any really accessible blind holes, screws, or anything like that...

[Ron1200]

Just an Idea... The dual Webers on my Alfa are supported via an adjustable (for length) rod that supports the bottoms of the carbs. It attaches at the lower end to the motor mount. It kinda looks like a 'T' .

[datzenmike]

Did anyone else measure their manifold vacuum on each runner? Was it low as in previous discussions? Will, or does having a line from each runner increase the vacuum signal up to a normal range of about 18-20 at idle???

 

Need vacuum for brake booster.

[DADZSUN]

Good to see this thread plugging along.

 

1) I'm running the Yamaha clamps and they're staying on tight. However, I noticed the 4 new OEM clamps I purchased to complete my set stretch a LOT. When it starts to get a little loose the carb will cough on start-up. Once tighten it up the problem is gone or substantially reduced.

 

2) I purchased a Pipercross airfilter from Bogg. I had the holes slightly offset up on the backplate to clear the hood - fits perfect. It's a *really* nice setup with no noticable loss in performance - but we are talking about a stock L16. I'd post a pic but this forum doesn't appear to host files, so once I get off my lazy @ss and post it on my site, I'll provide a link.

 

3) Vintage: A KA24E has been purchased from a pickup and will be installed over the winter after a rebuild. To restore some of that power the truck KA looses compared to the 240sx, I also purchase a JWT cam (A2409-N00S1) which apparently works with OEM valvetrain etc... From JWT's site "E256 / I248 .422" GOOD IDLE EXCELLENT TORQUE CURVE". With a lightened flywheel, the cam, loss of cat and short/open intake runners with R1 carbs, I'm pretty sure the car will offer lots of pep compared to a 240sx. ;-)

 

4) There was talk earlier about A/F ratios. Why not a Innovate MTX setup? They're cheap and seem to provide reliable data. The potential fuel savings with a proper tune should pay it off after a year - not to mention the piece of mind.

 

5) Speaking of fuel. Bogg suggested the Pilots be left alone and he sent me 2.0mm jets as a starting point for the KA. Apparently he's run as high as 2.5mm jet on his brother's race 2L engine.

 

6) Vacuum setting. Datzenmike, I did measure my pressure with a buddy's gauge but I can't remember the numbers. I do recall it seemed to be fair strong but it was bouncing around a lot to get an exact number. This winter I plan to get another manifold from Bogg for the KA and am still unsure if I'm even going to bother with a feed off each runner to balance for the dizzy.

[datzenmike]

6) Vacuum setting. Datzenmike, I did measure my pressure with a buddy's gauge but I can't remember the numbers. I do recall it seemed to be fair strong but it was bouncing around a lot to get an exact number. This winter I plan to get another manifold from Bogg for the KA and am still unsure if I'm even going to bother with a feed off each runner to balance for the dizzy.

 

It might bounce because of single pipe per cylinder as compared to 4 cylinders averaging into a common manifold. I've thought about it and each cylinder should average 18-20 else 8 cylinders would be higher, 12 cylinders even higher. I've heard talk of running a pipe from all pipes to a common one for a vacuum source. Be nice to have some input on this.

[VintageRice]

Good to see this thread plugging along.

 

1) I'm running the Yamaha clamps and they're staying on tight. However, I noticed the 4 new OEM clamps I purchased to complete my set stretch a LOT. When it starts to get a little loose the carb will cough on start-up. Once tighten it up the problem is gone or substantially reduced.

 

2) I purchased a Pipercross airfilter from Bogg. I had the holes slightly offset up on the backplate to clear the hood - fits perfect. It's a *really* nice setup with no noticable loss in performance - but we are talking about a stock L16. I'd post a pic but this forum doesn't appear to host files, so once I get off my lazy @ss and post it on my site, I'll provide a link.

 

3) Vintage: A KA24E has been purchased from a pickup and will be installed over the winter after a rebuild. To restore some of that power the truck KA looses compared to the 240sx, I also purchase a JWT cam (A2409-N00S1) which apparently works with OEM valvetrain etc... From JWT's site "E256 / I248 .422" GOOD IDLE EXCELLENT TORQUE CURVE". With a lightened flywheel, the cam, loss of cat and short/open intake runners with R1 carbs, I'm pretty sure the car will offer lots of pep compared to a 240sx. ;-)

 

4) There was talk earlier about A/F ratios. Why not a Innovate MTX setup? They're cheap and seem to provide reliable data. The potential fuel savings with a proper tune should pay it off after a year - not to mention the piece of mind.

 

5) Speaking of fuel. Bogg suggested the Pilots be left alone and he sent me 2.0mm jets as a starting point for the KA. Apparently he's run as high as 2.5mm jet on his brother's race 2L engine.

 

6) Vacuum setting. Datzenmike, I did measure my pressure with a buddy's gauge but I can't remember the numbers. I do recall it seemed to be fair strong but it was bouncing around a lot to get an exact number. This winter I plan to get another manifold from Bogg for the KA and am still unsure if I'm even going to bother with a feed off each runner to balance for the dizzy.

 

THANK YOU! !

[VintageRice]

Did some fabrication today.

 

This should keep the carbs from ever falling off.

 

Welded

 

 

Painted

 

Installed(temp, its coming back off soon)

 

 

[72240z]

Thats pretty neat, gj

[spudly13]

I like it! its a lot more extravagant then i was thinking! Vintage are you gunna make the next northenders meet on the 25th?

[VintageRice]

I like it! its a lot more extravagant then i was thinking! Vintage are you gunna make the next northenders meet on the 25th?

 

WHAT what WHAT?!?! I never heard! Heck yes I am!

 

I need details.

[HudsonMC]

Did some fabrication today.

 

This should keep the carbs from ever falling off.

 

Installed(temp, its coming back off soon)

 

Are you planning on running an air filter?

[VintageRice]

I should rig something up. I really like the way it looks now though and any filter is going to gay it up..........I dunno......

 

Maybe some screen in the horns.......Maybe a quick release oval foam filter I can take off........Maybe screen caps on the ends of the horns......

 

Any better Ideas?