Sterling

Realizing that many of the people here have ported engines, I can't leave them out of my intake poll. However, since there are so many different types of porting, I will limit myself to one poll to include just street ported 12As. They are inexpensive to do yourself, and it's my guess that there are more of them around than any other types.

yayarx7

FI rules......period.(except for price)

4ohfour

I vote the last one, go fatty go!

cheers'

kylekyle

stock Nikki with street ported motor -- is it OK??

kylekyle

this summer I wili make street port and I need info, whot everithing need changed

82streetracer

iTrader: (1)

im going with the streetport weber from mazdaracing

yayarx7

I still would run a yaw on anything on the street, unless I had FI

DriveFast7

iTrader: (1)

Dellorto on a Lake Cities intake manifold. Best throttle response of all the carb/manifold combinations. Mid and upper rpm's SCREAM. And with 37mm chokes, it makes same low end torque as the RB 2 piece mainfold.

BradP

RXcetera

Haha, which means... NONE!

DriveFast7

iTrader: (1)

Nope. U ever driven one? I would pull away from my friends 325i straight 6 coming out of the turns. Those 6's are known for torque.

Swing and a miss!!!

BradP

RXcetera

haha... guess you havent been on here much huh?! I rebuild Dellorto's on the side... I've driven (drive) them.

I can safely say (and so can anyone else running Dells with RB manifolds on here) that they have minimal low end torque. Stock Nikki's are better and faster below 4000rpm but the Dellorto SHINES at high rpm. Smaller chokes or spacers on the RB manifold will increase low end torque somewhat but will kill high rpm power. The carb can be jetted/choked to perform the same with the lakecities manifold, but there's no way you'll get more torque at low AND high rpm. It's either one or the other. Such is the nature of the big 2 barrel beast lol.

Dude, you and me have write ups on Daves site . How is your tuning going? What kind of jetting are you running now?

SilverRocket

I will safely say that as well! As in, no low end torque. As in, floor the gas in 5th gear at 3k and fall asleep before you hit 4k lol. But drop it down to 4th gear and hang on...

DriveFast7

iTrader: (1)

I got the same torque and much better hp especially at hirpms with the lake cities manifold and smaller, 37mm chokes. I didn't say more torque than RB manifold, just the same torque. Yeah, the torque on the RB manifold and dell isn't fabulous (the manifold don't flow well so to compensate they put in larger 39mm chokes to get more air in there, which hurts low end), but that setup is very driveable and makes good hp. I prefer it over my trick Rx-3 Nikki carb anyday.

Big chokes in a 2bbl, low rpms, and flooring the gas = bog.

If you want torque, you've got the wrong motor. Rotaries are hirpm hp and not much torque. Like a local engine builder told me "there will be no discussion about torque. these are rotaries!"

As for my tuning of the dellorto, it's been in a box in my closet since August when the junk yard motor broke. I got a 12a bridge being built, will be ready late June. Then the tuning starts all over again with the dellorto.

How'z your dellorto going now?

Later,
BradP

RXcetera

My personal one is great.... the systems that support it are crapping out though lol. It was great last fall and got even better when I went to 220 main fuel. 90 pumps made a huge difference in driveability too, but really hurt mileage. I'm having some serious fuel delivery problems though. I guess those RB Facets arent cutting it. Finding a ACCURATE 0-6psi gauge would be nice. What pump are you using again? I was thinking of picking up a Carter street/strip pump but it's waaaayyy too loud for me .

SilverRocket

Lol, bet you woulda picked one up if you hadn't heard mine first...

RXcetera

You got that right. Imagine that thing on my car with zero soundproofing? Ouch .

DriveFast7

iTrader: (1)

I use a Holley Blue 110gph. It is loud even with the little rubber gasket inbetween pump and body. I didn't think it was annoying, just audible. A friend built a subframe for his out of a metal box. Metal box mounts to floor, pump to metal box. Isolated sound.

That pump supplied pleanty of fuel on my 12a sp, wide open exhaust, going 120mph full throttle down straighaways on the track lap after lap.

As for fuel pressure gauges, I just use the Autometer one and I kept adjusting the fuel pressure until I liked it: didn't run out of fuel on straights, didn't drip fuel out venturi's, didn't run rich and bog. Turned out to be 2.25psi on my gauge. Even if the gauge is off, and I'm really running 3.0psi for example, it don't matter. The entire fuel system from pressure to carb jets was tuned properly as a whole and made very good power.

Facets are junk. RB should have been selling Holley fuel pumps instead.

Later,

BradP

RXcetera

That's the thing with "regular" gauges... they're a VERY innacurate. The recomended fuel pressure for an RB Dellorto is 4.5psi. It WILL starve at 3 psi and overflow at ~6psi. I know my carb is getting the 4.5 psi, but when I hook up a typical gauge, I'm looking at maybe 2-2.5 psi. Same deal with Silvers car and his 4-9psi reg. The most we could get on the gauge was 2.5-3psi.

We even tried hooking it up to a stock RX7 and the gauge read 1 psi . This prompted us to pick up a new gauge... with slightly different (but just as useless) results.

I need an accurate gauge to figure out what is happening at WOT. What might be perfect while the car is idleing might be less than great when you're at wot in 3rd and 4th.

Those Facets have actually served me quite well until now... and even then, I'm not sure if the problem is the pump...

peejay

Don't expect to make much more power than stock.

It's what I was running last year. It "works" in that the engine starts and drives but the top end is pretty flat.

REVHED

Yeah, most of the gauges on the market are useless. I've tried a few different ones with poor results but the Speco gauge I have now is pretty accurate.

Kill No Cone

iTrader: (6)

Paul Yaw has done of ton of research on fuel supply systems and he requires that if you use one of his carbs, you must use the modified fuel gauge he sells as well. (Here is the URL for his gauge - http://personal.riverusers.com/~yawpower/access.html)

Hey, you guys with the Dellortos, what setup would you use with a Dellorto on a Mazdatrix manifold running on a stock 12a?

I am using the Carter street/strip pump (which is not as load as a Holly blue) and a Holly regulator.

RXcetera

Start with what RB recomends... 230 fuel and air, 80-90 pumps, 75 idle jet, 39mm chokes.

Kill No Cone

iTrader: (6)

Thanks RXcetera,
I will start there. From that point which way did you go - richer or leaner?

rotorhead

here's another question: i've been running my del for about a year, and i think it's running quite a bit too rich. i've tried 235 mains(which i'm guessing is a step in the wrong direction). still haven't had the chance to get the a/f meter on there and now my streetport's been put on hold( i thank my isuzu trooper for dying at the most inopportune moment ). here's the deal, i don't know when the streetport will happen, but it WILL happen. what's a good suggested range of jets so i can fiddle and tune to find the right settings for now and for later. also, i can't find the 300 needle and seat anymore... the rebuild kit i had came with a 210 i believe, and it's in there now. is that a prob? i know there's power lurking in this carb... i just gotta find it! at the moment, i've got 117 rwhp out of it with a krappy exhaust. the dyno chart looked pretty scrambled as it climbed. definitely not a nice pretty line. it idles fine, but at any partial throttle opening, it's got lots o' stuttering. and who want to sell me a lake cities manifold for cheap?

RXcetera

You’ll need the #300 needle and seat. Try CBperformance.com , they might have some. Your Irregular acceleration and stumbling could be caused by this. If you’re really out of luck, PM me.

As far as jetting is concerned, the 12A RB Dellorto is jetted pretty rich out of the box. In fact, jetting hardly varies between their 12A and 13B Dell setup. If anything, you should experiment with leaning out your carb a little. 220 main fuel with 230 air correctors works pretty good, but anything more specific will vary between cars and setups.

If you're getting stumbling when quickly applying throttle, check the size, condition and alignment of your pump jets (80-90) and make sure your accel pump circuit and pump are functioning properly. You want to get AT LEAST 13/32" of travel from the pump arm from idle to WOT.