Bridgeport Woes
Old [Sch|F]ool
Joined: May 2001
Posts: 12,860
Likes: 568
From: Cleveland, Ohio, USA
One of my friends bought a used system for $450ish.
I paid $200 for my midpipe and muffler, but had no header. Had a $100 dual outlet header from some other manufacturer, spent way too much effort mating the two. https://www.rx7club.com/build-thread...system-990786/
I paid $200 for my midpipe and muffler, but had no header. Had a $100 dual outlet header from some other manufacturer, spent way too much effort mating the two. https://www.rx7club.com/build-thread...system-990786/
Dont get the full rb exhaust, quiet but its too restrictive. header into a dual 2.25, or single 2.5 plus a rb universal presilencer, ending with a rb universal muffler. For dual, collector above the axle is good.
Fair enough. Also, a bridge has no low end. It can improve but not by changing carb.
With what? Running different carburetors on the same engine?
If thats what you mean, yep. I have tried everything except the Dell on my bridgeport 12A.
I have done
1) weber downdraft IDF AND IDA, IDF had 38mm chokes, and the IDA had 42mm chokes. I worked on and drove a friends with NO chokes at all, and it was a fun car, but I didnt own it, so I didnt get to play with it a lot.
2) Weber sidedraft DCOE, in both DCOE 45 and 48 sizes/flavors, great carb, but tuning it was a bitch, never got either of them 100% where I wanted it. Biggest problem with both carbs was tip-in.
3)Holley 4150/4160. I have seriously messed with these more than I'd like to talk about. Its 90% of my experience. I have gotten these better tuned than any other carb, (on a dyno) but were impossible to live with on a day to day. They for whatever reason were never consistent, and even stuff like idle speed was different one day to the next.
4)Nikki (stock AND modified) My most recent experience on stock and BP was a rather large 31mm secondary nikki I built last summer. It is almost identical as Jeff20B's "boost prepped" carbs other than I had to go to an even larger pump nozzle (1.28) and the secondary jets were 170, up from 155. Primary mains were 120.
Set up like jeff20b builds them they run almost like stock on stock port and street port, but when I tried it on my aging pineapple rebuild BP 12A, i may have gone overboard with the venturi sizing, making it a little more finicky. I also had a relatively stock intake manifold (dual plane) from a 79, that I'm wishing I would have hogged out into a plenum area around 25mm open to get crossflow between rotor 1 and 2 for a little extra top end.
In the end, the only real choices for a bridge in my mind (based on how they ran and drove) were the IDA and the Nikki. And my Nikki was far from perfect.
The IDA had a racecast intake mani, which now belongs to another forum member, and 6 years ago I never thought to measure the runner lengths for a real side by side comparison, but they are close to an early 12A intake.
The only real difference between driving both carbs (while the engine was still in a car), was pedal feel. Power and throttle response was slightly in favor of the IDA above 6k RPM, but everywhere below that the Nikki was better. I also think that if I had properly channeled the intake manifold I could have all but mirrored the IDA completely.
Only drawback of my setup with a nikki is that I used a dual plane intake, and it sort of undersized my carb for the application. The Weber was probably too large, which is why it ran the best with a 42mm choke, but hey.
That about sums it up. I have a few other fleeting experiences with webers I didnt actually own, but just helped to get running/started or whatever. But I only ever owned one bridgeport, and only ever had a single IDA.
If thats what you mean, yep. I have tried everything except the Dell on my bridgeport 12A.
I have done
1) weber downdraft IDF AND IDA, IDF had 38mm chokes, and the IDA had 42mm chokes. I worked on and drove a friends with NO chokes at all, and it was a fun car, but I didnt own it, so I didnt get to play with it a lot.
2) Weber sidedraft DCOE, in both DCOE 45 and 48 sizes/flavors, great carb, but tuning it was a bitch, never got either of them 100% where I wanted it. Biggest problem with both carbs was tip-in.
3)Holley 4150/4160. I have seriously messed with these more than I'd like to talk about. Its 90% of my experience. I have gotten these better tuned than any other carb, (on a dyno) but were impossible to live with on a day to day. They for whatever reason were never consistent, and even stuff like idle speed was different one day to the next.
4)Nikki (stock AND modified) My most recent experience on stock and BP was a rather large 31mm secondary nikki I built last summer. It is almost identical as Jeff20B's "boost prepped" carbs other than I had to go to an even larger pump nozzle (1.28) and the secondary jets were 170, up from 155. Primary mains were 120.
Set up like jeff20b builds them they run almost like stock on stock port and street port, but when I tried it on my aging pineapple rebuild BP 12A, i may have gone overboard with the venturi sizing, making it a little more finicky. I also had a relatively stock intake manifold (dual plane) from a 79, that I'm wishing I would have hogged out into a plenum area around 25mm open to get crossflow between rotor 1 and 2 for a little extra top end.
In the end, the only real choices for a bridge in my mind (based on how they ran and drove) were the IDA and the Nikki. And my Nikki was far from perfect.
The IDA had a racecast intake mani, which now belongs to another forum member, and 6 years ago I never thought to measure the runner lengths for a real side by side comparison, but they are close to an early 12A intake.
The only real difference between driving both carbs (while the engine was still in a car), was pedal feel. Power and throttle response was slightly in favor of the IDA above 6k RPM, but everywhere below that the Nikki was better. I also think that if I had properly channeled the intake manifold I could have all but mirrored the IDA completely.
Only drawback of my setup with a nikki is that I used a dual plane intake, and it sort of undersized my carb for the application. The Weber was probably too large, which is why it ran the best with a 42mm choke, but hey.
That about sums it up. I have a few other fleeting experiences with webers I didnt actually own, but just helped to get running/started or whatever. But I only ever owned one bridgeport, and only ever had a single IDA.
Thread Starter
Rotor Wizard
Joined: Jan 2016
Posts: 77
Likes: 0
From: Clemson, SC
Yeah I'm trying to get my hands on a 2-1/2 maf. Does RB make something like that?
SO, Update time:
I took the '7 on a test drive just to see how she was doing, and the dang secondary air pipe fell off the exhaust :/ I took it off and am looking for a way to reattach it, but that's a different story (It's rusted at the monolith side). Out of curiosity, I hooked up the timing light to make sure everything was still good. I didn't know it when I timed the engine before, but the dial on the back of the timing light was set to ADVANCE the timing by 30 degrees! I know I know, stupid mistake. I can't believe I missed that. So when I lined it up with zero and checked again, the timing was waaaay off. So I messed around for an hour or two trying to recover my timing (Since I had timed it inappropriately, I had also adjusted the carb idle as a consequence). It was a constant back and forth, adjusting the timing a little, then adjusting the carb to prevent the engine from dying. I had the engine running so high for so long that when I looked over at the exhaust, the first monolith was literally glowing from being so hot. I turned the engine off and popped the air cleaner and all four barrels of the ole' Nikki were chock full of exhaust fumes. Yeah, I know, you guys warned me. The exhaust is totally killing my BP. SO:
TL;DR-
I messed up the timing.
Subsequently, I messed up the carb idle.
Exhaust is so full of buildup that it is red hot from choking down the exhaust.
I had to quit the tuning tonight to let the engine cool down, but tomorrow I'll hit it hard. I'm going to pull the exhaust to fix that pipe, and I might try to clean out the monoliths.
SO, Update time:
I took the '7 on a test drive just to see how she was doing, and the dang secondary air pipe fell off the exhaust :/ I took it off and am looking for a way to reattach it, but that's a different story (It's rusted at the monolith side). Out of curiosity, I hooked up the timing light to make sure everything was still good. I didn't know it when I timed the engine before, but the dial on the back of the timing light was set to ADVANCE the timing by 30 degrees! I know I know, stupid mistake. I can't believe I missed that. So when I lined it up with zero and checked again, the timing was waaaay off. So I messed around for an hour or two trying to recover my timing (Since I had timed it inappropriately, I had also adjusted the carb idle as a consequence). It was a constant back and forth, adjusting the timing a little, then adjusting the carb to prevent the engine from dying. I had the engine running so high for so long that when I looked over at the exhaust, the first monolith was literally glowing from being so hot. I turned the engine off and popped the air cleaner and all four barrels of the ole' Nikki were chock full of exhaust fumes. Yeah, I know, you guys warned me. The exhaust is totally killing my BP. SO:
TL;DR-
I messed up the timing.
Subsequently, I messed up the carb idle.
Exhaust is so full of buildup that it is red hot from choking down the exhaust.
I had to quit the tuning tonight to let the engine cool down, but tomorrow I'll hit it hard. I'm going to pull the exhaust to fix that pipe, and I might try to clean out the monoliths.
Thread Starter
Rotor Wizard
Joined: Jan 2016
Posts: 77
Likes: 0
From: Clemson, SC
Alright guys, I've pulled the exhaust from the maf back to the muffler pipe and am currently making a new one without the converters on it to open up the flow. I shouldn't need to include that secondary air pipe should I? It should remain fairly cool since there is no more flow resistance from the converters. I'll post pics of my setup later. It's not pretty, but it will help the BP until I can get a good exhaust going.
i've got to weld the oil drain pipe and flange to the front cover(all is weld prepped just waiting for it to be warm).. then reinstall front cover...and send the coolant return somewhere.. then throw the downpipe on and i'm done... intercooler, TID all that is already done..
Thread Starter
Rotor Wizard
Joined: Jan 2016
Posts: 77
Likes: 0
From: Clemson, SC
Update time:
I whipped up a barbaric replacement pipe for my clogged converters and got it installed today. The '7 sounds much better and idles a little smoother, also there is no more exhaust backup into the carb. Hooray! However, power is still lacking, so my next weekend plan is to start looking at the carb for improvement/replacement.
I whipped up a barbaric replacement pipe for my clogged converters and got it installed today. The '7 sounds much better and idles a little smoother, also there is no more exhaust backup into the carb. Hooray! However, power is still lacking, so my next weekend plan is to start looking at the carb for improvement/replacement.
Last edited by Ricardio Frenz; Apr 9, 2016 at 10:38 PM.
Originally Posted by lastphaseofthis
we left mine stock 20mm didn't we?
Congrats on your progress, by the way. And yes I'm in talks with a local guy about me doing a 12A turbo for him.As for the thread starter, congrats on your progress so far. Keep on keeping us updated.
Old [Sch|F]ool
Joined: May 2001
Posts: 12,860
Likes: 568
From: Cleveland, Ohio, USA
Joined: Mar 2001
Posts: 31,833
Likes: 3,232
From: https://www2.mazda.com/en/100th/
I think I can get the Nikki running good enough to support the bridge, otherwise I'll have to get a new carb and that's $$$ I don't have lol. Is anyone on this site brave enough to vouch for a carb that ISN'T a Weber or Holley? I'm interested to see what else is out there and hear what people think.
+1
2k rpm is an understatement. More like above 4k rpm.
Ps. Kept loosing 4g connection so i have to edit my orig post
Last edited by Siraniko; Apr 10, 2016 at 08:06 PM.
Your mom is going to beat you. She won't be able to hear you scream. JK.
True story. The last time my 1985 was on the road, in 2003, I let my mom drive it because her car was down. It overheated and she toasted the engine.
True story. The last time my 1985 was on the road, in 2003, I let my mom drive it because her car was down. It overheated and she toasted the engine.
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Stranger8808
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