Any Rotary Carb tuners???
05-28-20, 10:31 AM
#3
Junior Member
Thread Starter
05-31-20, 10:35 PM
#6
not to steal JoshG's thunder, but I need help too! in NJ. Car is 100% custom Lotus 7 type roadster, 5-letter 13B with Holley 650 double pumper. Runs great with exception of random stalls. Would love to see a professional but also would appreciate some DIY help if you think it's doable - have never tuned a carb before. Thanks!!!
06-01-20, 07:13 AM
#7
alfisti,
If it was a Nikki carb the guys here could easily help you out, but on a "universal" Holley you'll have a lot of trial and error. I'd suggest getting a Holley book to understand how each carb circuit works (I like David Vizard's books) and research research research. Many here have tried that carb, so a google search of "Holley 650 on 12A rotary" should pull up lots of hits, mostly on this forum.
Note, that carb is too big to run right on a stock-ish street motor. It mighIt be okay at the upper RPM's, but probably won't ever behave in the low-mid range where most street cars live.
If it was a Nikki carb the guys here could easily help you out, but on a "universal" Holley you'll have a lot of trial and error. I'd suggest getting a Holley book to understand how each carb circuit works (I like David Vizard's books) and research research research. Many here have tried that carb, so a google search of "Holley 650 on 12A rotary" should pull up lots of hits, mostly on this forum.
Note, that carb is too big to run right on a stock-ish street motor. It mighIt be okay at the upper RPM's, but probably won't ever behave in the low-mid range where most street cars live.
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06-01-20, 08:26 AM
#8
Actually it's a 13B, but regardless, that is REALLY good info. I bought it this way, so I wouldn't know if it was a bad decision =:-O
it is CLOSE to running right - other than the random stalling, it actually runs very well. But the builder removed the whole choke mechanism and milled off the tower so it can't be added back - which is MADDENING. Is there an inexpensive way to move to fuel injection, that would not give up too much performance? Reminder: this is not an RX-7, there is no plumbing or wiring for ANYTHING. Just a carb sitting on the engine. Thanks!
it is CLOSE to running right - other than the random stalling, it actually runs very well. But the builder removed the whole choke mechanism and milled off the tower so it can't be added back - which is MADDENING. Is there an inexpensive way to move to fuel injection, that would not give up too much performance? Reminder: this is not an RX-7, there is no plumbing or wiring for ANYTHING. Just a carb sitting on the engine. Thanks!
alfisti,
If it was a Nikki carb the guys here could easily help you out, but on a "universal" Holley you'll have a lot of trial and error. I'd suggest getting a Holley book to understand how each carb circuit works (I like David Vizard's books) and research research research. Many here have tried that carb, so a google search of "Holley 650 on 12A rotary" should pull up lots of hits, mostly on this forum.
Note, that carb is too big to run right on a stock-ish street motor. It mighIt be okay at the upper RPM's, but probably won't ever behave in the low-mid range where most street cars live.
If it was a Nikki carb the guys here could easily help you out, but on a "universal" Holley you'll have a lot of trial and error. I'd suggest getting a Holley book to understand how each carb circuit works (I like David Vizard's books) and research research research. Many here have tried that carb, so a google search of "Holley 650 on 12A rotary" should pull up lots of hits, mostly on this forum.
Note, that carb is too big to run right on a stock-ish street motor. It mighIt be okay at the upper RPM's, but probably won't ever behave in the low-mid range where most street cars live.
06-01-20, 08:43 AM
#9
Actually it's a 13B, but regardless, that is REALLY good info. I bought it this way, so I wouldn't know if it was a bad decision =:-O
it is CLOSE to running right - other than the random stalling, it actually runs very well. But the builder removed the whole choke mechanism and milled off the tower so it can't be added back - which is MADDENING. Is there an inexpensive way to move to fuel injection, that would not give up too much performance? Reminder: this is not an RX-7, there is no plumbing or wiring for ANYTHING. Just a carb sitting on the engine. Thanks!
it is CLOSE to running right - other than the random stalling, it actually runs very well. But the builder removed the whole choke mechanism and milled off the tower so it can't be added back - which is MADDENING. Is there an inexpensive way to move to fuel injection, that would not give up too much performance? Reminder: this is not an RX-7, there is no plumbing or wiring for ANYTHING. Just a carb sitting on the engine. Thanks!
The carb might be tuned perfectly then - no way to tell from here. Cutting off the choke horn makes it a Summer-only car in my experience. I'm just North of Philly and all the PR guys I know do that. Unless they keep it in a heated garage they have a heck of a time getting them started in the Fall and Winter.
Car might just need some minor tune-up attention - plugs, fuel filter, etc.. Does the motor still have the OMP? (Oil Metering Pump). On custom/modded rotaries it's not uncommon to remove it, but if he did you MUST put pre-mix in the gas tank with each fill. You will absolutely destroy the motor (quickly) if you don't. Ask the PO if not sure.
Also, I'm not the best at diagnostics. There are many long-term rotary experts and mechanics on the forum. I suggest you start a new thread showing the car and get specific about it's symptoms. Good luck.
Last edited by Maxwedge; 06-01-20 at 09:41 AM.
06-01-20, 09:46 AM
#10
Thanks!! Yes, the OMP is gone, it has been consistently premixed. I can go through and do the basics as you say - plugs, filters, etc., but I believe most of that was done just before I got the car (November). I agree about the choke - it's MADDENING. But I have been warming it up with foot on the throttle in cooler weather and it is "livable but really annoying". I'll take your recommendation and start a new thread. It would be GREAT to find a professional within driving distance (I'm halfway between Philly and NYC) to get a proper baseline tune done, before I go messing with it. So the original question - anyone who can tune carbs on a rotary in this area - still stands. :-)
Thanks
Thanks
Ah a good running 13B is closer to that carb's size then. Sorry, writing this while in a phone conference about the protests/riots. They broke out all the windows on our office building's first floor this weekend. Good times.
The carb might be tuned perfectly then - no way to tell from here. Cutting off the choke horn makes it a Summer-only car in my experience. I'm just North of Philly and all the PR guys I know do that. Unless they keep it in a heated garage they have a heck of a time getting them started in the Fall and Winter.
Car might just need some minor tune-up attention - plugs, fuel filter, etc.. Does the motor still have the OMP? (Oil Metering Pump). On custom/modded rotaries it's not uncommon to remove it, but if he did you MUST put pre-mix in the gas tank with each fill. You will absolutely destroy the motor (quickly) if you don't. Ask the PO if not sure.
Also, I'm not the best at diagnostics. There are many long-term rotary experts and mechanics on the forum. I suggest you start a new thread showing the car and get specific about it's symptoms. Good luck.
The carb might be tuned perfectly then - no way to tell from here. Cutting off the choke horn makes it a Summer-only car in my experience. I'm just North of Philly and all the PR guys I know do that. Unless they keep it in a heated garage they have a heck of a time getting them started in the Fall and Winter.
Car might just need some minor tune-up attention - plugs, fuel filter, etc.. Does the motor still have the OMP? (Oil Metering Pump). On custom/modded rotaries it's not uncommon to remove it, but if he did you MUST put pre-mix in the gas tank with each fill. You will absolutely destroy the motor (quickly) if you don't. Ask the PO if not sure.
Also, I'm not the best at diagnostics. There are many long-term rotary experts and mechanics on the forum. I suggest you start a new thread showing the car and get specific about it's symptoms. Good luck.
06-01-20, 10:17 AM
#11
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not to steal JoshG's thunder, but I need help too! in NJ. Car is 100% custom Lotus 7 type roadster, 5-letter 13B with Holley 650 double pumper. Runs great with exception of random stalls. Would love to see a professional but also would appreciate some DIY help if you think it's doable - have never tuned a carb before. Thanks!!!
not sure where the adjustments are on a holley, but you should start there.
06-01-20, 10:25 AM
#12
Thanks. When warmed up, the idle is significantly higher than that - about 1000-1100 RPM I believe. I'll give a try to what you said below.
stalling/weak idle is a symptom of being a little lean, the rotary will lean misfire earlier than a piston engine. i would suggest setting the idle speed, the factory idle speed is 750rpm, and then the idle mixture. set the idle mixture like you would anything else, just to best idle quality/highest intake vacuum. the factory would then have you lean it out a tad, but if you leave it there it will help with the not having a choke. mileage will go down, lol. there is a happy medium.
not sure where the adjustments are on a holley, but you should start there.
not sure where the adjustments are on a holley, but you should start there.
06-18-20, 05:43 PM
#14
Junior Member
Thread Starter
Ah a good running 13B is closer to that carb's size then. Sorry, writing this while in a phone conference about the protests/riots. They broke out all the windows on our office building's first floor this weekend. Good times.
The carb might be tuned perfectly then - no way to tell from here. Cutting off the choke horn makes it a Summer-only car in my experience. I'm just North of Philly and all the PR guys I know do that. Unless they keep it in a heated garage they have a heck of a time getting them started in the Fall and Winter.
Car might just need some minor tune-up attention - plugs, fuel filter, etc.. Does the motor still have the OMP? (Oil Metering Pump). On custom/modded rotaries it's not uncommon to remove it, but if he did you MUST put pre-mix in the gas tank with each fill. You will absolutely destroy the motor (quickly) if you don't. Ask the PO if not sure.
Also, I'm not the best at diagnostics. There are many long-term rotary experts and mechanics on the forum. I suggest you start a new thread showing the car and get specific about it's symptoms. Good luck.
The carb might be tuned perfectly then - no way to tell from here. Cutting off the choke horn makes it a Summer-only car in my experience. I'm just North of Philly and all the PR guys I know do that. Unless they keep it in a heated garage they have a heck of a time getting them started in the Fall and Winter.
Car might just need some minor tune-up attention - plugs, fuel filter, etc.. Does the motor still have the OMP? (Oil Metering Pump). On custom/modded rotaries it's not uncommon to remove it, but if he did you MUST put pre-mix in the gas tank with each fill. You will absolutely destroy the motor (quickly) if you don't. Ask the PO if not sure.
Also, I'm not the best at diagnostics. There are many long-term rotary experts and mechanics on the forum. I suggest you start a new thread showing the car and get specific about it's symptoms. Good luck.
My 13b blowthrough turbo rx7 is very hard to start could that be from not having a choke once I get it running which is like 4 to 5 times it's fine but I cant touch the throttle all of a sudden or it will choke out what can be my resolution?Also their is a huge backfire everytime I turn the car off what could that be?
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