Pdornellas

I have a 1990 NA vert that is swapped to a 650 Holley carb instead of fuel injection. When I press on the gas pedal too hard the engine will bog. This includes at high rpm. Any idea how to mess with the air/fuel mixture without me screwing something up?

diabolical1

iTrader: (3)

welcome to the board.

you'll first have to provide some more information.

what fuel pump?

what plugs?

your timing?

what porting?

what 650 Holley - RB-prepped or off-the-shelf?

... and of course, you may have to get the jetting information on it.

Pdornellas

I just got this car the other day so I'm not positive as to whether this info is right but according to the dude I got it from everything is stock other then the Holley 650 double pumper carb, MSD's and a street porting.

diabolical1

iTrader: (3)

well, i know it's not your fault and you're clearly new to this, but that makes no sense.

streetporting is not simply bolting on a part, and neither is a proper carburetor conversion. i'm guessing by MSDs you mean amplifiers (the boxes)? none of that stuff is simple. assuming you understood everything the previous owner told you, he was either a bit dense or he was trying to deceive/take advantage you in some way. i guess that's all irrelevant now though. your first priority is to find out exactly what you have and then seek help from there forward.

finding out which fuel pump you have is key because any pump meant for EFI is going to flood the car. some people use them anyway and just us a pressure regulator to restrict flow down. personally, i don't believe in that, but people do it. the point is find out what you HAVE as of now. the simplest way to do this is trace the fuel lines back toward the tank. (by the way, i obviously don't know what you know or don't, so if you know all of this already, say so. it will save us both some time.)

for the ignition, i know some people used the stock CAS and i have read of at least one case where people have gone so far as to trick the stock ECU to run with a carburetor. the simple solution of course would be using a distributor. again, you need to know what you HAVE before anyone can help you. the simplest thing i can think of with this is count ignition wires - do you have 4 or 6?

it is my opinion that a 650 is still too much carburetor for a streetport, but it can be made to work. this may turn out to be a part of your problem. the Holley question i asked is still unanswered, but it will also be important. it would be better to find out if you have an off-the-shelf Holley or a RB-prepped one. at this time, i don't have any guidance as to how to go about doing that though. i don't know if they put any of their logo stampings on them, but it won't hurt to look. at any rate, inventorying your fuel system and ignition system are the priorities now. we can deal with the carb itself later.

Pdornellas

I took a closer look and the only place there is a part number on the carb I would have to remove it to look at. I've got the MSD ignition boxes and MSD blaster 2 ignition coils. I do have a fuel pressure regulator. And there appears to be 6 wires?

Pdornellas

My friend that has an rx7 believes it is my secondary coils due to the fact that in Nuetral it doesn't bog when the gas is applied but off the line it does

lduley

iTrader: (1)

Doubtful, i agree that a 650 dbl pumper is ALOT of carb for a rotary, a 650 dbl pumper is made to feed 5+ liter engine, not 1.3 liter engine, if you found a nikki carb off a 12a and changed the jets to a little bigger size, you'd probably be golden

Pdornellas

Thanks, the stock fuel injection stuff came with the car would I be able to switch back to that without changing my ignition setup?

diabolical1

iTrader: (3)

check this out:

https://www.rx7club.com/1st-generati...m-carb-479469/

can it be done? of course, but it begs the question, why? it would be much simpler to just remove the distributor and return the CAS setup. the stock computer stays happy with no trickery.

Pdornellas

So I took my air filter off and I seem to be missing the flap that regulated the amount of air intake. Does that matter?

lduley

iTrader: (1)

No, thats for allowing the engine to pull warmer air from the exhaust for emissions/running in colder weather. There should be a slinky like hose going down to your exhaust manifold and hooks to a heat shield.....thats if its still there

Pdornellas

Is there any way for me to post a picture?

lduley

iTrader: (1)

yes, just attach it from your computer just like an email

motoron

Is this a 2 or 4 bbl carb? if 4 does it have 2 float chambers.

lduley

iTrader: (1)

Its a 650 double pumper, its a 4 barrel with 2 fuel inlets IIRC

motoron

"When I press on the gas pedal too hard the engine will bog."

Have you tried removing the brass plug from the secondary float bowel to see if fuel
is present?

Evil Aviator

Which major city in Florida are you near? If you do not have the skill to identify the fuel pump, then you are in way over your head and you need to take the car to a professional shop. Fortunately, Florida has some pretty good shops. You would be better off getting this fixed by a pro, and then try to tackle easier tasks on your own as you are learning more about cars. Trust me, with a car this old there will be plenty of simpler things to fix so you will get lots of practice, lol.

I think he means the AFM.

lduley

iTrader: (1)

Whoops, forgot his is a s5, i was thinking a FB

Pdornellas

I'm in cocoa beach

Pdornellas

I did, and The fuel level was right at the bottom of the hole the other one has fuel a few mm beneath the hole

motoron

Good now remove the linkage from the secondary barrels to make it essentially a 2 barrel and drive. Make sure they stay shut with wot.

Evil Aviator

There is an outstanding shop about a 3-hr drive from your location. See if you can get it running well on your own, but if it can drive on the freeway and you want it really well-tuned then I highly recommend Lowe Performance in Sarasota. Since it is so far away I would recommend calling them first.
Servicie | Repair of Rotary Engine Vehicle - Lowe Performance

Pdornellas

Sorry I'm not sure what you mean by the linkage.

Pdornellas

Thanks I'll give them a call

motoron

Look thru the top of the carb (engine off of course) with the choke fully open (if applicable) see if the secondary butterfly's are opening. They either open by vacuum or are controlled mechanically either way disconnect the linkage that makes them open.
Its rare that a car would FLOOD out when secondary's open. By driving the car on two barrels that should eliminate any questions of electrical problems. More likely not enough fuel like a giant vacuum leak when secondary's open. Easy to try but remember
no rotors came equipped with a holly 4bbl stock so it could go either way.