ForsakenRX7

The new lil 81 rx7 I bought came with a full exhaust and a holley intake setup. Problem is that its running a 650 and it is just killing plugs imediatly. I was told that it has 64s in the primary and the secondary is a .7 metering block. Its obviously too much for the stock port 12a. It supposedly ran fine for the most part when the previous owner had his msd boxes hooked up. I don't want to buy msd boxes and I'm surely not gonna buy another carb. So the question is what should I jet this carb down to, to get it to run right?

81gsl12a

iTrader: (1)

lol it will never run right... what manifold do you have for it? is the carb a DP or a vac 2nd? do you have a power valve in it? what size are the air bleeds? what pump cam is in it? what spring is on the acc pump? what acc pump is in it?

there are lots of things you are going to have to do to get it to run ok it will never run RIGHT with a stock port..

also a wide band will help you tune it but i guess that is out of the question if you dont want to shell money out for a new carb or msd. and to tell you the truth the msd didnt help out that much he was lying if he said it ran good with the msd and he didint change anything else

teddyrx2

iTrader: (33)

Not true my friend^ but those are things to take into consideration...but there your going into way to much detail for the simple backyard mechanic..

people think that carbs run like fuel injection and they don't...as weather changes tune ups are needed on regular to keep the car running up to par...You can't just expect to run like god is behind the wheels everyday...


dude the car is fine...the carb is fine...it's just fine tunning...So lets start here...star out buying new plugs... for your year and make...there are two ventures to adjust the amount of air on the carb...close them all the way and then open them back up two full turns...if your that worried about the jet size go down to 62's 60 max after that your going to start leaning it out...

81gsl12a

iTrader: (1)

a 650 carb will never run right.. it will run but not right there will be a dead spot when you do WOT in the transtion between idle to wot there will always be a hickup.. the carb is just to big. you can jet it down but then you mess with the way the carb is ment to preform witch will also caz it to have hickups

and if its just a holley that some1 put on it off a camaro it ment to have a open plenum.. and a racing beat manifold is made to not work with an open plenum. so there carbs are modified..

the right carb will make a world of diff..

check your float bowls make sure they are not to high... make sure the fule is not going past the needle and seat, check your FPG if you dont have 1 get 1 and check it you want it at aroud 5psi no higher then 7.5 (you dont need it that high)

teddyrx2

iTrader: (33)

i don't know man usually people who know what the hell there doing never run into these bumps in the roads...Ran a 650 vacume seconds on a stock 12a back in the days **** ran cherry...but to each there own...

not only the right carb but the right tunner...

But help us here post some pics of the carb and lets see what your running...and what you have to work with...

Latin270

I'd swtich to second gen ignition mod to help improve spark. Then I'd make a few changes to the carb but w/o details of the carb set up its tough to give advice. Is it a DP, mech or vac sec's, whats the fp set at, etc?

ForsakenRX7

ok, sorry I should have included, the carb is a single pump vac secondary. It also is running a holley fuel pump.
I'm used to the fuel injection of second gens so this holley carb stuff is rather different (and new) to me. So please bare with me. As far as buying new plugs, the car just had a set put in. They were fouled in 15 minutes.

Latin, you spoke of a FC ignition swap. A buddy of mine has a complete ignition from a second gen. Whats involved?

As far as the acc pump, air bleeds, and general internals of that carb go I have no idea. I'm gonna have to buy a FP gauge, cause the car doesnt have one so I unfortunatly cant even tell you that. I havent started ripping into the carb cause I havent bought a book on holley carbs yet and I didnt want to screw anything up worse.

Point blank....I'm gonna have to get a different carb aint I?

Latin270

lol, I'm the opposite! I'm not used to the FI stuff so I'm going back to carby on my 6 port. I'm going to be running a Holley 600 cfm on a Street ported 13b in my 91 s5. I had this set up on my previous 13b (83 gsl) and the thing pulled very strong! If you plan on getting another Holley, PM me as Ill share my trusted carb source w/ you. As far as the 2nd gen ign. set up, its very simple and there is tons of good info on here. Do a search under: 2GCDFIS.
Heres a link to get you started. https://www.rx7club.com/showthread.p...hreadid=243350

Sterling

Yes. I'm not here to try to sell you my carb; That 600 is just too big.
Since you have the Holley manni already, maybe you should consider a Racing beat Holley 465.

Latin270

Better yet get a Sterling Carb! Cant go wrong. I'd get a Sterling over a RB Holley for a 12a any day and a stock 12a mani's come a dime a dozen.

ForsakenRX7

decisions, decisions.
Good news is that selling a 650 holley aint exactly hard.

I cant really bitch though, I just got this car for 500 bucks and its nice as hell other than the carb problem.

OneRotor

iTrader: (3)

your 650 is way way too big for a stock port, or even a street port 12a. The poster who said that he ran a 650 on his stock 12a and it ran "cherry," beauty is in the eye of the beholder. It may have been great for you, but for someone else it may have been unbearable.

A 650 is good for a BP or a supercharger

I can tell you from personal expierence with a Holley 465 from RB that, with mechanical secondaries (screw trick), it would stumble at transition, and then absolutely scream 'til redline. My buddy from school had never been in a RX-7 before (he's a hardcore V8 guy), and I had him giggling like a little girl after a few pulls with mechanical secondaries.

What pump do you have? Red? Blue? I used to have a red on mine, but when it fried I bumped to a Blue with -6 feed and stock feed converted to return with a Holley FPR and a gauge from BWaits at ReSpeed. The new gauge and mount for my FPR helped out a ton last summer, before my side seals went and the motor blew up.

I've heard that Sterling carbs are phenominal, but have no personal expierence with them.

If I were at home, I'd offer to sell you a good condition stock carb and manifold for cheap so you could send it off to Sterling to have it rebuilt.

Here is my suggestion:
Buy a Holley tuning book
Tell us what model your pump is (Holley Red or Blue)
If you have a Blue pump, get yourself a FPR and gauge, and plumb a return line for it and turn your pressure down to 6psi.
put in new plugs, wires, cap, and rotor to make sure you have good spark.
Get yourself a RB 465 for that intake.

bad 83

iTrader: (3)

I don't want to start an arguement here, but I am running a 600 Holley on my stockport SA. Big trick here, pull the power valve and put the power valve plug in. Your stock ignition will not be enough. I am running a second gen leading coil, and the second gen leading plugs. I DO NOT have any hesitation in the throttle at any rpm, and it pulls like ****** to redline in every gear. I drove this SA to Atlanta GA in a caravan with 3 other RX7s, and I got 22mpg. The only change that was made to the Holley was pulling the power valve. I am running 64 primary jets, and the secondary metering plate that is the same as 67 secondarys. I will not lie, it runs a little rich on the low end, but I have not fouled any plugs since I set this up 6 months, and 6000 miles ago. http://www.youtube.com/watch?v=8LnqZVvQWmo

ForsakenRX7

Well this 650 supposedly has the same size primaries and it will foul a set of plugs in about 15 minutes. For the lil bit it will run its obviously running way to rich. In the time since I last posted I already found someone to buy my 650. Problem is that the RB carb is a wopping 550 bucks. I have read good things about Sterling's carb but what's the cost? Cause if its just as much as the RB carb by the time I find a stock lower then I might as well just keep my current lower and get the RB model. I know I sound like I'm being cheap but half a grand aint something that comes easy nowadays.

84stock

iTrader: (5)

Jet the primaries down to 60, see what vaccuum you are pulling at idle with the engine warm, and put in the right powervalve (if you get 8 inches of vac, go with a 5.5 or 6.0 powervalve. Don't do the powervalve plug, just tune the carb with the right powervalve (no offense bad 83). Next get a vac secondary spring kit, start with a stiff spring and work your way down unitl you get a bog or "hickup" at wot, then go one spring heavier. Keep the fuel pressure under 6 psi. Adjust the floats. Sure the carb is too big, but if you tune it right and put in the right secondary spring it will work like a stock nikki with mech secondary mod done. The secondaries will only kick in when the engine can use them. Last of all, and a "MUST DO" you have to use an open spacer. 1 inch would be ideal, but 1/2 inch would be okay. Being 45 I speak from years of experience with holleys on a variety of cars. In my garage I have a Barry Grant 650 blower carb, and 850 double pumper holley, 600 vac secondary holley and a 650 edelbrock. Last, get an accelerator pump cam kit and experiment with a variety of pump cams to dial in the right throttle response. OOOOOOOOOOOOOOOOOH, and buy a holley book while you're at it.

bad 83

iTrader: (3)

You can buy a off the shelf 450 Holley and rock with it. Remove the power valve. The primary jets on it should be 52, and the secondary plate 55. Most people that give Holleys a bad rap have never had a new one, or a properly rebuilt one. Therefore it's hard to compare someone else headache to a new carb. The main reason to pull the power valve is because it makes it a heck of alot easier to tune. When you pull the power valve, its like dropping two jet sizes on the primarys.

81gsl12a

iTrader: (1)

the RB carbs have lots of tricks down to them.. they are not so much tricks as things that have to be done to get it to work 100% jetting a carb down so it will run is not the way to get 100% out of the carb or set up.. its to much carb i think sterling said that the stock motor only needs around a 390 or so(i could be wrong)

anyways the carb racing beat sells is an offroad avanger carb its like a $300 carb with 250 for there tricks but it runs gr8

i would start there or send me an im and i may be able to help you out i have a racing beat carb. i need a biggre carb now

also if your pump is red you dont need a FPR if its blue you need FPR and if its black you really need FPR get a holly book also it will make life way ez'er

cheers PaTricK

bad 83

iTrader: (3)

Just so you guys know, Racing Beat DOES NOT run a power valve it their carbs.

81gsl12a

iTrader: (1)

+1 but i would do a powervavle plug at first till you get the carb working right. powervavles help with MPG.. if i remember right it needs the pink cam

like 84stock said and i said b4 a reg holley works on a open plnum you need a spacer if its not a RB carb

teddyrx2

iTrader: (33)

WOW first off thumbs up to you for the comment could care less...and well stock or no stock that car can be tunned with that 650...It's just that his skills are limited and he's looking for the best solution to remedy his problem...So going into full detail of what he can do to the carb and cause him more of headache is not going to help him...He dosen't want to spend the extra money on the parts or he wants to avoid spending the money on the parts to get the car to run the way the original owner had it...

So i offered him the best solution...work with you have...or if you feel that he must get rid of the carb which by all means is not that hard to do sell it...Get the sterling, or the the little old 465 from racingbeat...problem solved

ForsakenRX7

Working on the carb doesn't scare me. Hell I've rebuilt all four mikuni carbs on my kawasaki.I just don't know anything about these kinda carbs. If I can work with what I've got that would be great. To me its more of a headache to have to look at the car sitting there waiting till I have enough cash than tuning it out. But that's just me.
You guys have given me a lot of good info. Although there's some conflicting opinions I'll just try em till I work it out. Worst case scenario it doesn't tune out and I end up buyin a carb.
I am also going to do the fc ignition swap. That seems to have helped in drivability for everyone I've read that's done it.

Latin270

Its true...the dinosaurs RB sells are very out dated and in my opinion not worth the money. However if you got the cash spend go for it.

djessence

not gonna lie i didnt read all of the last few posts but a sterline costs about 450 plus shipping if you dont ship a core back, you get 50 back if you ship him a nikki back

84stock

iTrader: (5)

You could always disconnect the secondaries and focus on tuning "just the primaries" in the meantime. Here you can dial in the powervalve (which incidentally bumps 6-8 jet sizes when it opens during acceleration) and dial in the accelerator pump. At this point you will end up with a decent running 325 cfm carb. Then reconnect the secondaries and experiment with different spring rates for the vac secondaries. Racer remove the powervalves, for a streetcar keep it in and dial things in right.

Sterling

That's inaccurate. It's $450.00 initially. The carb rebuild, mods & refinishing is 380 bucks. Add the refundable $50 core charge, plus 20 bucks shipping. For $400 you end up with a carb that will blow the socks off any Holley. -And if you don't agree, you can send it right back (within 30 days) and I'll refund your money. But I doubt that'll happen. Then you can sell that Holley boat anchor to teddy or bad 83.