chedda_j

Hey im chedda_j, a well known member of Redpepperracing.com. I usually specialize in first gen honda crx's or 3rd gen civic's, but im about to buy a rx7. its a well kept 1980 and i was wondering if there is anything i should watch out for technically. The car currently is a gunmetal colour with the stock rims and tires, a very well kept engine, and no rust. The car has two problems, one being that its harder than a MF to start in the cold, and something having to do with the E.M. Im not too sure whats wrong with the E.M yet but someone told me that its sitting 1/8th an inch off the block. So im assuming, from sources, that it has the 12A rotary engine, sometype of carb, with about 100 hp and 95 tq. Which is totally awsome because my honda came stock with 72 hp..haha. But my honda is about 400 pounds lighter if the sources were correct when they said the rx7 is about 2100 pounds. Just wondering where i should start, weak points? Get a book from haynes? What suspension should i get, i want to lower the car about an inch, throw on my 15" eagle alloy rims with 185/55 kuhmo escta tires, get about 135 hp out of it, and be able to beat some ricers. So where should i start?

chedda_j

Im glad that everyone is so helpfull and friendly here

85-GSL

well you have a few options for power, one of witch would be an engine swap, you could swap to the 13b (fuel injected) and make 135hp stock. or you could do bolt ons to try and and get your power, some popular bolt ons, are headers and full exhaust (racing beat's a great company) they will give you the most bang for your buck. also the rats nest (emissions components) will lighten and simplify once you remove it. an electric fan will replace the fan and, give you a little bit of power, but more importantly it will cool better. the #1 killer of roarty engines is heat. if the heat gauge EVER goes over half stop the car turn it off and tow it home. wellcome to the roarty family, search and check the archive theres great information in there. and you will find out the bolt pattern is crazy for your car its 4x110

chedda_j

Thanks. i was thinking a turbo. Maybe one off a firefly because they are small and run about 7 psi. So im going to have to get my rims machined for them to fit in other words. I hear you can do that, just machine 5mm out of each hole and they will work properly. Or should i ditch the rims and get some off of a supra or something, hear they are 110 mm. Speaking of that, what rims are interchangable.

so heat is what i have to worry about, hmm well i have some electric fans off my honda so could i just swap them in, have some of those "ready brackets", and run it on a toggle. they work prety good i hear.

As for the header, that would be one of the first things i would love to do. Do you need the catalytc coverter because i swore i saw one when i was under there. So the emissions can be removed correct, il make sure to read over that thread so i know what im doing. i have a video of a tripple rotor rx7 that does 7 seconds in the quatermile, its so amazing. Im going to love the rotary engine. Btw, is the carb on these cars side draft or down draft, is the I.M sidedraft or down draft?

drunkclever

Looking at the car check for rust inside the rear wheel wells. Other places like under the car, in the rear window track, the bottom of the doors and even around the hinges. Since your in Canada I would pull the bins behind the seats and check the inside of the wheel well. Sometimes if theres no rust out side, its going be on the side. The problem is the plates that are in the wheel wells. Over times water and salts will corrode this area. If there are no plates there then obviously body work has been done. Might want to check under the rear bumper also.

Some mods you might want to do are bypassing the fuel relay switch, direct fire ignition, change from vacume secondaries to machanical.

Going turbo.. is rather easy.. as long as you got the cash. With the front cover and oil pan of a gsl-se which has the 13B you can basically swap any turbo engine.. from the popular S4 and S5 turbos to the infamous 13B-REW found in the '93 + rx7 here in the states.

You can get quick with lil cash if you go with a carb on a 12A thats been bridge ported.

The carb is a 4 barrel (2 primary 2 secondary) its called a nikki carb. Its a down draft. There are lots of threads that show the modifications that can be done to them.

chedda_j

Wow its a 4 barrel eh. Thanks for the help, il have to look into everything youve said. Any links for me?

aussiesmg

iTrader: (1)

I have to disagree about electric fans cooling better, they do free up a few hp but do not cool as well as the clutch fan.

Remove the storage boxes behind the seats and look for rust under there, its the usual place for problems.

13BT as per above is easy wasy to get good hp for the $. Talk to 680RWHP in his section under Rotaryshack about supplying you an engine with warranty.

Cold start problems could be as simple as plugs, wires and basic tune of the carb, or it could be early signs of the engine losing compression.

Sorry to tell you but once you're gone trochoid you'll never go back....

chedda_j

haha i could only imagine. I want to bump up the hp but i cant really afford anything right now as in a motor swap so im thinking just a header, all the emissions bull ****, and a few other things. Hopefully get 125 hp, id be happy with that for now.

steve84GS TII

Welcome.

125HP is easier than you think......
Rotaries respond very well to exhaust mods,plus being an '80 model,ditching the thermal reactor exhaust will save you some 75lbs!
Headers and a presilencer are a good,cheap start.You might not like the sound initially,but itll be a cheap first mod.A good RacingBeat muffler is expensive,but as a second mod,itll finish off the exhaust modifications.
A cheaper aftermarket/universal muffler will get rid of the high pitched "weedwhacker" noise,but itll be loud....very loud.The RB is the only muffler out there that can tame the noisy rotary effectively while not strangling power.

The ignition system of the 80 is kinda funky.It can easily be upgraded to the full time operation,81-85 igntion system with the more common ignitors on the distributor.While your at it,another cheap and quite effective mod is the MSD direct fire setup.This basically copies the wasted spark setup used by the 86-92 2nd gen RX-7's,and youll pickup the smooth idle and increased fuel economy that the MSD box provides.Some high power coils(like Blasters) are also a good idea...youll need 3....or use a stock 2nd gen leading coil from a wrecking yard,and one Blaster on the trailing system.The stock FC leading coils are cheap and very powerful.

The 79-80 models already have the best intake manifold of the 12A carbed engines,but their carbs are tuned rich for operation with the thermal reactor.Leaning out the carb,or just switching to an 81-85 12A carb can gain you some power and economy.Please be aware that by this point you will have been well into smog illegal territory.Rotaries pollute a lot if you remove anything,and its tough to make power with the 12A and not break smog rules.

A light flywheel is a pricey mod,but WELL worth the gains.The stock flywheel is heavy and masks the rotaries topend punch.Running a 12 or 8lb flywheel will really let the engine rev like it wants to and is most noticable in the first 3 gears.You will have to get used to start-up clutch work on hills,but its a minor thing,easily compensated for in a couple days worth of driving.

Congrats on the purchase.Well cared for SA's are getting rare.The 79-80 versions of the 1st gen are the simplest and can be made even lighter.Many of the options of the later years can be bolted on easily,like bigger dics brakes,rear discs and LSD differentials.It all depends on if you wanna stay stock and true to the SA chassis or dont mind integrating some of the FB's(81-85) advancements.It sounds to me like you want power and performance.
The bone stock 12A engine can be made to put out 150 crank HP...thats a 50% increase without any internal mods,and itll still be stock reliable!The one mod thatll push you there,after the exhaust and igniton mods,is a carb.A Weber,Dell or Sterling Nikki can feed the engine the air needed to get to 150HP.
The tradeoffs are smog and fuel consumption,but hey,its a sports car,right?

chedda_j

Thanks for all the info. that was basically what i was looking for. Im going to pick up the car in a week or so. I was told it was a 1980 but im going to check the papers. I was already looking for carbs and stuff but why cant i just make my own intake mani with a holley 650. it would be easy enough and i could get a shortly used carb for about 150 bucks. While the intake mani would be easy to make with some mandrell bent steel and a tig welder, then just make the plate that mates to the engine with a 1/4 inch piece of steel with a milling machine.

steve84GS TII

No reason you couldnt make a manifold,if you want to.
Others may argue it,but the Holley 650 is too much carb for a stock 12A.If you saw the size of the stock exhaust ports,youd understand.
The Sterling carb (or a Yaw carb if you could find one used) is a warmed over stock carb that flows as well as a properly sized Holley(400CFM range).Since its based on the stocker,itll bolt right up to the stock intake and requires no custom stuff to work.The 79-80 cars already have smooth intake runners without all the clutter of the 81-85 intakes.
Years and years ago,I ran a Yaw Nikki with all the mods I listed above.The throttle response, and power over stock was amazing.It was like driving a 4-wheel dirtbike.The Nikki has 4 barrels and vacuum secondaries,so there was no lag or bog, no matter how you drove.Tuning was also easy.I ended up advancing to EFI and turbos because there was no way in hell to get that setup smogged,and I wanted more power.But it was very entertaining and very reliable in the 150HP range.I even succesfully adapted all the mods to a 4-port 13B,which pushed me to about 170HP,with a better torque curve.In the end,EFI was the logical choice for more power and ease of tuning....

chedda_j

Ya i know that EFI is all that but i love carbs, im sorry to say it, but i love carbs. I love to stay old school, but in the near future i may thing about going to efi. So i should look for a smaller 4 barrel 400 cfm carb. Well i just happen to have four honda goldwing singles lying around that i might have to make runners for.

rx7owner

sorry for the hijack but im pretty much the same sitsuation..but what about a street port....that gives a huge boost in power and is still reliable is it not??

chedda_j

a Street Port being?

aussiesmg

iTrader: (1)

Its a rotary thing, best comparison is a port and polish to the head/s for a boinger, lets more gas and air into the engine, thereby more power. It can get expensive though. A good carb and exhaust with decent ignition should be good for 150 hp.

I recommend a Mikuni carb for a stock port.

chedda_j

Heres a picture of the carbs i want to adapt to the engine

http://www.gdlcycles.com/general/94carbs.jpg

aussiesmg

iTrader: (1)

Nice, hope you can tune....

chedda_j

Oh i can tune like a mother ******. I couldnt find an injector on a EFI engine (jk) but i can tune a carb, or multi carb like a mother. I have a question...two or one rotor in my engine, why is there 4 intake holes?

3rd and final 7

iTrader: (9)

its a 2 rotor pretty much any rotary car you find in the states is going to a 2 rotor unless it was a special job done by someone. im not % why but im sure that there is 4 intake ports for better airflow even more when your secondairys open up but like i said im not really sure so im going to shutup b4 i make a fool of myself!

chedda_j

So it will work fine with the motorcycle carbs. Im wondering if its been done or if it will work at all. I know that it works well with higher compression engines with higher horsepower. The stock engine in my car has a ratio of something like 9.2-1 is it not? At that compression the motorcylce carbs will work good but i can tune them for good low end or good high end...but since there is four intake ports, i can tune two with a slightly richer mixture (the two larger ones) and run the two smaller ones with a little less mixture so that its good over all power. Its different with a 4 cylinder engine because each carb powers a cylinder, but il have two for one cylinder.

steve84GS TII

Thing is,the rotary pumps a lot of air for its size.
The official engine displacement might be 1.1L,but the 12A actually moves as much air as a 2.3L piston engine.Thats part of why there are 4 intake ports even though there are only 2 rotors.The rotory has 3 combustion chambers for each rotor,each chamber working at a different cycle as the rotor spins.But all 3 sides feed from those intake ports,thus the large volume of the ports.The two in the middle are primary ports,for idle,lowend and midrange.The outer ports are for topend breathing and are matched to the larger secondary barrels of the carb.I highly doubt that there are any motorcycle carbs that will flow enough air for a rotary,especially since the primary and secondary ports flow at different CFM rates.

For the record,the size and shape of the intake/exhaust ports on a rotary,is equivelant to camshaft profile and valve size/timing on a piston engine. And,like a piston engine,in order to port the passages out for more power,you must tear down the engine.A streetport will give you anywhere from 10-25% more power,but you must do a full engine teardown and rebuild to accomplish it.And the more you port,the more you shift power to the topend,which can/will comprimise lowend torque,idle quality and fuel consumption.

680RWHP12A

/\/\/\/\/\/\ steve, very nicely put /\/\/\/\/\/\\\\\


first things first.. welcome to the rx7 club....what kind of cheese do you like? maybe you will get the answers you seek.
do you know the difference between mild cheddar cheese and sharp cheddar cheese? mmmm tasty

Nicholas P.

iTrader: (1)

680likes cheeseeee.

chedda_j

Tell you the truth i love cheese on everything i eat. Thanks for the help so far. Its answering alot of my questions, but i have one more. I heard that these engines run good at 450 cfm, my indavidual carbs are rated at 125 a piece, bringing up the cfm to a total of 500. Is that not enough cfm, or was someone bull shitting me?

680RWHP12A

no ,thats enough cfm for a stockport 12a... i think you should try them, lots of work to get the linkage to work, but if you can get the carbs cheap, it might be worth it...