4af performance tuning - Toyota Nation Forum : Toyota Car and Truck Forums

gasman · 01-20-2004, 08:59 PM

hi i have a 1991 corolla gl with a 4af carbed engine and want to tune it up and with out replacing the engine. i want to do this a cheeply as possible. what things can i do to it?

btw it has only done 118000kms and my parents bought it brand new.

|PuNiSh3R| · 01-20-2004, 09:29 PM

Ok, so.. do a tune up.. get new plugs.. dizzy cap and wires.. rotor.. air filter etc etc

gasman · 01-20-2004, 10:30 PM

i got the tune up and plugs (and no difference but still good for car) and my air filter hasnt been changed since 1991(getting on to that) . any way i was thinking more along the lines of going past the normal stuff an to new parts that make a difference.

btw whats a dizzy cap

|PuNiSh3R| · 01-20-2004, 11:01 PM

dizzy cap is the distributor cap.

how much money do u wanna spend on this car/engine.. do u plan on keeping it for a LONG time or a short period.. are you eventually interested in turbocharging or keeping your vehicle naturally aspirated? Basically, not exactly turboing the 4af.. but do you have a desire that makes you want to turbo a car.. if so you may not be interested in the 4af.. it's all about how much work you want to put down.

gasman · 01-20-2004, 11:10 PM

what can a dizzy cap do for performance?

i intend to keep the car for a long time and am intrested in in keeping it na. money wise i got it it just take time to get it and i got time on my hands. i want to keep the 4af because reading other forums and threads the 4af engine is a engine with lots of un taped potential( and also being able to say that they got beaten by a 4af most commonly knowen in new zealand as a crappy engine)

|PuNiSh3R| · 01-20-2004, 11:13 PM

Drop me an IM on AIM

|PuNiSh3R| · 01-20-2004, 11:14 PM

Dizzy caps just get worn out.. the contacts inside for the wires.. and they can get moisture inside of them.. etc etc.. it's just part of a complete tune up.. along with the fuel filter

gasman · 01-21-2004, 04:41 AM

Quote:

Originally posted by |PuNiSh3R|
Drop me an IM on AIM

what do u mean by that?

gasman · 01-21-2004, 04:45 AM

i read on the "tuning my corolla" thread that u can increase accleration buy advancing the inlet cam buy two teeth from stock. can any one tell me how to do that? ( pics will help )

|PuNiSh3R| · 01-21-2004, 11:33 AM

heh.. You don't want to advance it 2 teeth! one would be sufficient.. beware though that it drops your top speed then.

you know.. aol instant messanger.. or MSN messanger pink_floyd17@hotmail.com

All you gotta do is pop your valve cover, set your timing to TDC (top dead center).. So you use a ratchet to turn the crank pulley.. ALWAYS TURN CRANK PULLEY CLOCKWISE!

Turn it until you see the timing belt gear, there is a knotch in the gear.. turn the crank till you see the knotch straight up and you can look through the knotch and match it up with another knotch which is on the block.. With the valve cover off look at the side of the cam gears and they have 2 dimples on the side of the gears, that's 2 dimples per gear.

2 of the dimples should be matched up facing eachother.. the other 2 should be facing straight up.. you're at TDC now.

Then undo the intake cam by removing the caps that hold it down. They are 10mm bolts. Be gentle and it doesn't matter really in which way you undo them but you have to put them back down in the correct order.

You will probably need a rubber mallet to tap the end cap off.. Once you do that.. gently coherse the camshaft out.. Then turn it so it so that dimple that was lined up with the exhaust cam gear is now sitting 1 tooth up from the exhaust dimple.. set the cam back in.. make sure that you did it right.. then in this order.. facing the windshield.. you put the caps back in!

Do not torque the caps yet.. just put them down in this order and use the bolts to just pull the cam back down in place but don't torque them.

3rd cap from the left
4th cap from the left
2nd cap from the left
5th cap from the left
1st cap on the left

Then torque to 15ft/lb's, which I believe is also 18N/m (newton meters) TORQUE THE CAPS IN THE SAME ORDER!!
It really doesn't matter in which order you put down the caps down in just the order in which you torque.

Correct me if I'm wrong on any of my procedures.. I know my instructions are correct.. I've done this about a dozen times now.. I think that cap order is right..

You may or may not need to retard or advance your spark timing.. and possibly retarding or advancing your crank timing may help as well.. I'm not sure.. If you get pinging you could try and retard your spark timing and if you get dieseling you can try and advance your spark timing

gasman · 01-22-2004, 05:09 AM

wow thanks for that i think i will go get a torque wrenck an try it in the week end.

rospen · 01-23-2004, 06:52 AM

Friend you can try this: Remove your whole stock air filter system and in place of that, install a velocity stack on your carburetor.be careful though that the stack you use is no more higher than the height of the shock mountings on each side of your car. If you are familiar with air freshener cans, you can use one of those. MOdify your stock carb man. Have them bored out using porting tools by removing the aluminum that divides the primaries and the secondaries at the top of your carb. remove the breathers too. remove the choke flap as they restrict airflow. smoothen the edges of the top insides of the carb for smoother airflow. port the top insides of the carb so that more volume of air can pass through it.Have the primary and secondary jets open simultaneously just like those side draft carburetors. You can achieve this by modifying the linkage of your carbs, or if your secondary is vacuum controlled, relocating the spring inside the vacuum from the bottom and placing it on top causes the secondary jets to open simultaneously with the primary jet.Rejet your secondary jet to 190. You can also advance your timing a lil bit if you want. Install headers man, since your engine is normallly aspirated, use 4-2-1 1 3/8" headers. As you would notice if you look under your car, you have 2 resonators on your exhaust. You can opt to use one or remove them both. These mods make a difference man specially if you are driving a manual. Happy motoring.

Dicipleofthelie · 01-23-2004, 10:31 AM

i dont think his car.........or many rollas have 4 jets........or am i mistaken

secondaries tend to be on higher end carbs

|PuNiSh3R| · 01-23-2004, 11:55 AM

No, the stock 4AF carb has a secondary.. it's 2 barrel.

But what rospen just explained is useless.. After you are doing blowing your money and time on trying to make something that is already a piece of economy shit into a "performer" you could have made a custom manifold for a set of bike carbs.. or webers or whatever that would truly make a difference.

rospen · 01-25-2004, 01:00 AM

"But what rospen just explained is useless.. After you are doing blowing your money and time on trying to make something that is already a piece of economy shit into a "performer" you could have made a custom manifold for a set of bike carbs.. or webers or whatever that would truly make a difference."

Its not useless friend coz i've tried it and my car is running faster. My engine is 5A which is just 1500 and with that carb mod and exhaust upgrade, im creaming this 92 rolla with a 4AF engine(which i believe is a better able engine than mine) in quarter mile, leaving him 2 cars behind. But i agree with you though, i have a pair of solex 40's which i plan to install in the near future.
Question guys: would a 4af head fit on my 5a engine? someone is selling me a modified 4AF head,(ported, polished and shaved) for only less than $50.(thats about 2500 philippine pesos. How much hp gains would that reward me, say i install the modified head(if its possible) and the twin solex 40 carbs? anyone care to help? thanks