twin exhaust cam set up?

[robby50cal]

what, if any would be the bennefits of having a 2 exhaust ('91, with the longer duration) cam set up on a 95 KA?

[sunnys14]

yes! better top end for the cost of low end. my power band seems to shift up about 750 rpm with that setup.

[DjPantsSpecR]

i wanted to chime in on this because i used to use these cams. I really liked the top end and it really pulls from 5000-6500.

However after reading a lot of stuff elsewhere, i decided to make use of my "useless" S14 cams. Useing the S14 exhaust cam on the intake and the stock S14 exhaust cam on the exhaust side you obtain a 248/232 setup.

On the butt dyno, the loss in top end is unnoticable, but the gain in midrange is incredible. Power gains from 2000-5000 are noticable.

I've heard of this mysterious dyno sheet on freshalloy, but i havent seen it, and it compares 248/248 to 248/232 and the the loss in the top end is one horse but the gain in the midrange is four horse. but of course, i've never seen this sheet, so i wont believe it. However the butt dyno makes me believe its true.

On a boosted car, like you have sunnys14, less overlap, like the 248/232 gives you would be more ideal for spool up, and a lotta KA-T guys are useing these. I figured i would suggest trying it since i assume you have a set lieing around.

[InsanityInc]

i wanted to chime in on this because i used to use these cams. I really liked the top end and it really pulls from 5000-6500.

However after reading a lot of stuff elsewhere, i decided to make use of my "useless" S14 cams. Useing the S14 exhaust cam on the intake and the stock S14 exhaust cam on the exhaust side you obtain a 248/232 setup.

On the butt dyno, the loss in top end is unnoticable, but the gain in midrange is incredible. Power gains from 2000-5000 are noticable.

I've heard of this mysterious dyno sheet on freshalloy, but i havent seen it, and it compares 248/248 to 248/232 and the the loss in the top end is one horse but the gain in the midrange is four horse. but of course, i've never seen this sheet, so i wont believe it. However the butt dyno makes me believe its true.

On a boosted car, like you have sunnys14, less overlap, like the 248/232 gives you would be more ideal for spool up, and a lotta KA-T guys are useing these. I figured i would suggest trying it since i assume you have a set lieing around.

How do they compare to 240/248?

[1991S13]

However after reading a lot of stuff elsewhere, i decided to make use of my "useless" S14 cams. Useing the S14 exhaust cam on the intake and the stock S14 exhaust cam on the exhaust side you obtain a 248/232 setup.

Do you mean using the S13 exhaust cam on the intake and S14 exhaust cam on the exhaust side to get a 248/232 setup? I thought both S14 cams were 232 degrees...

I also heard about this mysterious Fresh Alloy dyno sheet, and after searching for the better part of a night I could not find it either.

[DjPantsSpecR]

ah, see i originally had that, but i havent had that for a few months. I'd also be curious to know how my 240/240 set will do in my automatic.

also i know someone on here said 248/232 to him felt mushy in the lows and 240/232 was nicer for him.

The best i can answer that question for you is:if 248/248 felt better in the top end than 240/248, but the low end felt worse and the midrange was shifted up significantly. Now, on the butt dyno the midrange with 248/232 feels WAY better than 248/248 and the top end feels the same (however the noticeable loss is only between 6500-7000) but just about everyone knows to shift before that.so through reason, which is barely ever right, 248/232 should feel better than 240/248, and to my recolection, it does.

Now if you think for a second why this is true it makes a little more sense, and thats what convinced me to complete this swap. Useing the 248 on the intake side allows for a lot of duration to fill the cylinder. Also the 248 used on the exhaust side allows a lot of time to evacuate exhaust.

Unfortunately typical automotive reason would lead you to believe that bigger numbers make bigger power, thats why fools put 1500cfm carbs on their 350s. All this duration leaves a gang of overlap, which you already knew about, and its only good for producing power up in the high rpms, which i'm sure you already knew.

now, we want to have as much intake as we can handle, but we can decrease overlap with a smaller exhaust cam (by smaller i mean less duration). This decreases overlap and changes when a lot of events happen. Now changing the duration on the exhaust cam seems to do the most work in shifting the powerband.

So in the most long-winded answer ever:speaking completely theoretically, i think 240/248 would not allow as much intake charge as a 248 would, and it still has the "high powerband shifting" 248 exhaust cam.

This thinking is kind of contradictory in that i said earlier changing from 240/248 to 248/248 shifts the power band up a bit higher. i don't believe this to be true, i think the additional intake duration just exploits where the 248 exhaust cam wants to put the power band. There is also the fact that a 248 intake cam rotated four teeth to actually work is off by about three degrees.

I wish i had a more clear, concise answer for ya, but i just cant remember 240/248 as well. i'd also like to just drive home that with 248/248 i always wish i had anoth thousand rpm to really use it because it comes alive so late.

[DjPantsSpecR]

sorry i was writing up this monsterosity when you asked that question

yes one s13 exhaust cam rotated four teeth to work on the intake and one s14 exhaust cam in the stock position on the exhaust side

swaping cams is really easy so i suggest every give it a shot to see what they like.

also i read some crap about putting the igniton timing at 15 btdc, and thats bull, 20 does it fine. i used to run a little more when i was 248/248 but its no longer necessary

[240sxjeff]

I'm a little new to the KA engine so I kind of wanted to ask a question real quick. What you guys are talking about is swapping the stock s14 KA cams around right? Putting the exhaust on the intake side and the intake side on the exhaust side? OR are you sayin just swapping the s13 intake cam into the s14 intake side. I'm a little confused and probally not making any sense right now sorry

[:: orion ::]

Swapping the S13 intake cam into the S14 motor...

S13 has 240 degree intake, 248 exhaust...or 240/248.

S14 has 232/232...

So 240/232 is S13 intake with S14 exhaust cam.

248/248 is 2 S13 exhaust cams...

Etc, etc...

- Brian

[InsanityInc]

I would definitely believe that 248 on the intake is better than 248 on the exhaust, as I've found in general cam tweaking that overlap isn't really all that useful, and what seems to give the biggest gains is having the intake close point at the proper place for any given RPM, where a higher intake duration would move that point higher in the RPM range, whereas a 232 cam on your exhaust is still going to evacuate it just fine.

[DjPantsSpecR]

exactly, and this helps give you a lil more time to build compression too because the exhaust closes earlier. if you swap from the 248/248 to 248/232 you can literally hear the difference in overlap.

240sxJeff: what i am pitching is using an S14 232 exhaust cam in the stock position on the exhaust side. And taking an S13 248 exhaust cam and rotating it counterclockwise four teeth to work on the exhaust side.

i'm just trying to inform you, if youre going to try this definately research your balls off, because i dont wanna see someones first time with cams ending up with bent valves.

[sunnys14]

248/248 made me loose mad torque off the line when i was NA. I can barely launched on my friends 05 Scion tC!

[DjPantsSpecR]

from what i've read, because i've never personally used 232/232, even 248/232 can't replace the torque lost, but it does a much better job of it, and it replaces a gang of midrange.

and thats too bad, cuz tC's are slow, put back that 232!

[240sxjeff]

[QUOTE=DjPantsSpecR]

240sxJeff: what i am pitching is using an S14 232 exhaust cam in the stock position on the exhaust side. And taking an S13 248 exhaust cam and rotating it counterclockwise four teeth to work on the exhaust side.

QUOTE]

Do you mean the s13 exhaust on the intake side? And also when you say rotating it counterclockwise four teeth you mean on the cam gear, correct?

[InsanityInc]

If you fiddle with your cams, make sure you can turn the engine a full revolution or two by hand before you try to start it.

[DjPantsSpecR]

yes sir:

in order to get the s13 exhaust cam to work as an intake cam you need to rotate the cam gear four teeth counterclockwise. Then, you need to rotate the cam until the pin on the cam goes into the hole on the cam gear, this is the poor mans way of re-pinning the cam.

Good point insanity, definately rotate your engine with a 24mm socket on the crankshaft pulley/nut to ensure you dont have any clearance problems, and if at anypoint it gets too hard to turn by hand stop, because even turning it by hand can bend valves if your cams are off.

The first picture on the S13 cam sticky at the top of the KA section has always bothered me. He takes these pictures directly from his website and it say that the cam gears are rotated three teeth to work, but thats just not true, if you read his website he realizes he made a mistake and he meant four teeth, but he physically set it up correctly. I dont have the internet at my house so i was going by memory when i swapped cams and rotating it three teeth eventually caused me to bend about twelve valves. This was about six months back, but i still wish it didnt say "rotated three teeth" on that cam sticky, because its a great sticky and it caused me to mess up, but thats all learning....

so be prepared to make mistakes, but just make sure to turn the engine over by hand to see what it feels like before you start messin with your cams, then make sure that after you swap your cams that turning the crankshaft over by hand feels exactly the same as it used to, or you has to fix some problem or risk bent valves, and thats gonna be harder than if everything was at tdc, but you cant turn the crankshaft with the camshafts in. This is not a zero clearance motor and you will bend valves, so if everything is kosher, pull the camshafts out.

also if you've never taken your camshafts out before, i dont know if you have, but you need to unbolt the bearing caps in many many steps

[InsanityInc]

You shouldn't be able to bend your valves by hand unless you're extremely strong or are using a very long breaker bar to turn the crank.

[240sxjeff]

hmm, the reason why I was asking some of these questions was because I am planning on removing my timing chain guides and powdercoating my valvecover, so I figured I would replace my intake cam with the s13 exhaust cam like you guys were mentioning; but it seems a bit too risky to me so I think I will just leave it alone. All the bending valves stuff has me a little worried

[DjPantsSpecR]

see, thats what i was afraid of, i don't mean to scare you, but rather to inform you of what COULD happen, the information you have been given is pretty good, and if you're even the slightest bit mechanically inclined you should be able to do this with out any problem, you just gotta make sure you are at the tdc mark on the crank, make sure the rotor on the dist points to one and then do your cam work. Its really easy, even for a first time job, just make sure you match the picture.

I really want you to try this if you are up to it, dont be scare of head work man, thats not my intention.

and yes you definately shouldnt be able to bend valves by hand, i agree with that entirely. But i do use a good sized bar to turn the engine over, and i know if the bar stoped moving some guys first instinct is to muscle it...

but try it, i mean free torque!

[1991S13]

If you are worried about messing up when you're setting the exhaust cam on the intake side back 4 teeth on the chain you can always take the cam to a machine shop and get it repinned so it fits.

This is what intimidated me, so I stayed away from it. I have done head work before though, and you shouldn't be intimidated by it. It's actually pretty easy.

[240sxjeff]

I know you didn't mean to scare me away from this, lol. I still don't know maybe I'll grow some balls and go ahead and do it. I'm a little mechanically inclined, I've put together motorcycles from the ground up so I dont really know what im afraid about Would any of you know where to go to get just the one cam, it seems everyone sells both cams as a pair?

I really would like to do this because the KA is too slow for me, it feels like it lags alot kinda like the car wieghs a ton

[DjPantsSpecR]

then do something about it. This car certainly is not fast, but everything ive done to it thus far is free minus the intake i made that cost me about 60 bones.

it's easy to take a lot of weight out of your car, mine has barely anything left in it, just over 180lbs removed from the car.

its still not a fast car, you cant expect to be fast easily in an NA KA, but it is very, very satisfying. Punching it at 70mph in fourth gear for example, very satisfying. l

ike in the way driving a six speed transam is satisfying, it gets going real quick, but the car still feels heavy, its just like driving a fast lincoln. its still satisfying

a lightened 240 give the illusion of torque, but although it isnt fast it feels just right

[1991S13]

Have you called any salvage yards to find a cam? Im sure they would sell you just one. Might even give you both for the price of one instead of keeping an engine with just one cam sitting in it.

[240sxjeff]

Have you called any salvage yards to find a cam? Im sure they would sell you just one. Might even give you both for the price of one instead of keeping an engine with just one cam sitting in it.

I actually have not. I have not started looking too deep into this because of the whole bending valves thing, but I think first thing Monday morning I will start calling around.

Also I see a couple of sets on ebay would any of you advise not buying it from there. Is there any things I should look for when I go to buy a cam or does it not really matter? And how would I know that they are true s13 cams?

[1991S13]

I try to stay away from buying any critical parts off of eBay because I don't trust people. If you found what someone claimed to be a set of S13 cams, they could wind up being S14 cams then you just bought something you already have. I'd want to see the car they came out of.

I don't really know what to say about how you could tell it's truly a set of S13 cams. In S13's the intake cam has an orange spot and exhaust cam has a green spot, and I think S14's are opposite.

I've never bought used cams, and haven't really heard of anything to look for. (This is when someone else can chime in, lol.) Maybe after being used for a long time the lobes could get scarred up from contact with the valves?

[DjPantsSpecR]

best thing you can do is mic the lobes to see if they are in spec if you are worried about that. i personally wouldn't worry about buying used cams

i know that on ebay a set of "hot 91 S13 cams" could really be some S14s that some guy is pawning off becasue he just bought some S13 cams. I dont like to see anything claiming to be the 91 cams, because that was a long time cross misinformation about which cams were in fact the 240/248, and its easy to take people in with that scam, becasue they were already dumb enough to believe that 91 cams are so incredible

i think the truth about cams is, and now i cant entirely remember correctly, but every KA from 91-93 cars has 240/248 cams, and more than half of the 94 KAs had them. However, the only true way to tell if you are getting 240/248 is if the intake manifold has the secondary butteryfly valves, aka the swirl control valve.

I'm almost positve you are right 1991S13, in that S13 exhaust has orange paint on it and the intake has green on it. Now just to confuse everyone, on S14 its just the opposite, green exhaust, orange intake.

If you have a cam with orange paint, you can figure out if it is an S13 or an S14 based on where the first lobe points compared to the pin. i just did another swap about an hour ago, and i cant remember which way goes what. So either show me a picture, or i'll figure this out a little later, take care

[240sxjeff]

well I can give you the link to the ebay auction if you want its is http://cgi.ebay.com/ebaymotors...%3AITI see in the picture that it looks like one has an orange smudge and the other has a green smudge on it. Other than that I really do not know how to see if they are real s13 cams or not

Oh and 1991s13 I actually had time to call a few yards today, well at least the decent ones, and none of them seemed to have any s13 cars, which means I am out of luck once again lol

BTW just wanted to thank you guys cause all of you have been extremely helpful.

[1991S13]

I may be mistaken, but aren't both S14 cams 232 degrees? If so, this guy is wrong when he says the exhaust cam is 238, and that could be a red flag. If he doesn't know the correct S14 specs, how could he know for sure they are S13 cams, know what I mean? I wouldn't trust eBay sellers...

I had to call nearly every salvage yard in the yellow pages to find all the parts for my manual swap, so it will probably be pretty hard to find an S13. There are some places you can call and tell them what you need and they will try to find it for you, check if you have any in your area.

You're welcome.

[DjPantsSpecR]

you are correct, S14 cams are both 232.

now for the answer no one asked for, but i'm sure someone is curious about: my friend has an automatic s13I just installed one 232 intake cam as his exhaust cam (has to be rotated four teeth clockwise to work) and his own s13 exhaust cam rotated four teeth counter clockwise to work as his intake cam. He says it still doesnt feel as fast as he wants it to be in the top end, but it doesnt feel slower. He drifts his automatic, and he says it drifts much easier and it never broke it loose that easy before.this is my answer of the 240/248 vs the 248/232 cams. unfortunately, this impression is on an automatic, and with a passenger in the car, so i can only imagine that it felt even better when the car was warmed up and minus 170 lbs

[240sxjeff]

hmm this is all very interesting. I guess I will just keep on looking until I find a cam that I am sure about.Once again thanks to all you who have helped me on this topic