Dual 248 cam setup on ka24de-t motor

[rn240sx]

Just curious to all u guys out there that have the 248/248 cam setup in their 240sx.. Ever since we got these cams in CORRECTLY, the idle is a tiny bit jumpy with a mis-fire every couple of seconds. Its ALOT better than b4 cause we put them in wrong the 1st time which made the idle rediculously bad..

And now when i rev up the motor and release, once the rpm's drop down to idle status, the motor stalls out. Im not sure if all this is cams related or if its my distributor thats still off timming..If it WAS the distributor, i have no way of timming it cause the ASP pulley has the timming marks in the WRONG place (after hours of troubleshooting)

Any clue's...??

[Redline240]

High duration cams always have trouble with keeping a smooth idle and sometimes dip too fast when coming down from higher rpms...no doubt that has something to do with the rough idle, bump it just a little and you'll live with it...but i don't think 248/248 is enough to cause it to stall coming down, i'd suspect something else like you mentioned(timing)...

Redline

[WDRacing]

So you have no way to check your timing??? Thats sucks, I'd out the stock crank pulley on and check my timing.

[NateDogg]

rn240sx: you can be a hero if you do a little "how-to" with pics to show converting asp timing marks to stock timing marks and show how much adjustment is required.

[WDRacing]

If the circumference is the same the timing should be very close.

[rn240sx]

Well, what i did was got the # 1 piston on TDC on the compression stroke and made a mark on the asp pulley where the timming needle is to imitate where the TDC is supposed to be. This way i wont have to drop in the extension down the spark plug hole every time i needed TDC..Now since that TDC mark has been placed on the asp pulley, I was gonna go to the OEM pulley and measure the distance between timming marks and go to the asp pulley and start making timming marks to resemble the oem pulley. This way i can check and adjust the timming from the asp pulley. I havent done this yet cause im just so fed up from working on this motor for well over a week now trying to figure out this bad idle problem. Now that we got the cams in right, the idle is much better, but not perfect. Thats why i was asking if this 248 cam on the intake side would be the cause of my funny idle or is that just my timming that is still off...

[NateDogg]

I believe that others using the 248/248 cams have noticed a little funkier idle. Remember Nissan didnt incorporate these cams into their engine management values. So it's not going to be perfect. I think you have the right cam and distributor timing. If the thing drives without any coughs then you're probably ok.

I'm looking forward to what you find out about the ASP pulley timing marks and I definitely hear you about working on the engine for so long. I had my cams off a couple teeth and the engine ran like that for about 6 months. I kept failing emissions testing and after about a month and $500 in new parts I figured it out.EDIT: I just checked the timing marks on my ASP pulley and they seem to be pretty damn good. I was hoping to have something to fix, oh well back to studying.
Modified by NateDogg at 2:20 PM 11/30/2004

[rn240sx]

OK, finally got my idle smooth and stable..!!!

It was the intake cam the ENTIRE time... For some reason we were not getting it postioned correctly. After seeing the post on the ka section, we realized that my intake cam was still off. We then fixed it to LOOK identical to the picture and that was 1 tooth OFF from where we were supposed to be. We fixed it and it cranked up and idle'd as smooth as can be..!!I still get a slight mis-fire every other minute or so but its 100% better than b4..!!I took the car out and drove it around, hit it a few times with boost and it held fine and no hesitation. I didnt keep it in boost too long, i just spiked it with spurts of boost from 8-15 psi just to break the motor back in..!! After all the motor has been sitting in the garage for 5 months..Now i just have to burn off this gas and give it 1/2 a tank of 100 octane so that i can run this motor at 15 psi and keep it cool.

THANKS TO JACK for the help..!!