New motor won't idle. BC 264 cams?

[MRSUPRA]

Just installed my built 7M-GTE with BC 264 cams.(Still on the stock ECU and AFC). For some reason the car will not idle. It will keep going if I step on the gas, but it will fall into a very rough idle and die.

I know there could be lots of things going on, but I went over just about everything. Even changing back to my original 550cc injectors.

I read in the NA section about a guy having trouble with his BC cams on his 7M-GE. Has anyone on the 7M-GTE installed these cams With or Without any issues?

 

[need new tires]

i would check timming. did you degree your 264's?
also make sure all of the IC piping is on :nono: dont ask


side note: stock injectors are 440's

 

[MRSUPRA]

Intake and exhaust cam gears are at 0 degrees. I do not have adjustable cam gears (yet). I figured it should run right with them at 0 since that's what BC reccomends.

"side note: stock injectors are 440's" Thankyou.

 

[Zazzn]

did you reset the comptuer, lots of time it takes time for it to reset and learn to idle.. I know the 7m sucks for trying to idle when things are changed for air things... (afm ect)

Also, you may need timing.. Sounds like the cams have overlap which is why you have shitty idle... which IMO sucks.. I hate overlap on turbo cars...

I found crowers had the same problem and i made less power in low end and top end compaired to cams with no overlap when i was doing 1jz testing.

 

[MRSUPRA]

Thanks for the suggestions. I did disconnenct the battery for a minute to reset the ECU.
I also tryed to check the timing. With the T and E terminal shorted, I was at about 15-20 degrees with me trying to get the idle as low as possible before stalling. So it's probably not an accurate measurment. And that was with the CPS turned to the max.

So I geuss if there is too much overlap, the only way to take care of that is with cam gears.

 

[bowsercake]

Does this sound correct:
To decrease overlap? Advance the Exhaust Cam and Retard the Intake Cam

 

[need new tires]

Does this sound correct:
To decrease overlap? Advance the Exhaust Cam and Retard the Intake Cam

wouldnt that increase the overlap?
i think its the other way, not 100% tho

 

[bowsercake]

Exhaust closes sooner, intake opens later. that was my reasoning, I may be incorrect though.

 

[MRSUPRA]

Yeah, I believe to decrease overlap, you need to advance the exhaust and retard the intake. And yes, Zazzon is right, lots of overlap will help mid to topend power but hurt idle and low speed drivability.

 

[amichie]

I have just installed BC264 cams in my 7M-GE. I find that the idle at standard cam setting is marginal and if you decrease the overlap then it improves dramatically. I imagine the problem would be worse on a turbo engine.

If you are prepared to remove the timing belt again you can change the position of the drive pin on the vernier cam gears and achieve +/- 3, or +/-4.5 cam degees on either cam.

My exhaust is set at +4.5 with the vernier wheel and my intake is set at +4.5with an adjustable wheel. So no change in overlap and idle is still marginal at these settings but this gave me excellent performance. As soon as my second adjustable wheel arrives I will try to reduce the overlap a little more by advancing the exhaust cam even further.

I have found that 1 degree of reduced overlap makes a huge difference to the idle quality.

BTW what clearances did you set your shims at??? I am going to try to increase all the clearances by about 2 thou each to try and reduce overlap further and achieve an earlier inlet valve closing time. Early inlet valve closing time seems to be the key to getting good performance out of these cams. It's as though they have a little too much duration. I used to find with the stock cams that they went better if you retarded the inlet cam effectively delaying the inlet valve closing time.

 

[MRSUPRA]

Thanks for the info amichie. Looks like cam gears are on my buy list.

As for the clearance on the shims: I just kept the clearance within what the manual said. Can't remember what that was off the top of my head.

 

[IJ.]

With my 280 grind my car idles like a kitten at 700 rpm.

 

[bowsercake]

With my 280 grind my car idles like a kitten at 700 rpm.

Did you do anything special to get the idle that low? What is the lift on your cams? ALso, what adjustments have you made to your cam timing?

 

[IJ.]

.351"/9mm lift 280 degrees duration (226 @ 50thou)

13>15 thou lash.

Cams are currently installed to 0 per their timing tag

Nothing special other than it's all screwed together right and tuned properly, light crank and good balance might be helping a little at idle.

 

[bowsercake]

I bet that MoTeC helps a lot with getting the idle situated. Are you using the stock Idle Speed Control, or a GM ISC, or what? The stock ECU might not be too good at figuring out the idle with cams that aggressive.

 

[7M-fanatic]

With my 280 grind my car idles like a kitten at 700 rpm.

As did my HKS 256s, and most likely my TODA 264s when the engine is back together.

Double check your cam timing, it's easy to get one a tooth off.

 

[IJ.]

I bet that MoTeC helps a lot with getting the idle situated. Are you using the stock Idle Speed Control, or a GM ISC, or what? The stock ECU might not be too good at figuring out the idle with cams that aggressive.

I was running a 2 wire Ford ISC but this time around I'll let the DBW handle it all.

 

[amichie]

.351"/9mm lift 280 degrees duration (226 @ 50thou)

13>15 thou lash.

Cams are currently installed to 0 per their timing tag

Nothing special other than it's all screwed together right and tuned properly, light crank and good balance might be helping a little at idle.

Hi IJ

Can I ask if you set the clearances up to 13 to 15 thou deliberately or did you end up with these clearances through your tuning process. I'm just curious because I feel that my next step is going to be to slightly increase all the clearances. At the moment they are all in the range 8 to 12 thou which is pretty much in the factory range.

Andrew

 

[IJ.]

Andrew: 13 is the spec supplied by Wade Cams I use non adjustable shimless buckets so have my head guy set them to 15 to allow for the slight settling/recession.

This ensures that they never close up in use and hang a valve open (had this happen on all 24 when using a multiangle valve job with narrow seats)

 

[figgie]

Hey IJ.

Finally went DBW

from Holden LS1 based car or .........