Brian Crower 7M cams and ignition timing issue

[7M-fanatic]

Wow, that is a hell of a lot of variance in bearing journal size !
I just checked my TODAs, and they are all 26.95mm,
each and every one of them.....
I wonder who BC actually had them made by ?

 

[BLACKCAT]

Yes very dissapointing that my new cams should have such variances especially as I paid almost as much for them as I did for the entire car.:3d_frown:
Now I know why its impossible to find a clear large picture of these cams, covering the important sections, even though various people are selling them.
Even the picture Kyle took of the 272's shows scuffing on one of the journals if you look closely.
Will probably install them next week & CHECK wear after a few hundred km.:icon_evil
Hope the things are not a PITA to tune but am not confident considering Andrews issues.:nono:
Overall numerous hurdles with these things so hopefully their performance will outweigh the annoying issues along the way.

 

[7M-fanatic]

Yes very dissapointing that my new cams should have such variances especially as I paid almost as much for them as I did for the entire car.:3d_frown:

Overall numerous hurdles with these things so hopefully their performance will outweigh the annoying issues along the way.

Just be careful that the largest journal has enough clearance......
Never seen where plasti-gage was needed on a cam before, but with tolerances that erratic, I sure would check.
If you end up with less than .02mm clearance, you may have problems.

 

[amichie]

Hope the things are not a PITA to tune but am not confident considering Andrews issues.:nono:
Overall numerous hurdles with these things so hopefully their performance will outweigh the annoying issues along the way.

Hi Blackcat

If you start off with both cams set at +3 advance you will hopefully find that you are close to the optimum settings. Overall I have found the performance gains to be worth all the effort and really the only thing I could seriously grumble about is the original ignition timing issue that I posted up.

BTW I scoured the crower cams website and found a timing card for a very similar cam designed for the 2jz engine and on the crower cams timing card it says to set up the inlet cam on 106 degrees Lobe centre angle. This corresponds to +2 cam degrees advance.

Crower cams and Brian crower are related somehow but the crower cams website is far more comprehensive and informative.

Update. I have reinstalled the supra intake and tested the car with the ACIS valve open and closed. With these new cams I now get a much stronger response from the ACIS system I guess due to the larger valve overlap. My performance now on LPG is better than it was before on unleaded. I think my next step will be to install your ported exhaust manifold.

I'm also still hunting for a 4.1 or 4.3 diff.

I must say thanks to everyone on supramania for their helpful suggestions.:icon_razz :biglaugh: I.J., Cuel, 7M Fanatic and Blackcat + others
If this forum had +rep like toymods I'd be dishing it out.

Also I got a copy of the book "4 stroke performance tuning" about a week ago and I can't put it down. It has really informative info about how to set up cams and what to expect when you mke a change. It is a really good resource for the NA tuner but doesn't talk much about forced induction.

Andrew

 

[cuel]

Measured the BC 264 cams:

Intake:
Journals: 26.96mm .92 .90 .92 .93 .91 .92
Lobes: 39.20 .22 .21 .22 .21 .19 .21 .19 .20 .19 .21 .19

Exhaust:
Journals: 26.98 .93 .93 .92 .93 .92 .92
Lobes: 39.22 .22 .23 .23 .22 .21 .20 .20 .20 .20 .19 .19

http://cygnusx1.net/Supra/Library/TSRM/MK3/manual.aspx?S=A&P=4

Clearances for cam journals:

No.1 26.949 to 26.965mm
No.2 - 7 26.888 to 26.975mm

Looks like No1 for the intake is just barely in spec., but the exhaust is .015mm to big. Might need to have it turned down a bit.

 

[amichie]

I think I have fixed the idle issues with the air con off.

I managed to trick the ecu into thinking the A/C is always on so minimum idle speed is now about 700rpm.

I will wait and see how it runs before posting how I did it. I should know within a day or so if there are any side effects.

 

[amichie]

OK here is the bodge.

Seems to work but I highly recommend you get a spare ECU and try it on that first. Do it at your own risk.

Basically cut the A/C pin of the connector on the back side inside the ECU and jumper it to the B+ pin. That way the ECU thinks the A/C is always on.

 

[BLACKCAT]

Well I finally installed the cams last night, setting the valve clearance at pretty close to 8 thou intake & 10 thou exhaust.

Put them as close to 0 & 0 as I could see, didnt have to be 100% accurate as I have adjustable cam gears on both which gives me +/- 12 degrees to play with.

Cranked it over & you were right Andrew it idled like crap, could not get any more than about 5 degrees of static timing.
Reset both cams to +3 & ran the cams in for about 30 minutes at varying speeds from 1500 to 3000rpm.
Let it settle for a while & changed the oil & filter.

They are listed as having a slight lope & needing minor tuning, yeah right:aigo:
Even at +3 the idle could be classified as 5/10 at best.
At 0 forget it as it will stall as soon as you put it in drive:3d_frown:

I would STRONGLY recommend installing both cams to at least +2 & tuning from there.

I set the static timing to 12 degrees with all the following cam adjustments & drove it without air conditioning on:

+5 exhaust & +2 intake (112 1/2 LSA), -5 valve overlap, idle is reasonable, performance is good down low & gets much better as the revs rise.

+4 exhaust & -4 intake (110 LSA), 0 valve overlap, idle reasonable, performance only fair down low but very good at 4000+.

+4 exhaust +4 intake (114 LSA), -8 valve overlap, rough idle (just driveable) but very good performance.

Tried some different settings, for idle quality only:
0 I +2 E 113 -6 fair
+4 I +2 E 115 -10 poor
+4 I +5 E 113 1/2 -7 poor
0 I +4 E 112 -4 good
-4 I +5 E 109 1/2 +1 fair

Will have to try a whole stack of different settings but the idle quality is only going to be fair at best running the standard ECU.

From the little bit of driving I have done the performance is very good & only gets better as the revs rise.
For someone installing them with a standalone engine management they will be very happy once they are tuned properly.
Will put the car on the dyno in the next fortnight & see how the figures compare to my previous setup running the turbo intake cam.

Cressidas version of variable timing: an 8 & 14 mm spanner plus adjustable cam gears:naughty:

Time for more adjustments & road testing but its coming down in buckets at the moment:cry:

If I get very good performance & a mediocre idle I can live with that:biglaugh:

 

[amichie]

Hi Blackcat

Looks like your cams have responded exactly the same as mine.

Have you noticed the lovely exhaust note you get with the exhaust cam advanced. Sounds like a Ferrari or something like that.

Mine are both set at +3 advance ATM. My idle quality is good now except when cold it seems a bit ordinary.

My shims are set at a slightly bigger clearance though. About 13thou exhaust and 11 thou inlet. This improved idle quality and general driveability but I do think I lost a little power after increasing the valve clearances.

Overall I'm really happy.

BTW if you want to get your hands on a spare ECU I am happy to do the mod for you. That way idle set point is never below 700rpm.

 

[BLACKCAT]

OK more fiddling with idle only:

I -3 E+4 110 1/2 -1 good idle
I -6 E+4 109 +2 good idle

I dont think the ECU likes the negative overlap of around -8 or more.
Under that figure its reasonable.
You can definately feel the strong pulses when you put your hand behind the exhaust pipe at idle.

Will see how the car drives, when the weather clears, with my preferred setting of -3 & +4.
Cannot believe it likes to idle at 109 LSA but not 114:aigo:
If I want to change my performance range its only a five minute alteration.:love:

 

[disturbed1]

reading all thjis has put me off buying a set of stage 3 cams off my mate

 

[BLACKCAT]

Hi
I certainly would not be put off by what has been said in this thread.
The 272's have more aggressive specs, & will probably be more effective after 4,500 rpm compared to the 264's.

All we are saying is that they are not a straight drop in & expect perfect idle/manners.

They need a bit of tuning to find out what your engine likes as most engines are different based on machining etc.

The performance is very good & WELL WORTH FITTING.

 

[disturbed1]

can that be proven??

 

[amichie]

can that be proven??

Can what be proven?

 

[disturbed1]

The performance is very good & WELL WORTH FITTING.

 

[AJ'S 88NA]

The performance is very good & WELL WORTH FITTING.

As with any cam change with any motor I've modded, the more you do to make the motor breath better, the better thr cams will work. Tuning plays a big part of it, if you tune it wrong sometimes they will hurt performance, and if they are more cam then what you need the same thing may happen.

 

[amichie]

The performance is very good & WELL WORTH FITTING.

Well I would agree and I have the same cams. But this is not proof, just the experience of the only two people I know of that have fitted these cams and played with the timing.

Andrew.

 

[BLACKCAT]

More fiddling with cam timing setting & found that 0 Intake & +4 exhaust ( 44 degree overlap) idles very good & I would use this as a starting point setting if installing these cams for the first time.
With this setting you can obtain a lot of static timing advance avoiding having to file the dizzy slot.
If you do not have adjustable cam gears have a look at the picture below as the stock gears have identical teeth to this & you can use it as a guide.


Found more info on seat-to-seat timing specs:

IO 22 BTDC
IC 62 ABDC
EO 70 BBDC
EC 14 ATDC

36 Degrees overlap
264 duration
114 LSA

 

[amichie]

Where did you get the seat to seat timing info?? And how do your cams perform with those settings.

 

[7M-fanatic]

Instead of filing the dist. hole, use electronics.
I just used the knobs on my Apex Super-ITC to dial in the timing when I put cams in or change the exhaust cam setting.
It gives me +/- 15 degrees.