Hi..

Just started to tune my engine, and for what I can see it likes much timing.

Ex. Idle 30deg at 900 rpm
Cruise 55mph 60 kPa 2000rpm 45 deg, but I think I can rasie it some
Wot 32 deg. This I will rasie to about 35-36deg

Am I off here or?

The cam is a CC306 and the comp is 9.0:1 with this combination I think I needs alot of timing or am I way off here?

 

Your cylinder heads combustion chamber design has as much to do with the advance requirements as the compression.

More than 40 degrees is not commonly needed at cruise.
Full throttle may approach 34-36, just not with boost...

What are your A/F ratios at various loads? Excessive rich and/or lean mixtures will increase the advance requirements.

How is the charger install coming?

 

Hi Lonnie

Had some trouble after the new intake install........

I just started tuning without the F1 now, aiming at 14.7 as a starting point, will go to 16.5 at highway if it can take it, at WOT am aiming at 12.2 as a starting point.

The belt was to long, so I need to get a shorter one, otherwise the install is done, will send pictures soon. Just want the tune to be done without the blower on first........

pictures can be found at http://medlem.spray.se/gta324 soon to be updated! Movieclip of 1 test drive without blower: http://www.tacs.nu/forum/download.php?id=5624

 

Not sure the engine will be happy at much leaner than 14.7:1. You can try, but be sure to keep an eye on the EGT's. As you first go leaner, the EGT's will increase & then eventually start to drop again (as efficiency drops off from being too lean).

With the cc306, 14.5:1 is generally as lean as I go for drivability reasons. All this effort may not be worth the slight mileage increase.

At WOT, shoot for 12.8-13.0 without boost.
With boost, start in the 10.0 to 10.5:1 range & carefully lean out from there.

Keep me posted on your results.

 

Did some tuning yesterday, with weird results...

Was using closed loop with narrowband O2 in LH header, WB is in RH header

At 90km/h BLM Was 144 then the WB showed 14.3
At 110km/h BLM was 142 Then WB showed 13.3

I Will have to check for
- exhaustleaks
- Intake leaks
- Bad O2

/N.

 

I view EGTs as starting to drop on the lean side of stoich. IOW, peak EGT should be at (appr.) 14.7 AFR, with falling EGTs actually, on EITHER side of that (appr. stoich) peak. Agree?

 

Ok........

Now I've changed
- Header gaskets
- Collector gasket
- New O2
- Intake gasket
- Injectors
- Plugs
- Wires
- Checked for cracks in headers
- Sprayed for vacuum leaks
- Checked for AC current disturbance from alternator

Nothing helps.........still showing rich on the RH side........

Switch side with O2 and WBO2 and now the the WBO2 is showing lean, So it looks lika somekind of leak on LH side but I cant find it I have tried everything (read above)........... The diff between NBO2 and WBO2 increases with rpm.........

 

Might wanna check the intake for the leak in the lifter valley. If you had things machined (block decked a bunch, heads milled or angle milled, etc..) it can throw off the mating surfaces just enough to cause issues. Worth checking out..

Dave C.

 

The only thing I have machined is the HSR after it was welded to be able to port it to 1206. I also have RTV sealent on both sides if the gasket to be sure..........

/N.

 

Update..
Without blower I ended up with 36deg at WOT and AFR 12.5, it felt good and no KR. I tested to put 38 deg and still no KR but I decided to stop tuning it N/A and but the blower on.

The pulley I got only gave me 6-7psi of boost at 5700 where I shift for now.
I started with a really rich mixture 10.0-10.5 and 26 deg of timing. Now I'm at 32 deg of timing and 11.5AFR, and it seems like my engine likes/can handle alot of timing........

I have a 4.25" pulley on the way now so I will start tuning it soon....Hopefully I will se 12 psi of boost

Lonnie I will keep you updated........

/N.

 

You are low on the RPM with your heads/com. At 6200, you will likely see 2-3 additional # boost & should make good power to near 6500 with an additional # boost at this RPM. Just pull some timing at these RPM's to compensate for the additional boost.

Good luck & keep us posted.

 

My setup is close to yours in na - funny thing is it seems to be the reverse; ie all the tunes i try always have way to much advance. Even mail order tunes from notable fbody people retard at idle in park & even more in cruise.

Odd.. either the fbody tuners have no clue on how to tune low cr or my car has a gremlin.

 

Hmm, thats odd...... I got my 4,25" pulley mounted now so I just need to find some belt and then its tuning time again, hopefulley I will see 12psi.

I can post a pic of my current timing table if you want?

 

I had an 8.5/1 355 with the GM 847 cam (234/242). After lots of testing, it made most power at 42 deg total timing.

 

42deg, ouch thats much..............

/N.