Okay i just swapped my ls head to a built ls head. I have it idling pretty good, but seems to have less vacuum. Is this normal? Sitting at 500ish mbar and at 800-900rpm.

Cam gears 0,0

Cant get igntion timing to advance to 16* with distributor fully advanced. It's more retarded atm.

 

Ls block have b16 pistons 10.8-11.0 compression

 

Do those cams have a lot more duration than stock cams?

 

Yes, they do have a lot of duration. Low idle vacuum is what happens on big cams

It also sounds like your mechanical timing might actually be off if you cant get it set to 16 degrees after engaging the timing lock in your tuning software (if it can do that)

 

here's the specs:

Stock Specs
B18B IN / EX
Advertised Duration 234 / 236
Duration @ .050" 194 / 196
Gross Lift w/1.75 395 / 380

Crower
Honda / Acura - B18A/B & 1st Gen B20A
Performance level 4 - Stage 3 - 3⁄4 Race - Recommended for mostly strip use in N/A applications. Rough idle.
INT/EXH -
Dur @ .050” Lift: 216°/214° RR: 1.75/1.75
Gross Lift: .445”/.434” LSA: 109°

RPM: 1100 to 8200 Redline: 8700

 

Im using crome and idk if it can lock. I try to adjust ignition the original way earlier but cant get it to 16* with distributor advanced all the way and service connector jumped. I just ask a local tuner and he said try advancing the camgears. I'll give that a shot tomorrow

 

If you don't know how to lock it then how are you synchronizing ignition? Is the ignition output of the Ecu even 16*BTDC when you are lighting the mechanical timing? My guess is your big cams are pulling a low vacuum which is putting your idle region in an area with lower ignition advance and you are trying to sync your ignition at less than 16*. Whats your table ignition value at that cell in your screenshot? I bet its around 14*.

 

He said "in the program" and im not sure how to lock it in Crome, but i jumped the service connector to lock it in. And yes you are right about "your big cams are pulling a low vacuum which is putting your idle region in an area with lower ignition advance and you are trying to sync your ignition". Now that i thought about it i dont know if it's correct to adjust igntion timing to 16* degrees at that vacumm???


If it's idling about 12.87" of vacuum @ 800-900rpm. Would syncing it to 16* be correct? I was told i need to advanced the camgears to be able to sync it in at 16*

 

Did you degree them to the specs on the cam card? You need to start there if you haven't, and you need to measure and map your P2V clearances before you start moving things around.

 

Solved the problem. The cams are supposed to idle around that vacuum/area because of aggressive cam lobe.

Muckman was correct. I was trying to adjust ignition timing at distributor first then set it in the program after. Wrong lol.....So i synch program to 16.5* then adjust at distributor and got it synch correctly, but distributor was advanced all the way. Either way it idle smoother....Thanks everyone.