Crower cams idle and vaccum

[techghost]

I'm done with my budget head build, got Crower 64413 (272/272) cams, BC springs and TI retainers and MLS gasket.
just started the car.... idle is very loopy, vaccum sits around 0.4 (on stock cams it was 0.7/0.6) quite crappy idle.

Is that normal? i compression tested my car (on NOT) and i got 150~155psi on all 4 cylinders.

sounds ok?

 

[NOSLO2PT0]

Sounds like you might have a vacuum leak or two still. Either that, or you timing is off a tooth, depending on what method you used to replace the cams. Vacuum on stock cams should be around 14-16", and approx 10-12" vacuum with the 272 cams.

 

[jongreene]

Sounds like you might have a vacuum leak or two still. Either that, or you timing is off a tooth, depending on what method you used to replace the cams. Vacuum on stock cams should be around 14-16", and approx 10-12" vacuum with the 272 cams.

thats pretty weak vac. i regularly see 18-21psi at idle stock cams. 14-16psi with 272's

 

[techghost]

My boost gauge vacuum unit is different
I use to get -20 on stock cams which translated to 0.6-0.7 in this one and after cams I have -0.4

 

[jb2zero0six5]

Sounds about right to me, bigger cams will give you a lopy idle.

 

[hubz91talontsi]

He is referring to bar's.. Only 6psi at idle seems low to me. I have kelford 272's which are much more aggress than bc's, and i get 12-14 at idle.(almost a bar)

 

[donniekak]

He is referring to bar's.. Only 6psi at idle seems low to me. I have kelford 272's which are much more aggress than bc's, and i get 12-14 at idle.(almost a bar)

Everyone is having a problem with different units of measurement. 1 bar is 14.7 psi. If you have 14psi of vacuum, you have an almost perfect vacuum. 14psi of vacuum is over 28 inches of mecury. It's normal for 272's to have 15 in hg, .5 bar, 7.4 psi vacuum, at stock idle rpm. These are all the same amount of vacuum. Upping the idle to 900-1000 rpms will help with the smoothness of the idle, and hold a little more vacuum.

 

[RED AWD GSX]

Yes, I have 272s with stock cam gears, timing at factory, idle at 950 with my chip and I idle at 10 in vaccum.

 

[techghost]

ok, sounds like my vacuum is quite ok

What AFR do you guys see on your wideband when idling?.

 

[doayamaha]

Sounds to me like you just have some overlap something you will have to deal with since you have stock cam gears some adjustable cam gears and degree the cams may give you some better results and be less prone to knock

 

[techghost]

my timing is spot on, i triple checked it and every mark lined up well. in this case what typical setting should i do in order to reduce overlap?

i just drove the car (without boost though) and it was pretty ok, missed a bit of low end torque.

why should it knock? previously before these upgrades car ran smooth/fast at 11.3afr without any knock but why should i expect knock now?

 

[doayamaha]

Aftermarket cams have a different cam centerline than the factory came meanning that the cam needs to be adjusted ever so slightly usually just by a couple degrees but because of the valve timming being of could not say for certain that it will but could make it more likely to knock

Did you buy these cams new or used if you bought them new it should have a cam card with it to tell you the cam centerline

Aftermarket cams have a different cam centerline than the factory came meanning that the cam needs to be adjusted ever so slightly usually just by a couple degrees but because of the valve timming being of could not say for certain that it will but could make it more likely to knock

Did you buy these cams new or used if you bought them new it should have a cam card with it to tell you the cam centerline

Sorry not shure what happened there ^^^^

 

[techghost]

^^ i bought them brand new from MAP. cam card was missed on their way to my country. but i can download it from crower website (dont know how to use it though)

 

[doayamaha]

do a little searching on how to degrees cams, there are quit a few write ups out the on the matter but that should exsplain your cam card. however all of this is useless without adjustable cam gears.