how much duration/ overlap/ can one go before fuel smell gets bad
02-07-2011, 05:16 PM
#1
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how much duration/ overlap/ can one go before fuel smell gets bad Is there a general rule of how much duration, lobe separation tightness and overlap a cam can have before it wouldnt be enjoyable street driving due to fuel/ exhaust fumes at idle? Just a rough idea perhaps? I run hi flow cats BTW if that makes a difference on a 03 Z06.
Thanks
Thanks
02-07-2011, 05:41 PM
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I am probably not much help. My car smells pretty bad when it's sitting in the garage idling. It's not the tune because I have tried leaning it out at idle and playing with the timing. But I don't have cats, and I rarely notice it when I'm driving other than once in a while when sitting still for a few minutes with the windows down.
02-08-2011, 01:04 AM
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thanks for the great technical info so far 
I'll get down to brass tax here guys!
Im wondering how "stinky" a 234/236 112 cam would be with an optimal tune and cats!
I'll get down to brass tax here guys!Im wondering how "stinky" a 234/236 112 cam would be with an optimal tune and cats!
02-08-2011, 03:26 AM
#7
I recall reading somewhere that anything more than about 2 deg. overlap will have a bit of a rich smell. With cats though I'd think you could get away with more. This thread tells a different story:
https://ls1tech.com/forums/generatio...rlap-cats.html
https://ls1tech.com/forums/generatio...rlap-cats.html
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02-08-2011, 07:45 AM
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As much as I love driving a zero-to-lightspeed machine I've come to realize, just as you have, that a stinky car isn't very classy.
Top Gear would say "When you go to pick up Kristin Scott Thomas she's going to ask you why your car's broken."
Top Gear would say "When you go to pick up Kristin Scott Thomas she's going to ask you why your car's broken."
02-08-2011, 08:05 AM
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i'm running a 235/243 113lsa with catless mids and i smell fuel when at idle. it can get strong when in an inclosed area like the garage but i dont let it idle much in the garage. I'm going to get it retuned soon to see if i can get it toned down though.
02-08-2011, 08:22 AM
#11
Is there a general rule of how much duration, lobe separation tightness and overlap a cam can have before it wouldnt be enjoyable street driving due to fuel/ exhaust fumes at idle? Just a rough idea perhaps? I run hi flow cats BTW if that makes a difference on a 03 Z06.
Thanks
Thanks
Since you are already getting your intake from Vengeance, their VRX3 (226/228 114) cam would be a nice cam choice for you. BTW that cam has -1 Degrees overlap @ .050.
Last edited by SideStep; 02-08-2011 at 09:54 AM.
02-08-2011, 01:35 PM
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In general (for your setup) +2 degrees overlap @.050 is about where the gas smell starts. I have swapped in and out 15 cams and I will say +4 is just about guaranteed to have the gas smell. NOW, that being said you can reduce that smell by increasing the Idle Spark Table. Mine is currently set to 22 degrees of advance, but I have a very small cam, -2 degrees. Increasing the Idle Spark Table will also smooth the idle.
Since you are already getting your intake from Vengeance, their VRX3 (226/228 114) cam would be a nice cam choice for you. BTW that cam has -1 Degrees overlap @ .050.
Since you are already getting your intake from Vengeance, their VRX3 (226/228 114) cam would be a nice cam choice for you. BTW that cam has -1 Degrees overlap @ .050.
Thanks for all the replies so far. I dont mind some smell. Just dont want nothing too obtrusive. SideStep, I picked up a used VR FAST 90/90 a couple months ago. The VRX3 is too mild for what Im looking for. I want to maximize my 4.10's with as healthy of a street/strip cam I can get without too much fuel smell. I guess I'll have to live with some anyway.
02-08-2011, 06:16 PM
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In addition to the spark timing changes, the injector timing can be bumped to increase the offset of the opening of the injector to compensate for the overlap a bit. My cam is a futral F-14 - 234 / .601 and there's very little 'gas' smell even without cats.
Bird
Bird
02-10-2011, 10:12 AM
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Thanks for all the replies so far. I dont mind some smell. Just dont want nothing too obtrusive. SideStep, I picked up a used VR FAST 90/90 a couple months ago. The VRX3 is too mild for what Im looking for. I want to maximize my 4.10's with as healthy of a street/strip cam I can get without too much fuel smell. I guess I'll have to live with some anyway.
02-11-2011, 09:42 AM
#19
239°/247° 110°+2° (108° ICL) No cats True duals.
But it is 421ish cubes.
Smells a bit right now, but I need to play with the tune some. Lean it out and bump the spark timing. Might try the injector timing like Bird said.
No cats True duals.But it is 421ish cubes.
Smells a bit right now, but I need to play with the tune some. Lean it out and bump the spark timing. Might try the injector timing like Bird said.
Last edited by 1CAMWNDR; 02-12-2011 at 10:58 PM.
