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Cam phasing vs. intake reversion #825534 10/09/10 01:10 PM 10/09/10 01:10 PM
Joined: Jan 2003 Posts: 15,439 Val-haul-ass... eventually B BradH OP Taking time off to work on my car
BradH OP Taking time off to work on my car B Joined: Jan 2003 Posts: 15,439 Val-haul-ass... eventually	If you wanted to reduce the likelihood of intake reversion w/ a particular camshaft, would you want to advance it to close the exhaust sooner OR retard it to delay the point where the intake opens?

Re: Cam phasing vs. intake reversion [Re: BradH] #825535 10/09/10 01:14 PM 10/09/10 01:14 PM
Joined: Feb 2007 Posts: 5,080 organ M maximum entropy master
maximum entropy master M Joined: Feb 2007 Posts: 5,080 organ	i would get the appropriate cam. if you advance the cam, you'll have pulse reversion, and if you retard it, you'd get pulse and exhaust. i think. or is it the other way around? for what is the good life if not doing things thoughtfully?

Re: Cam phasing vs. intake reversion [Re: BradH] #825536 10/09/10 02:34 PM 10/09/10 02:34 PM
Joined: Jan 2003 Posts: 5,486 SoCal Brian Hafliger master
Brian Hafliger master Joined: Jan 2003 Posts: 5,486 SoCal	Quote: If you wanted to reduce the likelihood of intake reversion w/ a particular camshaft, would you want to advance it to close the exhaust sooner OR retard it to delay the point where the intake opens? reducing overlap is usually going to help so advancing or retarding will only show you "trends". Closing the exhaust sooner is more likely to help reversion problems but without changing overlap it's not going to make much of a difference. This is for WOT tuning only. Brian Hafliger

Re: Cam phasing vs. intake reversion [Re: Brian Hafliger] #825537 10/09/10 03:20 PM 10/09/10 03:20 PM
Joined: Oct 2005 Posts: 976 ontario canada mac56 super stock
mac56 super stock Joined: Oct 2005 Posts: 976 ontario canada	Good to see a post from you Brian. I haven't noticed you posting much lately. I always like to hear your opinions. Mark

Re: Cam phasing vs. intake reversion [Re: BradH] #825538 10/09/10 03:32 PM 10/09/10 03:32 PM
Joined: Apr 2004 Posts: 1,056 Mt.Vernon IL Twin Turbo Mower super stock
Twin Turbo Mower super stock Joined: Apr 2004 Posts: 1,056 Mt.Vernon IL	you could try a anti reversion plate.

Re: Cam phasing vs. intake reversion [Re: mac56] #825539 10/09/10 03:39 PM 10/09/10 03:39 PM
Joined: Jan 2003 Posts: 5,486 SoCal Brian Hafliger master
Brian Hafliger master Joined: Jan 2003 Posts: 5,486 SoCal	Quote: Good to see a post from you Brian. I haven't noticed you posting much lately. I always like to hear your opinions. Mark Nice to be posting again...been soooo busy!! Thank you!!!!! Brian Hafliger

Re: Cam phasing vs. intake reversion [Re: BradH] #825540 10/09/10 04:13 PM 10/09/10 04:13 PM
Joined: Jul 2010 Posts: 3,502 SOUTH JERSEY HEMIFRED master
HEMIFRED master Joined: Jul 2010 Posts: 3,502 SOUTH JERSEY	Quote: If you wanted to reduce the likelihood of intake reversion w/ a particular camshaft, would you want to advance it to close the exhaust sooner OR retard it to delay the point where the intake opens? where is the occurring and why assuming a likelihood ? home of the Sox and Martin Hemi Duster

Re: Cam phasing vs. intake reversion [Re: HEMIFRED] #825541 10/09/10 04:47 PM 10/09/10 04:47 PM
Joined: Jan 2003 Posts: 15,439 Val-haul-ass... eventually B BradH OP Taking time off to work on my car
BradH OP Taking time off to work on my car B Joined: Jan 2003 Posts: 15,439 Val-haul-ass... eventually	Quote: where is the occurring and why assuming a likelihood ? When Dwayne P. freshened up the heads, he mentioned seeing more indications of reversion in the intake ports than expected. The cam's worked well on the dyno and the track, but might have a bit more overlap than "ideal" for a full exhaust system and street-driven car. No plans at this point to change the cam (again), so I was curious if the phasing might have any impact on it.

Re: Cam phasing vs. intake reversion [Re: BradH] #825542 10/09/10 04:57 PM 10/09/10 04:57 PM
Joined: Jan 2003 Posts: 5,486 SoCal Brian Hafliger master
Brian Hafliger master Joined: Jan 2003 Posts: 5,486 SoCal	Quote: Quote: where is the occurring and why assuming a likelihood ? When Dwayne P. freshened up the heads, he mentioned seeing more indications of reversion in the intake ports than expected. The cam's worked well on the dyno and the track, but might have a bit more overlap than "ideal" for a full exhaust system and street-driven car. No plans at this point to change the cam (again), so I was curious if the phasing might have any impact on it. What are the engine/cam/exhaust specs? Brian Hafliger

Re: Cam phasing vs. intake reversion [Re: BradH] #825543 10/09/10 05:34 PM 10/09/10 05:34 PM
Joined: Nov 2003 Posts: 5,160 Texas dannysbee master
dannysbee master Joined: Nov 2003 Posts: 5,160 Texas	Did the reversion occur at cruising speeds or wide open throttle or both? Without knowing that, it would be hard to know if it was hurting your performance. Getting old just means you were smarter than some and luckier than others.

Re: Cam phasing vs. intake reversion [Re: dannysbee] #825544 10/09/10 06:20 PM 10/09/10 06:20 PM
Joined: Jan 2003 Posts: 15,439 Val-haul-ass... eventually B BradH OP Taking time off to work on my car
BradH OP Taking time off to work on my car B Joined: Jan 2003 Posts: 15,439 Val-haul-ass... eventually	Quote: Did the reversion occur at cruising speeds or wide open throttle or both? Without knowing that, it would be hard to know if it was hurting your performance. How would somebody be able to tell under what conditions it was happening?

Re: Cam phasing vs. intake reversion [Re: Brian Hafliger] #825545 10/09/10 06:24 PM 10/09/10 06:24 PM
Joined: Jan 2003 Posts: 15,439 Val-haul-ass... eventually B BradH OP Taking time off to work on my car
BradH OP Taking time off to work on my car B Joined: Jan 2003 Posts: 15,439 Val-haul-ass... eventually	Quote: What are the engine/cam/exhaust specs? RB 452 w/ ported Stage VI heads, 10.8 CR, Comp XX 266 @ .050", .600", 1.5 rockers, 108 LSA (104 ICL measured at .050"), Victor 4150 intake w/ BG 4150 carb w/ 1.42" venturi x 1.75" throttle, 2" TTI headers & 3" x-pipe exhaust system.

Re: Cam phasing vs. intake reversion [Re: BradH] #825546 10/09/10 07:24 PM 10/09/10 07:24 PM
Joined: Dec 2008 Posts: 1,200 UK 6 602heavy pro stock
602heavy pro stock 6 Joined: Dec 2008 Posts: 1,200 UK	I think seat to seat duration has a direct effect regard reversion , closing intake valve too late can cause a positive pressure differential between cylinder & back of intake valve.....had reversion problems with a 440 , advanced ICL from 108* to 104* & reversion cleaned up , i believe the earlier closing int valve helped regards reversion..........same applied with the 605" , tightened intake lash .006" tighter from cam card & noticed soot around intake runners & underside of carb , loosened lash & reversion cleaned up.

Re: Cam phasing vs. intake reversion [Re: 602heavy] #825547 10/09/10 07:26 PM 10/09/10 07:26 PM
Joined: Dec 2008 Posts: 1,200 UK 6 602heavy pro stock
602heavy pro stock 6 Joined: Dec 2008 Posts: 1,200 UK	Quote: posted twice Last edited by 602heavy; 10/09/10 07:29 PM.

Re: Cam phasing vs. intake reversion [Re: BradH] #825548 10/09/10 08:11 PM 10/09/10 08:11 PM
Joined: Nov 2003 Posts: 5,160 Texas dannysbee master
dannysbee master Joined: Nov 2003 Posts: 5,160 Texas	Brad I was just making a point. But you could clean every thing up, take it out and cruise it a bit then pull the intake. Getting old just means you were smarter than some and luckier than others.

Re: Cam phasing vs. intake reversion [Re: BradH] #825549 10/09/10 09:25 PM 10/09/10 09:25 PM
Joined: Jul 2010 Posts: 3,502 SOUTH JERSEY HEMIFRED master
HEMIFRED master Joined: Jul 2010 Posts: 3,502 SOUTH JERSEY	Quote: Quote: Did the reversion occur at cruising speeds or wide open throttle or both? Without knowing that, it would be hard to know if it was hurting your performance. How would somebody be able to tell under what conditions it was happening? I understand that reversion occurs big time upon deceleration and it might show to be misleading but has no effect on much else home of the Sox and Martin Hemi Duster

Re: Cam phasing vs. intake reversion [Re: HEMIFRED] #825550 10/09/10 09:39 PM 10/09/10 09:39 PM
Joined: Feb 2003 Posts: 12,675 Columbia, CT M moper I Live Here
moper I Live Here M Joined: Feb 2003 Posts: 12,675 Columbia, CT	I think the reversion may be occuring at lower rpms and less than WOT. Kind of what I think Fred's talking about. Well, art is art, isn't it? Still, on the other hand, water is water! And east is east and west is west and if you take cranberries and stew them like applesauce they taste much more like prunes than rhubarb does. Now, uh... Now you tell me what you know.

Re: Cam phasing vs. intake reversion [Re: moper] #825551 10/09/10 09:56 PM 10/09/10 09:56 PM
Joined: Jul 2010 Posts: 3,502 SOUTH JERSEY HEMIFRED master
HEMIFRED master Joined: Jul 2010 Posts: 3,502 SOUTH JERSEY	home of the Sox and Martin Hemi Duster

Re: Cam phasing vs. intake reversion [Re: BradH] #825552 10/09/10 10:20 PM 10/09/10 10:20 PM
Joined: Jan 2003 Posts: 5,486 SoCal Brian Hafliger master
Brian Hafliger master Joined: Jan 2003 Posts: 5,486 SoCal	Quote: Quote: What are the engine/cam/exhaust specs? RB 452 w/ ported Stage VI heads, 10.8 CR, Comp XX 266 @ .050", .600", 1.5 rockers, 108 LSA (104 ICL measured at .050"), Victor 4150 intake w/ BG 4150 carb w/ 1.42" venturi x 1.75" throttle, 2" TTI headers & 3" x-pipe exhaust system. If it was driven on the street even a short time you'll see exhaust in the intake tract. Sometimes all the way up to the carb! No way to get rid of it carbed. I will say that with full exhaust system, I will run as much as 12� split between intake and exhaust lobes. Brian Brian Hafliger

Re: Cam phasing vs. intake reversion [Re: HEMIFRED] #825553 10/09/10 10:25 PM 10/09/10 10:25 PM
Joined: Jul 2010 Posts: 3,502 SOUTH JERSEY HEMIFRED master
HEMIFRED master Joined: Jul 2010 Posts: 3,502 SOUTH JERSEY	now here's a chart to follow use only the red path unless it's past 5pm and you are using 89 pmup. otherwise the black and race gas 6241808-ctrp_1008_01+intake_reversion+.jpg (217 downloads) home of the Sox and Martin Hemi Duster

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