Reversion what is the impact?
05-12-2006 | 12:03 PM
#41
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Posts: 1,546
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From: Layton, Utah
Re: Reversion what is the impact?
Originally Posted by Rage
If a previous post is correct and the following are the cam specs for.......
Merc HP525EFI 236 int,246 exh, 114 sep, .06++ lift
Merc HP500EFI 230 int,236 exh, 114 sep, lift int .598 exh .610
.....then for my cam : 230 int,236 exh, 114 sep, lift int .598 exh .610 to have reversion what could be the contributiong factors (in addition / other than an exhaust leak)?
Merc HP525EFI 236 int,246 exh, 114 sep, .06++ lift
Merc HP500EFI 230 int,236 exh, 114 sep, lift int .598 exh .610
.....then for my cam : 230 int,236 exh, 114 sep, lift int .598 exh .610 to have reversion what could be the contributiong factors (in addition / other than an exhaust leak)?
500EFI and 525EFI have CMIs vs the stock 496 manifolds which will eliminate reversion in that cam range.
05-13-2006 | 06:28 AM
#42
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Posts: 79
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From: psl, fla
Re: Reversion what is the impact?
i am running a comp cams xm 262 cam,at oo6, int opens at 21,closes at 61, exh opens at 68, closes at 20, lift is 505/515, total timing is 34 degrees, also using a performer intake, stainless marine exhaust, harland sharp roller rockers,ign module is a tbolt 5,idle is 650 in gear-maybe should i raise the idle speed??
05-14-2006 | 12:26 PM
#43
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Posts: 710
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From: Babylon N.Y.
Re: Reversion what is the impact?
Simply put in an earth shattering, scientific equasion
Reversion + time + more reversion + time = DESTRUCTION
Eventually will have corroded valve stems that break,
or a whole host of other problems of varying degrees.
Avoid this plague , use the right marine cam, don't even trust the cam manufacturer. Have it put on a cam doctor.
Install shutter's in the exhaust. Stainless marine makes a pair for $60. Very cheap insurance.
I had custom copper elbows with about 15" rise made up for a 21' boat with big block that sucked water and recked 3 motors.
Exhaust has to be adequate for motor. especially where water mixes and exits water jacket.
On my 24 Formula with the silent choice , I shut the through hull exhaust off when slowing down to make sure no backwash happens. BBB
Reversion + time + more reversion + time = DESTRUCTION
Eventually will have corroded valve stems that break,
or a whole host of other problems of varying degrees.
Avoid this plague , use the right marine cam, don't even trust the cam manufacturer. Have it put on a cam doctor.
Install shutter's in the exhaust. Stainless marine makes a pair for $60. Very cheap insurance.
I had custom copper elbows with about 15" rise made up for a 21' boat with big block that sucked water and recked 3 motors.
Exhaust has to be adequate for motor. especially where water mixes and exits water jacket.
On my 24 Formula with the silent choice , I shut the through hull exhaust off when slowing down to make sure no backwash happens. BBB
05-15-2006 | 01:43 AM
#45
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Joined: Sep 2005
Posts: 1,987
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From: Missouri
Re: Reversion what is the impact?
Originally Posted by Big Block Billy
Simply put in an earth shattering, scientific equasion
Reversion + time + more reversion + time = DESTRUCTION
Eventually will have corroded valve stems that break,
or a whole host of other problems of varying degrees.
Avoid this plague , use the right marine cam, don't even trust the cam manufacturer. Have it put on a cam doctor.
Install shutter's in the exhaust. Stainless marine makes a pair for $60. Very cheap insurance.
I had custom copper elbows with about 15" rise made up for a 21' boat with big block that sucked water and recked 3 motors.
Exhaust has to be adequate for motor. especially where water mixes and exits water jacket.
On my 24 Formula with the silent choice , I shut the through hull exhaust off when slowing down to make sure no backwash happens. BBB
Reversion + time + more reversion + time = DESTRUCTION
Eventually will have corroded valve stems that break,
or a whole host of other problems of varying degrees.
Avoid this plague , use the right marine cam, don't even trust the cam manufacturer. Have it put on a cam doctor.
Install shutter's in the exhaust. Stainless marine makes a pair for $60. Very cheap insurance.
I had custom copper elbows with about 15" rise made up for a 21' boat with big block that sucked water and recked 3 motors.
Exhaust has to be adequate for motor. especially where water mixes and exits water jacket.
On my 24 Formula with the silent choice , I shut the through hull exhaust off when slowing down to make sure no backwash happens. BBB
What is a " cam doctor"?
05-15-2006 | 09:10 PM
#46
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Joined: Sep 2005
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From: Missouri
Re: Reversion what is the impact?
Originally Posted by Rage
The cam is a Crane #OEM0988 and the intake does close at 44 degrees ABDC.
Any comment on this cam with stock exhaust for reversion potential. Any ptential fixes to reduce reversion if it is a problem with this paticular cam.
Bill
05-15-2006 | 09:32 PM
#47
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Joined: Oct 2005
Posts: 314
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From: Ankeny IA
Re: Reversion what is the impact?
An old Indian trick is to use Rhoades Lifters. I am running a crane 100072 (228@050, 112LSA) and I have little if any lope at idle. I know without the Rhoades lifters that cam would have a lopey idle. The 'lopey idle' is what causes reversion.
05-16-2006 | 02:54 PM
#49
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From: Missouri
Re: Reversion what is the impact?
Originally Posted by jmherbert
An old Indian trick is to use Rhoades Lifters. I am running a crane 100072 (228@050, 112LSA) and I have little if any lope at idle. I know without the Rhoades lifters that cam would have a lopey idle. The 'lopey idle' is what causes reversion.
05-16-2006 | 03:10 PM
#50
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From: Ankeny IA
Re: Reversion what is the impact?
They 'bleed down' at lower RPM levels, effectively making the duration and lift of the cam smaller. They act like normal hydraulics around 3500 RPM. They claim the same feature that makes them do this also helps them from pumping up at higher RPM's. I don't know about that, but we typically don't see that RPM on our boats anyhow.
They are popular in certain stock car racing classes that require a certain amount of vacuum at RPM. They allow the racers to run larger cams than they would otherwise.
This is my first expereince with them, but I know some car guys that swear by them.
http://www.rhoadslifters.com/default.html
They are also available thru Jegs, Summit, and others.
They are popular in certain stock car racing classes that require a certain amount of vacuum at RPM. They allow the racers to run larger cams than they would otherwise.
This is my first expereince with them, but I know some car guys that swear by them.
http://www.rhoadslifters.com/default.html
They are also available thru Jegs, Summit, and others.
