HP500/Gil Offshore/Reversion
10-29-2010, 07:43 PM
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HP500/Gil Offshore/Reversion
Gen VI HP 500 Clone
111* Intake lobe centerline
169611
9.4/1
088s
Large oil cooler wo/thermostat (no room)
MSD
Gil Offhsores (Early short risers)
Getting ready for some heads, old ones had a very poor leak down #s, mostly on exhaust.
Like most early carb HP 500s I have a reversion issue with the exhaust.
Gil remedied the reversion problem by producing a taller riser (which will not fit under my hatch)
On some of the older short risers they changed the water dump to lessen the reversion issue.
Does anyone know how Gil revised the water dump????? Pics?
If I extend the inner dry tube a few inches (3 or 4) would reversion be reduced?????
Any ideas? I cannot run dry exhaust due to local laws
THANKS!
111* Intake lobe centerline
169611
9.4/1
088s
Large oil cooler wo/thermostat (no room)
MSD
Gil Offhsores (Early short risers)
Getting ready for some heads, old ones had a very poor leak down #s, mostly on exhaust.
Like most early carb HP 500s I have a reversion issue with the exhaust.
Gil remedied the reversion problem by producing a taller riser (which will not fit under my hatch)
On some of the older short risers they changed the water dump to lessen the reversion issue.
Does anyone know how Gil revised the water dump????? Pics?
If I extend the inner dry tube a few inches (3 or 4) would reversion be reduced?????
Any ideas? I cannot run dry exhaust due to local laws
THANKS!
10-29-2010, 08:48 PM
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Fixx
Gen VI HP 500 Clone
111* Intake lobe centerline
169611
9.4/1
088s
Large oil cooler wo/thermostat (no room)
MSD
Gil Offhsores (Early short risers)
Getting ready for some heads, old ones had a very poor leak down #s, mostly on exhaust.
Like most early carb HP 500s I have a reversion issue with the exhaust.
Gil remedied the reversion problem by producing a taller riser (which will not fit under my hatch)
On some of the older short risers they changed the water dump to lessen the reversion issue.
Does anyone know how Gil revised the water dump????? Pics?
If I extend the inner dry tube a few inches (3 or 4) would reversion be reduced?????
Any ideas? I cannot run dry exhaust due to local laws
THANKS!
111* Intake lobe centerline
169611
9.4/1
088s
Large oil cooler wo/thermostat (no room)
MSD
Gil Offhsores (Early short risers)
Getting ready for some heads, old ones had a very poor leak down #s, mostly on exhaust.
Like most early carb HP 500s I have a reversion issue with the exhaust.
Gil remedied the reversion problem by producing a taller riser (which will not fit under my hatch)
On some of the older short risers they changed the water dump to lessen the reversion issue.
Does anyone know how Gil revised the water dump????? Pics?
If I extend the inner dry tube a few inches (3 or 4) would reversion be reduced?????
Any ideas? I cannot run dry exhaust due to local laws
THANKS!
10-30-2010, 01:43 AM
#4
Charter Member # 55
Charter Member
Its the cam that is the issue. Merc put a bandaid on it when the modified the risers to be taller with more angle.
You are talking about new Dart heads in the other thread. If you are going to spend that much coin, spend another $500 and get a new cam less prone to reversion that will match well with the flow numbers of the heads.
You are talking about new Dart heads in the other thread. If you are going to spend that much coin, spend another $500 and get a new cam less prone to reversion that will match well with the flow numbers of the heads.
10-30-2010, 02:49 PM
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THANKS for the replies!
Mild
Never thought of Dry exhaust w/mufflers. Reversion is not that much of a problem. Mufflers would look kind of funky on a 22 Classic
mrfixx
Yep it's me
Turbulators are installed. Reversion is minor. It's only an issue moving around the docks when engine is VERY cool i.e. start up and/or extended idle w/cold seawater temps.
Giff
I am trying to upgrade heads wo/pulling engine (recovering from a broken back ). I will upgrade to the 731 when I refresh the bottom end in a few years. I am using stock GM lifters and dog bones. I'm not sure they would work w/.610 lift cam. Do you know if the base circle is smaller on the HP 500 EFI cam? Do you know anyone with a HP 500 EFI takeout? What is the difference in overlap and timing between the 169611 and EFI cam? I was surprised when degreeing cam that the 169611s intake lobe centerline was 111*??????? (cam card states 105?????). That might be part of the issue also.
Mild
Never thought of Dry exhaust w/mufflers. Reversion is not that much of a problem. Mufflers would look kind of funky on a 22 Classic
mrfixx
Yep it's me
Turbulators are installed. Reversion is minor. It's only an issue moving around the docks when engine is VERY cool i.e. start up and/or extended idle w/cold seawater temps.
Giff
I am trying to upgrade heads wo/pulling engine (recovering from a broken back
). I will upgrade to the 731 when I refresh the bottom end in a few years. I am using stock GM lifters and dog bones. I'm not sure they would work w/.610 lift cam. Do you know if the base circle is smaller on the HP 500 EFI cam? Do you know anyone with a HP 500 EFI takeout? What is the difference in overlap and timing between the 169611 and EFI cam? I was surprised when degreeing cam that the 169611s intake lobe centerline was 111*??????? (cam card states 105?????). That might be part of the issue also.
Last edited by RickR; 10-30-2010 at 02:56 PM.
10-30-2010, 04:26 PM
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fixx
THANKS for the replies!
Mild
Never thought of Dry exhaust w/mufflers. Reversion is not that much of a problem. Mufflers would look kind of funky on a 22 Classic
mrfixx
Yep it's me
Turbulators are installed. Reversion is minor. It's only an issue moving around the docks when engine is VERY cool i.e. start up and/or extended idle w/cold seawater temps.
Giff
I am trying to upgrade heads wo/pulling engine (recovering from a broken back ). I will upgrade to the 731 when I refresh the bottom end in a few years. I am using stock GM lifters and dog bones. I'm not sure they would work w/.610 lift cam. Do you know if the base circle is smaller on the HP 500 EFI cam? Do you know anyone with a HP 500 EFI takeout? What is the difference in overlap and timing between the 169611 and EFI cam? I was surprised when degreeing cam that the 169611s intake lobe centerline was 111*??????? (cam card states 105?????). That might be part of the issue also.
Mild
Never thought of Dry exhaust w/mufflers. Reversion is not that much of a problem. Mufflers would look kind of funky on a 22 Classic
mrfixx
Yep it's me
Turbulators are installed. Reversion is minor. It's only an issue moving around the docks when engine is VERY cool i.e. start up and/or extended idle w/cold seawater temps.
Giff
I am trying to upgrade heads wo/pulling engine (recovering from a broken back
). I will upgrade to the 731 when I refresh the bottom end in a few years. I am using stock GM lifters and dog bones. I'm not sure they would work w/.610 lift cam. Do you know if the base circle is smaller on the HP 500 EFI cam? Do you know anyone with a HP 500 EFI takeout? What is the difference in overlap and timing between the 169611 and EFI cam? I was surprised when degreeing cam that the 169611s intake lobe centerline was 111*??????? (cam card states 105?????). That might be part of the issue also.
10-31-2010, 12:54 PM
#7
Charter Member # 55
Charter Member
Griff
I am trying to upgrade heads wo/pulling engine (recovering from a broken back
). I will upgrade to the 731 when I refresh the bottom end in a few years. I am using stock GM lifters and dog bones. I'm not sure they would work w/.610 lift cam. Do you know if the base circle is smaller on the HP 500 EFI cam? Do you know anyone with a HP 500 EFI takeout? What is the difference in overlap and timing between the 169611 and EFI cam? I was surprised when degreeing cam that the 169611s intake lobe centerline was 111*??????? (cam card states 105?????). That might be part of the issue also.It looks like Crane just redid their website and the 500efi cam (169621) won't display.
Here are the specs on the 500efi cam
292*/298* Adv
230*/236* @ .050
.598"/.610" @ valve
114* LSA
109* ICL
119* ECL
10-31-2010, 09:54 PM
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Extending the inner pipe of the risers will help some. If you extend it, be sure to put a small bell mouth in the end of the inner pipe. This will help the water to move away from the end of the pipe as the water and exhaust meet each other.
Eddie
Eddie
11-01-2010, 11:01 AM
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Extending the riser's...And installing a simple x pipe should cancel reversion if it is not severe from the start.
http://www.carcraft.com/techarticles...ion/index.html
It does work...merc racing has done some on this too i believe
http://www.carcraft.com/techarticles...ion/index.html
It does work...merc racing has done some on this too i believe
Last edited by Pliant; 11-01-2010 at 03:13 PM.
