502 Mag Mpi (re)Build - Mild Cam Upgrade
#1
Registered
Thread Starter
Join Date: Dec 2009
Location: Saint Louis, MO
Posts: 72
Likes: 0
Received 0 Likes
on
0 Posts
![Default](/forums/images/icons/icon1.gif)
I'm rebuilding a 502 Mag Mpi (Gen Vi).
It's in a 27' eliminator cat. The stock exhaust manifold will be replaced with some "plug-n-play" aftermarket exhaust manifolds, ie .., stainless marine, dana, hardin, etc.. Haven't decided on manifolds so any shared experiences are appreciated. The stock manifolds dump immediately downward into "S" pipes which exit below the swim platform.There are some baffles at the tailpipes.
I'd like to bump the cam up a little without loosing durability.
I would like to use the stock GM hydraulic roller lifters. The stock cast Iron 118cc rectangular port heads are at the shop getting refreshed and fitted with aftermarket studs for roller rockers. (Redrill / tap the stud bosses for 7/16" threads -vs- 3/8") I'm open for roller rocker suggestons that will work with my stock valve covers. (I like to Crane gold, will they work by just removing the valve cover inside drip plates?)
Here's (2) "mild" comp cams I'm interested in, one is on comp's website and the other seems to be an "exclusive" to CP performance & KE. Any pro's / con's between these two?
Comp Cams #'s
01-419-8 [37] 0.51" Int, 0.52" Exh, 230 Int, 236 exh, 114 LSA
(Comp website)
295-012508 0.566" In, 0.575" exh, 223 int, 230 exh, 114 LSA
(CP & KE specials?)
My "unqualified" research leads me to believe with this mild of a cam selection, along w/ 114 LSA, reversion should not be an issue, even with the poor exhaust configuration. the "ceiling" on cam selection is keeping the low ecm idle (650 rpm) and limiting reversion potential.
I know this is "small peanuts" stuff but I'm having fun learning !!!
Thanks,
It's in a 27' eliminator cat. The stock exhaust manifold will be replaced with some "plug-n-play" aftermarket exhaust manifolds, ie .., stainless marine, dana, hardin, etc.. Haven't decided on manifolds so any shared experiences are appreciated. The stock manifolds dump immediately downward into "S" pipes which exit below the swim platform.There are some baffles at the tailpipes.
I'd like to bump the cam up a little without loosing durability.
I would like to use the stock GM hydraulic roller lifters. The stock cast Iron 118cc rectangular port heads are at the shop getting refreshed and fitted with aftermarket studs for roller rockers. (Redrill / tap the stud bosses for 7/16" threads -vs- 3/8") I'm open for roller rocker suggestons that will work with my stock valve covers. (I like to Crane gold, will they work by just removing the valve cover inside drip plates?)
Here's (2) "mild" comp cams I'm interested in, one is on comp's website and the other seems to be an "exclusive" to CP performance & KE. Any pro's / con's between these two?
Comp Cams #'s
01-419-8 [37] 0.51" Int, 0.52" Exh, 230 Int, 236 exh, 114 LSA
(Comp website)
295-012508 0.566" In, 0.575" exh, 223 int, 230 exh, 114 LSA
(CP & KE specials?)
My "unqualified" research leads me to believe with this mild of a cam selection, along w/ 114 LSA, reversion should not be an issue, even with the poor exhaust configuration. the "ceiling" on cam selection is keeping the low ecm idle (650 rpm) and limiting reversion potential.
I know this is "small peanuts" stuff but I'm having fun learning !!!
Thanks,
#2
Registered
Join Date: Jul 2009
Location: west of chitown, il
Posts: 461
Likes: 0
Received 0 Likes
on
0 Posts
![Default](/forums/images/icons/icon1.gif)
no matter what cam you chose here if it is "other than stock" you will have to get your ecu remapped.. Get with whoever you will/ would use to do it and you can both agree on what cam you want/ need
#3
Registered
Thread Starter
Join Date: Dec 2009
Location: Saint Louis, MO
Posts: 72
Likes: 0
Received 0 Likes
on
0 Posts
![Default](/forums/images/icons/icon1.gif)
mr3;
Thanks for your response, I've got the MEFi (re)burn lined up. Certainly a must do.
I'm hoping that someone has used either of these cam #'s and wondering if they had reversion issues.
Input on the rocker arm and exhaust manifold selection appreciated too!
Thanks for your response, I've got the MEFi (re)burn lined up. Certainly a must do.
I'm hoping that someone has used either of these cam #'s and wondering if they had reversion issues.
Input on the rocker arm and exhaust manifold selection appreciated too!
#4
![Default](/forums/images/icons/icon1.gif)
Regarding reversion, I have a SBC with a very similar spec'd roller cam and have no reversion issues (GLM exhaust via stock Merc stainless risers out 4" thru hull). I would suspect you will not have an issue with your BBC. I'm using a Crower EFI roller and can't comment on the ramp rates compared to the Comp Cams stuff. I'm on a 114 LSA.
Check your injectors to see what they flow at (lbs/hr) and make sure you have enough 'head room' for the power you want/anticipate to make. Injectors don't like to work that well beyond 80% duty cycle. There are formulas out in the internet world that will help you calculate the correct sized injector. You may have enough injector now, but double check.
On initial start-up and run use the stock program. It will run fine even (albeit not perfectly) with the mods. You may need to set base timing and do some leak checking. When that is done then you can start playing with the MEFI burn stuff. SAVE YOUR STOCK CALIBRATION! Make a working copy and subsequent modifications should apply to the copy.
Make sure you have a wide band O2 system set up for tuning. The MEFI stuff will be useless without it. Heck I'd use a wideband on a carb motor too. Takes all the guess work out.
Don't worry about the 650 rpm idle. You can bump it up to 700-750 if need be and you shouldn't have any shifting or docking issues. (There's a table for idle speed based on coolant temp)
I can't tell you what roller rockers will fit under the BBC valve covers, sorry.
Check your injectors to see what they flow at (lbs/hr) and make sure you have enough 'head room' for the power you want/anticipate to make. Injectors don't like to work that well beyond 80% duty cycle. There are formulas out in the internet world that will help you calculate the correct sized injector. You may have enough injector now, but double check.
On initial start-up and run use the stock program. It will run fine even (albeit not perfectly) with the mods. You may need to set base timing and do some leak checking. When that is done then you can start playing with the MEFI burn stuff. SAVE YOUR STOCK CALIBRATION! Make a working copy and subsequent modifications should apply to the copy.
Make sure you have a wide band O2 system set up for tuning. The MEFI stuff will be useless without it. Heck I'd use a wideband on a carb motor too. Takes all the guess work out.
Don't worry about the 650 rpm idle. You can bump it up to 700-750 if need be and you shouldn't have any shifting or docking issues. (There's a table for idle speed based on coolant temp)
I can't tell you what roller rockers will fit under the BBC valve covers, sorry.
#5
Registered
Join Date: Aug 2009
Location: CONCORD, CALIF
Posts: 410
Likes: 0
Received 0 Likes
on
0 Posts
![Default](/forums/images/icons/icon1.gif)
Just a suggestion but you might want to contact Bob Madara on this site (rmbuilder). He is THE MAN when it comes to valve train and will not steer you wrong. Very knowlageable and a very nice guy! He owns Marine Kenetics.
#6
Registered
Join Date: Jun 2012
Location: Jeffersonville, IN
Posts: 15
Likes: 0
Received 0 Likes
on
0 Posts
![Default](/forums/images/icons/icon1.gif)
I'm rebuilding a 502 Mag Mpi (Gen Vi).
It's in a 27' eliminator cat. The stock exhaust manifold will be replaced with some "plug-n-play" aftermarket exhaust manifolds, ie .., stainless marine, dana, hardin, etc.. Haven't decided on manifolds so any shared experiences are appreciated. The stock manifolds dump immediately downward into "S" pipes which exit below the swim platform.There are some baffles at the tailpipes.
I'd like to bump the cam up a little without loosing durability.
I would like to use the stock GM hydraulic roller lifters. The stock cast Iron 118cc rectangular port heads are at the shop getting refreshed and fitted with aftermarket studs for roller rockers. (Redrill / tap the stud bosses for 7/16" threads -vs- 3/8") I'm open for roller rocker suggestons that will work with my stock valve covers. (I like to Crane gold, will they work by just removing the valve cover inside drip plates?)
Here's (2) "mild" comp cams I'm interested in, one is on comp's website and the other seems to be an "exclusive" to CP performance & KE. Any pro's / con's between these two?
Comp Cams #'s
01-419-8 [37] 0.51" Int, 0.52" Exh, 230 Int, 236 exh, 114 LSA
(Comp website)
295-012508 0.566" In, 0.575" exh, 223 int, 230 exh, 114 LSA
(CP & KE specials?)
My "unqualified" research leads me to believe with this mild of a cam selection, along w/ 114 LSA, reversion should not be an issue, even with the poor exhaust configuration. the "ceiling" on cam selection is keeping the low ecm idle (650 rpm) and limiting reversion potential.
I know this is "small peanuts" stuff but I'm having fun learning !!!
Thanks,
It's in a 27' eliminator cat. The stock exhaust manifold will be replaced with some "plug-n-play" aftermarket exhaust manifolds, ie .., stainless marine, dana, hardin, etc.. Haven't decided on manifolds so any shared experiences are appreciated. The stock manifolds dump immediately downward into "S" pipes which exit below the swim platform.There are some baffles at the tailpipes.
I'd like to bump the cam up a little without loosing durability.
I would like to use the stock GM hydraulic roller lifters. The stock cast Iron 118cc rectangular port heads are at the shop getting refreshed and fitted with aftermarket studs for roller rockers. (Redrill / tap the stud bosses for 7/16" threads -vs- 3/8") I'm open for roller rocker suggestons that will work with my stock valve covers. (I like to Crane gold, will they work by just removing the valve cover inside drip plates?)
Here's (2) "mild" comp cams I'm interested in, one is on comp's website and the other seems to be an "exclusive" to CP performance & KE. Any pro's / con's between these two?
Comp Cams #'s
01-419-8 [37] 0.51" Int, 0.52" Exh, 230 Int, 236 exh, 114 LSA
(Comp website)
295-012508 0.566" In, 0.575" exh, 223 int, 230 exh, 114 LSA
(CP & KE specials?)
My "unqualified" research leads me to believe with this mild of a cam selection, along w/ 114 LSA, reversion should not be an issue, even with the poor exhaust configuration. the "ceiling" on cam selection is keeping the low ecm idle (650 rpm) and limiting reversion potential.
I know this is "small peanuts" stuff but I'm having fun learning !!!
Thanks,
Last edited by BaggMann; 06-22-2012 at 07:57 PM.
#8
![Default](/forums/images/icons/icon1.gif)
I second that thought. Bob set me up with a mild solid roller for my 557. Floats like a butterfly at the dock then stings like a bee out in the open. 4 seasons of dependable, and great power.
#9
Registered
![Default](/forums/images/icons/icon1.gif)
I also run the EMI manifolds with the long stainless risers. The long risers make reversion a non-issue and open up your cam selections. Bob is also a great wealth of knowledge.
Last edited by Gimme Fuel; 06-26-2012 at 02:53 PM.
#10
Registered
Join Date: May 2012
Location: Gibraltar, MI
Posts: 720
Likes: 0
Received 0 Likes
on
0 Posts
![Default](/forums/images/icons/icon1.gif)
X2! These guys will work together and give you a very nice cam and matching computer tune....great guys.
I also run the EMI manifolds with the long stainless risers. The long risers make reversion a non-issue and open up your cam selections. Bob is also a great wealth of knowledge.
I also run the EMI manifolds with the long stainless risers. The long risers make reversion a non-issue and open up your cam selections. Bob is also a great wealth of knowledge.
http://www.marinekineticsonline.com/
Last edited by BBCLiberator; 06-26-2012 at 03:04 PM.