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502 Mag Mpi (re)Build - Mild Cam Upgrade

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502 Mag Mpi (re)Build - Mild Cam Upgrade

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Old 06-21-2012, 07:45 PM
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Default 502 Mag Mpi (re)Build - Mild Cam Upgrade

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,
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Old 06-21-2012, 11:06 PM
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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
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Old 06-22-2012, 05:43 PM
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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!
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Old 06-22-2012, 06:27 PM
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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.
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Old 06-22-2012, 07:09 PM
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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.
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Old 06-22-2012, 07:53 PM
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Originally Posted by low buck View Post
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,
I am glad you started this thread. I just put the second cam you mentioned (223/230 @ 50, 114 LSA, 566/575 lift) set in @ 109 ICL, in a 454 Mag and I am having major reversion with my EMI Thunders with the Alum risers. I am thinking about going to the EMI short stainless risers, but am not sure it is going to cure the problem. My mechanic runs the same exhaust (EMI with short S/S risers) and an S pipe, on a 60 over 502, with 9.5 comp, and a much larger cam (236/240 @50, 112 LSA, 614 lift) set in @ 109 ICL with more than 10 degrees of over lap and does not have an issue. Can any one shed some light on this? I really didn’t want to buy all new exhaust. Would the EMI Thunders with the short stainless work or do I need the long wet riser? Really want to keep the silant choice option.

Last edited by BaggMann; 06-22-2012 at 07:57 PM.
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Old 06-24-2012, 08:45 PM
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BagMan

Great Info.

I'm going to take a look at the EMI's
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Old 06-25-2012, 04:16 PM
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Originally Posted by mustangmark View Post
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.
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.
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Old 06-26-2012, 02:47 PM
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Originally Posted by mustangmark View Post
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.
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.

Last edited by Gimme Fuel; 06-26-2012 at 02:53 PM.
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Old 06-26-2012, 02:59 PM
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Originally Posted by Gimme Fuel View Post
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.
Yeah, Bob should be your first call. I have a cam from him and have no reversion with short riser SM manifolds. Not just for cams, he will help you put together a reliable package and has fair prices. Great guy.

http://www.marinekineticsonline.com/

Last edited by BBCLiberator; 06-26-2012 at 03:04 PM.
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