Camshaft specs. needed, modification feasible?

[mdaddy]

I'm searching for oem camshaft specs. (lift, duration, etc...) for my engine, a 2008 Mercruiser 5.0L vortec TKS engine, 2bbl carb (serial#:1A322719). I had to rebuild bottom end (pistons bored to 30 over) due to piston scoring from spark plug debris in #7 cylinder and compromised cam cap/plug. Looking to maximize performance without making overlu aggressive changes. Probably, a stage 1 or 2 cam, new valve springs, and maybe even a high performance 2 bbl carb. What I don't want to do is lose the original performance which was very adequate (good hole shot, excellent high end speed)! I will happily. re-assemble the eninge with just bottom rebuild to 30 over pistons with everything else staying the same (mild HP incease?). Feedback very welcomed! Thanks!

 

[markhodges78]

Do you have original exhaust or through transom is your exhaust through the transom.. this is important when changing the cam ,,,

 

[stresspoint]

measure your camshaft you have. you can take it to an engine reconditioning shop if you don't have the tools or skills.

 

[mdaddy]

Do you have original exhaust or through transom is your exhaust through the transom.. this is important when changing the cam ,,,

the plan is to go through transom with 3-4" outlet

 

[jimmbo]

Likely Mercruiser # 431-811658

Duration @0.050": Intake 197; Exhaust 207
Lift: Intake .430; Exhaust .450
Lobe Centerline in degrees: Intake 106 ATDC; Exhaust 112 BTDC
Lobe Separation in Degrees 109

 

[Bondo]

I'm searching for oem camshaft specs. (lift, duration, etc...) for my engine, a 2008 Mercruiser 5.0L vortec TKS engine, 2bbl carb (serial#:1A322719). I had to rebuild bottom end (pistons bored to 30 over) due to piston scoring from spark plug debris in #7 cylinder and compromised cam cap/plug. Looking to maximize performance without making overlu aggressive changes. Probably, a stage 1 or 2 cam, new valve springs, and maybe even a high performance 2 bbl carb. What I don't want to do is lose the original performance which was very adequate (good hole shot, excellent high end speed)! I will happily. re-assemble the eninge with just bottom rebuild to 30 over pistons with everything else staying the same (mild HP incease?). Feedback very welcomed! Thanks!

Ayuh,..... You'll be safe with an RV cam, 'n 4bbl. carb,....

 

[Scott Danforth]

Make sure it's a marine cam for wet exhaust

Do not exceed 270 degrees of duration.

Make sure you check the cam card to make sure no overlap

Have had good luck with the Comp cams XM264HR

Xtreme Energy 212/218 Hydraulic Roller Cam for Chevrolet Small Block

Xtreme Energy 212/218 Retro-Fit Hydraulic Roller Cam for Chevy Small Block. Mild performance applications. Very good mid-range. 3.23-3.73 gear.

www.compcams.com

 

[stresspoint]

the plan is to go through transom with 3-4" outlet

be extra careful on camshaft selection , that 4inch outlet will make a good 4 inch suction pipe with too much overlap.
as posted ,your best bet is to get an RV or truck cam grind. either will work for you.

 

[jimmbo]

be extra careful on camshaft selection , that 4inch outlet will make a good 4 inch suction pipe with too much overlap.
as posted ,your best bet is to get an RV or truck cam grind. either will work for you.

Best bet, is to get a Marine Grind. I have seen far too many "RV/Truck" grinds, that just don't work well in Boats.

 

[stresspoint]

Best bet, is to get a Marine Grind. I have seen far too many "RV/Truck" grinds, that just don't work well in Boats.

i agree to get a marine grind if possible , ultimately a new Mercruiser unit is best but a bit on the expensive side,
most shops here in Australia do not understand marine specs ,so they will set customers up with a grind that suits a lazy truck motor unless you specify the grind you want.

while i know this is not optimal, a RV or truck spec camshaft for the most part will work just fine for most boat applications.

there are too many variables to consider when asking the shop for a ""marine grind """ so they will be a little reluctant to take pot luck and hope what they do is correct for your application, reputations are at stake .

 

[jimmbo]

i agree to get a marine grind if possible , ultimately a new Mercruiser unit is best but a bit on the expensive side,
most shops here in Australia do not understand marine specs ,so they will set customers up with a grind that suits a lazy truck motor unless you specify the grind you want.

while i know this is not optimal, a RV or truck spec camshaft for the most part will work just fine for most boat applications.

there are too many variables to consider when asking the shop for a ""marine grind """ so they will be a little reluctant to take pot luck and hope what they do is correct for your application, reputations are at stake .

A bit more money spent initially by getting the part from MerCruiser, which will work very well, is money well spent.
All the tweaking in the world of the Timing and Carbs, can not compensate for a non-marine grind

 

[mdaddy]

Thanks for feedback....

Likely Mercruiser # 431-811658

Duration @0.050": Intake 197; Exhaust 207
Lift: Intake .430; Exhaust .450
Lobe Centerline in degrees: Intake 106 ATDC; Exhaust 112 BTDC
Lobe Separation in Degrees 109

correct!

 

[mdaddy]

Make sure it's a marine cam for wet exhaust

Do not exceed 270 degrees of duration.

Make sure you check the cam card to make sure no overlap

Have had good luck with the Comp cams XM264HR

Xtreme Energy 212/218 Hydraulic Roller Cam for Chevrolet Small Block

Xtreme Energy 212/218 Retro-Fit Hydraulic Roller Cam for Chevy Small Block. Mild performance applications. Very good mid-range. 3.23-3.73 gear.

www.compcams.com

What Stage would this cam spec. fit under #1 or #2?

 

[stresspoint]

What Stage would this cam spec. fit under #1 or #2?

no such thing as ""stages "" for camshafts when it come to grinds to suit boat engines.
you hand over the specs you want or your old camshaft to the bloke at the machine shop and they make it for you.
what a strange concept !.something that does not come pre made in a box from china.

 

[jimmbo]

A different Grind will affect the Torque Curve of an Engine. What is good for making HP for a Car/Truck, is far from what a Boat requires. I know some People here swear by "RV and/or Truck" Grinds, I swear at them, the Grinds, not the people. Rump pa rump Cam Grinds loved in Cars/Trucks will pretty much destroy a Marine Engine if it has a Wet Exhaust, and all I/Os do, simply from Water getting sucked in the Exhaust Ports, then Hydro Locking

You can contact Mercury Marine to see if they offer a Higher Performance Cam for the Engine, but be prepared for other parts(Carb-Intake) needing to be changed to accommodate the deeper Breathing, and then there is the Issue of Propping. More Horsepower at higher Rpm, results in lower Torque at low Rpm. So your higher Hp boat becomes a dog out of the hole. Less Pitch will help, and the Higher WOT Rpm Range might be high enough to actually result in more top speed. But don't expect huge gains. a 30hp increase is about 5-6 mph

 

[Scott Danforth]

What Stage would this cam spec. fit under #1 or #2?

there really isnt a stage 1 or stage 2 anything outside of some idiots in the JDM market and some red necks in the LS market.

thats a game played facetubers, video gamers and wanabee racers

its as stupid as the greasers talking about a 3/4 race cam in the 60's.

its not a real thing its marketing name that doesnt mean anything

however for a stock motor its about as hot a cam that you can run in a boat with wet exhaust. especially a 5 liter. myself, I ran a similar cam in a 5.7 and it really woke the motor up, yet could idle

the hottest grind you can run in a 5.7 liter or above roller motor is a XM270HR. however you need to watch for reversion and you need to watch your base timing

before you run any different cam, know that you need to pull your heads, and modify them for screw in rocker studs and you need to have the machinist relieve the valve guides and install better seals and the valve springs recommended for the larger cam. a stock vortec head is good for 0.42" lift max without spending the $100 at the machine shop

before COMP screwed up their website, they used to have a chart like this
(borrowed from a go-fast boat supply company their part numbers vs Comp's )

best price on the cams is either Summit or Jegs

the roller cams are in yellow

 

[stresspoint]

A different Grind will affect the Torque Curve of an Engine. What is good for making HP for a Car/Truck, is far from what a Boat requires. I know some People here swear by "RV and/or Truck" Grinds, I swear at them, the Grinds, not the people. Rump pa rump Cam Grinds loved in Cars/Trucks will pretty much destroy a Marine Engine if it has a Wet Exhaust, and all I/Os do, simply from Water getting sucked in the Exhaust Ports, then Hydro Locking

You can contact Mercury Marine to see if they offer a Higher Performance Cam for the Engine, but be prepared for other parts(Carb-Intake) needing to be changed to accommodate the deeper Breathing, and then there is the Issue of Propping. More Horsepower at higher Rpm, results in lower Torque at low Rpm. So your higher Hp boat becomes a dog out of the hole. Less Pitch will help, and the Higher WOT Rpm Range might be high enough to actually result in more top speed. But don't expect huge gains. a 30hp increase is about 5-6 mph

ha ha , could not have said it better myself, well said.

FWIW, i don't get involved in the what nots and whatever when it comes to camshafts in my boat motors (500hp vortec 5.7 atm in my TR2 going on 4 years now and thrashed like i stole it every time i drive it).

i go and sit with a mate ,the mad engine professor i call him builds race car and high performance boat motors.

we chat about what bolt on etc i have to use or will get , what i expect from the motor , give over some cash and bourbon , a week later i get a phone call to come get my motor bits, they are all nicely and accurately machined and balanced.no info shared or warrantee on what's been done.
the only thing required of me as far as camshaft goes is to dial it in correctly during assembly.
i like to do my own assembly as i don't like anyone else messing with my mates work (he would not allow it anyway).
i don't even have to check anything as i know from 30 years experience of this bloke working in my motors everything is spot on.

 

[Scott06]

there really isnt a stage 1 or stage 2 anything outside of some idiots in the JDM market and some red necks in the LS market.

thats a game played facetubers, video gamers and wanabee racers

its as stupid as the greasers talking about a 3/4 race cam in the 60's.

its not a real thing its marketing name that doesnt mean anything

however for a stock motor its about as hot a cam that you can run in a boat with wet exhaust. especially a 5 liter. myself, I ran a similar cam in a 5.7 and it really woke the motor up, yet could idle

the hottest grind you can run in a 5.7 liter or above roller motor is a XM270HR. however you need to watch for reversion and you need to watch your base timing

before you run any different cam, know that you need to pull your heads, and modify them for screw in rocker studs and you need to have the machinist relieve the valve guides and install better seals and the valve springs recommended for the larger cam. a stock vortec head is good for 0.42" lift max without spending the $100 at the machine shop

before COMP screwed up their website, they used to have a chart like this
(borrowed from a go-fast boat supply company their part numbers vs Comp's )

best price on the cams is either Summit or Jegs

the roller cams are in yellow
View attachment 382814

Glad someone mentioned about the head work - valve spring and retainer to guide clearance issues. Even if it should work on paper check. I had an issue where someone messed up an older valve job , left the exhaust valve guides .090" higher when cutting down for viton seals. even with stock lift (.407") the retainers were kissing the top of the seal.

 

[stresspoint]

Glad someone mentioned about the head work - valve spring and retainer to guide clearance issues. Even if it should work on paper check. I had an issue where someone messed up an older valve job , left the exhaust valve guides .090" higher when cutting down for viton seals. even with stock lift (.407") the retainers were kissing the top of the seal.

how about the """ i have a racing cam in my motor people """ LMFAO at these ones .

 

[mdaddy]

Make sure it's a marine cam for wet exhaust

Do not exceed 270 degrees of duration.

Make sure you check the cam card to make sure no overlap

Have had good luck with the Comp cams XM264HR

Xtreme Energy 212/218 Hydraulic Roller Cam for Chevrolet Small Block

Xtreme Energy 212/218 Retro-Fit Hydraulic Roller Cam for Chevy Small Block. Mild performance applications. Very good mid-range. 3.23-3.73 gear.

www.compcams.com

with this camshaft will I be ok sticking with the 2 bbl carb in the short term while I work 2wards a 2 bbl high performamce carb. and what type of performance to expect?