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-   -   Cam and valvetrain longevity....??? low duration high lift... (https://www.offshoreonly.com/forums/general-q/341258-cam-valvetrain-longevity-low-duration-high-lift.html)

JRider 10-07-2016 09:50 AM


Originally Posted by JRider (Post 4489226)
I am not so sure about that small of runner head on a 540+CI marine engine. My 548s have Dart 360s speced by Teague and made great numbers. Bob recommended AFR 305s for my 502ci 575sci, I thought that was small as well, or was it just what he had on the shelf? As far as my cams they are Crane Hydraulic Roller 254/262 680/680. 982 and 984 a side at 8psi

Just to be clear Bob M recommended the 305s not Bob Teague.

MILD THUNDER 10-07-2016 09:51 AM


Originally Posted by JRider (Post 4489226)
I am not so sure about that small of runner head on a 540+CI marine engine. My 548s have Dart 360s speced by Teague and made great numbers. Bob recommended AFR 305s for my 502ci 575sci, I thought that was small as well, or was it just what he had on the shelf? As far as my cams they are Crane Hydraulic Roller 254/262 680/680. 982 and 984 a side at 8psi

Nice to see someone finally put some cam in an engine. These. 240* 540s are a dime a dozen .

That is a big port, prob wouldnt go that route for an NA 540 marine build, the 320 darts would prob work better. But with that roots up top, low end shouldn't be an issue. Im sure yours made plenty of torque.

JRider 10-07-2016 09:54 AM


Originally Posted by MILD THUNDER (Post 4489371)
Nice to see someone finally put some cam in an engine. These. 240* 540s are a dime a dozen .

That is a big port, prob wouldnt go that route for an NA 540 marine build, the 320 darts would prob work better. But with that roots up top, low end shouldn't be an issue. Im sure yours made plenty of torque.

Yeah, missed the part about NA

Full Force 10-07-2016 11:14 AM

A buddy talked to kip today at cam motion said they have not had issues with harness, he wants cams to check, I plan to have frock style check them local also and compare results, I have 4 guys that wanna check them, so hard to have many involved... He did also say he's not a fan of small duration high lift but had to give Bob what he asks a for, also said I am a solid 10 degrees duration away form good power... I will be calling him myself personally later and let you guys know how my convo goes.

Baja Rooster 10-07-2016 02:44 PM

I see that MK was spec'ing high lift short duration for pretty much everything. So what is the theororetical value of such relative short duration? I'm flipping through a comp cams catalog and all of their cams for marine use ~.550 lift but about +20* on the duration. These seem flat and wide compared to the MK cams.

Full Force 10-07-2016 03:08 PM

Looking at my Dyno sheets the power spikes and falls super fast... Horrible for marine use...

Baja Rooster 10-07-2016 04:05 PM

It seems like that tight of a duration would give you a peaky spread of more power. Which makes sense as folks were having to prop down to let the engines get to that power, and then it would fly. Please correct me if that's wrong.

bck 10-07-2016 04:19 PM

I know Tim's cams had more lift than mine but mine still are outside of the norm I guess. I don't know that my power curve was particularly peaky. Perhaps I'm mistaken though not being exposed to as many combinations as some here

bck 10-07-2016 04:26 PM

1 Attachment(s)
This was the peakiest pull with the 2 in spacer. I went with the 1 inch spacer because it was broader than this one and higher in torque. I don't have that graph in the phone to upload here

Boatally Insane 10-07-2016 04:45 PM


Originally Posted by Full Force (Post 4489200)
Most look ok, there's a couple that might look like they bounced around a little,

Just curious.. What pushrods are you running ?


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