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Help picking out a cam...

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Help picking out a cam...

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Old 10-06-2016, 03:15 PM
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Last edited by Baja Rooster; 10-06-2016 at 03:19 PM.
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Old 10-06-2016, 03:16 PM
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Given the static floating around about MK cams I'd like to let the OSO brain trust handle this one

I plan on swapping out the ZZ502 cam this winter largely because of the 110lsa, idle quality could be better, and I have a Vortech RaceM charger/intercooler that I'd like to use but still have the option of not using it. This boat is largely used for towing tubes and the occasional wakeboarder during the summer, so low end manners are appreciated, with some wide open times in the bay and delta during the fall. It's an all around pleasure cruiser but a little more pep would be nice.

Thoughts? Leave well enough alone?

Baja 272 Islander
502 crate motor ~500hp
QF850M carb
CMI headers (may switch to SM manifolds)
9.6.1 static comp
Comp cams steel roller rockers and push rods 1.7 ratio
Felpro head gaskets/ARP bolts
Forged internals
Performer RPM Dual plane manifold
Performer RPM oval port heads (fresh rebuild)

Cylinder Head Specifications:
Combustion chamber volume: 110cc
Intake runner volume: 290cc
Exhaust runner volume: 110cc
Intake valve diameter: 2.19"
Exhaust valve diameter: 1.88"
Valve stem diameter: 11/32"
Valve guides: Manganese bronze
Deck thickness: 9/16"
Valve spring diameter: 1.55"
Valve spring maximum lift: .700"
Rocker stud: 7/16"
Guideplate: Hardened steel
Pushrod diameter: 3/8"
Valve angle: 26
Exhaust port location: Stock
Spark plug fitment: 14mm x 3/4 reach, gasket seat
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Old 10-08-2016, 11:44 PM
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The current ZZ502 cam has.527 intake / .544 exhaust
Camshaft Duration (@.050 in.): 224 intake / 234 exhaust

It seems like Crane is having the better choice of cams these days so I'm kicking around these options. It seems like the 791 with its 114 Lsa would be a nice upgrade or the 731 that is the same but with 112lsa.
Am I even in the right boat of thinking here?
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Old 10-08-2016, 11:47 PM
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Actually the 761 looks like a solid choice. I'm trying to keep the existing valve train. I don't know the lifter brand but they are not tied together.
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Old 10-09-2016, 04:21 AM
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You shouldn't have any issues with idle quality and the current cam you have. The 525 efi cam would work really well with that setup and it responds very well to boost. 236/244 @.050 114 lsa. I have one coming out of a motor in the next week. Johnson lifters as well. Cam does have a flat nose for mark iv block...
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Old 10-09-2016, 06:53 AM
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can't help much on cam, but I ran a HP500 with a procharger for years, several carbs and EFI, last setup had to go down to a 750 from a 850 to keep from leaning out at WOT, thanks god for widebands. the air was being blown thru so quickly that would not pull fuel, the 750 worked perfectly
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Old 10-09-2016, 08:53 AM
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Originally Posted by Baja Rooster View Post
Actually the 761 looks like a solid choice. I'm trying to keep the existing valve train. I don't know the lifter brand but they are not tied together.
thats the one I'd put in.you'll be in the 525hp area n/a and 700hp blown

Last edited by sutphen 30; 10-09-2016 at 09:15 AM. Reason: just saw he had a blower.oops
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Old 10-09-2016, 09:07 AM
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I like the 525 EFI cam or similar

Since you tow tubers and wake boarders, I'd look into selling the centrifugal, and picking up a 250 blower. Couple that to those oval ports , should make more than enough low end, and good top end as well. Throttle actuation and response down low with a roots is very good.
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Old 10-09-2016, 09:15 AM
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I'm just thinking of his poor drive.700+hp is not gonna be kind.
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Old 10-09-2016, 09:31 AM
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Originally Posted by sutphen 30 View Post
I'm just thinking of his poor drive.700+hp is not gonna be kind.
Very true. Maybe he could stay NA, and just run a low pitch prop for those wakeboarding and tubing days. Then when not playing mastercrafter, he could bolt the big prop back on.
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