brivander

Ok guys as my rebuild has progressed it's time to pick a camshaft.

It started life as a 502OMC and I yanked all that garbage and put a standard distributor in it. I lost oil pressure and pulled for a re-build.

Block crank and heads all checked out. Block is getting decked about .010-.015" due to some pitting and we are going to mill the heads a mild amount to bump it to 9.25 compression from 8.75. Sticking with the stock JE700 pistons, honing all the cylinders (all were checked and are ok), new rings, stock rods with ARP fasteners. Boat has stainless marine manifolds and an 850 Holley. Shaving the crank .010. Cylinder heads re-done to stock specs w/new springs (but were in great shape) It had a Comp Cams 11-232-3 in with the following specs:

Comp Cams 11-232-3 Xtreme Marine Camshaft Hyd. Flat Tappet 1000-5000rpm Adv. Dur. 262 Int./268 Exh. Valve Lift .505 Int./.515 Exh. Lobe Angle 112 deg. (NOTE THIS IS A FLAT TAPPET CAM)

This is kind of a bummer, I was hoping to use the stock cam as a guide, even though this started life as an OMC, thats a pretty mild cam if you ask me...I am NOT converting to roller since I don't have $1500 burning a hole in my pocket at this point. Converting to an adjustable rocker studs also.

GM has this cam: "14096209 Hydraulic Flat Tappet "502"
This hydraulic flat tappet "502" is a good street high-performance and marine cam used in the Gen V 502 H.O. engine P/N 10185085. (Use spring P/N 3970627.) The duration at lash point in degrees (intake/exhaust) is 328/324; duration at .050" tappet lift (intake/exhaust) is 220/220; and maximum lift with 1.7:1 rocker ratio (intake/exhaust) is 500/500. Valve lash is zero/zero and lobe centerline is 115 degrees.
Technical Notes: Distributor P/N 1104067 or melonized distributor gear P/N 10456413 must be used on all crate engines with steel camshafts."

This is the stock cam on a 450hp 502, and I would like to move up to the next size, but keep my RPM's below 5500.

Any advice would help. I did talk to Bob at Marine Kinetics and he is out of the flat tappet business (but did offer to help select something once I knew more, so I need to give him a ring back). And once the engine is done it looks like I'll have Orlandi performance (I spoke to Brian tonight, he's a stand-up guy) dyno test and install the engine.

Thoughts? Recommendations?

brivander

I did, he won't and for good reasons, he's only doing roller now.

EDIT: I talked to Bob again today, and he still does flat tappet camshafts I apologize for the confusion here, he just wasn't comfortable putting his name on something he didn't know was going to be broke in properly, etc. And for this I completely understand, when he stamps his name on it, he just wants to ensure everything will go smoothly. He's been a ton of help here so let me be clear, he highly suggested going roller and was more than willing to help, but unlike every other person in the US I try not to spend money I can't pay for right now

Smitty

iTrader: (1)

Sorry I didn't read all the way to the end !!! My bad !!

Smitty

iTrader: (1)

See if you can find a regular cam that has similar specs to the Crane cam that ends in 631. It is a roller tho.. That cam is a good middle of the road cam.

brivander

Couple options with a quick look:

Current: Comp Cams 11-232-3 --1000-5000rpm, 218/224 duration, 505/515 lift, 112 degree lobe separation.

Options in "order" of aggressive nature:

Stock 502 HO: 14096209 RPM Range???, 220/220 duration, 500/500 lift, 115 degree lobe separation.

Comp Cams 11-306-4 --1000-5700rpm, 222/226 duration, 525/525 lift, 110 degree lobe separation.

Comp Cams 11-236-4 --1000-5800rpm, 226/236 duration, 544/547 lift, 112 degree lobe separation.

Not sure how far to go here, what I will gain and what I will give up...I mean I know direction, but not magnitude, anyone have any experience here? Don't want to go to aggressive to give up livability. I though the stock HO cam was good to about 5500, (not that you want to spin it that high 5200 is what most marine HO were rated too I believe, can I assume the 5700 cam would be ok in that range? and the 5800 cam run ok in the 5400 range'ish??

FIXX

iTrader: (2)

the flat tappet cams i like to use are

1... Isky marine 270/280 mega hyd
vary snappy cam and has a mild lopy idle..
http://www.iskycams.com/pdfcatalog/2004-05/page162.pdf

2..comp cam xtreme marine,,need to advance this one +2*

http://www.jegs.com/i/Comp-Cams/249/...rentProductId=

Griff

Crane #134241 or 134242 in a kit with lifters
http://www.cranecams.com/product/car...detail&p=24014

I would stay away from 110 lob sep cams unless you have dry exhaust. Go with a 112 or 114.

brivander

This is pretty funny you guys are pretty much listing all the cams under onsideration Smart people

Here is the deal, since this started life as an OMC and was rated at 420HP (crank), 375 prop and everything else seems to be the same as the Merc other than that, pistons compression etc. would going to the stock merc cam actually be an upgrade? I can not find any specs on the stock OMC cam, part # OMC 986765 or Volvo 3854016.

The merc cam is 510/510 lift, 224/224 duration @ 115 lobe separation. My goal is to go ONE step past this nothing crazy and I don't want to increase the RPM's much for durability, talking with Bob quickly today (he wasn't in the office so I need to catch him tomorrow) that's about what he recommended and I can get an old stock cam immediately from Brian Orlandi (who is also awesome by the way) -- is this the best thing to do with all the flat tappet issues everyone seems to have with the aftermarket cams?

Like I said I'm not looking for something to crazy, with the extra compression and the stainless marine manifold it should run pretty good even with the stock cam...possibly...hell I'm not sure what to do here....

1BIGJIM

iTrader: (1)

I have a brand new zero hour stock Merc cam out of a 502 Gen VI . With springs and retainers $75. The springs alone cost over a $100 when you replace a cam.

offthefront

iTrader: (1)

I am upgrading my motors and have the entire Valve train available if your interested ...Motors had 326hrs and Aready sold one set and it looked to be in very good condition..the remaining motor is in better shape ...m

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