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Is the cam change worth it?

Old 03-31-2004, 09:52 AM
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Default Is the cam change worth it?

27' baja, twin 350 mags, 1987, all stock. running 64gps.

looking at this comp cam CCA-12-236-3
Specifications:
* Advertised duration: 262 intake/268 exhaust
* Duration at .050 in. cam lift: 218 intake/224 exhaust
* Gross valve lift: .462 in. intake/.477 in. exhaust
* Lobe separation: 112 degrees
* RPM range: 1,300 to 5,500
* Biggest cam for inboard/outboard
* Good mid range with excellent response, noticeable idle

Is this the best cam for my app, and do you think i would see enough difference in speed to make it worth the switch?

what would you guess on a speed change?
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Old 03-31-2004, 10:13 AM
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BajaRunner

1987 was the transition year for the roller conversion in the SBC. Most of the 1987s (but not all) came with the roller. The 12-236-3 is a hyd flat. I would verify what cam is in the engine now before you decide on an upgrade.
Bob
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Old 03-31-2004, 10:23 AM
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dumb question, whats the best way to check. also whats a good replacement?
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Old 03-31-2004, 10:32 AM
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damn i just looked at the price difference on the flat vs roller.

im trying to pick up 3-5 mph, do you think this is the best way to go about that on a 350 mag?
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Old 03-31-2004, 12:01 PM
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BajaRunner

Check your pushrod length.
OEM flat 7.794"
OEM roller 7.195"
If you are OEM roller you wont need the retro kit and the costs will be reduced significantly.
Bob
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Old 03-31-2004, 04:18 PM
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If you are looking for 3-5 mph on a stock setup, an alternative way that I usually try first is to upgrade exhaust and props. If you have stock exhausts, you could go to something like EMI exhaust or something similiar, which would drop the weight of each engine by 60-70 lbs, and add approx 10% more HP. Removing 130-140 lbs of weight alone from the stern of the boat will help significantly, along with a few extra ponies from the exhaust performance. Merc stock style exhausts are the worst for performance. Also, not sure about the cam you mentioned, but if you go too big on the cam, you can create a reversion condition (aka suck water up into the motor) which requires upgraded exhaust to fix anyways.

Also if you may be able to pick up more speed by changing props. Obviously try the new props after the exhaust change if you go that route, as you may be able to go up in pitch.

My philosophy is just try to stick with the "bolt on" upgrades first before tearing into the motors.
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Old 03-31-2004, 06:11 PM
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Bajarunner
The least expensive way to increase the performance of your roller cam engine is to remove the camshaft and send it to Comp Cams for regrinding. They will charge you a reasonable amount and you won't have to pay for a new cam core. Use your old lifters and install the recommended valve springs.
Have them grind it to the same specs as the 08-422-8 XR276 HR camshaft.
Regrinding the old camshaft works great and you will be sure that it is compatible with your distributor gear and fuel pump pushrod.
The XR276 HR specs are the same as the specs you mentioned but with 110 centerlines (better for low speed torque).
Sincerely
Dennis Moore

P.S.
The stock Chevy/Mercruiser camshaft is ground on 109 degree centerlines and has plenty of base circle to increase valve lift and duration on a regrind.
 
Old 04-01-2004, 08:41 AM
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Keep the cams stock and have the heads ported cam might be good for 15 - 20 HP the heads would be good for around 100 HP. Hoter cams just try to get more air flow through the same hole.
 
Old 04-01-2004, 11:51 AM
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Hey Dennis,
You may have an idea for me too.
Is there enough meat on a L-29 BBC cam to have it reground?
I may just give comp cams a call...
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Old 04-22-2004, 08:06 AM
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For my Chevy 350 bored over .040. 2000lb donzi like boat, apha drive.
Spent alot of time with Jegs and Comp cam looking to replace my cam and suggestion was to use Comp Cams 12-240-4 Numbers are
.480 intake / .489 exhaust
226 intake / 236 duration duration
112 LSA

All with Edelbrock performer Heads, Performer Intake and Holley 750 double Pumper with 4 inch exhaust, and MSD ignition
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