Off the shelf cam options for marine engines
#102
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we have 10 pages and bob has not jumped in,i hope he does pretty soon.in my dealings with bob he has been straight forward and in my opinion he is a smart guy who has been in the game for a long time.it appears to me that he has a lot of satisfied customers.when i see guys who have used him for head&cam combinations that have not yet run their engine but are second guessing their decision it just makes me shake my head.i have no dog in this arena but i can,t see this thread doing bob,s business any good.nothing against alex ,i don,t think he started this thread to shatter anyone,s business or reputation.
#103
Gold Member
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we have 10 pages and bob has not jumped in,i hope he does pretty soon.in my dealings with bob he has been straight forward and in my opinion he is a smart guy who has been in the game for a long time.it appears to me that he has a lot of satisfied customers.when i see guys who have used him for head&cam combinations that have not yet run their engine but are second guessing their decision it just makes me shake my head.i have no dog in this arena but i can,t see this thread doing bob,s business any good.nothing against alex ,i don,t think he started this thread to shatter anyone,s business or reputation.
Seems as if he's washed his hands of this site for one reason or another.
#104
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I have a pair of 502's from 08 or 09 with some MK cams similar to crane 731's. They make excellent power and are still going strong. I have another pair of blown 555's around the same vintage with tight lash solids that have been extremely easy on valve train parts over the years. Moderate duration, conservative lift.
#105
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The Crower backset rockers take care of the issues on the intake valve for the BBC AFR, or shaft rockers. Of course the heads need a bit of clearancing around the pushrods when the geometry is correct, even with a 3/8 rod. The thinnest wall I've used on an NA build is a .096 Manton. But in reality, they shouldn't be required for some of the milder builds. I've got a pretty good handle on geometry at this stage.
#106
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How much of an advantage is going to a 55mm cam?
Lighter springs and less agressive ramp.
Also, a .904 lifter with a bigger wheel has to provide some benefit over an .842, no?
Lighter springs and less agressive ramp.
Also, a .904 lifter with a bigger wheel has to provide some benefit over an .842, no?
#107
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In my view, "aggressive" is different then unstable. There are many compromises in the bbc, including rocker "geometry". But having said that, there are tons of engines that are able to make good reliable hp without having to run tool steel race lifters, huge spring pressure, etc.
#109
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I had a Marine Kinetics cam in my last boat. I really don't know how many hours I ran it, but it was enough that if there was an issue, it would have turned up. With that engine, Bob spec'd the entire thing, and Dave at Wesco Racing build it. I really respect both Bob and Dave, and I never had any issues ever with that build. I would go so far as to say, it is the best marine engine I have owed so far.
Now currently I'm running a Crane 741 cam in my current engines. The specs on this cam are similar to the specs of the cam I had Bob design for me. It's really hard to compare the engines, as the Bob designed engine had AFR 265 heads and Prosystem carb and it was a single engine vs twin engines in my current boat. My engines now are essentially HP 450 clones with a 741 cam. I'm very happy with the new engines but they are not as crisp or responsive as the Bob engine. A lot of that, I'm sure had to do with the port velocity of the AFR heads, some of it could have been with the cam and the carb. Either way, I never had any issues with the engine Bob designed. So while it seems everyone that used to be pro-custom cam isn't any longer- I was a very satisfied customer of Bob's!
Now currently I'm running a Crane 741 cam in my current engines. The specs on this cam are similar to the specs of the cam I had Bob design for me. It's really hard to compare the engines, as the Bob designed engine had AFR 265 heads and Prosystem carb and it was a single engine vs twin engines in my current boat. My engines now are essentially HP 450 clones with a 741 cam. I'm very happy with the new engines but they are not as crisp or responsive as the Bob engine. A lot of that, I'm sure had to do with the port velocity of the AFR heads, some of it could have been with the cam and the carb. Either way, I never had any issues with the engine Bob designed. So while it seems everyone that used to be pro-custom cam isn't any longer- I was a very satisfied customer of Bob's!
Last edited by endeavour32; 02-14-2016 at 03:16 PM.
#110
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Dyno tests , especially ones that remove a "custom" cam, and install a different cam back to back, tells alot, as far as that area goes. And it has been done quite a few times recently, and the results were not in favor of the "custom" cam.
Then there is the field testing part of things.
Then there is the field testing part of things.