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-   -   Off the shelf cam options for marine engines (https://www.offshoreonly.com/forums/general-q/334544-off-shelf-cam-options-marine-engines.html)

ARB38 02-24-2016 07:54 PM


Originally Posted by Black Baja (Post 4408117)
Cause his $900 upgrade that is suppose to make 20 more horsepower than anything else actually makes 30hp less than an out of the box Holley.

I have used them in the past and they worked fine. I did not compare them to anything else at the time since I had no problems with them. I will try some other carb's on it to see if I get more out of the engines when I run the boat. That will be better than a dyno test for a horsepower comparison.

vintage chromoly 02-24-2016 07:58 PM


Originally Posted by mike tkach (Post 4408114)
what compression ratio&cylinder heads.i built a 440 .030 over for a street car a few years ago ,just under 10 to 1 with hyd flat tappet cam that made 440 hp.

9.25 to 1.
906 Chrysler heads

This is a numbers matching engine for a 39,000 original miles car, so the idea was to keep it simple, cost effective and reliable. It's an ice cream cone getter.

mike tkach 02-24-2016 08:40 PM


Originally Posted by vintage chromoly (Post 4408044)
Maybe 450 to 475. Expecting a lot of torque.
I wanted to keep it stock appearing. To that end, it has worked iron heads, a 800 cfm carter AVS and iron manifolds. I also used old school ISKY ductile iron rocker arms.

i don,t think it will make 450.what was the factory hp rating?

MILD THUNDER 02-24-2016 08:57 PM

2 Attachment(s)

Originally Posted by Full Force (Post 4408077)
That's impressive that's exactly what I need there... High TQ numbers more then HP ..was yours also 540 with 088?


Tim, at 5500RPM in the boat, at 5500RPM on the dyno, your engines and Alex's engine, are very similar in power output. In my opinion, what you need, isn't more "torque" if you want the boat to go faster. What you need, is a combo that produces more upper RPM power. Unless I am missing something, how would Alex's combo there, make your boat have a higher top speed considering your current combo is hitting a wall at 5400-5500 in the boat?

With that being said, its pretty sad that Alex's combo here, is making similar peak power, and more low end power, than your 325 AFR CNC chambered combo, with Chevy Iron castings! Between 5400 and 5800, you picked up 11 horsepower. I know your goal was a 6000RPM 700HP combo. Something was giving up short. I doubt it was the 325 AFR heads, I doubt it was the 1050cfm 4150 carb.

Full Force 02-24-2016 08:59 PM

Just figure the TQ would carry the heavy hull easier, like my old engines, that 30ftlbs each missing I can feel, the boat was more "zippy" before...

needs boost lol

[QUOTE=MILD THUNDER;4408180]Tim, at 5500RPM in the boat, at 5500RPM on the dyno, your engines and Alex's engine, are very similar in power output. In my opinion, what you need, isn't more "torque" if you want the boat to go faster. What you need, is a combo that produces more upper RPM power. Unless I am missing something, how would Alex's combo there, make your boat have a higher top speed considering your current combo is hitting a wall at 5400

Panther 02-24-2016 09:13 PM


Originally Posted by vintage chromoly (Post 4408142)
I watched each pushrod spin before we put the intake on.
It is nerve racking to start a fresh engine. I rigged a mech. Oil pressure gauge and had the timing right on.

It's definitely much more uneventful firing a roller cam engine you just built compared to a tappet engine, that's for sure!

MILD THUNDER 02-24-2016 09:19 PM


Originally Posted by Panther (Post 4408194)
It's definitely much more uneventful firing a roller cam engine you just built compared to a tappet engine, that's for sure!

I used to think so too. Until of course, I've seen hydraulic roller lifters collapse at start up. Sucks when it happens on the dyno, and you have to pull off the blower, intercooler, intake, distributor, and so on to replace the lifter. Of course still not as bad as a flat tappet going flat, but still a pain in the azz. :faint2:

mike tkach 02-24-2016 09:43 PM


Originally Posted by MILD THUNDER (Post 4408201)
I used to think so too. Until of course, I've seen hydraulic roller lifters collapse at start up. Sucks when it happens on the dyno, and you have to pull off the blower, intercooler, intake, distributor, and so on to replace the lifter. Of course still not as bad as a flat tappet going flat, but still a pain in the azz. :faint2:

it would suck even worse if the engine was in a twin engine boat.

SB 02-24-2016 09:47 PM

Almost the end of page 64 and we are now on flat tappets. Did we go so far we hit a time warp of 12-15 yrs ?

Panther 02-24-2016 10:29 PM


Originally Posted by MILD THUNDER (Post 4408201)
I used to think so too. Until of course, I've seen hydraulic roller lifters collapse at start up. Sucks when it happens on the dyno, and you have to pull off the blower, intercooler, intake, distributor, and so on to replace the lifter. Of course still not as bad as a flat tappet going flat, but still a pain in the azz. :faint2:

Had that happen last year with a brand new Johnson lifter in a friends boat. I suggested he fire the engine without the valve cover on and adjust the valve while it was running. Backed off the lash and it pumped right back up.

I also prime the engines now without the pushrods installed until the lifters are fully pumped up and there's no air in the system.


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