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In small boats with Holley Vac secondaries, the faster you open them, the faster they plane. I have a few boats with the lightest spring Holley offers. They are so light they can sometimes keep the secondaries open a tad when the boat is brought back to idle speed. Engine has to be shut off and then restarted for the secondaries to close.
Absolutely brutal on the ALfalfa drive acceleration. LOL. |
People tell me all the time you shouldn't open them so fast and a small block only needs blah blah blah blah amount of CFM at a certain rpm.
My answer is simple. Step away from the computer and math and go freakin play with engines and tuning. Famous quote: If your results don't follow your theory, get a new theory. LOL. |
Originally Posted by SB
(Post 4143157)
People tell me all the time you shouldn't open them so fast and a small block only needs blah blah blah blah amount of CFM at a certain rpm.
My answer is simple. Step away from the computer and math and go freakin play with engines and tuning. Famous quote: If your results don't follow your theory, get a new theory. LOL. |
Originally Posted by SB
(Post 4142723)
Then your original engine was not stock. If not stock, then it was better than what you have now.
Stock 260/270hp motor in your boat is not 57mph capable. We need correct information from you so that we can give you correct information back to you. |
Here is the specs of the cam that was used. My builder is trying to dig up everything on my motor, hopefully I will he back from him soon. exhaust is stock manifolds, exhaust comes out the sides of boat, recently just put on some free flowing mufflers.
Comp Cams Cam Style:Hydraulic flat tappet Basic Operating RPM Range:1,200-5,200 Intake Duration at 050 inch Lift:212 Exhaust Duration at 050 inch Lift:212 Duration at 050 inch Lift:212 int./212 exh. Advertised Intake Duration:260 Advertised Exhaust Duration:260 Advertised Duration:260 int./260 exh. Intake Valve Lift with Factory Rocker Arm Ratio:0.440 in. Exhaust Valve Lift with Factory Rocker Arm Ratio:0.440 in. Valve Lift with Factory Rocker Arm Ratio:0.440 int./0.440 exh. Lobe Separation (degrees):110 |
Originally Posted by FIXX
(Post 4143248)
+1,,,, ps the hump back king cobra driver are 91 and up..yours is a dog clutch king cobra..
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Thank you for posting the cam !
You have a 300-310hp motor if the carb is tuned in right and working 100% correctly. This is assuming your Edelbrock Heads are the Edelbrock Performers. BTW: As a reference. I used to use that cam in 2wd Full Size Pickups with headers and 600 Holley's that towed. Great tow package - I miss those days ! If it didn't tow I'd use the 268H which was 218/218 at .050" on a 110. On I/O's with decent heads and an exhaust with water introduced a little back further from stock a HR with 218/224 on a 112 works perfect. |
Is the cam what is holding me up at 4400rpms and 47-48mph?
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21' boat... about 3500lbs wet....300hp 350...48mph sounds about right.
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whats worse is guys like me that buy a rebuilt motor and have no frigging idea whats inside then need you guys to give me advice!
In the end you have no idea how much help your info is to a rookie, we learn what not to do next time
Originally Posted by SB
(Post 4142935)
You sound like me.
Gawd I feel bad for you. He, he. ======== 99.5% of the time people ask for help on forums (I won't mention real life because that's what I do and it can become worse) they don't or can't give us all the info and we are expected to come up with the right answer. All we really need to know is the old cam (#'s will be on it) and new cam and we can go from there. You know how many times I get told, "Yeh, it's an RV cam." My answer always is "What the f*k is an RV cam ?" I also get " I have a Stage 4 Computer Chip " and my answer always is "What the f*k is a Stage 1,2,3,4,5 or whatever anything ?" LOL. One's who get pissed and think I'm stupid get let go. The one's who smile, shrug there shoulders, gigle, or anything that shows "Yeh, I know, that means nothing" gets help. |
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