what gives?

[oilfieldtrash]

i have an 18 ft nordic bubble deck. this past winter i went threw the motor and installed new bearings and rings a cam and a set of closed chamber heads off a 396. i had the heads built with new valves, new springs and roller rockers. installed a new set of rewarder ot headers and a new 850 cfm holley dp. the engine is a 454 bored 30 over. my question is that i still cant turn it past about 4500 rpm, last year with my 30 year old motor i was pulling 4300 rpm. what gives? i now my pump is worn out, it also is 30 years old without any overhauls sense new. i now this because i got the boat from the original owner. any help or a point in the right direction i would appreciate it greatly!

[ap67et10]

what heads were on it before? what kind of compression? how big a cam? it kind of sound like the engine stuff you did might not have increased your power much...typically a refresh doesn't gain a lot of power unless the thing has some major blowby issues and is a complete pig...but if you didn't really step it up with the heads and cam and intake (what intake?) you may have only gained 30-40 horse which shows with the rpm increase. maybe take a look at the impeller charts, it should give you a rough estimate of the power your boat has. the only other thing that would cause low rpm is poor engine runability...is it misfiring or falling on its face or doing anything that shows its not tuned right and low on power?
AP

[Moneypitt]

Too fat......Over carbed, big time....Try a 650 and check the difference......MP

[oilfieldtrash]

what heads were on it before? what kind of compression? how big a cam? it kind of sound like the engine stuff you did might not have increased your power much...typically a refresh doesn't gain a lot of power unless the thing has some major blowby issues and is a complete pig...but if you didn't really step it up with the heads and cam and intake (what intake?) you may have only gained 30-40 horse which shows with the rpm increase. maybe take a look at the impeller charts, it should give you a rough estimate of the power your boat has. the only other thing that would cause low rpm is poor engine runability...is it misfiring or falling on its face or doing anything that shows its not tuned right and low on power?
AP
i am not to sure of the compression they are flat top pistons with closed chsmber heads. the intake is a old style edelbrock torker the cam is comp cam part # 11-209-3. valve lift is I .507 E .531. the other engine was clean and reliable it ran every weekend i just figured with the heads, cam, headers, and carb i would pick up a little more then that. the other heads were open chamber stock late 70's

[oilfieldtrash]

Too fat......Over carbed, big time....Try a 650 and check the difference......MP
the first time i took it out i ran a 700 holley it ran like crap it would not pull on the top and mid range was weak. i put the 850 on saturday and went out and it ran alot better pulled hard all the way to the top out of about 4500 rpm. it feels like there is more there, it just would go past 4500

[Moneypitt]

the first time i took it out i ran a 700 holley it ran like crap it would not pull on the top and mid range was weak. i put the 850 on saturday and went out and it ran alot better pulled hard all the way to the top out of about 4500 rpm. it feels like there is more there, it just would go past 4500
Regardless, the 850 is too big. That motor can't use that much air/fuel. What is the list # on the 700???????............MP

[oilfieldtrash]

Regardless, the 850 is too big. That motor can't use that much air/fuel. What is the list # on the 700???????............MP
the # on the 700 is 4778-2. ok then why doe it run better with the 850? i am new to this so any knowledge i gain is knowledge i didnt have.
thanks casey

[gbelt]

What are you running for ignition? Is it all in top shape? What kind of advance are you running? Fresh fuel? Did you degree the cam? Just some other things to consider.

[oilfieldtrash]

What are you running for ignition? Is it all in top shape? What kind of advance are you running? Fresh fuel? Did you degree the cam? Just some other things to consider.
i am running an HEI distributor with msd wires all in good condition. the shop that did my motor work said to set the timing at 32 deg. total. the fuel is fresh 91 octane. and no i did not degree the cam. the guy who did my motor work said there was no need to because this was just a mild motor.
thanks casey

[Moneypitt]

the # on the 700 is 4778-2. ok then why doe it run better with the 850? i am new to this so any knowledge i gain is knowledge i didnt have.
thanks casey
I'm guessing the 700 had some issues the 850 doesn't have. The motor wouldn't run like shit with the 700, it might lay down a little around 6500 if it were truly starving for fuel. The 850 seems to run better because the extra fuel is crutching the motor, simular to a manual choke on a Chevy 6 while cruising at low RPMs......As mentioned, alot can be said for ignition timing, camshaft location, compression ratio, etc etc etc......Again, IMO, 850 is too much fuel for a 460 turning under 5K.............However, IF the 850 makes the boat drivable, and you're having fun, go for it, enjoy..........MP