Reply With QuoteDepends on the size of your impeller. AA maybee, A or B and I would say that you have some problems. Cam seems a little small for that motor.
so what rpm should a 496 turn? 850 carb, victor jr intake,10:1, 188 factory heads,comp cams .564 lift.. 234* 237*@.050, on a 112 ..12jg pump a impeller freash from MPD..just curious..I only saw 4800 rpm...is this right?
Depends on the size of your impeller. AA maybee, A or B and I would say that you have some problems. Cam seems a little small for that motor.
so what rpm should a 496 turn? 850 carb, victor jr intake,10:1, 188 factory heads,comp cams .564 lift.. 234* 237*@.050, on a 112 ..12jg pump a impeller freash from MPD..just curious..I only saw 4800 rpm...is this right?
How much total ignition timing are you running?With the engine off have someone push the gas pedal all the way open look inside the carb and make sure you are getting full throttle.
so what rpm should a 496 turn? 850 carb, victor jr intake,10:1, 188 factory heads,comp cams .564 lift.. 234* 237*@.050, on a 112 ..12jg pump a impeller freash from MPD..just curious..I only saw 4800 rpm...is this right?
What exhaust are you running? With my roller 496 with a 246 @50 .622 lift comp, 950HP, air gap, JG with "A" berk and logs I could only turn 5000. I put in TT headers and immediately turned 5500 with no tuning.
Gugs
For one thing, you camshaft is too small by about .100" to make real power with that many cubic inches.
ok, sorry I forgot some details..carb is all the way open, currently running log manifolds w/ small tips 2 7/8 ..Impeller is an "A" berkley alum....total timing this time out was 34*..cam setup is a hyd. flat tappet. cam claims 2000-6200..someone pls make it all better.....thanks guys..by the way its a 21 ft bahner closed deck
Another thing you might do, is to check and make sure your tachometer is accurate.
ok, sorry I forgot some details..carb is all the way open, currently running log manifolds w/ small tips 2 7/8 ..Impeller is an "A" berkley alum....total timing this time out was 34*..cam setup is a hyd. flat tappet. cam claims 2000-6200..someone pls make it all better.....thanks guys..by the way its a 21 ft bahner closed deck
With the rpms you are turning that impeller the JPC shows you are only making 350hp.
GUGS102 numbers on the JPC with logs shows 395hp to turn 5000rpms and with the increased rpms with the TT headers shows 525hp to turn the A berk impeller 5500rpms.A 130hp increase!!! According to the JPC.
I dont know how accurate the JPC is but when I run the numbers for my boat with a AT-B impeller at 5500rpms it shows 450hp to turn it and I was running a 450hp 502 crate motor.The JPC is 100% accurate with my setup not sure about others but I would bet it is very close.
SQUIRT I suggest you get a better exhaust system before you worry about the cam size being too small.It wont matter how large of a cam you run if you cant get the exhaust out of the motor.
First off thanks for all the information guys,I really apreciate it..What is JPC that 502 jet is refering to?.And to HTP tach is going to the gauge shop monday for calibration just to be sure...Sorry still new to this boat engine thing.Im not to worried about cam size and I know that exhaust is my next investment ..just curious as to how much the pump/water load really affects the overall RPM of the Engine.I do know this the engine runs a hell of alot better than the old stock 454,it RPM'S very quickly and pulls real hard...I haven't stayed in it for a long time to see what it will do,still breaking it in for what thats worth..oh yeah how accurate are those water pick up speedo's? Theres one in the boat and it works just not sure how accorate it is..once again thanks for all the info....
how much power should this 496 make..10.25:1 ,188 factory as cast heads, .564/.567 lift 234/237 @.050 on a 112 LC cam ,matching springs etc. 850 demon victor jr intake..4.250 stroke 6.385 rod..just curious never even asked the builder..
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