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Originally Posted by mrfixxall
(Post 3782888)
dont know if its the same gut i talked to a few weeks ago but he said he had the plugs at .040..
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Originally Posted by Bowtiepower00
(Post 3782967)
What Ignition? Stock HEI? Might need an ignition upgrade, cam appears on the small side, which would explain a lot, but definately throw a WB O2 on 'er, and keep that thing rich or you're going to be melting pistons...
How does she act when the power falls off? Any breaking up or misfiring? Or just feels soft when the power builds? Could be spark or fuel, double check both before changing anything internal... I agree with staying Hyd Roller, but not sure if the hot cam is the best choice with boost.... If everything else checks out (spark, air, fuel) add more cam... Good luck... |
Originally Posted by Bowtiepower00
(Post 3782967)
What Ignition? Stock HEI? Might need an ignition upgrade, cam appears on the small side, which would explain a lot, but definately throw a WB O2 on 'er, and keep that thing rich or you're going to be melting pistons...
How does she act when the power falls off? Any breaking up or misfiring? Or just feels soft when the power builds? Could be spark or fuel, double check both before changing anything internal... I agree with staying Hyd Roller, but not sure if the hot cam is the best choice with boost.... If everything else checks out (spark, air, fuel) add more cam... Good luck... |
I hate to tell you this, but the entire build is all wrong for reliable marine engine. The pistons are not what you want for a blower engine. The hyper pistons are marginal for a performance engine, the comp ratio is about the max you would want for a naturally aspirated engine and 9.5 is certainly too high for a blower engine. A forged crank would be much better. The cam is small, but is being cheated by using 1.6 rockers instead of standard 1.5's.
It really sounds like this was pieced together with a bunch of leftover parts. |
Originally Posted by Griff
(Post 3783725)
I hate to tell you this, but the entire build is all wrong for reliable marine engine. The pistons are not what you want for a blower engine. The hyper pistons are marginal for a performance engine, the comp ratio is about the max you would want for a naturally aspirated engine and 9.5 is certainly too high for a blower engine. A forged crank would be much better. The cam is small, but is being cheated by using 1.6 rockers instead of standard 1.5's.
It really sounds like this was pieced together with a bunch of leftover parts. |
Prop down to a 19" prop and see if the same thing happens. 15" diameter 22" pitch is a lot for a small block. A prop change is an easy non-invasive test.
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Originally Posted by Trash
(Post 3784094)
Prop down to a 19" prop and see if the same thing happens. 15" diameter 22" pitch is a lot for a small block. A prop change is an easy non-invasive test.
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Originally Posted by michaelb63
(Post 3788793)
does the same thing with a 13.750x23 3 blade the 350 mag would spin it at 5200 rpm . but seeing that boat season is pretty much done here .going to go ahead and pull the motor out and reuild it this winter. ditch the hyper pistons, go with flat top forged pistons ,any suggestions on cam size while i got it tore down ?
The numbers are off somewhere. |
fixx
Originally Posted by Trash
(Post 3784094)
Prop down to a 19" prop and see if the same thing happens. 15" diameter 22" pitch is a lot for a small block. A prop change is an easy non-invasive test.
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Originally Posted by mrfixxall
(Post 3789462)
really? :eekdrop: i swing a 26'' prop to 6200 with a 355 through a old volvo penta drive with a 1.62 ratio..mild small block..
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