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Engine build /compression question combination

Old 10-14-2013, 09:08 PM
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Default Engine build /compression question combination

I have 548 ci blocks bore 4.5
Merlin heads 30630 119 cc 2.3 and 1.88 valves
je /src pistons #257943
crank 4.25 stroke
rods 6.38

The compression ratio appears to be 8.5 to 1 is this correct? if so or if not will I need to change out the pistons?

The plan is to put a dart intake and carb ...the one that came on the 500 carb engines...(not sure what size to use)

and a a hyd flat tappet cam in it (dont want rollers due to price) dont know which one to use

I'm looking for input here what hp would these be? I'd be happy with 500 to 600 hp as the boat origionally came wit 500's and ran 88 (dont want to pop the bravo's 88-98 mph is good for me)

I was looking at the merc website looks like the bulldog is aprox 8.5 to 1 also

is this a viable build? im trying to save what I can and not put the wiand 250 blowers back on

I would like to keep in the low octaine fuel due to not knowing what you get these days

hope this makes sense with what I am asking
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Old 10-15-2013, 06:36 PM
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with a 119 cc head, piston in the hole .010 and a ,041 head gasket compression will be at or near 8.4 to 1,the hp500 is 8,75 to 1,so you are close,i would not use a flat tappet cam,go with a crane 741 hyd roller and you should be close to 500 hp.if you install the blowers it will really wake up.
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Old 10-15-2013, 08:11 PM
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I did a 540CI, Merlin 320 Iron Heads, 9:1, 741 Crane hyd roller cam, single plane dart intake, 1050 Holley. Right around 600HP and 615ft lbs.
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Old 10-15-2013, 09:18 PM
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I hate to say it but Bite the bullet now and put the Hyd Roller cam in it.
Skimp on something later like new gauge bezels, painting the dash or taking the girl/wife out for dinner a few times.
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Old 10-15-2013, 09:21 PM
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I agree . Sometimes you can find a crane 741 cam cheap here , or the 525efi cam. Those are gen vi cams though I believe and you'll need a gen vi timing set. The 525efi cam is the 741 but on a 114Lsa rather than a 112
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Old 10-16-2013, 06:26 AM
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I have 2 complete 500 EFI roller cam sets for sale.
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Old 10-16-2013, 07:01 AM
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you are pissing in the wind trying to run a flat tappet cam anymore...the core they are ground on are junk..no quality control...call Bob M. @ marine kinectics...he will set you strait...listen to him...nuff said
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Old 10-16-2013, 12:00 PM
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Give Bob a call on a cam and he can get you taken care of. Worked with him on mine, 548 tall deck, AFR 305's 9.2:1 comp and his cam and we are making a nice 650hp/675 lbft
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Old 10-17-2013, 08:19 PM
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rollers it is then, I make the GF take me to dinner any way LOL
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Old 10-17-2013, 10:08 PM
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That`s two shots for anyone reading this thread btw!!

Last edited by ICDEDPPL; 10-18-2013 at 12:26 AM.
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