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holley jet sizing for my mild 355 merc ?

Old 07-16-2013, 06:30 PM
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Default holley jet sizing for my mild 355 merc ?

had my boat out 4 times since i put the new carb on, the carb is a marine holley 4160 600 cfm, the boat is a 1991 22ft century with a alpha one gen II, and the engine is a mercruiser 350 .030 to a 355, virgin camel hump heads, comp cams 280 flat tappet marine cam, comp cam valve springs, stainless steel valves, about 10:1 compression, keith black pistons, eagle crank and eagle rods, gm performance bowtie cast iron intake and 1'' phenolic carb space, 6.5 psi of fuel, now since i told you a little about my boat here's the issue, iam still having a issue getting up on plane, if iam in the boat with one person it gets on the water fair but not fast at ALL, i had 6 people in it which was crammed and will never do that again and i couldnt get on plane for $hit, the back of the boat seems like a was draggin a 1000lb anchor lol, the engine wasnt boggin it jus wouldnt rev up, i can give it full throttle half throttle and it was jus dogging through the water, also it has a 19pitch stainless prop, other than that the boat runs great once it get on plane with 1 or 2 people in it had it up to 55mph and it was choppy out too, SOOOOO.. what iam trying to get at is what jets and power valve should i have in my carb and could i have a ignition issue, could the timing not be advancing? or have a bad distrubuter pick up or a bad ignition module? i know the coil is good. any help is apprciated thanks matt
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Old 07-16-2013, 06:42 PM
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Originally Posted by monte383sbc
had my boat out 4 times since i put the new carb on, the carb is a marine holley 4160 600 cfm, the boat is a 1991 22ft century with a alpha one gen II, and the engine is a mercruiser 350 .030 to a 355, virgin camel hump heads, comp cams 280 flat tappet marine cam, comp cam valve springs, stainless steel valves, about 10:1 compression, keith black pistons, eagle crank and eagle rods, gm performance bowtie cast iron intake and 1'' phenolic carb space, 6.5 psi of fuel, now since i told you a little about my boat here's the issue, iam still having a issue getting up on plane, if iam in the boat with one person it gets on the water fair but not fast at ALL, i had 6 people in it which was crammed and will never do that again and i couldnt get on plane for $hit, the back of the boat seems like a was draggin a 1000lb anchor lol, the engine wasnt boggin it jus wouldnt rev up, i can give it full throttle half throttle and it was jus dogging through the water, also it has a 19pitch stainless prop, other than that the boat runs great once it get on plane with 1 or 2 people in it had it up to 55mph and it was choppy out too, SOOOOO.. what iam trying to get at is what jets and power valve should i have in my carb and could i have a ignition issue, could the timing not be advancing? or have a bad distrubuter pick up or a bad ignition module? i know the coil is good. any help is apprciated thanks matt
you really need a bigger carburetor,,i run a 750 cfm on my 355 and used the same carb on my old 314 in my boat....what intake are you running? also you have to have a lifter vally baffel installed if your not using a single plane intake or a air gap style,,the oil beating on the bottom of the intake will bake the bottom of the intake and make the intake fuel charge warm and the engine will struggle to get on plane.been here before..also what is your intinal timing set at? and total is?? that also plays a big part trying to make your boat plane out..
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Old 07-16-2013, 07:06 PM
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Is your carb a vac secondary with a metering plate (not metering block) on secondary's?
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Old 07-17-2013, 10:52 AM
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Thanks for the reply but i belive my 600 cfm holley is ok for a 355. Iam not turing over 6k iam wayyyy under that rpm range. But thankyou for the tips and help
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Old 07-17-2013, 10:55 AM
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Originally Posted by Sonic30ss
Is your carb a vac secondary with a metering plate (not metering block) on secondary's?
Yes its a new 4160 marine with the metering plate on the secondarys. Only the primarys have a metering block. And yes its vaccume secondarys

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Old 07-17-2013, 10:56 AM
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Originally Posted by Sonic30ss
Is your carb a vac secondary with a metering plate (not metering block) on secondary's?
Yes its a new 4160 marine carb with the metering plate on the secondarys. Only the primarys have a metering block. And yes its vaccume secondarys
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Old 07-17-2013, 04:49 PM
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What RPM's are you getting at top speed? Should be at least 4800 RPM at WOT top speed. If not, you are either over-propped or just not making the power you thought you would. Have you checked the simple things like initial and total timing, made sure the drive is going all the way down, etc.? Also, with vacuum secondaries, you need to make sure they are opening up when needed. You may have to get someone to watch while you nail it to make sure they are coming in. Maybe play around with different secondary springs, although I would expect a boat to require one of the heavier springs since it is under load most of the time.
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Old 07-17-2013, 09:42 PM
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Originally Posted by monte383sbc
Thanks for the reply but i belive my 600 cfm holley is ok for a 355. Iam not turing over 6k iam wayyyy under that rpm range. But thankyou for the tips and help
ok if you think so,,i just so happen to have the same boat and its now sitting with tuliped valves because the owner thought a 600 cfm carb would be ok on a 300 hp small block..its your valves !! good luck to you..
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Old 07-17-2013, 10:53 PM
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Originally Posted by FIXX
ok if you think so,,i just so happen to have the same boat and its now sitting with tuliped valves because the owner thought a 600 cfm carb would be ok on a 300 hp small block..its your valves !! good luck to you..
ok thanks buddy, iam here asking for help, why dont you tell my why my carb is to small? iam sure other people would like to know also. and i bet you had valve issues for another reason not becasue that carb was to small.
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Old 07-18-2013, 06:14 AM
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I had the same issues with that carb on brand new engines, I only ran it once for about 10 min like that.
Holley calls the tune on that carb a universal tune...read very mild.
I installed a secondary metering block, rejetted all 4 corners, 76 in the rear and installed a 6.5 power valve
I don't remember what jet I put in front, I used the Holley web site to get jetting for the performance tuned 600 and went up 2% on jet size. I have GLM manifolds and Imco risers straight out the back no mufflers
Boat burns ave of 20 GPH at cruise and 60 wide open
Have about 290 hrs on this set up and runs well
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