420 hp to 540c.i.d.
08-28-2011, 10:40 PM
#11
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08-30-2011, 02:40 PM
#12
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I got some nice hydraulic roller cams that would work nice for you too! Depends though on how long your tailpipes are though. If they are the long TRS style Gils, that pretty much go to the inside of the transom before they end, you should be good. 232/[email protected] .578/.578 lift. A little hotter than the 228/236* 530/551 lift 420 flat tappet cam. But the roller grind itself should pick some power up do to the ramp speeds and frictional loss. Either cam though works well with a blower.
If the engines are low hours, and healthy, I'd bolt the blower on it, and keep the boost 5psi or under, and timing 28-30* total. Upgrade to a better fuel pump and fuel lines. You buy my blowers and they come with six valve Holley Mechanical pumps and #8 lines to carb feeds, all AN nickel finish stuff. Youll be making more power than a stock 525SC, due to the larger blower, and extra compression you have.
Just a guess, but I would think the blower package would add 8-10mph in your boat. Which i assume would put you somewhere in the 80mph range..
If the engines are low hours, and healthy, I'd bolt the blower on it, and keep the boost 5psi or under, and timing 28-30* total. Upgrade to a better fuel pump and fuel lines. You buy my blowers and they come with six valve Holley Mechanical pumps and #8 lines to carb feeds, all AN nickel finish stuff. Youll be making more power than a stock 525SC, due to the larger blower, and extra compression you have.
Just a guess, but I would think the blower package would add 8-10mph in your boat. Which i assume would put you somewhere in the 80mph range..
08-30-2011, 02:54 PM
#13
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Back around 1990 I was at Trenton Marine talking to Dean Nickerson who was doing business there at that time.He was telling me about the blower installations they were doing on 420's/TRS in Formula 357's and 311's.They would increase prop pitch by 4" with the blower.I didn't ask the blower size but it did not look like the small 177 unit.Claimed it made 530 horsepower,said the 357 did about 72mph and the 311's went close to 80.
08-30-2011, 03:47 PM
#14
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Wonder what a 250 blower would do on a pair of 496s. hey also what should i do about my stock 420 valve covers they blow oil out the cheapo caps. What are you guys using?
08-30-2011, 04:11 PM
#15
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I have two sets of non plus mirage 25's, I wonder if they could be worked that far. I currently only turn my 25's to 4900 but with the non plus 23's I can spin all the way past 5200 which gets me my best speed of 69.8 gps. I would think the blowers would more than let me turn the 25's all the way to 5200. Thanks for all the input guys!
08-30-2011, 04:17 PM
#16
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As for the stock valve covers, they do that. Oil gets in the Fins, and sucks to clean. You may try a new filler cap, with a tension spring to keep it tight. I believe the 420's came with the springs, one end went thru the filler cap ear, the other went thru a small hole drilled into one of the fins.
09-02-2011, 12:57 PM
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So, of the guys on here running 250 blowers with single carb setups. What timing combo are you running?
