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43 Max RPM Range

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marada1

Regular Contributor
"I just noticed in my service

"I just noticed in my service manual that the range on a 1990 4.3L HO is higher than the standard 4.3L. Whats the difference? Aren't the engine internals the same
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I guess my real question is wh

I guess my real question is why not run mine in the 4400-4800 range?
It's not that I want to but I have propped down to a 19" that may put me there. Just think'in it may not be a problem in short bursts.
Your thoughts?
 
"I don't think it would be

"I don't think it would be a problem, what kind of RPM's are you pulling now at WOT?

I guess I misunderstood your original question I thought you had the 4.3HO and just wanted to know why yours was spec'd higher than the 2bbl?"
 
"Hey Bob,
I think you read my

"Hey Bob,
I think you read my posts here http://www.marineengine.com/discus/messages/12488/215211.shtml
about the Titan 4 prop. Anyway the 21" had me on the low end at 4400 with a lighter than normal load. Bought the 19" and still havn't run it but I'm anticipating around 4800 with it. Just thinking ahead a little and noticed that the max RPM on the HO is 4400-4800. I have been thinking this was based more on engine internals and not ignition. As far as I know the "spitfire" and maybe a 4bbl were the only things different about the HO.
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"I used to have a 29' with

"I used to have a 29' with a pair of 1989 4.3 HO's. At the time I think they were advertised as having 205 hp each and the 2bbl were 175 (at the crank) The 89's did not have Spitfire (thank god!) but as far as I know the only real difference was the 4 bbl. So when are you changing the intake and carb???
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"Been there, Done that already

"Been there, Done that already.
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Over the winter I put on Vortec heads and Edelbrock Performer Intake and carb. I should be at around 210HP. Original engine was 160 (at the prop I think). It's quite a bit stronger than last year. Just couldn't swing that 21" Titan to suit me.
Still don't understand these max rpm numbers and why they were different on the HO. Oh well...."
 
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