Carb HP 500 effect of compression ratio on jetting??
05-08-2010 | 09:38 PM
#11
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Joined: Feb 2009
Posts: 8,356
Likes: 1,515
From: NW Michigan
Heads are 119cc but block was line bored and using 20 thou longer rods with change in pistons. I am relying on my builder to cc the heads and measure everything up. From that he will either cut the heads and or select a non stock head gasket thickness. It is up to him to get the CR at what I request. I think I will spec it at 9.0 and call it good. He has the tools to mill the intake if needed.
Whole point of this project is de-powering from a B&M 250 Supercharged engine. Going with a little milder cam and non forced air. Lowers my insurance and reduce maintenance interval and expense. 80 MPH was a tad much for my Force 235 hull anyway.
Whole point of this project is de-powering from a B&M 250 Supercharged engine. Going with a little milder cam and non forced air. Lowers my insurance and reduce maintenance interval and expense. 80 MPH was a tad much for my Force 235 hull anyway.
Sounds like your on the right track. With that little bit off the heads I would see no need to have any concerns with cutting the intake as well. You'll be fine. Of course your engine builder can make that call. Good luck with everything. Sounds like you'll have a reliable 70 MPH boat with out the concerns of what might let go at any time. LOL...
05-09-2010 | 01:15 AM
#12
Charter Member # 55
Joined: Oct 2000
Posts: 20,241
Likes: 2,490
From: Omaha/LOTO
9.0 will be fine on 89 octane fuel. I would use the 500EFI cam or Crane 731 cam instead of the carb HP500 cam if you have the option. The carb cam was a lot more prone to reversion.
You would not need to change anything else to use either of these cams.
You would not need to change anything else to use either of these cams.
