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mjk1234

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Hello guys n gals, new here and just looking at using old stock on the shelf. I have a 95 5.7 with a cracked block. Has 217 heads. I have an old 358ci good running short block (I believe) 4 eyebrow dish pistons. I’m going to pull the camel hump heads and put the 217 heads with intake and carb on this short block. I have an old/new 280h style cam .480 lift I believe range 2000-6000 rpm. If I put this cam in and advanced it 4 deg. Will this work to drop tq/hp down 500 rpm and possibly get over 325hp? I’m doing this on a budget and trying to use stuff I have already purchased! Thank for any advice in advance! Cheers
Marty
 
mjk1234 said:
Hello guys n gals, new here and just looking at using old stock on the shelf. I have a 95 5.7 with a cracked block. Has 217 heads. I have an old 358ci good running short block (I believe) 4 eyebrow dish pistons. I’m going to pull the camel hump heads and put the 217 heads with intake and carb on this short block. I have an old/new 280h style cam .480 lift I believe range 2000-6000 rpm. If I put this cam in and advanced it 4 deg. Will this work to drop tq/hp down 500 rpm and possibly get over 325hp? I’m doing this on a budget and trying to use stuff I have already purchased! Thank for any advice in advance! Cheers
Marty
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No that cam will not work get a marine cam. Rpm range for marine is idle to 5000 rpm, marine cams LSA and overlap are designed to prevent reversion of water in wet exhaust. Comp cams extreme marine 264 is a good example of a marine cam for this application. Need to check heads for retainer to seal clearance and springs .

Keep compression to 9.4 or so
 
Dieter said:
No that cam will not work get a marine cam. Rpm range for marine is idle to 5000 rpm, marine cams LSA and overlap are designed to prevent reversion of water in wet exhaust. Comp cams extreme marine 264 is a good example of a marine cam for this application. Need to check heads for retainer to seal clearance and springs .

Keep compression to 9.4 or so
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Thank you sir. Appreciate the response. So if the cam was advanced you do t think it would drop the power and tq curve enough? Yes I’m aware of revision and the retainer to seal clearance as well. Thank you
 
Also, you'll be pushing the same hull with the same prop, so you will not go faster. Perhaps you'll get on plane quicker, but the top speed will not change.
 
mjk1234 said:
Thank you sir. Appreciate the response. So if the cam was advanced you do t think it would drop the power and tq curve enough? Yes I’m aware of revision and the retainer to seal clearance as well. Thank you
Click to expand...
Normally boats use what would traditionally be labelled as an old school towing/truck/RV cam vs traditional hot rod cam that works with gearing and higher stall converter to allow it to get in its power band.

Not sure the complete specs in terms of LSA, overlap and duration at .050" but typically advertised 280 duration isnt a combo that works in a relatively stock (i.e. non perf) boat. Typically LSA above 110 or 112 very little overlap and .050 duration in the 195-210 range are stock marine cams. Of course a lot of guys run something slightly hotter but not what you currently have. Compare specs to some of the milder comp cams marine grinds I think you will see the diff
 
Here is a performance cam that has been reported to work well. Confirm it will work with your block and heads/comp ratio
 

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One additional note,

If this is a boat with an alpha out drive.
A standard gear set is only good to about 300hp.
Anything higher would require a heavy duty gear set in the upper gear case.
 
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