getrdunn

1.7 is std on bbc. Heads will work ok just not ideal for your application as you’re basically hearing. I doubt you’ll have any clearance issues but what a perfect time to get a good flowing set of aftermarkets tailored to your CI. (290-315 cc) Mentioned in earlier post.

But then it’s cam, intake and exhaust but pending your end goal it may or may not be worth it. JMO

hogie roll

I bet if combined with an edelbrock rpm or rpm air gap dual plan manifold, it would make great torque.

articfriends

That would be a interesting dyno test, throw a set of heads on a engine that are by all means too big of runner then band aid it with various intakes, including maybe some oval ports. Ive already seen how bad a perfomer rpm can kick a Victor jrs ass on anything from about 515 down thruout majority of power band. Smitty

Hoodoo 2.0

Thats interesting, what outcome would you expect if the reverse were done? As in running 325 heads on a 615 ci that has a high flowing intake such as profiler snipers?

SB

Then test the two in a small light single boat like a velocity 22 to see what makes better power in actuality. Man, i miss going to the drag strip to test parts/theories/ideas

502nova3

ya not looking to buy new heads or exhaust only Plain on keeping it maybe anther 2 summers than upgrading but would consider a new cam for the heads I'm looking at if u have any recomendations. Since i ownded the boat it would never rev much over 4500 its a 1986 27foot nova iii single engine i have a 21p prop and a23 would do 50 to 52 mph with the 23 at 4400 to 4600 ish rpm should I be able to get more rpm out of it?

getrdunn

Nice looking! Based on what you said I’d find another fresh set of 990’s and leave all else alone unless you’re willing to do the whole combo - heads, intake, cam and exhaust. You’ll thank me later 😉

502nova3

Believe me I'd have a set of 990s of i could find em been looking for months and dont want to buy a used set off the internet cause ya never know what your getin. can't imagine you'd loose mutch more than than 20 to 30 ft lb of torque with these heads and I bet the boat may still work better than it has sine I owned it I put prob 60 hrs on it my self and would bet they both been cracked since i got it that's prob why I got it for 7k. I would say the only reason it lost enough power for me to notice an issue was because enough coolant got in the oil to Rase the oil pressure enough to pop the rocker off

cheech

Who said that?

getrdunn

Looks like int and exh rocker got switched at some point also but relevant and no biggy as your covers evidently clear.

BTW - you sure you don’t have a collapsed lifter or bad cam lobe? Did you identify the cracks in heads? I’m assuming you didn’t but just asking. If it’s from freezing the blocks almost guaranteed to be cracked before the heads. A little more history might open the door to other things to check and confirm.

Did you recently notice a drop in rpm or always been the same last 60 hours? I see a 200-300 more rpm at least.

Most generally (for me anyway) those cracks on the underside are difficult to see without magnafluxing.