glassdave

iTrader: (1)

well . . got my new boat a few weeks ago an i was thinkin about do'n a few performance mods this winter. its a 26 foot chris craft stinger with a pair of 260 small blocks. anyway they have only 400 hrs on them and are very solid and in stock trim. i would like to get them up to about 300 to 325 HP. was thinkin about cams/intake/carbs. any thoughts on combos. i would like to do this without getting into the bottom end. (is that OK stock) thanks all

pullmytrigger

small blocks! small blocks! . Im pretty sure you can get 300 with a camshaft change alone. check Dennis Moore's book, you could probably get another20 or 25 with some port work

pullmytrigger

And you could certainly keep the Q Jets at that power level. Dennis Moore's Book........

Havasu Hangin

Hey Dave- 400 hours? how are the rings? Did you do a leakdown/compression test?

As for the bottom end, IMHO, the stock forged stuff will be OK up to 325HP. I think you could get there with cams/intake/carbs, but a set of heads w/2.02 valves would make it alot easier. What kind of exhaust do you have?

TomZ

iTrader: (2)

Stock forged stuff?? Last time I looked at a stock 260 it had cast pistons and a cast crank. A 260 is nothing more an assembly line truck engine; same as found in your 1/2-3/4 ton Chevy/GM pickup.

With that said... cam and intake will get you there. Again, check out Dennis Moore's book. A lot of good information!

glassdave

iTrader: (1)

holy crap . . i keep forgetin i have that book i'm just so used to askin the board. actually Havasu you told me to get it about two years ago when i got my daycruiser ( its the yellow 23 mirage i posted on hotboat askin "help me identify" similar boat to yours) hated to see that go but i got a smokin deal an this one. rigth now the boat has stock exhaust to the prop but i picked up a set of 4 inch risers and trhu hull tips. i was thinking about an edelbrock performer intake and cam set. maybe the air gap intake .

jafo

TomZ is correct- you have 2-bolt mains, cast crank, and cast pistons in a 260. Not to worry, these are up to the task for what you are asking. As far as 400 hours on a SBC? That may have worn out most BBC's, but is nothing to a small block. Do a compression/leak-down check. The only concern may be the valve keepers and retainers. I have seen them fail on stock 260's that have spent their time in a performance environment. That = dropped valves! Been there, done that.

I think a cam and intake manifold change will help, but you probably should do something about your heads. Vortec or World Products won't break the bank, and give great performance increases. CompCams make great marine cams (TomZ has experience with them)- I used a dual- pattern Isky, and am happy. A full roller set-up is not necessary for what you want, and is very expensive, especially when doing 2 engines!

I used Edelbrock's Performer RPM Q-Jet intakes- you can use your existing carbs that way, which are Dennis' choice anyway. Tune it per his book. Same with the Thunderbolt IV.
Obviously, any increases made to incoming air flow can only be utilized with a corresponding ability to get rid of it. That = aftermarket exhaust. Changing just the manifolds on a SBC will yield little or no results (but weight loss), but new manifolds or headers will give you benefit with head, ,cam, and intake mods. I used EMI Thunders, and am happy with them as well.

Have fun!

Airpacker

Hey Dave,can you say bye bye Alpha drives

Havasu Hangin

Sorry...I meant cast...maybe my brain is cast, too.

florida gator

I have same motor in my 21' Donzi. Mine needs head work. I know a guy that works in a machine shop doing there marine applications. I asked about better perf. since he will be pulling the heads anyway. He sugg. he could add approx 30 hp just doing valve job.