PROP STAR

So very true Tahoe on the parts scenario waited 12 weeks on MLS head gaskets, 10 weeks on Alum Rods ,6 months for AFR 385s ,and ordered pistons in October they promised beginning of December then Xmas then New Years now yesterday said there done being coated and in my hands in 7 Days ... Only one that was good was Comp Cam 5 days custom gring and delivered to my door

F-2 Speedy

iTrader: (6)

no waiting on parts, if fits you build spec's

https://www.offshoreonly.com/classif...le-o80988.html

smokediver

I recently had a 540 carb built from my 502 mag mpi. 712 tq @ 4700 and 711 hp at 5600. It’s in my donzi 22 Classic. I am really happy with it. I am currently ditching the emi exhaust and going to stainless marine.

getrdunn

iTrader: (7)

Very nice! What cnc heads do you have. What a trip your Donzi must be. I remember back in the 80’s-90’s seeing those screaming at 70. You gotta be pushing low mid 90’s I’d think. 🤔

ThisIsLivin

Try a Jomar 1" phenolic tapered spacer, it improves signal and boosts midrange torque. Couldn't believe the difference it made for me. I also added a 1" open and it helped my top end. Both were noticeable improvements you could really feel in the boat.

articfriends

iTrader: (1)

Very nicely port matched Dart intakes he bought with the heads. I probably pulled #1 of these two motors 80 times on dyno trying different carbs, carb spacers, air bleeds, stagger jetting etc trying to get those hot cylinders cooled down without flooding the cold cylinders. They had Crane 651 cams. a very lazy cam for a NA motor with its short lift vs high duration. We were making about 640 corrected hp and 630 ft lbs of tq using highly modified 4150s my dyno partner norm did ( was hot/humid out, our raw numbers were like 580-590 hp/570-580 ft lbs of torque). The AFRS were worst Ive ever seen though. No carb spacer or staggering of jets could fix it, motor just was lazy and had horrible intake signal/velocity, cylinders in mid 10s and others in mid 15's in certain spots, mid 14's in alot of spots So essentially we had some coal black plugs on verge of fouled and ash white plugs.
We also had Daytona boxes, I found the happiest timing curve vs power right away and it had very little effect on the afrs. Ultimately we took off the modded carbs and put ones on that flowed less, gave up 20 MORE hp and foot lbs of tq and afrs were "only" 3.5 points apart instead of 5. I threw fuel at it until the burn down cylinders were in mid 13's and lost even more power, but a boats got to be able to run at wot and not melt a piston on every outing! Smitty

articfriends

iTrader: (1)

We did, made zero difference, we tryed every possible spacer, etc to fix the distribution issues. Thes "best" spacers I tried out of all of them on this deal were some un modded chinese speedmasters and it didnt fix the afr problems by any means, would maybe get us to 4.5, 4.2 points apart vs 5 in widest spread area

getrdunn

iTrader: (7)

At least they weren’t your builds. Damm the guy still had near or the same amount of money as builds making a lot more lower with better afr’s to boot. Nice to learn off someone’s mishap also.

articfriends

iTrader: (1)

I can only imagine the money he had wrapped up in these, DART big ms, good rotatings, ati super dampners, daytona boxes, BUT too low of compression, too much cam, too big of heads, Im not real fond of Dart intakes either, Smitty

smokediver

I am still getting her dialed in. Just have 20 hours on the new set up. The builder spec’d dart 335 heads with a custom ground cam. The 50 to 70 acceleration is awesome. I really didn’t want or need low end torque with that hull. I don’t think there is any one best generic build. The needs of the hull is probably most important.