endeavour32

iTrader: (4)

When I was talking to bob about the 439 vs the 468 he said that "long stroke equals more torque" is a myth and that its all about total cubes and not stroke length. Trust me I asked! I built the 427 because I already had the crank and quite a few people talked to said I would get a wider powerband with it. Plus my interest was having power up high and not down low. I could have easily built a bigger engine with lower quality parts and hit my goal... Instead I picked top quality parts in a small, high reving bbc. For the record, the help that I have got from Bob on this project has been second to none, and I would choose Marine Kenetics in a heart beat if/when I decide to change things. I just want that to be clear.

As far as the drive goes. Mr. Gadgets has told me that my drive is happy up to 6500 as long as the tolerences are in check!

HaxbySpeed

Anyone who works on drives will tell you the same thing. They are much happier spinning a small prop at 6000rpm then turning a big prop at 5000. Torque kills drives..
Get all your rigging issues figured out, prop that thing to spin to 6k and go have fun.

endeavour32

iTrader: (4)

Ok- I'm getting closer!!! Maybe I'll love this engine yet! I drilled 4- 1/8" holes in my thermostat (I'm running a crossover) Heating problem solved! I called patrick at prosystem and we are jetting the carb up 4 sizes and droping the air bleeds to solve the lean issue. Today with the mirage plus 23 I hit 59 mph at 4800 rpms without cracking the 4 barrels. I don't want to push it until the new jets are in. Once again, will report back!

As far as the valvetrain goes, I'm using morel lifters, the new scorpion marine endurance rockers, custom push rods, inconnel exhaust valves... I'm confident my valvetrain is perfect!

I sure hope this topic helps someone else avoid the headaches I've had fine tuning this.

jmrapp

What did you use to remove the bottom paint? I need to start to work on mine.

endeavour32

iTrader: (4)

I tried everything! Petit, back to nature marine stripper, kleen strip for fiberglass, west marine stripper... The best was something I just tried for the he!! of it... Behr Priemium deck stripper from home depot! $20.00 a gallon and worked better than all the $70.00 gallon marine strippers and it had no negitive effects on the gelcoat. I applied it with a pump up sprayer and removed it with a power washer and a roto tip nozzle. If you go this route you must have the roto tip nozzle!

jmrapp

Ok Sounds easy. Mine should go pretty quick there is only one coat to deal with.

Griff

You are definately lucky. In many cases that would equal a hole in a piston or burned valve.

jmrapp

Any updates??

endeavour32

iTrader: (4)

Ok I finally got the boat back in the water now that the ice is gone, so here is an update to my thread. Over the winter I made a few changes. 1. I removed the Stainless Marine Exhaust and installed Eickert headers. That said I picked up 200 rpms and much better throttle reponse. 2. rebuilt the raw water pump, the case was shot as was the impeller, solved the over heating issue. 3. Swapped out the old Mirage 21 non-plus, for a Mirage 21 Plus. Top speed is now 69 mph. So basically other than getting a lot of bugs worked out, the results of getting the bottom paint free and getting the correct prop on the boat I picked up a solid 12 mph, my prop slip went from 26% to 13%. Thanks for all your help guys. Now its time to get ahold of BBlades and let Bret do his magic.