3200 rpm max on chapparall

[pine island fred]

friend has a 91 chapparall model 2370. volvo/penta 501 (small block chevy to me ) 305. duo prop outdrive. max rpm is 3200. choke type baffel on top of 4 barrel is opening. quite a bit of rattaling at high power settings. have removed a lot of debris out of finger filter on the gas tank dip tube. am afraid of detonitation at high power setting. friend has spent 3 grand on the boat so far and it will still turn 3200 max. i know pratts, ge,s rolls and allisons but this has me baffled. any suggestions ???? thanks fred

 

[Boomyal]

Re: 3200 rpm max on chapparall

Is it running smooth at 3200? The rattling, is it detonation? Bad gas? Possibly a timing issue. Check both inital advance and total. Are there any hull obstructions or fouling. Possibilty of a prop pitch issue.

 

[pine island fred]

Re: 3200 rpm max on chapparall

thanks for your response. engine runs smooth at wot but still seems to be laboring. gas is fresh. the rattaling sounds like nut/bolts banging around in the engine. hull has just been pressure washed. believe the props are factory issued but who knows. friend has a manual on the boat but it is written in 4 different languages, none of them english. all languages do show a minimum of 4000 plus rpm at wot. have considered checking timing but cant figure out what it shound be at idle and higher rpm. any ideas ? thanks fred. rattaling only showes up at high power settings

 

[Boomyal]

Re: 3200 rpm max on chapparall

Not the expert on Chebbies but I think that somewhere around 6-8 deg BTDC for initial and 27-32 total. will get you in the ball park for checking. I hope the rattling is not in the outdrive. Also I know nothing about duo props. It seems it wouldn't take much to create discordance between the two, causing loss of efficiency.<br /><br />It's a new day and maybe someone with more exptertise will jump in.

 

[deckhand]

Re: 3200 rpm max on chapparall

Have you checked to make sure the throttle is going WOT? Has this issue just developed? Is this a repower ? Sounds like you have "traditional 290 Duoprop" props should be from B series propbably B3's. B4's and 5's work better on 350's. You need to take the props to a Volvo dealer and let him compare the number's. The props are sold as matched sets (but you can buy just one) and they need to be from the same series. If you have mis-matched props they will fight each other. A B3 front and a B4 rear will make strange noises from the drive.

 

[FreeBeeTony]

Re: 3200 rpm max on chapparall

Sounds to me like the timing is too far advanced. That could cause the "pinging" at higher RPM's.

 

[pine island fred]

Re: 3200 rpm max on chapparall

friend had to replace the water pump and am now ready to check the timing. found no vacume advance on the distributer. took off cap and only found a big plastic block where they use to put points. do these things have centrifugal advance or is it all done electronically ? yes,throttle plates are opening fully. problem came with the boat about 3 months ago. he is the 3 rd. owner. will definately try to stumble over something simple before we start to fool with the props. looks like there is a final filter in the float bowl. could it have gotten gumed up over the years ? thanks for your help. fred

 

[rodbolt]

Re: 3200 rpm max on chapparall

hello<br /> voilvo used the delco EST for a time that was all electronic and requires a shunt to set the timing. they also used the prestolite bid system that had a round module under the cap. the EST has a flat black plastic module and quick connects. ther BID does not. the BID has centrifical advance .<br /> go through your fuel system carefully before changing props around. has anyone actually seen the boat run correctly with those props. its not uncommon to have a boat overpropped from the factory as they dont water test them and usually the dealer installs them and some dont water test.<br /> good luck and keep posting. PS its an engine. suck,squeeze,bang and blow.

 

[rybad]

Re: 3200 rpm max on chapparall

I had similiar problem on '87 271 w/290dp. Spun at 3100 WOT.. had valve job done, and ran like a champ.

 

[pine island fred]

Re: 3200 rpm max on chapparall

friend bought a book covering this engine. looking at the ignition section it says that there is a speed reduction in the system and to disconnect it if it fails and does not allow higher rpm. however the book does not tell witch wire to unplug or what the unit looks like. anybody ever fooled with this system ? regards fred