470 low speed question

Lamont270 · #1 08-07-2010, 04:01 PM

Hi guys,

I have an 82 V20 with the 470 in it and I tried to troll with it the other day and the plugs kept loading up. I have no problems with running at low speed or docking normally, but after about 2 hours of running at 2 to 3 mph it would start to stall so I would rev it up in neutral and the water behind the boat would be black and then I could troll some more. The motor always shakes and does not seem to like running that slow but it never stalls when running in a no wake zone or docking. I was wondering if this is normal for this motor or if my carb needs adjusting. I also was wondering if an electronic ignition would help, I still have points. Has anyone else trolled with their 470? I usually run my kicker motor when trolling but it had water in the tank and would not run. Thanks...

spareparts · #2 08-07-2010, 09:04 PM

I would definalty advise changing out to electronic ignition, try Pertronix, they make an easy kit. as far as the smoke goes, check the choke, make sure its not staying on. Check for voltage on teh choke coil adn make sure the coil is grounded. Remove the flame arrestor and check the choke flap position. Most people set them up tight to make sure they crank easy, I prefer to set them on the loose side to make sure they don't load up the engine. You adjust the choke by loosening the three screws on the choke coil cover, and rotating it. If the choke looks ok, you need to check the carb out, with the engine running at low rpm, look down teh carb throat and see if you are getting a lot of gas dribbling into the engine. You may need the arb rebuilt

Lamont270 · #3 08-08-2010, 09:51 AM

I checked the choke that day and the flap was wide open and I looked for excess gas and it seemed ok. Also the flame arrestor is clean. Is there a low speed jet that could be out of whack? It is the Mercruiser carb. What brand of plug is recommended, I have Autolite plugs in it now and was thinking about switching to NGK. I will look into the Petronix kit I was going to put one in this winter when I had the engine out but ran out of spare cash after the other repairs.

spareparts · #4 08-08-2010, 07:53 PM

NGKUR5 , it has one single adjustment screw under the float bowl

Lamont270 · #5 08-10-2010, 09:27 AM

Thanks all, I'll grab some NGK's and I will be out on the St.Lawerance river later this week and will mess with the carb a little. If that does not work I'll grab a carb kit and rebuild it..

breastman569 · #6 08-11-2010, 11:55 AM

how is you fuel pump? i was having the same problem but at idle under load it would die, we did change out the points and that didnt seem to help we thought that due to the points that after running at high speeds it would be stuck to advance, that seem to help a little but still die at low speeds. so next we changed out the plug wires, cap rotor and fuel pump and it runs so smooth, the best its run in 30 years. i know your thinking if it had a bad fuel pump would it effect it at high speeds? all i know is when i took the old pump apart all the diaphragms reall hard as a rock.

cfelton · #7 08-29-2010, 11:07 AM

Follow Spares advise and get a Pertronics electronic ignition to replace the points/ condenser. I also installed the matching Flamethrower coil from Pertronics and it made a HUGE difference in starting, idling, pickup and WOT! Its probably the best upgrade I've done to my 170. Also, it never hurts to get a rebuild kit and go through your carburator. They're really easy to rebuild. One thing I had trouble with was a small spring in the bowl needle, had to go back in and replace it with a solid pin in the needle to get it to stop loading up when at idle. Hope that helps!