470 overhaul info needed

[Lamont270]

Hello all,

Been a while since I last posted hope yall don't hold that against me. I have some questions about fixing the common 470 failures. I finally took the motor out of my 82 V20 and it is on the stand ready for work. I did a compression test and the spread was 127-131 across the cylinders. I have leaky cam seals which I've read about the speedy sleeves and a local guy said they dont last long and I need to have the cam welded and ground down. Also I am doing the alt conversion and I was going to remove the magnets so they don't come loose at a bad time and he said if I do that it will throw my balancer out of balance and my boat won't idle right because of it being lighter without the magnets in there. I have to change the oil pan because it has pin holes in it so should I change the oil pump and bearings while I am in there? The alternator I have is a 32 amp delco-remmy is this big enough or should I go bigger? If there is anything else I should do to the motor while it is out please let me know beause I don't want to have to pull it out again for a long while. I have included pic's of the boat how it was when I bought it and how it looks now, I know you guys love pics.... Thanks all...

 

[spareparts]

speedy sleave will work, just put some JB weld on teh shaft before you install it, teh JB weld fills in the groves that teh seal cut and supports teh speedy sleave so it won't colapse in teh groves of the shaft. make sure you wipe up the excess. your compresion isn't that bad, pull teh head, see if you have any scoring or if there is a ring groove, if there isn't any. Do a head job adn stick it back together. These 3.7's can get real expensive. I wouldn't do anything to the bottom end unless it needed. BTW, hte oil pump requires a line up shaft to install. Make sure you use Merc gaskets when you put it back together, especially the head gasket and the riser gasket. I wouldn't worry about the magnets, I've knocked tehm out numerous times. Teh balance is balanced with them in there, if you knock them all out, they are still balanced, That motor idles rough anyway, knocking them out isn't going to make any differnce. Its better than haveing them slide around and get completely off balance liek they are prone to do. BTW, I have a brand new 3.7 balancer for sale if any one needs it. That altenator sounds a bit on the small side. Whats wrong with teh charging system now anyway.

 

[Lamont270]

Thank you for the info spareparts. My current charging system is charging around 19 volts and it keeps poping my 50 amp breaker so I'm assuming the voltage regulator is bad. I priced regulators and I can do the alt conversion for the same price. From what others have said it is not worth fixing the charging system as they are prone to failure.

 

[cfelton]

Lamont, I agree with Spare. The cam seal surface can be fixed in different ways. It can be sprayed and resurfaced or fixed with a speedy sleeve. Also price a new one it might not be too bad. When I rebuilt my 170 it had a ring of old burnt rubber on the sealing surface. I removed it with WD-40 and a razor blade, sliding it flat on the surface. The sealing surface was like new. Also when replacing the seals pack grease in between them when installed. My charging system had been upgraded with a 60 amp Marine alternator, works great. I didnt replace my oil pump, wish I had. The older 170s had an aluminum pump housing and would swell and reduce oil pressure when hot. The newer upgraded model has a cast steel housing but you also have to buy a redesigned pickup tube if you upgrade. I would definately have a head job done and replace valve seals and check spring pressures. Also use NEW head bolts and retorque after about 10 hours run time. If it were me I'd check cylinder wear and if none I'd hone the cylinders and rering the pistons and check the crank journals and replace the main and rod bearings. You can order a complete gasket set from Mercruiser. I also run 40wt. motor oil and 1/2 qt. Lucus oil stabilizer in mine, it runs cool and keeps the oil pressure up. If you have any questions ask away. Ive got tons of info and part resourses on these motors! These are Great motors if well taken care of, I love my 170!
Carroll