Mercruiser 470 service manuals

[Tonyboyscarbz]

Hello,

Since the boatinfo links are not working, I hope to find any service manuals for the mcm470. can someone share a link? specifically, there is a service manual 08 that was mentioned in another thread, that I think may help.

Where is timing tab SUPPOSED to be - 1987 Mercruiser 3.7 ????

It's not where I think it SHOULD be on this engine and I am trying to check and reset. Thanks

forums.iboats.com

I have a 1986 470/170 and am having problems with backfiring. It only seems to backfire while under load. out of the water, with muffs, the engine sounds clean. In the water, hitting anything around 1000-1500 RPM, we immediately get backfire every few seconds

MANY things have been done since we purchased this project. here is a short list of things that were done, maybe to help shed some light on the situation. Any suggestions would be appreciated.

Here is what we have done:
- carb rebuild
- Intake and exhaust manifold gaskets
- Starter rebuild (although shouldnt have anything to do with backfire)
- fuel removed from tank and used a spare tank to provide fuel
- replaced fuel pump and fuel lines/filter leading up to the pump
- looks like the points were replaced before we purchased the boat
- changed the condenser

My biggest concern is that the timing is FAR off from the factory spec of 4 degrees BTDC- we're sitting closer to 10 degrees, in order to have the engine sound clean while running. Anything close to 5 degrees BTDC, and the engine basically turns off. I can share a video if that helps.

 

[Bt Doctur]

A few things to check
remove dist cap, bring balancer to the 0 mark , watch rotor and turn motor backwards. Note how many degrees before the rotor moves. This will determine how much slack is in the tining chain and gears.
Next verify #1 TDC . TDC and timing mark on balancer should agree.
If not harmonic balancer as rotated, remark balancer and test operation

 

[nola mike]

Also, double check firing order. Have you checked compression?

 

[Tonyboyscarbz]

will have a look at all your suggestions. We did compression, but last year, before we did a bunch of work. Its a good idea to do it again though...

 

[Scott Danforth]

Hello,

Since the boatinfo links are not working, I hope to find any service manuals for the mcm470. can someone share a link? specifically, there is a service manual 08 that was mentioned in another thread, that I think may help.

Mercury Marine Parts Accessories and Manuals

you wont find a "link" to anything other than in a scam site today. since Adobe flash went away, boatinfo went away. Boat info would buy a manual and share. however that is also copyright infringement. so the only legal place to get factory manuals is direct from brunswick in the link I provided.

 

[Tonyboyscarbz]

So we got everything timed correctly. at roughly 650RPM, we were timed at 4 degrees and everything is running MINT.

Get out on the water, we didnt start. panic happened, real bad...

I think our fuel/air mixture screw on the carb has been messing with us. it seems loose, esp mounted on an engine where vibrations are constant... In any case, we got us back running but seeing some strange things so maybe yall have some suggestions.

here are a few symptoms:
- at IDLE, we run clean
- when throttling, my RPM's seem to drop
- when I can get it to 3000 RPM, we backfire

Here is what I've checked:
- cleaned carb - it was rebuilt many months ago but opened to clean the reservoir and run with fresh gas. It still looks clean
- compression - basically 150 in all cylinders - I didnt crank it long enough on cylinder 1 but it read 138 PSI, which I figured was good; the rest were all 150 ( I actually couldnt believe it)
- Fuel was run from a clean jerry can
- fuel filter, and fuel pump filter were cleaned; fuel pump works although getting a fuel pump tester to fit the fuel lines was troublesome and therefore wasn't done.