1971 Formula with a Mercruiser 165(straight 6). Damper timing mark off.

[CaptRon66]

Picked up an old boat for parts I need . Instead of stripping it for the parts I replaced the head with one I had . Ok...I'm a glutton for punishment. The old one had burnt valves recessed in the head. 2 cylinders real bad. It now has good compression between 155 and 165. I attempted the timing and found the marking on the damper off approx 70 degrees. I bumped the engine around and got the #1 cyl as close to tdc as I could by looking in through the plug hole with a mag light. It's close but I could be off a little one way or the other. Engine is running good at idle.
Is it possible a different damper was used ? Maybe from a small block? Should I accurately determine tdc and remark the damper ? Or has the damper slipped on it's hub and if so how is it determined? This really drove me nuts until I figured out the timing mark was off.

 

[CaptRon66]

Re: 1971 Formula with a Mercruiser 165(straight 6). Damper timing mark off.

After looking at Mercruiser 165 pictures it seems the timing tab is in a different spot. It is on the left side of the timing cover instead of the right side just above the engine mount. What the heck is going on? I feel like Vinny Barbarino "I'm so confused".

 

[mike165]

Re: 1971 Formula with a Mercruiser 165(straight 6). Damper timing mark off.

The balancer on my 165 has two marks 90 deg apart

 

[Fishermark]

Re: 1971 Formula with a Mercruiser 165(straight 6). Damper timing mark off.

I suppose it is possible for the balancer to slip. I rebuilt an old 165 a few years ago that was badly rusted up - the timing tab was gone. So I took the time to mark the top dead center before doing much else to the engine. Here a couple of pictures I took at the time. The first picture points out the groove on the balancer - the second picture extends the pencil to where the tab needs to go. Don't know if that helps or not - but it shows roughly where the timing marks and tab should go.

You can always rig up a tool (or buy one) that shows the exact top dead center and then figure out things from there.

 

[CaptRon66]

Re: 1971 Formula with a Mercruiser 165(straight 6). Damper timing mark off.

My balancer is different from the pic . The flat space between the pulley grooves is twice as wide. Today I marked tdc using the zero mark on the existing tab and the bolt tool through plug hole in cyl 1. Notched a new mark on the balancer with a dremel after rotating the crank in both directions by hand and making marks with whiteout. So I now have timing marks that line properly. It will be easy to tell if it slips now. Engine is now timed properly after which it ran great on plane for about 10 minutes and then began to miss after cruising steady at 3500 rpm(wot is 4200). Miss comes and goes. I thought it was bad gas as it seemed to get worse after steering the boat hard or hitting a wake. The plugs were pulled upon return and the porcelain on all 6 were very white(they weren't before). The only temp gauge on the boat is one of the old style with the green and red area and it is running halfway in green. Entire water pump in the outdrive was replaced prior to launch. I will be connecting another gauge and checking exhaust for temp next. Will try to check water flow coming from outdrive to make sure hose(13 7/8") is not kinked. It was replaced this year too so I doubt it. Any suggestions?

 

[Fishermark]

Re: 1971 Formula with a Mercruiser 165(straight 6). Damper timing mark off.

The plugs were pulled upon return and the porcelain on all 6 were very white(they weren't before).

Sounds like they are getting "steam cleaned." Which would indicate water getting in the cylinders. All Six would be unusual I would think however. Bad manifold and / or riser?

 

[CaptRon66]

Re: 1971 Formula with a Mercruiser 165(straight 6). Damper timing mark off.

You nailed it Fishermark. Took the manifold and riser off. Rusty in both. Found some water sloshing around in the manifold exhaust runner. The riser and manifold were let to sit with acetone and did not leak or change level. Block and head pressure tested with 12 psi for an hour and dropped about .7 psi. So it hardly moved. The big water pump hose was still on the engine and the block plug had the very slightest leak(barely detectable) and there are other hoses and clamps on the make shift tester. . The riser gasket surface has a very shallow low spot between the exhaust and 1 of the water holes. I think this is the problem but not sure how much water would get in through such small low spot. Seen cracked,exhaust head,blocks that wet the plugs before . Usually saw water on top of the pistons while peeking through the plug holes or rusty or salt crusted plugs. The " steam cleaned " plugs is the 1st time for me. Thank you for the engine saving advice. One last question if I may..how flat does the riser/manifold gasket surfaces have to be?

 

[Fishermark]

Re: 1971 Formula with a Mercruiser 165(straight 6). Damper timing mark off.

One last question if I may..how flat does the riser/manifold gasket surfaces have to be?

Perfectly flat.

I take a flat metal file and run it over both surfaces till all the imperfections are gone.

You need a good quarter inch of clean shiny metal - not black looking carbon.

Make sure you also use the Quicksilver brand black graphite gasket - NOT the green paper one. Those are truly worthless.

 

[CaptRon66]

Re: 1971 Formula with a Mercruiser 165(straight 6). Damper timing mark off.

The engine is running great for over a week now! Found a intermittent loose/corroded connection in the ignition circuit. It was causing the miss. There is a post on this forum which mentioned running a temp jumper to the positive on the ignition coil when the engine is missing. Did this and the problem went away. A heat shrink crimp had its insulation melted onto the terminal ring preventing contact on 1 side of the terminal and was loose. Also put on another manifold and riser. Water problem gone. Now it's time to get started on my other boat. Finally getting around to prepping a Chevy 250 ready for marine life.