TOPIC: Inline 6 Timing pointer adjustment

Hello All,

I understand the procedure in the manual, I guess what I am having trouble is reading the dial indicator I got, it is a one inch travel and just cant figure out of to read it. Is there another way to set the pointer? Must be having a brain cramp...

1977 1500

Thanks

delta07d1,

WELCOME ABOARD.

yours, satx

You can use the dial indicator to find TDC, rotate the flywheel back and forth at TDC and watch the indicator needle. There is quite a "dead spot" on the needle when you are at TDC, get a feel for how big that is and then move the flywheel again (clockwise) until the needle stops moving (entering the dead spot). Then set your pointer to TDC instead of trying to read the dial indicator. When you are setting the timing reduce the timing to 20 degrees to save that engine. You will not notice the difference at WOT but you will save the engine from detonation during high load situations.

Ok, got it, but what about setting the pointer at the .464 mark on the flywheel timing mark? Is that required, from what I have read it is...

Thanks!

Hope the attached pictures help. No need to worry about the .464 if you follow these instructions.
Doc Frankenmerc

Thanks Doc, (always wanted to say that.)

Anyway what is the piston stop for? Guess I need to review the Cturboaddict videos from awhile back.

I don't recall him setting the pointer at .464, I guess I am fixed on that setting... Just what to get it right.


Thanks

The piston stop is used to stop the piston from being able to reach TDC.
With it installed, and as you rotate the crankshaft both ways, the stop stops rotation at the exact same distance from TDC.
Then when you identify the middle of these two points, you'll find true TDC.
Another way to explain it would be that with the stop installed, the crankshaft and flywheel's TDC point on the timing decal will stop rotating clockwise about 3" clockwise from your timing pointer, and about 3" before the flywheel's TDC point on the timing decal when rotating the flywheel counter-clockwise.
Mark the top cowl support at these exact two positions that the TDC point on the timing decal stops up against the piston stop.
Use a straight edge top put the make exactly where it should be by aligning the center of the crankshaft with the flywheel's TDC point on the timing decal, and mark the cowl support.
Divided correctly, should be at the exact center of the adjustable timing pointer. If not spot on, adjust the timing pointer to the exact center of the two points on the cowl support.
Make sense??
doc

That and the pictures will help, I will work on this over the upcoming long weekend. Hopefully I will get it running.

Thanks!

Those instructions and pics really helped, got the timing set and after a few tries she started, I don't have the lower unit in yet so a water test wont be done until next weekend. I hooked a hose to the water tube, and it seemed to run ok, didn't mess with the carbs yet.

Thanks for all the help, and I will post back after I get it on the water.

Thanks.

Ok have it running good except at WOT only get 4600, last year was getting 5800. Only difference is the lower unit is from a 1972 1150, which may have a different gear ratio (maybe)??? Pretty sure lower unit I was running last year had a 2.1 and I think this one may have 1.78. Would that be the cause, or not? Running the same 17P prop.

Thanks,

OOOOOH!!!!!! yes it will.

Ok, so what options do I have, different prop pitch, have the gears swapped? The lower unit that was on when I bought it was a short shaft with a 5 inch extension kit, which was getting to be a pain to reinstall so I found the one from the '72 1150, thought the gear ratio was the same...

Thanks!

I think I'd try a 15P prop, sure easier than changing gears!

Delta07d1,
The 1.78:1 originally came on the 1350, which is the early edition 1150's big sister. You would be opening a real can of worms if you attempted to swap out the gears.
You might be able to swap that 1.78:1 for a 2:1 with someone running an inline-6 on a light speedboat who is looking for more speed.
doc

Doc, thanks for the info, what about replacing the short shaft with a long shaft, which I have from another 1500 lower unit or is trying to work on these lower units myself out of the question. The other lower unit had the shift shaft pulled up by p/o can that be fixed or does that require a complete teardown.

Thanks!

If the shift shaft was pulled out by the p/o, you can install one without total teardown. It is quite an undertaking, but with 'the patience of Job' and the instructions from the good doctor,...It can be done.
I have created a write-up on this procedure, and will attempt to find it and re-post it.
To replace a short shaft driveshaft with a long shaft driveshaft requires a couple things. an identical model lower unit and if the 'luck of the Irish' is with you (rather than old Murphy) the shimming will remain the same and it will work out for you.
Risky business swapping parts from one lower unit to another though & it can result in a real mess if the shimming in incorrect.
There are 12" gear bullets and 13.25" gear bullets, spiral cut gears and square cut gears, ball bearings, tapered roller bearings with their race underneath, and tapered roller bearings with their respective race above them. Crazy little details that can seriously complicate the best of intentions.
doc

Doc, I have the shift shaft back in place and can shift into F N and R. Is this the part needed to complete this, have no idea what happened to the one that was there...

BUSHING ASSY

23-77631A2

Thanks!

Yes, you will need the bushing assembly.
New costs about $20.
Take a careful look at the shift shaft where the bushing's seal will make contact. If the surface of the shift shaft there is rusted or pitted, you may need to replace the shift shaft to keep water out of the gear oil.
The shift shaft is NLA in many cases, but they show up on eBay quite often in NOS condition.
doc

Got it on order.

This lower unit is from a 74 or 75 1500 and the gear ratio is 2 to 1. That's one turn of the prop = 2 turns of the driveshaft, or is that the other way around?

Thanks again.

OK, pulled boat out of the water and noticed that in the prop exhaust hub there was a white milky "goo" and when I drop the L/U found more of the same in the exhaust area. Pulled the plugs and 6, 5 had the same white substance. The others looked ok. Could this be caused by leaking lower crank seals? I would think this would contribute to the loss of rpms... Or would the inner water jackets cause this?

Thanks

Normally bad crankshaft seals would show up as water on #6 only.

I'd bet that the exhaust baffle has perforated and is spraying into the exhaust ports.

Hopefully you have a fresh-water motor, 'cause those exhaust manifold cover bolts can be stuck purty darned bad! The Doc had some good tips on another thread about loosening-up those pesky stuck bolts. You'll definitely need some serious heat if they're tight.

Once you get the exhaust manifold cover off, you can inspect the baffle & inner water jacket cover for problems. If the inner cover is leaking, it'll be pretty obvious where, as there will be "milk" all over the place and carbon deposits will be "washed" clean.

HTH & G'luck.......edc

Removed exhaust cover and baffle plate, this is what I found:

Already answered over on Johns, but you do need to pull that last plate, Doc is the real expert on these, and Ed Mac.

There is some great info in this thread on timing the 6 cylinder motors. Is the process the same on the fours? I have a 1960 Merc 400.

Just had it apart to check / set the points and I should probably check the timing before I put the cover back on.

Is there a thread out there in the forum that shows the process on the four cylinder models?

Thanks,
Gadabout