Distributor timing problems

[Steve390Gold]

EST ignition system on what should be a 2002 3.0L mercruiser. Block #0M375010. Ran fine before I pulled the distributor to check the cylinder #1 lifters. Still has spark. A bit yellow, instead of blue spark, but still a thick, strong spark.

Following the mercruiser service manual the engine does NOT fire in any capacity. Not a backfire. NOTHING. Also the mercruiser service manual leaves a LOT to be desired with concern to being specific with instructions. (It would never pass as a toyota FSM - I've done numerous successful top end rebuilds on late model OHC and DOHC toyota engines - 3vze and 5vzfe to be specific.)

The diagram employed by the mercruiser SM has cylinder #1 post of the distributer being almost perfectly in line with the rotor and the actual #1 spark plug. (See attachement) This is NOT how it was before when it was running. Before the #1 cylinder was being fired by what the MSM shows is cylinder #3 and so on around the dizzy.

Also as far as determining if the engine is in cylinder #1 firing, with spark plugs removed cylinder #1 was sealed tight as a drum and would hold pressure for a while with the timing marks lined up on the crank. (#4 was ALSO sealed up tighter than a drum too...so that method is out for determining if cylinder #1 is TDC firing....)

So on to youtube I go. Zachs Garage has his distributor arrangement set up exactly how mine was before when it was running which is NOT what the MSM shows is correct.

Then a few other youtubers show a different arrangement from Zach's as well.

At this point Im about to rip this POS engine out, throw it in the gulf where it belongs, and swap an LS 6.0 in there which at this point would be far far simpler and easier to get running.

 

[Steve390Gold]

Then there's this gem from the MSM:

"Position rotor to point toward front of engine (with distributor housing held in installed attitude), then turn rotor counterclockwise approximately 1/8-turn more to the left and push distributor down to engage camshaft. It may be necessary to rotate rotor slightly until camshaft engagement is felt."

Can you say ambiguous?

rotor POINTING at the actual front of the block or pointing parallel to the block and at the bow of the boat? It makes a big difference....

 

[Scott Danforth]

Make sure the distributor is installed correctly. If you dont know how to stab a dizzy, hire someone that knows. Its high school autos 101.

Stop looking to youtube. You either know what you are doing, or you go to the factory Mercruiser manual

At this point Im about to rip this POS engine out, throw it in the gulf where it belongs, and swap an LS 6.0 in there which at this point would be far far simpler and easier to get running.

Statements like this make me laugh.

If you cant figure out the simplest marine engine in existence, you wont handle everything required to modify the boat to install an LS marine motor

 

[achris]

First up, the Merc factory manuals are written for Mercruiser trained service personnel, not 'backyarders', and as such will not go into detailed step-by-step, explaining in child-like language what would be considered 'common knowledge for a factory trained tech'.

Secondly, you appear to not really understand distributors. It doesn't matter WHERE the rotor is pointing, as long as that post has the lead to the correct spark plug. Merc set up the distributor with number 1 post pointing to number one cylinder to make the lay of the spark plug leads more better (no lead crossing another to reduce cross-firing)...

The reason you are getting both one and four holding pressure at TDC is because there is no overlap valve at TDC on these engines. To find number one FIRING TDC you should pull the valve cover off and watch the valves as you turn the engine over. Or roll the engine to about 30 or 40 degrees before TDC and see which cylinder holds pressure (one will be on compression stroke, about to fire; the other on the exhaust stroke, with the exhaust valve open).

Chris......

 

[achris]

..Statements like this make me laugh.

You and me both!

 

[Eric 3.7LX Alpha 1]

Ideally you'd want the #1 post on the distributor and the rotor to be lined up perfectly when the timing mark on the harmonic balancer is at your desired initial timing say 4 or 6 or 8 degrees btdc. Whatever it is specified to be. Any post can be set as #1 cylinder when the distributor is dropped in.

 

[Steve390Gold]

Make sure the distributor is installed correctly. If you dont know how to stab a dizzy, hire someone that knows. Its high school autos 101.

Stop looking to youtube. You either know what you are doing, or you go to the factory Mercruiser manual



Statements like this make me laugh.

If you cant figure out the simplest marine engine in existence, you wont handle everything required to modify the boat to install an LS marine motor

Actually i already have LS swapped quite a few vehicles so get out of here with that pompous, condescending, and wildly unhelpful response.

First up, the Merc factory manuals are written for Mercruiser trained service personnel, not 'backyarders', and as such will not go into detailed step-by-step, explaining in child-like language what would be considered 'common knowledge for a factory trained tech'.

Secondly, you appear to not really understand distributors. It doesn't matter WHERE the rotor is pointing, as long as that post has the lead to the correct spark plug. Merc set up the distributor with number 1 post pointing to number one cylinder to make the lay of the spark plug leads more better (no lead crossing another to reduce cross-firing)...

The reason you are getting both one and four holding pressure at TDC is because there is no overlap valve at TDC on these engines. To find number one FIRING TDC you should pull the valve cover off and watch the valves as you turn the engine over. Or roll the engine to about 30 or 40 degrees before TDC and see which cylinder holds pressure (one will be on compression stroke, about to fire; the other on the exhaust stroke, with the exhaust valve open).

Chris......

i do understand them quite well thank you. My irritation was the very poor description of the actual procedure. I had assumed that the distributor posts were cylinder specific as they are on my toyotas. In any event about having compression on both; having minimal overlap make sense to prevent reversion and i hadn't considered that. My best guess is that I'm 180* out and the #1 cyl is on the exhaust stroke. I thought Id at least get a backfire or something out of this thing. Thank you for at least offering assistance unlike scott up there.

Ideally you'd want the #1 post on the distributor and the rotor to be lined up perfectly when the timing mark on the harmonic balancer is at your desired initial timing say 4 or 6 or 8 degrees btdc. Whatever it is specified to be. Any post can be set as #1 cylinder when the distributor is dropped in.

Thank you!! I had not considered that. On my toyota it was specific to the post. Total advance and retard of the ignition was somewhat limited to about 25* both ways vs this thing whose body freely swings almost 160* in anydirection...lol

 

[achris]

....

Thank you!! I had not considered that. On my toyota it was specific to the post. Total advance and retard of the ignition was somewhat limited to about 25* both ways vs this thing whose body freely swings almost 160* in anydirection...lol

Hence my comment of you not understanding distributors....

Chris...

 

[Scott Danforth]

you dont understand distributors so here is the process.

How to stab a dizzy the way I was taught by dad when I was 8 (also the way every high school kid was taught that took autos class)

with distributor out, plugs out. wire a remote start switch (every mechanic has at least one) put finger over #1 spark plug hole. crank engine with starter, your finger will do a small pffft on one revolution on the exhaust stroke and on the compression stroke, it will be a large PPPFFFFTTT and your finger will come off the hole - stop cranking. (you can also pull the valve cover and watch the valves for #1). if you are just before the timing marks, bump the starter to align the marks, if you are past the timing marks, bring the engine around again nearly 2 full rotations, this time bumping the starter to align the timing marks

then grab the distributor from the bench, mark the distributor body where #1 plug tower is (as Chris indicated, Mercruiser had the forward most tower as #1 for wire layout.

insert the distributor, the helix of the gears will turn the distributor about 20 degrees, pull the distributor out slightly, and index the rotor just enough that when you install the distributor, the rotor roughly lines up with the mark yuo put on the distributor body. at this point the distributor is in the engine, however the drive tang for the oil pump is not engaged

now holding the distributor, crank the engine until the distributor drops about another 1/4" into the oil pump

put the distributor clamp on the engine, leave it loose enough you can turn if need be, however fairly snug

re-install cap, rotor, and plugs

with the EST (delco voyager dizzy), add the shunt to put in base timing mode)

attach timing light, turn on ignition, and while cranking the engine, adjust the timing to spec (should be 1 or 2 ATDC). be advised, the engine will start, however because its in base timing, it will run like crap.

tighten the dizzy clamp and remove the base timing shunt.