Engine swop ? about Timing

[markhodges78]

I had an cracked head issue with My 1993 3.0 so I swopped the engine with A spare 88 3.0 that I had. I swapped over the manifold , carburetor, and distributor from the 93 engine. The 88 engine had points the 93 has Ignition Module, any way I set the timing per my 93 engine which would be 1° BTDC ( serial number 0F267594 ) but then when I checked it out of base timing the advance was 16° BTDC.
Per the manual there are 3 different base timing settings for this engine what determines what the settings are.
I did replace the distributor a few years back with a used distributor due to an issue with the pickup coil. should I be setting the timing at 1 of the other 2 settings 1° ATDC or 2° ATDC ?

 

[markhodges78]

Anyone ?

 

[Scott06]

I would match the intial (in base mode) and total timing of what it should have been on the 88 engine. Thinking match the timing curve for the head you are using. Of course when you mix and match components some trial and error may be needed…it is normal when you take it out of base mode that it will advance to 12-15 deg btdc .

you may want to search the threads as a couple months ago someone with an older 3.0 that i think was maybe points , swapped in a delco est like you are using. The est had less total advance than the original ignition so he was down on power. i think he had to play with the initial advance to get total advance at rpm in the correct spot

 

[Scott Danforth]

1990 and older 3.0 would have been points. 1991 and later one of many ignition systems

 

[markhodges78]

Anyone have a #10 service manual that could tell me what the timing should be on an 88 3.0 serial number 0C338853

 

[markhodges78]

1990 and older 3.0 would have been points. 1991 and later one of many ignition systems

Yes it had points that I converted to est

 

[Scott Danforth]

remember, the 1988 engine is the old design of cylinder head, pistons, etc. The distributor used mechanical weights and springs for the advance. timing on those motors was 4 or 6 degrees BTDC as base timing at idle

the EST is electronic advance and gets forced into base timing with the jumper. so with EST, you would set it to the 1 or 2 degrees ATDC as per EST, and you may have to adjust timing for total timing.

 

[markhodges78]

remember, the 1988 engine is the old design of cylinder head, pistons, etc. The distributor used mechanical weights and springs for the advance. timing on those motors was 4 or 6 degrees BTDC as base timing at idle

the EST is electronic advance and gets forced into base timing with the jumper. so with EST, you would set it to the 1 or 2 degrees ATDC as per EST, and you may have to adjust timing for total timing.

That's what I was trying to find out I don't have a manual for the 88 engine and not sure what the timing should be but I feel like if its 16 degrease with out advancing the when it advances its going to be to high

 

[Scott Danforth]

That's what I was trying to find out I don't have a manual for the 88 engine and not sure what the timing should be but I feel like if its 16 degrease with out advancing the when it advances its going to be to high

4 or 6 degrees with a mechanical advance.

-2 with an EST distributor

 

[Scott06]

you may want to read this thread - guy went to a delco est and had lower total advance and was down on power. Seems the older piston and head combo may need more advance than the delco est has- I think is limited to about 24 total.

Mercruiser 140 Points to Delco EST results in low RPM at WOT

I've been banging my head on the wall trying to figure out how to solve my low RPM at WOT issue that happened after I replaced the points with a Delco Est ignition. I've got a 84 crestliner with a merc 140, serial A330922, the boat got a replacement 140 to replace the blown up older 370 that...

forums.iboats.com

As scott lays out really what you need to tweak is your total at say 2800 rpm- You keep mentioning running 16 degrees at idle - when you take the EST out of base mode it will be automatically advancing it to run better so it will be in the 12-16 degrees - this is no issue.

Look at what the advance is when it is all in. Depending on the year it will be 24 to 36 degrees total (post # 10 in attached thread)

 

[markhodges78]

4 or 6 degrees with a mechanical advance.

-2 with an EST distributor

So I should set initial timing at 2° ATDC ?
That would get my base timing to 14°
Also according to the image below with points this engine (1988) should be 6° base and a total spark advance of 35° at 2000 rpm would the total spark advance still be relevant with the est

 

[markhodges78]

you may want to read this thread - guy went to a delco est and had lower total advance and was down on power. Seems the older piston and head combo may need more advance than the delco est has- I think is limited to about 24 total.

Mercruiser 140 Points to Delco EST results in low RPM at WOT

I've been banging my head on the wall trying to figure out how to solve my low RPM at WOT issue that happened after I replaced the points with a Delco Est ignition. I've got a 84 crestliner with a merc 140, serial A330922, the boat got a replacement 140 to replace the blown up older 370 that...

forums.iboats.com

As scott lays out really what you need to tweak is your total at say 2800 rpm- You keep mentioning running 16 degrees at idle - when you take the EST out of base mode it will be automatically advancing it to run better so it will be in the 12-16 degrees - this is no issue.

Look at what the advance is when it is all in. Depending on the year it will be 24 to 36 degrees total (post # 10 in attached thread)

I think were on the same page but you were faster then I.. Lol

 

[Scott06]

I think were on the same page but you were faster then I.. Lol

When ever you are mixing and matching parts, you have to work through somethings…. You want enough advance to produce power without causing detonation…would think start with a total advance around 24, see how it runs then advance it 2 or so degrees at a time. watch for detonation And wouldn’t go past the 35 total of old motor.
at some point either with head and piston changes they backed the total timing down to keep detonation and head gaskets from blowing.
the 3.0 head did have two different port sizes, hopefully you checked if your manifold ports lined up ok?
i think the different ports lead to different hp ratings, if i recall when my folks had a 91 searay 3.0 LX it was 135 hp, but the base engine was a 115 hp or so 3.0L … just a other thing to watch when mixing and matching.
on here you can see 3 different part numbers for the 3.0 cylinder head . https://www.michiganmotorz.com/products/marine-parts-accessories/cylinder-heads

Barr offers and adapter between head and manifold styles https://www.michiganmotorz.com/mercruiser-exhaust-manifold-adapter-plate-kit-high-output-3-0l-engine

not sure which of your heads and manifolds is which … or if both your 88 and 94 share the same patten

 

[markhodges78]

When ever you are mixing and matching parts, you have to work through somethings…. You want enough advance to produce power without causing detonation…would think start with a total advance around 24, see how it runs then advance it 2 or so degrees at a time. watch for detonation And wouldn’t go past the 35 total of old motor.
at some point either with head and piston changes they backed the total timing down to keep detonation and head gaskets from blowing.
the 3.0 head did have two different port sizes, hopefully you checked if your manifold ports lined up ok?
i think the different ports lead to different hp ratings, if i recall when my folks had a 91 searay 3.0 LX it was 135 hp, but the base engine was a 115 hp or so 3.0L … just a other thing to watch when mixing and matching.
on here you can see 3 different part numbers for the 3.0 cylinder head . https://www.michiganmotorz.com/products/marine-parts-accessories/cylinder-heads

Barr offers and adapter between head and manifold styles https://www.michiganmotorz.com/mercruiser-exhaust-manifold-adapter-plate-kit-high-output-3-0l-engine

not sure which of your heads and manifolds is which … or if both your 88 and 94 share the same patten

The adapter plate is to use my exhust manifold with a late model 1998 and above head... and from what I can tell with the heads listed
1 is for a 2.5. 63-89
1 is for a 3.0. 68-94 thus would be mine I believe
1 is for a 3.0lx. 90-97
And the last 1 is for a 98 and above 3.0 small port head

 

[markhodges78]

Ok so I have the boat on the water today doing a little fishing I have a few things to share..
First I left the timing set at 1°btdc as originally called for by the 1993 engine and est distributor.
I am getting no negative results in performance and actually I have gained 200 rpm and 2-3 miles per hour.
This could be due to the fact that the crack in the head I believe has been a small issue for some time.
Not enough to cause water in the oil but enough to cause it to run a little lean off of plain and idle 200 rpm higher until I blipped the throttle. Not sure if I should play
With timing and try to get a little more power are leave it.
The plain is to remove engine in the spring and re-power..

Thanks everyone for reading my post and assisting me with my

Also a picture of what I've caught so far thus morning 43 Pound blue cat

 

[Scott06]

Ok so I have the boat on the water today doing a little fishing I have a few things to share..
First I left the timing set at 1°btdc as originally called for by the 1993 engine and est distributor.
I am getting no negative results in performance and actually I have gained 200 rpm and 2-3 miles per hour.
This could be due to the fact that the crack in the head I believe has been a small issue for some time.
Not enough to cause water in the oil but enough to cause it to run a little lean off of plain and idle 200 rpm higher until I blipped the throttle. Not sure if I should play
With timing and try to get a little more power are leave it.
The plain is to remove engine in the spring and re-power..

Thanks everyone for reading my post and assisting me with my

Also a picture of what I've caught so far thus morning 43 Pound blue cat

View attachment 373653

If you are happy with it leave it alone, especially if it is coming out In a couple months

Less timing has less detonation potential.

You changed the whole engine so might have been loss of compression valve sealing etc or prob with old ignition

 

[markhodges78]

If you are happy with it leave it alone, especially if it is coming out In a couple months

Less timing has less detonation potential.

You changed the whole engine so might have been loss of compression valve sealing etc or prob with old ignition

Yes probably weak compression the hole is right behind the valve also I used the same ignition from the motor I removed

 

[markhodges78]

I used a lot of things from the engine I took out like thermostat housing, thermostat, water pump, valve cover, timing gear cover, the engine I just put in the boat came from a boat I bought back in the summer it hasn't been run in a very long time I believe 10 years are more