4.3L mercruiser with points. Timing question.

[kbreks]

you know your motor is a one-year wonder. its a 4.3 with a 2-piece RMS

not sure what an RMS is. and sorry i should have clarified. my boat is a 1985. i couldn't tell you what year the engine is. that may be half my issue. the 3.8 that came with the boat was replaced by the original owner with the current 4.3L not sure what year that was done and not sure what block was used.

 

[Scott06]

not sure what an RMS is. and sorry i should have clarified. my boat is a 1985. i couldn't tell you what year the engine is. that may be half my issue. the 3.8 that came with the boat was replaced by the original owner with the current 4.3L not sure what year that was done and not sure what block was used.

rear main seal. I believe Scott Danforth was mentioning the fact that the first year for the 4.3 in 1985 is the only year that used a traditional 2 piece rear seal vs the more modern single rear main seal.

If you have been running that much timing for 5-6 years and were detonating I think you would see it on a bore scope in the cylinders and have flecks of pistons on the spark plug.

This is a little stumping, would suspect there is an issue with the est system you have and it is more than just total timing difference between the two systems. Did you measure the strength of spark between the two systems? were you supplying full 12 to the coil on the EST ? I cant recall if you were taking the resistor out / back in when changing between the two systems.

 

[kbreks]

rear main seal. I believe Scott Danforth was mentioning the fact that the first year for the 4.3 in 1985 is the only year that used a traditional 2 piece rear seal vs the more modern single rear main seal.

If you have been running that much timing for 5-6 years and were detonating I think you would see it on a bore scope in the cylinders and have flecks of pistons on the spark plug.

This is a little stumping, would suspect there is an issue with the est system you have and it is more than just total timing difference between the two systems. Did you measure the strength of spark between the two systems? were you supplying full 12 to the coil on the EST ? I cant recall if you were taking the resistor out / back in when changing between the two systems.

yes i supplied full 12v between the systems. i did remove the resistor wire for est and reinstall for points. my main thing with this post and not my est diag post is more on if anyone could answer why there is such a huge timing difference required for points vs HEI. i guess if i do go ahead and try to run 22 degrees on the points system and i can get the boat to plane, then that would in fact lean towards issues with the EST. i am replacing the EST module though because i know its bad and i cant get it returned without at least trying that ( still no guarantee they will take it back, even after trying a new module). im just not sure i can put the points to 22 degrees total as it may not fire with base timing being so low.

 

[Scott Danforth]

not sure what an RMS is. and sorry i should have clarified. my boat is a 1985. i couldn't tell you what year the engine is.

Post the block casting number. that will dial into a generation.

the 3.8 (229) liter was done in 1984 as the 4.3 was replacing it (and it was a bit late coming out in 1985). those boats built with the 3.8 in 1985 were built with old stock.

the 4.3 for 1986 (starting July 1, 1985) were built with a 1-piece Rear Main Seal.

 

[kbreks]

Post the block casting number. that will dial into a generation.

the 3.8 (229) liter was done in 1984 as the 4.3 was replacing it (and it was a bit late coming out in 1985). those boats built with the 3.8 in 1985 were built with old stock.

the 4.3 for 1986 (starting July 1, 1985) were built with a 1-piece Rear Main Seal.

I will see if i can get a number off it.

 

[kbreks]

Hard to make out what this says.

 

[Lou C]

You will find the block casting on the bellhousing area behind the cyl head. Here's mine I touched it up in MS paint to make it easier to read.
So mine's an 011 block, 1987-1992, one piece rear main, roller lifter cam, pre-Vortec heads, no balance shaft.

 

[kbreks]

You will find the block casting on the bellhousing area behind the cyl head. Here's mine I touched it up in MS paint to make it easier to read.
So mine's an 011 block, 1987-1992, one piece rear main, roller lifter cam, pre-Vortec heads, no balance shaft.

I will have to see what I cant find when im back at the boat.

 

[Scott06]

yes i supplied full 12v between the systems. i did remove the resistor wire for est and reinstall for points. my main thing with this post and not my est diag post is more on if anyone could answer why there is such a huge timing difference required for points vs HEI. i guess if i do go ahead and try to run 22 degrees on the points system and i can get the boat to plane, then that would in fact lean towards issues with the EST. i am replacing the EST module though because i know its bad and i cant get it returned without at least trying that ( still no guarantee they will take it back, even after trying a new module). im just not sure i can put the points to 22 degrees total as it may not fire with base timing being so low.

That is a good plan. Maybe not at 22 degrees if initial is too low but say 25-26. That should give a good indication of if the issue is due to total timing or spark strength/quality. Even if idle quality suffers once you get into the throttle it will start advancing.

On the timing difference - Mercruiser did change timing of some engines in the field like on some 3.0 they backed off initial to prevent detonation and blowing head gaskets, even supplied a sticker to put over timing spec on engine sticker. May be coupled with changes to fuel quality /lead removal in 80's

In one of the other answers you mention a lot of this is testing on the trailer? Were you having issues with the delco on the trailer?

 

[kbreks]

That is a good plan. Maybe not at 22 degrees if initial is too low but say 25-26. That should give a good indication of if the issue is due to total timing or spark strength/quality. Even if idle quality suffers once you get into the throttle it will start advancing.

On the timing difference - Mercruiser did change timing of some engines in the field like on some 3.0 they backed off initial to prevent detonation and blowing head gaskets, even supplied a sticker to put over timing spec on engine sticker. May be coupl

most of the testing is on the trailer. i had issues with the delco on the trailer and the water twice and the points once since putting it back in. i will be going to the lake this evening to grab a new delco module. i will lower the points total timing and test that before yanking it back out. i will reinstall the delco one with the new module on the lake and see what i can come up with. is there any other suggestions for what i should test before i yank the points out again? this will be the absolute last time i yank the points. if the delco fails again. it will be yanked, points put back in and delco will likely end up on a shelf somewhere.

 

[Scott06]

most of the testing is on the trailer. i had issues with the delco on the trailer and the water twice and the points once since putting it back in. i will be going to the lake this evening to grab a new delco module. i will lower the points total timing and test that before yanking it back out. i will reinstall the delco one with the new module on the lake and see what i can come up with. is there any other suggestions for what i should test before i yank the points out again? this will be the absolute last time i yank the points. if the delco fails again. it will be yanked, points put back in and delco will likely end up on a shelf somewhere.

if you had issues on the trailer with the delco yes the module or trigger sensor in there is messed up. It takes absolutely no power to rev the engine up on the wagon with no load.

Have you used a spark gap tester on both. Willing to bet the delco is not putting out any spark strength. I believe the delco is a different coil ?would ohm it to see if the maybe they gave you a bad coil. Bad coils are rare but easy to ohm out.

 

[kbreks]

if you had issues on the trailer with the delco yes the module or trigger sensor in there is messed up. It takes absolutely no power to rev the engine up on the wagon with no load.

Have you used a spark gap tester on both. Willing to bet the delco is not putting out any spark strength. I believe the delco is a different coil ?would ohm it to see if the maybe they gave you a bad coil. Bad coils are rare but easy to ohm out.

i have not used a spark gap tester no. you are correct the delco is a different coil. i will see if i can find any specs on that.

 

[Scott06]

i have not used a spark gap tester no. you are correct the delco is a different coil. i will see if i can find any specs on that.

this is out of a merc 5.0/5.7 engine manual specs are same for both the EST coil and TB coil...

Primary side - .6-.8 oms
Secondary - 9,400-11,700 ohms

Attached is a snip of how to test the pick up coil in the est . This is for a delco but Ass/u/me yours is similar

 

[kbreks]

this is out of a merc 5.0/5.7 engine manual specs are same for both the EST coil and TB coil...

Primary side - .6-.8 oms
Secondary - 9,400-11,700 ohms

Attached is a snip of how to test the pick up coil in the est . This is for a delco but Ass/u/me yours is similar

Here is what my test papers say. Which checks out. I am headed to the lake now to grab the new module and play with the timing on the points distributor.

 

[Lou C]

Well all I can say is I have had the points set up for over 20 years and even though the total advance is a lot lower than what was specified for the V8, the engine has performed well given that it's a small engine in a pretty heavy 20' boat. It easily planes out the boat, top speed is low though because I have to use a 15x17 prop to get the WOT rpm where it should be. And, given the sea conditions where I am, you can't go much faster than 30 mph most of the time anyway, so I do a slow cruise at 3500 rpm and 22 mph. Fast enough and the little engine that could, is happy there.

 

[kbreks]

0⁰ base timing with points distributor brings me to 25⁰ total. I plane as soon as i hit 3200rpm. 30mph at 3500 rpm. So time to swap in the EST with the verified good module and see what happens.

 

[cyclops222]

32 Degrees is normal and accepted TOTAL IGNITION ADVANCE at 3000 rpms. In cars.

 

[kbreks]

12⁰ base. 24⁰ total. Seems good to go with new module.. leaking water at my base riser gasket now though.

 

[kbreks]

going to leave the current setup in while i wait for my new module. i have a loaner Delco module in the EST. 12 degrees base timing puts me at 24 degrees total timing. the boat planes slower than it did which is obvious (24 degrees vs 32-36 degrees total). at about 3200-3400 rpm i start to plane. i run 28-30 mph at 3500-3800 rpm. seems like fairly reasonable numbers. So it is verified now that a bad module was in fact my issue the entire time.

 

[Scott06]

going to leave the current setup in while i wait for my new module. i have a loaner Delco module in the EST. 12 degrees base timing puts me at 24 degrees total timing. the boat planes slower than it did which is obvious (24 degrees vs 32-36 degrees total). at about 3200-3400 rpm i start to plane. i run 28-30 mph at 3500-3800 rpm. seems like fairly reasonable numbers. So it is verified now that a bad module was in fact my issue the entire time.

Sucks when new chit doesn't work out of the box.