mercruiser 5.7 vortec timing issue?

[Swill008]

My engine cover has thunderbird ***** something on it, however the label is worn off. I have the procedures from the mercruiser manuals for a thunderbird iv and v, however when I try grounding the purple/white wire nothing changes. (In accordance with the Merc Technical Manual - perhaps incorrect wire) mine is on the right side mid intake area (looking from behind) around the stern drive res.

Engine is on a test stand.

I have pulled up the mercruiser website and parts manual and looked for the part numbers to see which is installed, but so far haven't figured it out. I have looked at the ecm and ignition module for any numbers or stamping -

BTCU 16184069 and 861253-1 5.7 ALPHA

Both are mounted on the Left Riser, nothing stated on the Distributor

I believe its an Thunderbird V due to the purple - white wire.

I have tried both ways wondering if my ecm is damaged. engine runs very rough at idle, my cover says to set timing to 10 btdc, the mercruiser manual says 8 btdc. Either is a moot point since timing advance is continuing to run.

Need to set timing to check if carb needs rebuilt. Knock sensor is hooked up and will idle around 700 but checking timing because the advance is still working sets timing to 0deg. When i ground the purple/white set to 10 btdc i can tell advance is still moving it around, and eng tries to stall, 0 with advance seems best, but i need to set baseline, drop it into the boat to break it in.

1999 Sea Ray 210 SunDeck

my engine sn# 0L091309

Fresh rebuilt long block from machine shop, previous engine cold busted and Im replacing it, and restoring this boat - winter project

heads casting# 0259906
engine casting # 1024388c

.030 over and flat top pistons.

compression @ 180psi

Thanks for any help,

If you need more information please ask.

 

[achris]

Re: mercruiser 5.7 vortec timing issue?

Hello and welcome.

Your ignition system is Thunderbolt V...

Even when set in base timing mode (grounding the purple/wht wire) the basic advance is still active, just not the 'enhanced' features (in particular the 'idle speed spark control'). So, ground the purple/wht wire, set the engine idle speed to 650prm and set the timing to 10 BTDC. If the idle speed changes while adjusting the timing (quite likely), just put it back to 650 and recheck the timing. It may take a couple of adjustments to get it all right. Once you have the timing at 10BTDC and the idle at 650rpm, remove the grounding wire...

Chris.....

 

[NHGuy]

Re: mercruiser 5.7 vortec timing issue?

Welcome to the forum!

Well I believe if you have a knock sensor it's a Thunderbolt V. You turn the key off and ground the wire, now you're in base timing mode. Warm it up, then time it, in that base mode. Reset your idle mix & rpm. Recheck.
Then shut it down, remove the jumper and restart. If you want to verify; then watch the timing light and the timing will pick up with rpms. Mercruiser timing is completely dependent on RPM, there's no vacuum signal to affect timing with engine load. It will have all it's advance by 3000 or 3200.
But more importantly if you have a new flat tappet cam you have to start it and run the break period in regardless of the timing. If it was me I'd time it to 14 or 16 degrees without turning off the motor during the 2000 rpm break in. And then re time it correctly once the break in is over.
180 is high compression. That means your guy built a powerful engine. Check total timing once you have done the proper base timing. At high RPM it should not go past 32 degrees. That's your "all in" maximum total.

On edit: Chris is the wisest of all. He knows all this stuff up and down. Do it his way and you'll be set.

 

[Swill008]

Re: mercruiser 5.7 vortec timing issue?

Thank you very much!

Im going to try this now, also It an all roller engine, so am I correct in thinking it does not need a "cam break in"?

Something else I worry about, I have about 1hr run time on this engine and I have two cylinders with compression at 195 psi, I read somewhere on the great uncle google that compression should be within 10% of each other, if so its fine, just wondering why so high on two cylinders.

Ill be posting my restore pics/thread in your restoration sub-form soon.

Thanks again

 

[achris]

Re: mercruiser 5.7 vortec timing issue?

....I have two cylinders with compression at 195 psi,...

Which two?

 

[Swill008]

Re: mercruiser 5.7 vortec timing issue?

just bought a screw in style compression tester, 50 bucks from auto-zone. I know its not "calibrated" but at least I can see the difference between cylinders.

1. 190
2. 195
3. 190
4. 180
5. 180
6. 180
7. 180
8. 190


about 4-8 puffs each. not sure if I should let it do more than 4 for the test. Was thinking as long as pressure was increasing to allow it. After 5-6 puffs all were pretty much done building pressure.

Also something I planned on researching, my right side exhaust is steamy - quite steamy and the discharge water from it is noticeably hotter than my left. My left is not steamy at all. Im thinking that it has to do with the way the water is split between my manifolds. I did check them for leaks by filling them with alcohol first to make sure no cracks.

 

[achris]

Re: mercruiser 5.7 vortec timing issue?

Those numbers look good enough. I was concerned that the high pressure cylinders were at the back (7 & 8), which can indicate water getting into the cylinders.