Tat timing for 5.7 350 2bbl yr 2000-gctid384833

[Guest]

what should the TAT ( total advanced timing ) be for a year 2000 5.7L 350 2BBL

mercruser be ? i believe it should be 10 deg at idle but im not sure of the

TAT and at what rpm.

Thank you in advance

[2850Bounty]

Merc shows quite a few different curves for their V-8's. Be sure you see the correct one.

Also, look in the BOC Library for links to Merc info.

http://www.boatfix.com/merc/Techbk/95/95HGB4.PDF

[Guest]

Thank you Rick !! i dont believe i have the thunderbolt ignition though

i dont see anything non thunderbolt in the link you sent.

Attached files [img]/media/kunena/attachments/vb/688467=28070-Photo0526.jpg[/img]

[captharv]

You have thrunderbolt Vs in that boat depicted. Thats those thingies mounted on the inside of the port side exhaust manifolds. Don't even think about trying to "power time" it.

Thr T-bolt V is a very complicated microprocessor based ignition/timing system. This allows 250 HP out of a 2 BBL carb, where it was 220 HP with the t-bolt V. There is also a comperable fuel saving at all RPMs.

The procedure is:

1. Buy a manual before screwing with the engine. Improper setting can burn a hole thru the piston tops.

2. Disable the knock sensor by grounding the purple-white wire to the starboard of the carburator.

Set the timing to the spec at idle (650RPM). Remove ground, Do not screw with the timing, as the knock module compensates for all conditions, 6 times a second.

No personal attack intended, but I have seen an engine where the owner tried to outsmart the microprocesser. The timing went way high, and burned completely thru #4, #7, and #8 pistons in a 2 hour run. He had to get a new long block.

[2850Bounty]

I agree with Harv. Set BASE or Initial, and let the system do what it's suppose to do.

However, this does not prevent you from looking and checking to see where the progressive and TA are..... and I suppose that's why you asked for an advance curve!

Now.... perhaps someone changed this from the Merc TB system. For this, we'd need a few good photos of the ignition distributors.

Or.... you pull a distributor cap and see if you can rotate the rotor.

• If it rotates approximately 10*, you'll have a mechanical advance system that was changed out by someone.
• If it acts ridged and does not rotate, then you have an EST system...... (i.e., the Merc TB, or Delco, or ????)

.

[Guest]

thank you Bounty and Captharv

i just installed a new coil,dist cap,rotor and plugs last night my motor idles way better now.IM still confused about which

ignition i have though.Captharv says T-BOLT 5 . QUOTE BY Captharv..

" Thr T-bolt V is a very complicated microprocessor based ignition/timing system. This allows 250 HP out of a 2 BBL carb, where it was 220 HP with the t-bolt V " This sentace does not make sense to me, it says T-BOLT V twice

i just got off the phone with the merc dealership and they said because the module is mounted on the side of the riser its a T-BOLT 4

i really need to know which one it is because they are two different base timing set ups.

i really dont want to doubt anyone on this board but i am getting coflicting information

i have attatched a older pic of my motor where you can see the module better

port motor ser# M018153 starb motor ser# M010718

thanks again guys.

Attached files [img]/media/kunena/attachments/vb/688698=28100-dist cap new.jpg[/img] [img]/media/kunena/attachments/vb/688698=28099-dist cap old.jpg[/img] [img]/media/kunena/attachments/vb/688698=28098-motor dirty.jpg[/img]

[2850Bounty]

seadaemon wrote:


i really dont want to doubt anyone on this board but i am getting coflicting information

i have attatched a older pic of my motor where you can see the module better

port motor ser# M018153 starb motor ser# M010718

What and who is giving you conficting information?

The controller on your Port side manifold highly suggests the Merc EST...... Merc TB Ignition! (EST = electronic spark timing)

Shosrt of that, the simplest method to know for certain, is to do the following:

2850Bounty wrote:
you pull a distributor cap and see if you can rotate the rotor.

• If it rotates approximately 10*, you'll have a mechanical advance system that was changed out by someone.
• If it acts ridged and does not rotate, then you have an EST system...... (i.e., the Merc TB, or Delco, or ????)

[Guest]

Rick..I undertand,but can you tell me if it is the thunderbolt 4 or the thunderbolt 5 ?

the merc dealer says T-bolt 4 and Captharv says T-bolt 5 both have differnt ways to set the base timing

[2850Bounty]

I believe that the actual distributor may be the same, but the module should state TB IV or TB V. Yes/No????

[Guest]

RICK...IM not sure,i will have to look when i get down to the boat tonight

i will take a bunch of pics

thanks for your help so far.

[captharv]

one more time......

The mercruiser ignition systems are as such:

The t-bolt IV has one module on the inside of the port manifold.

The t-bolt V has 2 modules, piggbacked on the inside of the port manifold.

The difference is the above mentioned knock module, which is the smaller of the 2 whbich are piggybacked.

Note: This is a biggie: If your mechanic does not know the difference between a IV and a V ignition, I would not let him touch my boat. Get a merc certified mechanic.

We engineers have a saying: "If you don't know what it does, don't screw with it"

[2850Bounty]

Look at 4B-5 here for the TB V (DESA). That should help you identify which system you have. It also confirms that the distributors are the same.

However, according to this page, the TB V knock sensor module is also mounted on the distributor.

Perhaps there are several versions of this whereby the modules are mounted on the manifold.

I agree with Harv. If you are not comfortable in doing this, seek the help of someone who is certified.

.

[Guest]

Captharv and Bounty i have attatched more pics to try and figure out if my ignition system

is the T-BOLT 4 or T-BOLT 5. My dealership still says T-BOLT 4 but from what Captharv says

i believe it is a T-BOLT 5.

Thanks again guys

Attached files [img]/media/kunena/attachments/vb/689741=28203-DIST 2.jpg[/img] [img]/media/kunena/attachments/vb/689741=28204-ENGINE 1.jpg[/img] [img]/media/kunena/attachments/vb/689741=28201-T-BOLT 1.jpg[/img] [img]/media/kunena/attachments/vb/689741=28202-T-BOLT 2.jpg[/img]

[Guest]

Rick....just looking at the pages from the electrical systems you sent

i cannot find the inital base timing for the T-BOLT 5 on my 5.7 L ,only the T-BOLT 4

the last page does show a T-BOLT 5 spark control graph.Would it be safe

to assume the initail timing is 8 DEG BTDC timed by jumping out the PUP/WHT

lead to ground and using a timing light.