?s on setting timing

[1979 Quartermasters]

Hi guys.

I did a compleete tune up a few weeks ago on my 5.7 (serial # in signature) and it is running great. Having said that, I noticed a little pinging when I punch it. Im assuming this is most likely timing do to the tune-up.

I would like to check the timing, but not sure which thunderbolt I have and how to get to base timing mode ( if required).




Its also surging a bit just off idle in gear. The carb was rebult last summer and it has fresh gas. New fuel filters.

Could this also be a timing issue.

Thanks for info.....

Ken

 

[1979 Quartermasters]

Re: ?s on setting timing

Anyone?

 

[wellcraft-classic210]

Re: ?s on setting timing

Pingng is often caused by timing being a bit too far adavnced. I have seen people set timning in the past on small block chevy by advancing until the valves ping and than back it off until the ping goes away.


As far as base mode and timing values -- not sure off hand but suspect a good manual will have all that.

 

[Don S]

Re: ?s on setting timing

Im assuming this is most likely timing do to the tune-up.

Did you move the distributor when you tuned it up? Nothing else would affect the timing.
You pictures look like a Thunderbolt IV distributor, but can't really tell for sure. What is your timing set at at idle rpm?
What spark plugs did you use?

 

[1979 Quartermasters]

Re: ?s on setting timing

Spark plugs are AC Delco R43T.

I did put a new cap and rotor in, but did not turn it.

Haven't checked timing yet because I didn't know if I had to do anything to the distributor before I started the proceedure

Do I need to do that jumper wire trick or do I not have that system.

 

[Don S]

Re: ?s on setting timing

No jumper with a TB4 system. Check your advance timing as well.

 

[1979 Quartermasters]

Re: ?s on setting timing

Thanks Don

 

[achris]

Re: ?s on setting timing

 

[1979 Quartermasters]

Re: ?s on setting timing

That chart is a little over my head. Maybe somebody could explain. Does it mean that if I rev my engine to 2000rpm, my timing should advance to 10.5 degrees.

The manuall says that my sparkplug gap should be .040 and the cover on my spark arester says .035. I didn't notice this till I regapped my plus to .040. Should I put tham back to .035 or should they be at .040?



Thanks....

Ken

 

[Don S]

Re: ?s on setting timing

Put them where they belong, then you will know for sure.

Have a look at this thread http://forums.iboats.com/showthread.php?t=549387&p=3772668&viewfull=1#post3772668 it should explain how to use the advance chart.

 

[1979 Quartermasters]

Re: ?s on setting timing

Put them where they belong

Not sure where that is. I'm thinkin the .035 that is on the cover?

Thanks for the link to that thread.

Ken

 

[Don S]

Re: ?s on setting timing

What manual do you have? The OEM says .035

 

[1979 Quartermasters]

Re: ?s on setting timing

Mercruser Service Manual 17

4B-2 - THUNDERBOLT IV AND V IGNITION SYSTEM

 

[Don S]

Re: ?s on setting timing

Hmmmm. Do you have an older paper version? The .pdf version shows the changes from a service bulletin.

 

[1979 Quartermasters]

Re: ?s on setting timing

Hmmmm. Do you have an older paper version?

Nope. I have the pdf version from this site.

I edited my last post and put the page number in.

Ken

 

[Don S]

Re: ?s on setting timing

Look at page 1B-7 (Tune up specs) the blue dotted line shows where the decals to cover the pages were added.

 

[1979 Quartermasters]

Re: ?s on setting timing

Got it thanks again......

Ken

 

[1979 Quartermasters]

Re: ?s on setting timing

Well I pulled the boat out of the shop, warmed it up to opperating temp. and hit it with the light. At an idle, it was at 15or 16 where the red arrow is. This may sound stupid, but which side of that zero mark is "before". I'm thinkin its toward the red arrow as there are more markings on that side




Do I need to back that mark down to 8 mark on the same side?

Thanks......

Ken

 

[Don S]

Re: ?s on setting timing

The sticker is correct, you just need to get the timing down to 8? where it belongs and your pinging will probably be gone. Idle speed should be in the 650-700 rpm range when you set the timing.

Set the mark on the timing cover to the blue arrow.

 

[1979 Quartermasters]

Re: ?s on setting timing

I set it dowm to your blue mark and it wouldn't idle. I reset the 2 screws on the carb to 1 1/4 turns out and turn the idle adjustment screw up to 650- 700 on dash tac. Seems to be runing good on muffs. I guess I'll have to put it in the water to see if that pinging is gone or not.

Thanks for the info.....

ken