Distributor rotor question

[sebas54]

Hi, I have a 1987 gm 4.3l Alpha 1. I was told to check the distributor by turning the rotor clockwise to see if it would snap back to the same position. If it didn't I was told that the weight is stuck?? Well i tried and the rotor turned a half an inch and stayed there. What does this mean???

Do I need a need a new distributor?


The engine runs and starts fine.

Thanks

 

[PINESOL]

Re: Distributor rotor question

why would it need a new distributor if the engine runs and starts fine ?

 

[sebas54]

Re: Distributor rotor question

I don't know. I am in the process of figuring out what prop I need. the prop that will get me to my recommended RMP's at WOT has a very low pitch, it would be a 15x13 and I was told that was not right. I was asked to check the throttle and the distributer rotor. The throttle opens all that way but the distributer rotor doesn't snap back???? I had a compression check done a couple of months ago and all was fine. I need to figure out why I can't spin a larger pitch prop.

 

[Bt Doctur]

Re: Distributor rotor question

you should be turning a 14 x 19 easily, a 13P sounds like the wrong gear ratio in the upper. Is this the original drive and did it ever work properly

 

[bruceb58]

Re: Distributor rotor question

to see if your weights are working properly you can check the timing at various RPMs and check to see if they match the spec in your service manual.

Unfortuantely, with weights stuck, your boat still may start fine. You just may not get enough advance at high RPMs or have pinging problems at low RPMs under load if they get stuck in the extended position.

 

[Don S]

Re: Distributor rotor question

Hi, I have a 1987 gm 4.3l Alpha 1. I was told to check the distributor by turning the rotor clockwise to see if it would snap back to the same position. If it didn't I was told that the weight is stuck??

First of all, you have a Thunderbolt IV ignition system, no weights in the distributor.

Second, who ever told you that, don't listen to them anymore about your engine.

Get a timing light and run your engine and see if the timing advances or not. This can be done in neutral and on muffs.

 

[sebas54]

Re: Distributor rotor question

This is not the original drive. The person I bought it from put it together. I don't know what the drive ratio is. It always worked this way.

So, the dist. rotor isn't supposed to snap back because there are no weights?
I will check the timing advance tomorrow.

 

[slasmith1]

Re: Distributor rotor question

post the drive ser# and maybe don can tell you if it is the correct ratio for your application.

 

[sebas54]

Re: Distributor rotor question

Where are the drives serial #'s located?

 

[Bt Doctur]

Re: Distributor rotor question

page 1A-2
http://www.boatfix.com/merc/Servmanl/6/6A1R3.PDF

 

[sebas54]

Re: Distributor rotor question

How do i check if the timing advances?
Use timing light. turn engine on raise rpms. But what is it supposed to advance to. Is it like one degree for every 1000rpms????
Thank you.

 

[Bt Doctur]

Re: Distributor rotor question

Did the boat ever operate correctly with this drive?
to accurately determine the fully advance setting you need a degree tape applied to the balancer to read out to 42 degrees, most timing tabs are 0-10.
even without the advance you should still be able to spin a 19 pitch prop to atleast 4000

 

[sebas54]

Re: Distributor rotor question

The boat always worked this way. When i bought the boat I didn't know much. The previous owner told me never to go past 3900 rpms because it would blow the engine???? I have learned that this is not true. He told me he was a mechanic and got the engine off a truck with low miles on it. He installed everything and put it together. I guess he did a good job because it has been running strong for three years except when it over heated and thats when I had to tare into it.


Can i purchase the timing tape at auto zone? I spun a 18 to 3900-4000rpms.

Thank you.

 

[sebas54]

Re: Distributor rotor question

Would the advance timing for a 4.3l gm 1987 be 22 degrees total spark advance at 2500rpms

 

[sebas54]

Re: Distributor rotor question

Ahem...I wasn't guessing I got those #'s from the service manual. The service manual is very vague. I thought that i could double check with somebody.

 

[sebas54]

Re: Distributor rotor question

Ok I finally checked the timing and the advance. All are working and set correctly. I also checked the tachometer and it is accurate. I still don't know what gear ratio I have. What else can cause my engine to run at WOT with only a 15x13 prop?

Thanks