Timing- Conflicting Information?

[KRH1326]

I have been chasing a problem that I have in a different post, but the direction of the original post has gone awry.

I think that I have found conflicting information found in my Seloc manual. I do not have an OEM manual to reference, and Don S. has made it clear to me that Seloc and Clymer's are NOT the "Bible".

In the "Tune Up Specs" , Seloc states that my 1976 235 HP should have a timing of 10 deg BTC, and that my idle speed should be 500-600 rpm.

I assumed, yeah I know, that meant with the engine idling at 500-600 I should have a timing reading of 10 deg BTC. That's what I did.

I have a high rpm issue, where I cannot reach WOT under load. I can just about get to 2000 - 3000 and a ticking or pinging developes that spooks me. I have been chasing the idea that it is my valve train making noise. I did have backfiring through the carb.

Like I said, I have been chasing this issue in many different directions.

I have been studying further and found the "Centrifical Advance Charts" deeper in the appendix.

The chart for mine reads:
Distributer--Start 0 deg @ 550 rpms, Max 13.5 deg @ 2000 rpm.
Engine--Start 0 deg @ 1100 rpm, Max 27 deg @ 4000 rpm.

I get the whole 2:1 ratio thing, BUT-

This, to me means, that I should be reading 0 deg on the damper until I hit 1100 rpm, then the advance should begin. The chart shows 0 at 1100 up to 18 deg @ 1800 rpm, then curve changes to 27 deg @ 4000 rpm.

Which is the right of it? 10 deg @ idle or what the chart reads?
Could my performance issues be something as rediculously simple as way over advanced timing?

PLEASE SAVE MY SANITY, what little is left.....

 

[bruceb58]

Re: Timing- Conflicting Information?

What they are talking about is the offset from the starting timing. Total advance will be 27 degrees from your starting point. In your case, the final advance will be 37 degrees.

10 degrees may be to advanced as a starting point. Usually, a manual has two strating points depending on the octane of the fuel you are using.

If your distributor is not advancing timing properly, you can definitely have trouble getting up to WOT.

 

[KRH1326]

Re: Timing- Conflicting Information?

Great Answer, Sir!!!!!!

Thank you for the frustration buster!

If you have the chance, could you look at this post:

http://forums.iboats.com/showthread.php?t=318086

Any help getting to the bottom of it will save my spring striper season.

 

[bruceb58]

Re: Timing- Conflicting Information?

Do you have an advance type timing light? If not you should get one and measure your advance every 200 RPM. This will tell you if you are advancing too much or too little and what the curve looks like. Not sure what the advance curve is supposed to look like for a Ford 351... probably fairly linear.

 

[KRH1326]

Re: Timing- Conflicting Information?

Yes , I have that type and will try that.

The "curve" is three straight lines. 0 @ 1100 steep line to 18 @ 1800, shallow line to 27 @ 4000 then flat line right out of chart.

 

[bruceb58]

Re: Timing- Conflicting Information?

Well...next step is to get your timing light out and test. I had a boat that did not advance correctly. I was not getting the advance I should have been. I took the distributor to a speed shop that had experience with setting advance curves for marine engines and had them re-curve my distributor.

You have to be careful if you re-curve your distributor. If you get too aggressive with your advance you can kill your motor quick with detonation.