Volvo 3.0 distributor hold down bolt to set base timing

[Donnyd21]

I’m trying to set base timing (05 185lx, 3.0 Volvo penta), I have the jumper plug and it’s currently at “0” for base with jumper installed and +12v, this is not correct (I can tell someone has adjusted it before as there is paint missing on the bolt and white paint on the timing markings). Looking at the bolt and it take some kind of security torx or allen, anyone know what the proper tool is? Second question, the Volvo workshop manual states -2 deg for base timing on all 3.0 models but the label on top of my engine states 2 deg ATDC, so which is it? I know the question of why I am even checking this is coming so I’ll say it, I’m extremely mechanically inclined and I like to go over everything I acquire with a fine tooth comb, I just happened to check base timing per the Volvo manual and found it’s off.

 

[GA_Boater]

Welcome aboard, Donny.

Moved your Volvo-Penta post into the V-P section. The brand of boat doesn't mean much when you have motor questions.

 

[Donnyd21]

Thanks for moving it

 

[Donnyd21]

Ok, after lots of digging I have acquired a 7/32 hex anti-tamper on eBay for $7, the OEM tool is $80. Can anyone answer my second question regarding base timing, is it -2 BTDC per the manual or 2 ATDC per the label on top of the engine?

 

[bruceb58]

-2 degrees BTDC is the exact same thing as 2 degrees ATDC.

Saying -2 is kinda weird. Not sure why they did that.

negative before=positive after

 

[Donnyd21]

Weird, I was under the impression that ATDC is Affer top dead center. Thanks

 

[Scott Danforth]

Weird, I was under the impression that ATDC is Affer top dead center. Thanks

it is. most timing is BTDC or before top dead center. so -2 degrees is 2 ATDC,

 

[Donnyd21]

So with my timing at “0” with the jumper in I would be advanced 2 degrees from where it should be? Just going to leave it set, it’s been that way for a long time and runs great.

 

[bruceb58]

So with my timing at “0” with the jumper in I would be advanced 2 degrees from where it should be? Just going to leave it set, it’s been that way for a long time and runs great.

Actually, 2 degrees retarded not advanced.

 

[Donnyd21]

Actually, 2 degrees retarded not advanced.

The stock spec is -2 deg (or ATDC), with it at "0" it would be 2 degrees advanced from stock spec. That's what I meant. Setting it to 2 deg BTDC would be a total of 4 degrees advanced from stock spec.

 

[bruceb58]

The stock spec is -2 deg (or ATDC), with it at "0" it would be 2 degrees advanced from stock spec. That's what I meant. Setting it to 2 deg BTDC would be a total of 4 degrees advanced from stock spec.

Correct