total advance on a Merc 228 hp 85 model

[ottawamerc]

I have a Tempest with a 228 hp chev 305 engine. I'm looking for the total advance and at what rpm?<br />It has a Mallory distributor with adjustable advance wieghts. It's misfiring @ rpm's above 3200 any help or info would be appreciated.<br />Thanks Scott

 

[rbezdon]

Re: total advance on a Merc 228 hp 85 model

I have an 88 305 230Hp and the advance is 21 @ 3000rpm

 

[Bondo]

Re: total advance on a Merc 228 hp 85 model

Don't forget to Add in the Base Timing...........<br /><br />Most SBCs like to run with about 30* to 32* Total Timing......... All In at about 3000/3500rpms.......

 

[ottawamerc]

Re: total advance on a Merc 228 hp 85 model

thanks for the reply Bondo, so to get this straight 30-32 total + 8* base timing or just 30-32*?<br /><br />Thanks<br />Scott

 

[Bondo]

Re: total advance on a Merc 228 hp 85 model

Originally posted by ottawamerc:<br /> thanks for the reply Bondo, so to get this straight 30-32 total + 8* base timing?

No,............<br /><br />Base, + Advance, = Total..............

 

[ottawamerc]

Re: total advance on a Merc 228 hp 85 model

Thanks much

 

[ottawamerc]

Re: total advance on a Merc 228 hp 85 model

I borrowed a timing light that has advance on it. At 3000 rpm I get 26* does this seem right?<br /><br />thanks<br />Scott

 

[rbezdon]

Re: total advance on a Merc 228 hp 85 model

A little low but close. Also depends on the base timing set. If you were at 8BTDC, then your advance is low most likely the springs/weights in the advance are binding or rusty. You should have around 21 of advance on top of the 8 base per specs. I have seen some postings that have said the SBC can run up to 32 total. I am running 8 base and 22 advance at 3000 but I also run 93 Octane normally. My guess is the suggestion of running at 32 total for the SBC is running the 93 Octane and not 87 or 89.

 

[ottawamerc]

Re: total advance on a Merc 228 hp 85 model

Thanks Ron for the advice. After my last post I went back out and rechecked the timing. Someone also posted that the base timing should be with no advance, so I slowed the motor from 750 rpm- around 600+ - rpm till I got the timing to stop moving. It settled on 4* I reset the timing to 8* and rechecked total timing, it was now at 29*-30* at 3000rpm. Is it normal to have the advance start at 650= - rpm?<br /><br />Scott

 

[rbezdon]

Re: total advance on a Merc 228 hp 85 model

Seems a little low to me but mine just starts to kick in above my neutral idle of 750 or 800. One thing you could also do is check what RPM it takes to get the full advance. If it less then 3000 then your springs may be a bit weak or one is missing. Full advance shouldnt come before the 3K mark.

 

[ottawamerc]

Re: total advance on a Merc 228 hp 85 model

Thanks for the reply<br /><br />The full advance comes in high 2900's to 3000 rpm's I had the distributor all apart on the weekend and the advance parts seem ok. One spring was a bit longer in design and one of the spring posts was bent out. I'm not sure if this is right?<br /><br />Scott

 

[rbezdon]

Re: total advance on a Merc 228 hp 85 model

I cant say for sure but that doesnt sound right to me. All the ones I have seen seem to be identical on both weights and the posts are straight but I am a shade tree guy, not a pro. I just cant see the manufacturer making an asymetrical part like that as standard. I have an aftermarket marine distributor with a customizable curve so I can not directly compare what it looks like but the data says you are almost right on the same curve I am8 BTDC@750 and 30BTDC total @3000, seems OK to me.

 

[ottawamerc]

Re: total advance on a Merc 228 hp 85 model

Thanks vatter for the info. My distributor is a Mallory seems to be a bit of a reject unit?