Timing doesn’t make sense

[Zev Fisher]

Hi All,

I bought a 75 245DL which has a 90s era B230 Penta engine (AQ151) in it with Petronix ignition and a Weber DGEV carb.

According to the book, the base timing for this engine should be 6° static at 850rpm and between 32 to 36° full advance at 4200rpm. This is similar to what the automotive (non-penta) b230 timing would be for a B230.

Here’s where things get weird. When I put a timing light on it and adjust the distributor it runs terribly down around 6° at idle and is much MUCH happier above 18° even closer to 23° base timing.

It’s been like this the whole time I’ve had it and I always figured the intermediate shaft was off by a tooth, but I just did the timing belt and can confirm that all 3 alignment marks were all dead on.

At that point I figured the damper had slipped, so I replaced it with a new one. Got the same weird readings when I redid the timing, so I further confirmed the balancer notch position with a piston stop tool, so I know the balancer mark is also correct.

I don’t understand why this motor would need so much static timing to run well. What am I missing?

 

[283SD]

Do you know that TDC is TDC?.

 

[bobxyz]

What is the Bosch # on the distributor? Can you find that distributor in the TP30432 greenbook? (see ozvolvo.org/archive) What book did the 6degree base timing come from?

 

[Jack]

What cam is in it ?
Checked compression ?

 

[dl242gt]

You probably need more advance because the carb has a modern smaller volume accelerator pump. So with more advance the lower volume of gas from the accel pump is enough for acceleration.

Besides all these old redblocks penta included like 10-12 degrees btdc timing. Try to get the number off the distributor if you can. I'm thinking someone used a B230A distributor which is another reason the timing is happier more advanced.