‘89 150 v6 rebuild kit

[Zep25]

What’s the purpose behind upsizing all the high speed jets following a rebuild? If that boat wasn’t running lean before, is this necessary? Is it just more precautionary?

 

[havoc_squad]

Might I recommend you watch the following Youtube video about compression ratio. This is why you must enrichen the fuel/air ratio with bigger jets and is "recommended" to run premium gas.

I saved the link to start at the part of the video that covers these details.

https://youtu.be/5qH_ThYLD6Q?t=269

Basically, when you oversize bore a cylinder or machine down, machine a cylinder head down enough, or change to a different cylinder head that reduces the head volume area, you are increasing the compression ratio.

When compression ratios get high enough, lean condition, detonation, and gas octane become a much bigger factor/issue.

 

[Faztbullet]

You can run up to .020 on stock jets...any bigger need to up a size.

 

[Zep25]

Finally, after many hours or sweat and a few tears... I’m ready to start this thing for the first time.
Any last minute recommendations, pointers, tips?

going with double oil, new ethanol free 90 octane gas.
upped my high speed jets 2 sizes
what should I set my timing to?

Thank you as always!