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The good the bad and the ugly
Posted: Tue Jan 23, 2024 7:03 pm
by DavidBarkey
Recent post got me to thinking .
What do thing was the best engine " of it's time "
NO wrong answers here this is just based on peoples experiences.
Me personally think the Onan P220 - proven block design, reliable ignition system , ample power without being too fuel hungry. with routine maintenance will go many thousand hours of use . (going off personal experience )
Re: The good the bad and the ugly
Posted: Tue Jan 23, 2024 9:52 pm
by Timj
DavidBarkey wrote: ↑Tue Jan 23, 2024 7:03 pm
Recent post got me to thinking .
What do thing was the best engine " of it's time "
NO wrong answers here this is just based on peoples experiences.
Me personally think the Onan P220 - proven block design, reliable ignition system , ample power without being too fuel hungry. with routine maintenance will go many thousand hours of use . (going off personal experience )
I think the P series is that way, my P216 and P218 just run and run well. P218 is heading towards 1500 hours, doesn't use oil, doesn't smoke.

Re: The good the bad and the ugly
Posted: Tue Jan 23, 2024 10:12 pm
by Jancoe
B block with p heads. B blocks had better valves and seats. Build from there with 20hp cam. Use p ignition. If I were to build one that is.
Sent from my SM-S906U using Tapatalk
Re: The good the bad and the ugly
Posted: Wed Jan 24, 2024 6:26 am
by DavidBarkey
Jancoe wrote: ↑Tue Jan 23, 2024 10:12 pm
B block with p heads. B blocks had better valves and seats. Build from there with 20hp cam. Use p ignition. If I were to build one that is.
Sent from my SM-S906U using Tapatalk
Curious , what is different in the valve and seats that make the B blocks better ?
Re: The good the bad and the ugly
Posted: Wed Jan 24, 2024 8:38 am
by Jancoe
B block has thicker valve stems
B valve stems are 11/32. ( .343 )
P valve stems are close to 9/32 ( .280 )
I don't hear of b blocks loosing a valve seat. Just p blocks. They changed to thinner valve stems and the valves couldn't carry the heat enough?
Sent from my SM-S906U using Tapatalk
Re: The good the bad and the ugly
Posted: Wed Jan 24, 2024 1:17 pm
by DavidBarkey
Jancoe wrote: ↑Wed Jan 24, 2024 8:38 am
B block has thicker valve stems
B valve stems are 11/32. ( .343 )
P valve stems are close to 9/32 ( .280 )
I don't hear of b blocks loosing a valve seat. Just p blocks. They changed to thinner valve stems and the valves couldn't carry the heat enough?
Sent from my SM-S906U using Tapatalk
Thanks , good to know. I like working with Onans . Always learning something new .
Re: The good the bad and the ugly
Posted: Wed Jul 24, 2024 4:33 pm
by Gregnew
DavidBarkey wrote: ↑Tue Jan 23, 2024 7:03 pm
Recent post got me to thinking .
What do thing was the best engine " of it's time "
NO wrong answers here this is just based on peoples experiences.
Me personally think the Onan P220 - proven block design, reliable ignition system , ample power without being too fuel hungry. with routine maintenance will go many thousand hours of use . (going off personal experience )
I deeply agree
Re: The good the bad and the ugly
Posted: Thu Jul 25, 2024 7:00 am
by MattA
Jancoe wrote: ↑Wed Jan 24, 2024 8:38 am
B block has thicker valve stems
B valve stems are 11/32. ( .343 )
P valve stems are close to 9/32 ( .280 )
I don't hear of b blocks loosing a valve seat. Just p blocks. They changed to thinner valve stems and the valves couldn't carry the heat enough?
Sent from my SM-S906U using Tapatalk
The thinner valve stems likely improve airflow by making more power. With more air flow you can add more fuel making more power and more heat. My "I don't own an Onan" understanding is the head overheats which causes the valve seat to come loose. Does the oil filter side exhaust valve usually come loose?
Re: The good the bad and the ugly
Posted: Thu Jul 25, 2024 8:33 am
by Spike188
Welcome to the CCIGT @Gregnew
Re: The good the bad and the ugly
Posted: Thu Jul 25, 2024 10:51 am
by Harry
Welcome Greg, please post in the intro area and lets us know about yourself. We would love to hear about your interests.

Harry