SOHC.co.uk Forums > CB350/400

CB400f -does anyone have an oil pressure gauge fitted, what readings do you get?

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K2-K6:
" I wonder why Honda, in this instance, chose not to have the oil pressure switch situated at the top end"

The cylinder head is effectively "open bath" lubrication with the pressure just delivering the oil rather than being a constant pressurized film as the crankshaft bearings are. After the restriction going from gallery to the head there's not that much pressure to monitor,  if failure occured (blocked preventing oil getting out) the pressure would rise not fall,  but then if too high pressure was present the relief valve would open on the pump.  So you'd not see the error from monitoring system easily.

It does look odd though as essentially there are two different delivery systems combined and split as noted, base mains etc and head system all occupying the same engine  :)

TrickyMicky:

--- Quote from: K2-K6 on October 04, 2021, 10:00:06 AM ---" I wonder why Honda, in this instance, chose not to have the oil pressure switch situated at the top end"

The cylinder head is effectively "open bath" lubrication with the pressure just delivering the oil rather than being a constant pressurized film as the crankshaft bearings are. After the restriction going from gallery to the head there's not that much pressure to monitor,  if failure occured (blocked preventing oil getting out) the pressure would rise not fall,  but then if too high pressure was present the relief valve would open on the pump.  So you'd not see the error from monitoring system easily.

It does look odd though as essentially there are two different delivery systems combined and split as noted, base mains etc and head system all occupying the same engine  :)

--- End quote ---
  A few million years ago I worked for a motor parts wholesaler, and we did a steady trade in selling camshaft kits for the Ford OHC Pinto engine. I think I'm right in saying that they also used the "spray bar" system to lubricate the top end, but, I never did find out if the problem was down to poor lubrication or other factors.  I seem to have a vague memory that the cam lobes wore prematurely.

Nurse Julie:

--- Quote from: TrickyMicky on October 04, 2021, 03:39:29 PM ---
--- Quote from: K2-K6 on October 04, 2021, 10:00:06 AM ---" I wonder why Honda, in this instance, chose not to have the oil pressure switch situated at the top end"

The cylinder head is effectively "open bath" lubrication with the pressure just delivering the oil rather than being a constant pressurized film as the crankshaft bearings are. After the restriction going from gallery to the head there's not that much pressure to monitor,  if failure occured (blocked preventing oil getting out) the pressure would rise not fall,  but then if too high pressure was present the relief valve would open on the pump.  So you'd not see the error from monitoring system easily.

It does look odd though as essentially there are two different delivery systems combined and split as noted, base mains etc and head system all occupying the same engine  :)

--- End quote ---
  A few million years ago I worked for a motor parts wholesaler, and we did a steady trade in selling camshaft kits for the Ford OHC Pinto engine. I think I'm right in saying that they also used the "spray bar" system to lubricate the top end, but, I never did find out if the problem was down to poor lubrication or other factors.  I seem to have a vague memory that the cam lobes wore prematurely.

--- End quote ---
On our SOHC/4 models, 99.9% of cam damage will be through oil starvation caused by a minute piece of debris in the restrictor jets in the oil passages which supply the top end.

allankelly1:

--- Quote from: TrickyMicky on October 04, 2021, 03:39:29 PM ---
--- Quote from: K2-K6 on October 04, 2021, 10:00:06 AM ---" I wonder why Honda, in this instance, chose not to have the oil pressure switch situated at the top end"

The cylinder head is effectively "open bath" lubrication with the pressure just delivering the oil rather than being a constant pressurized film as the crankshaft bearings are. After the restriction going from gallery to the head there's not that much pressure to monitor,  if failure occured (blocked preventing oil getting out) the pressure would rise not fall,  but then if too high pressure was present the relief valve would open on the pump.  So you'd not see the error from monitoring system easily.

It does look odd though as essentially there are two different delivery systems combined and split as noted, base mains etc and head system all occupying the same engine  :)

--- End quote ---
  A few million years ago I worked for a motor parts wholesaler, and we did a steady trade in selling camshaft kits for the Ford OHC Pinto engine. I think I'm right in saying that they also used the "spray bar" system to lubricate the top end, but, I never did find out if the problem was down to poor lubrication or other factors.  I seem to have a vague memory that the cam lobes wore prematurely.

--- End quote ---
I remember this system well

Normal ford carp  design

I think the cause was infrequent oil changes that then caused the spray bar to get partially blocked combined with an cylinder head /OHC design that had the cam shaft spinning in “fresh air” rather than the cam lobes constantly dipping into some form of trough that held a quantity of oil so that the cam was well lubricated even without a spray bar system

Any lack of oil feed to the spray bar cam on a pinto, and the cam was then toast

If you look at the 400f engine as well as a spray bar there is a trough system too to keep the cams well lubed during any temporary oil starvation


Sent from my iPhone using Tapatalk

400 Cafe Racer:

--- Quote from: Oddjob on October 04, 2021, 02:56:40 PM ---I had an amp meter and a oil pressure gauge mounted in a pod above the speedo/tacho so they were easy to see. The oil pressure take off was mounted where the current pressure switch was on a T piece so they both worked, it meant cutting out part of the chaincase guard but it did work.

--- End quote ---

Hi Oddjob,

Can you remember what variations there were on your readings with a hot engine, or when idling etc. Interested to  find our more.

Thanks

Dennis

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