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Bedford K Model Cylinder Compression 05 Mar 2020 14:22 #207172

  • Pierre
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Thanks for the responses guys.

1) No this engine hasn't been rebuilt that I'm aware of. It has the upgraded "Extra Duty"
engine & when it last ran it was quieter than my current Falcon at the time.
2) My other chassis was a 1950 K Model which after stripping the required parts has been sold.
My K is a very late 1953 the last before the J model.
3) This is a 6 cylinder no other pots
4) no don't have a leak down gauge only a compression test gauge. Not sure what that is?
5) I didn't check the tappets for stuck valves & I didn't check the throttle was wide open.

I've just checked & both the throttle & choke were in the closed position when I ran the tests!
Does this have a major impact on readings?

OK. so I'll take another set of readings & see what we get & check for stuck valves.
Stuck valve seats - Do you mean the Valve Spring Seats cobbadog?

Any other suggestions?

cheers
Pierre
Pierre

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Bedford K Model Cylinder Compression 05 Mar 2020 15:51 #207174

  • jon_d
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I've just checked & both the throttle & choke were in the closed position when I ran the tests!
Does this have a major impact on readings?


Yes it can.

A closed buttery fly can limit the air getting into the engine and hence give a low compression reading. (no air to compress)

Tight tappets can hold the valves open and the compressed air leaks out,

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Bedford K Model Cylinder Compression 05 Mar 2020 16:29 #207175

  • JOHN.K.
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I assume you have the 214 motor ,which was basically a Chev with improved full pressure oiling.Its easy to see if it has sticky valves ,the pushrods will come loose in their sockets .....Id be inclined to run the motor for a minute or two ,at least untill oil pressure is up,then check the compression ....the valve seats may have dirt or rust on them ,which disappears with a short run.

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Bedford K Model Cylinder Compression 05 Mar 2020 16:35 #207176

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3) This is a 6 cylinder no other pots


My Mistake mate, i thought it was/is a 4 Cylinder..

What were the Figures for the other 4 cylinders??
"Be who you are and say what you feel...
Because those that matter...
don't mind...
And those that mind....
don't matter." -

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Bedford K Model Cylinder Compression 05 Mar 2020 17:14 #207178

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Not sure if this helps....

My Bedford engine manual, TS1084 show the compression ration for the 214 CI as 7.0:1 and Compression Pressure at Cranking speed - Hot as 110lb/ft minimum with a maximum variation of 20 lb/sq in.

Note: 110lb/ft is quoted. Other specs indicate is should be 110lb/ sq in

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Bedford K Model Cylinder Compression 05 Mar 2020 17:39 #207181

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Hayseed, the figures I gave initially were a range across the 6 pots. Highest to Lowest readings for Dry & Wet.

Q:- When I have the choke & throttle flaps wide open should the oil bath air cleaner be removed as well?

r
Pierre
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Bedford K Model Cylinder Compression 05 Mar 2020 22:49 #207187

  • PDU
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jon_d on the early motors (even the later "Extra Duty" ones) the compression was a mind numbing 6.6:1 - K, M, or O B)
My Austin has low readings but still runs reasonably well. with no smoke from breather or exhaust.
Meanwhile I am sitting on a 1951 O type, which is where I wanted to be three or so years ago!

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Bedford K Model Cylinder Compression 06 Mar 2020 19:14 #207217

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OK, Compression Test results with Choke & Throttle both open & air cleaner removed.
dry wet
#1 115 110
#2 125 125
#3 50 50
#4 60 60
#5 80 85
#6 25 30

A big improvement but still issues with pots #3, #4, & #6.
All tappets are loose at the top of the stroke & all valves moving.
Looks like top overhaul & new rings is the go.
Any comments guys?
cheers
Pierre
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Bedford K Model Cylinder Compression 06 Mar 2020 21:18 #207218

  • PDU
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Ouch! But you won't be happy until it's done . . .
Any chance of a picture of the current state of the truck? :)
From both directions :S
Attachments:

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Bedford K Model Cylinder Compression 06 Mar 2020 21:38 #207219

  • Lang
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Pierre

Those compression figures say to me there is not much wrong with the rings. Oiling will only change compression if there is a ring or bore problem and your changes are insignificant. I would put big money on valves.

Last year, when I was doing my 1941 Chev Panel Van (very closely related engine to the Bedford) I had terrible compressions all below 50 and a couple at 10. Pulled the head off and the valves were worn away - amazing it still ran. I had the head rebuilt, checked the bores were not scored or displayed excessive wear ridges at the top, and stuck it back on.

Compressions all over 100 and ran like a dream.

Lang

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