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Poly 318 Valve Adjustment
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   Forward Look Technical Discussions -> Engine, Exhaust, Fuel and IgnitionMessage format
 
Rob
Posted 2018-05-19 9:15 PM (#563660)
Subject: Poly 318 Valve Adjustment


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I have a '58 Plymouth with a poly 318, factory four barrel. I've had the car 13 years, engine was rebuilt before I got it, engine runs well, never had a problem with it. It started clattering like a loose lifter from the passenger side, so I pulled the valve covers to do a valve adjustment...

I'm finding that the exhaust valves are adjusted very tight, .005 cold. Specs call for .018 hot. The intakes seem to be close to specs.

Why would someone adjust the exhaust valves so tight?
Engine seems to run fine, is there any bad effect from having them so tight?

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BigBlockMopar
Posted 2018-05-20 5:26 AM (#563675 - in reply to #563660)
Subject: Re: Poly 318 Valve Adjustment



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I would wonder more where the valve noise would have come from if everything still appears 'good'.
How did you check the valve lash? Both valves at once on the same cylinder (that would be wrong btw)?
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ttotired
Posted 2018-05-20 6:52 PM (#563712 - in reply to #563660)
Subject: Re: Poly 318 Valve Adjustment



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Sudden valve noise from 1 lifter in a solid lifter engine = wiped cam lobe, bent push rod, adjuster come loose (need a new rocker) ect

Find the noisey one and compare valve geometry and parts with another cylinder

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Rob
Posted 2018-05-20 8:41 PM (#563720 - in reply to #563660)
Subject: RE: Poly 318 Valve Adjustment


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I checked valve lash by setting the engine to TDC, and then following that diagram given, checking one intake and one exhaust, then bumping the engine 90 degrees, repeating, etc.

I have not checked all the valves as of now, but all the exhaust I've checked so far are at .005 cold, which according to the specs is wrong. Why would the rebuilder of the engine set the exhaust so tight? Are there any bad effects from setting them so tight.

Agreed, there's probably one valve that's gotten way too loose or wiped cam lobe or more serious problem.

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ttotired
Posted 2018-05-20 9:56 PM (#563728 - in reply to #563660)
Subject: Re: Poly 318 Valve Adjustment



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Depends on wether it was done hot or cold, If adjusted cold, the gap will tighten once it gets hot

Bad thing that can happen if to tight is burnt valves, valve seat, but if that's happened, you loose compression.

Start the engine without rocker covers and listen for the noise

And yes, it makes a mess, but easy to do.

Valve lash checking should find it though, but also look for one adjuster thread being different to the rest, may be a clue

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57chizler
Posted 2018-05-21 1:53 PM (#563766 - in reply to #563720)
Subject: RE: Poly 318 Valve Adjustment



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Rob - 2018-05-20 5:41 PM

I checked valve lash by setting the engine to TDC, and then following that diagram given, checking one intake and one exhaust, then bumping the engine 90 degrees, repeating, etc.


Not really a good way to do it due to overlap. The adjustment procedure below is good for any engine with the same firing order.



(valvelash.jpg)



Attachments
----------------
Attachments valvelash.jpg (22KB - 14 downloads)
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BigBlockMopar
Posted 2018-05-21 3:54 PM (#563773 - in reply to #563660)
Subject: Re: Poly 318 Valve Adjustment



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I think that's the way he did it.
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swede59
Posted 2018-07-25 9:43 PM (#567187 - in reply to #563660)
Subject: Re: Poly 318 Valve Adjustment


Member

Posts: 8

does anyone know where i can get tappet adjusting screws and a timing bracket that mounts on the bottom of water pump on a 318 poly
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