Re: [Chrysler300] Technical Engine Question - Re: Heads

[Bill Huff <czbill@xxxxxxxxxx>]

Can we assume that the compression is good in all cylinders?

How low is the vacuum at idle?  How high does it 
go if the engine is revved and the throttle snapped shut?

Usually a low vacuum signal would signify a leak 
and the engine would run lean, not rich.  Perhaps 
the two problems are not related?

Retarded ignition timing can produce low vacuum 
and also poor performance.  Have you verified the 
timing mark as straight up and then timed the 
engine with the vacuum line disconnected?

What are the signs of the richness?  Carbon in 
the tailpipe?  Smoke out the exhaust?  Poor fuel mileage?

A pretty good check for a vacuum leak is 
squirting a combustible fluid around places where 
the leak might be,(with the engine running) such 
as carburetor flanges, intake manifold flanges, 
vacuum lines, etc.  If a leak is found, the 
engine will change RPM.  I have used starting 
fluid, carb cleaner, anything that will burn is 
good, probably the starting fluid is not a good 
choice because it is explosive as well.

I doubt the cylinder heads are warped so the 
intake surfaces can't seal with the intake gasket 
in place, but that the block surface will seal to 
the head.  Doesn't make sense.  One possibility 
is that the heads or block were milled, but the 
intake surface of the head was not cut 
correspondingly.  This could make the head's intake surface the wrong angle.

Long read, sorry.

Bill Huff



At 9/25/200908:14 PM, Ryan Hill wrote:

>Some of you may remember trying to troubleshoot 
>the poorly running (completely rebuilt) 383 in 
>my '65 300 sport over the past several years. 
>Unfortunately I haven't had the time required to 
>undertake removing the engine again and starting 
>from scratch, which is what I'm about to do over this winter......I hope.
>
>
>
>My question at this point is simple. Is there a 
>possibility that interchanging the heads from 
>one side to the other could cause the intake 
>manifold to sit in a slightly different position?
>
>
>
>When I tore the engine down, I used the carbon 
>outline on the head and intake machined 
>surfaces, around the runners, to establish where 
>the valley pan gasket had been seated. I 
>re-positioned the gasket and sprayed it with 
>yellow paint, leaving a perfect outline of where 
>the gasket port opening on both the heads and 
>the intake. I proceeded to die-grind all of the 
>ports in an effort to improve efficiency and flow.
>
>
>
>When I reassembled the engine, the new valley 
>pan gasket fit perfectly over the intake ports 
>of the manifold and the head when placed on the 
>mating surfaces seperately. However, I have no 
>way to tell for sure whether the ports are now 
>perfectly aligned. (other than plasti-gauge or 
>plastercine perhaps) The tollerances are very 
>close now that I've narrowed the runner walls, 
>the gasket is only about 3/16 of an inch wide 
>between runners as I recall, and so are the manifold and heads now.
>
>
>
>The engine runs, but runs rich. It has vacuum, 
>but not as much as it should. I have researched, 
>tested, replaced parts, tripple checked 
>everything, and run down every suggestion 
>everyone has offered me. If the runners on the 
>heads are not perfectly alligned with the 
>runners on the intake manifold, I suspect I 
>could have a leak. Hope my description is clear 
>and makes sense. Does anyone know how accurate 
>these castings are? Are the dowels aligning the head always exactly the same?
>
>
>
>Special thanks to anyone who has even read this far :)
>
>
>Ryan Hill
>
>
>
>_________________________________________________________________
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>
>
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